Anything new on Yamaha conversions?

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I had seriously thought that the weber engine would become the one of choice, but it was available in only one snowmobile and now the Yamaha engine is available in 2 brands of snowmobiles and the weber is no longer available, the Yamaha seems to be winning by default.

the weber engine was dropped by polalaris because they they could make more money using their own in house 2 stroke engine
The weber engine is still alive and well in cars and you name it
Feel like im picked on!
 

Trackwelder

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Maybe it is just where I am at, but the only use of the Weber Motor I have seen was the Tigershark used to be built 70 miles north of me and the Polaris snowmobile, and like I said I was hoping it would become more popular so I would have a source of the engines.
 

NoWingsAttached

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Horsepower and torque have a well defined relationship Greg.

Horsepower = Torque X RPM divided by 5252.

This relationship appears to me to be missing on your posted dyno chart.

8,000 RPM X 74 foot pounds of torque divided by 5252 = 113 horsepower even though your chart shows 126 horsepower.

10.200 RPM X 68 foot pounds of torque divided by 5252 is 133 horsepower even though your chart shows 150 horsepower.

It appears to me that your chart is journalistic fantasy that often arises when the published numbers can’t be achieved.

Here is the data sheet used to produce the chart. The first torque column numbers were recorded before tuning, engine straight out of a new sled, not adjusted for atmosphere.

In the next column, if one does nothing more than take a brand new YG4 out of the crate and adjust for MSL the numbers work out to 140 HP sea level.

It was reported that following initial testing tuning improvements were made and numbers realized are indicated, resulting in 150HP at sea level corrected. These numbers are extrapolated.

If there are any other known sources for dynamometer data for these engines, please share them. Until then this is all we have, and anything else is pure conjecture and a lot of hot air.
 

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Vance

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Here is the data sheet used to produce the chart. The first torque column numbers were recorded before tuning, engine straight out of a new sled, not adjusted for atmosphere.

In the next column, if one does nothing more than take a brand new YG4 out of the crate and adjust for MSL the numbers work out to 140 HP sea level.

It was reported that following initial testing tuning improvements were made and numbers realized are indicated, resulting in 150HP at sea level corrected. These numbers are extrapolated.

If there are any other known sources for dynamometer data for these engines, please share them. Until then this is all we have, and anything else is pure conjecture and a lot of hot air.

My point from the beginning is your numbers are pure conjecture and hot air.

I have not changed that opinion.

I have run out of ways to explain it to you.

You do not have a new engine.

You have not tuned your engine for maximum output.

You have no way to know how much the numbers you have are exaggerated.

We are not racing gyroplanes.

In my opinion quoting horsepower numbers to prove some point is pointless.
 

Lee Scatt

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It matters not if new , tuned, tweaked, blessed by the gods, or whatever; torque and hp will cross at 5250 rpm no matter what you do to your engine. Your second chart shows this, your first graph is baloney.
 

NoWingsAttached

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My point from the beginning is your numbers are pure conjecture and hot air.

I have not changed that opinion.

I have run out of ways to explain it to you.

You do not have a new engine.

You have not tuned your engine for maximum output.

You have no way to know how much the numbers you have are exaggerated.

We are not racing gyroplanes.

In my opinion quoting horsepower numbers to prove some point is pointless.

Staying precisely on topic, unlike yourself, I remind you that we are discussing a power and prop speed chart (for various gear ratios), which I provided you and others as a reference tool at a presentation I gave introducing the YG4 for aircraft conversion use at Mentone 2012 - and have also posted on this thread multiple times, most recently just the other day to demonstrate output after reading someone else's unsolicited, intentionally derogatory comments.

My point from the beginning is your numbers are pure conjecture and hot air...I have not changed that opinion...In my opinion...
And my point is that the numbers are not conjecture and hot air, the numbers are hard, cold, factual data provided by a third-party dyno shop in Vermont who has no dog in this race, no bone of contention such as yourself - a man bent on maligning me every opportunity you get for unknown personal reasons.

I have not changed that opinion...In my opinion...
I dont' expect you to. You just continue to harangue, belittle, condescend and otherwise abuse my every post, wandering off topic at will, then pretend to be the victim when I insinuate you may be acting like a putz.

I have run out of ways to explain it to you...In my opinion...I have not changed that opinion...
All you need to do is provide factual data to support your arguments. Until then your opinions are nothing more than empty gas balloons.

I on the other hand have posted the dyno sheet provided by the professional shop for this type engine, the YG4. You can lead a horse to water, Vance...but it won't make a thorough bred out of an ass.

You do not have a new engine...I have not changed that opinion...In my opinion...

You have not tuned your engine for maximum output...In my opinion...I have not changed that opinion...

Since when are we discussing my own personal single example of the YG4? This is typical of you in every discussion to wander off into the woods in a futile attempt to divert attention from the heart of the matter: the fact that you have nothing of substance to offer when you are confronted with the facts and details that don't suit your whims. I do not find it reasonable nor necessary to have every single Yamaha 4 engine dyno tested under every possible condition just to address outrageous attacks and silly comments such as yours which have absolutely no bearing in fact on the matter in the least.

I have not changed that opinion...In my opinion...You have no way to know how much the numbers you have are exaggerated

So now you resort to attacking the third party dyno shop that provided the data, calling them liars. They have no reason to interfere with the results, they are a third party with no interest one way or the other; no reason in the least to shade or change the information. So because your argument and your abusive attacks on me are totally without substance you are now continuing this abuse and offense because to admit that a contrary truth is before your very eyes is something that you - and all small-minded egotists - find themselves unwilling to do.

Petty attack is now your choice of options left to further your whimpering drivel? Your opinions are, in the end, seemingly the product of an over-inflated ego of one who insists he is the end-all just because he built and raced bikes back in the day. If that is the yardstick you wish to use, then let me say that along such line of reasoning I will best you as I personally built and raced a ~500 hp (no dyno data available, just race results and video evidence as I paced other known quantities on the circuits) GT1 Porsche and won half a dozen races over a period spanning three years, beating factory teams and privateers who stood on the podium of Lemans the very same season I beat their pants off at tracks including Road America and Road Atlanta. Does that make my power and prop speed chart more palatable to you? I don't think so, but you are hardly the only one here who knows how to make things go fast and drive to victory lane.

So you raced bikes. Yawn. Your use of the past to bolster your opinion is fine, but in the final analysis your opinion it is still nothing more than unsupported hot air. Facts is facts, and no one is lying or exaggerating claims. You yourself ran a dyno in a shop at one point, supposedly, so you should know that the equipment is accurate to within a certain parameter. The work presented here was done by a neutral third-party with no dog in this race, no reason to inflate or deflate anything in the least. Your continued nonsensical dialogue, above, speaks volumes to your acute intent to malign me for no other reason than personal hatred for reasons unknown to me now or forever. I try - and you are certainly trying if anyone is - to put my personal feelings aside discuss the facts as a professional, not some egotist living in his past glory days of racing as you are so fond of doing as evidenced yet again in this thread ad-nauseum. It is tiring, Vance.

The raw fact sheet was provided here because you don't want to agree with the graphic display. The fact sheet has been provided for all to review. It is a moot point, senseless for you to continue your over-stated opinions and baseless claims that the data is incorrect. It is data. No one is lying, Vance. No one has overstated anything. You, on the other hand, have as of yet provided any of us anything whatsoever in the way of facts - instead resorting to bullying, meaningless attacks which you have not shown you can ever back up with even a smidgeon of real-world data.

I have not changed that opinion...In my opinion...We are not racing gyrocopters
That is pretty strange, as I don't recall anyone ever discussing racing gyrocopters anywhere on any thread in the entire forum, let alone this most recent bullying attack you so obviously continue to pursue without reason nor cause, and certainly without factual support for your opinions.

I have not changed that opinion...In my opinion quoting horsepower numbers to prove some point is pointless.
And your alternative to this concept - which is otherwise totally, universally and virtually accepted by every other mechanic, driver, pilot, and crew member in the world - is what? Am I to understand that according to Vance Breeze everyone in the world is crazy with the exception that Vance Breeze is sane? What, pray tell, is the new ruler by which we shall all discuss engine performance going forward, Vance Breeze's opinions?

I welcome any and all evidence which goes toward proving the info I have provided here is wrong, but I don't see the point in baseless, useless, nonsensical personal opinions from people with an obvious grudge and an axe to grind. But go ahead, keep on bullying me. I can take it, and I will continue to address your idiotic nonsense, and will freely acknowledge when I am wrong - something that my detractors obviously never seem able to man-up and do.

Again, I state Vance's own words from 2013 - that "in his opinion" as he observed my flight, the YG4 on my gyro was putting out 130-135 HP, as I was turning 8700 RPMs, yet now this month he has decided that's all there is to this engine, that my data charts and sheets are lies, it is not 140-150HP and never will be, because dyno shops lie to their customers, and only he knows the capabilities and true performance of an engine he has never worked with, never flown, and has never tested nor laid hands on first-hand test data.

And nothing will change that Vance Breeze opinion, and all of us talking about HP as a useful apples-to-apples comparison tool for engine performance is pointless.

I don't think so.

What would be nice is if we could gather some more factual information from more shops who have experience testing, and working on and with this engine. Until then, opinion are pointless, not HP statements.
 

Vance

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It is too bad you take things so personally Greg,

It is too bad you take things so personally Greg,

Staying precisely on topic, unlike yourself, I remind you that we are discussing a power and prop speed chart (for various gear ratios), which I provided you and others as a reference tool at a presentation I gave introducing the YG4 for aircraft conversion use at Mentone 2012 - and have also posted on this thread multiple times, most recently just the other day to demonstrate output after reading someone else's unsolicited, intentionally derogatory comments.

And my point is that the numbers are not conjecture and hot air, the numbers are hard, cold, factual data provided by a third-party dyno shop in Vermont who has no dog in this race, no bone of contention such as yourself - a man bent on maligning me every opportunity you get for unknown personal reasons.

I dont' expect you to. You just continue to harangue, belittle, condescend and otherwise abuse my every post, wandering off topic at will, then pretend to be the victim when I insinuate you may be acting like a putz.


All you need to do is provide factual data to support your arguments. Until then your opinions are nothing more than empty gas balloons.

I on the other hand have posted the dyno sheet provided by the professional shop for this type engine, the YG4. You can lead a horse to water, Vance...but it won't make a thorough bred out of an ass.



Since when are we discussing my own personal single example of the YG4? This is typical of you in every discussion to wander off into the woods in a futile attempt to divert attention from the heart of the matter: the fact that you have nothing of substance to offer when you are confronted with the facts and details that don't suit your whims. I do not find it reasonable nor necessary to have every single Yamaha 4 engine dyno tested under every possible condition just to address outrageous attacks and silly comments such as yours which have absolutely no bearing in fact on the matter in the least.



So now you resort to attacking the third party dyno shop that provided the data, calling them liars. They have no reason to interfere with the results, they are a third party with no interest one way or the other; no reason in the least to shade or change the information. So because your argument and your abusive attacks on me are totally without substance you are now continuing this abuse and offense because to admit that a contrary truth is before your very eyes is something that you - and all small-minded egotists - find themselves unwilling to do.

Petty attack is now your choice of options left to further your whimpering drivel? Your opinions are, in the end, seemingly the product of an over-inflated ego of one who insists he is the end-all just because he built and raced bikes back in the day. If that is the yardstick you wish to use, then let me say that along such line of reasoning I will best you as I personally built and raced a ~500 hp (no dyno data available, just race results and video evidence as I paced other known quantities on the circuits) GT1 Porsche and won half a dozen races over a period spanning three years, beating factory teams and privateers who stood on the podium of Lemans the very same season I beat their pants off at tracks including Road America and Road Atlanta. Does that make my power and prop speed chart more palatable to you? I don't think so, but you are hardly the only one here who knows how to make things go fast and drive to victory lane.

So you raced bikes. Yawn. Your use of the past to bolster your opinion is fine, but in the final analysis your opinion it is still nothing more than unsupported hot air. Facts is facts, and no one is lying or exaggerating claims. You yourself ran a dyno in a shop at one point, supposedly, so you should know that the equipment is accurate to within a certain parameter. The work presented here was done by a neutral third-party with no dog in this race, no reason to inflate or deflate anything in the least. Your continued nonsensical dialogue, above, speaks volumes to your acute intent to malign me for no other reason than personal hatred for reasons unknown to me now or forever. I try - and you are certainly trying if anyone is - to put my personal feelings aside discuss the facts as a professional, not some egotist living in his past glory days of racing as you are so fond of doing as evidenced yet again in this thread ad-nauseum. It is tiring, Vance.

The raw fact sheet was provided here because you don't want to agree with the graphic display. The fact sheet has been provided for all to review. It is a moot point, senseless for you to continue your over-stated opinions and baseless claims that the data is incorrect. It is data. No one is lying, Vance. No one has overstated anything. You, on the other hand, have as of yet provided any of us anything whatsoever in the way of facts - instead resorting to bullying, meaningless attacks which you have not shown you can ever back up with even a smidgeon of real-world data.

That is pretty strange, as I don't recall anyone ever discussing racing gyrocopters anywhere on any thread in the entire forum, let alone this most recent bullying attack you so obviously continue to pursue without reason nor cause, and certainly without factual support for your opinions.


And your alternative to this concept - which is otherwise totally, universally and virtually accepted by every other mechanic, driver, pilot, and crew member in the world - is what? Am I to understand that according to Vance Breeze everyone in the world is crazy with the exception that Vance Breeze is sane? What, pray tell, is the new ruler by which we shall all discuss engine performance going forward, Vance Breeze's opinions?

I welcome any and all evidence which goes toward proving the info I have provided here is wrong, but I don't see the point in baseless, useless, nonsensical personal opinions from people with an obvious grudge and an axe to grind. But go ahead, keep on bullying me. I can take it, and I will continue to address your idiotic nonsense, and will freely acknowledge when I am wrong - something that my detractors obviously never seem able to man-up and do.

Again, I state Vance's own words from 2013 - that "in his opinion" as he observed my flight, the YG4 on my gyro was putting out 130-135 HP, as I was turning 8700 RPMs, yet now this month he has decided that's all there is to this engine, that my data charts and sheets are lies, it is not 140-150HP and never will be, because dyno shops lie to their customers, and only he knows the capabilities and true performance of an engine he has never worked with, never flown, and has never tested nor laid hands on first-hand test data.

And nothing will change that Vance Breeze opinion, and all of us talking about HP as a useful apples-to-apples comparison tool for engine performance is pointless.

I don't think so.

What would be nice is if we could gather some more factual information from more shops who have experience testing, and working on and with this engine. Until then, opinion are pointless, not HP statements.

You keep bragging about your 150 horsepower engine and in my opinion you have never flown with 150 horsepower.

You post a dyno chart that is not related to the numbers you started with.

If your engine actually made 150 horsepower in my estimation at an all up weight of 950 pounds and what I estimate your drag you should be able to sustain a climb of 1,700 feet per minute and fly level at 100kts.

When I suggested you were not making more than 130 to 135 horsepower based on your climb out I was trying to explain the concept of the engine making less horsepower at the lower rpm you were operating at. At the time you appeared to me to reject that concept. I had not done the calculations because I didn’t have enough information. In my opinion based on my observation of your performance you were making less than 80 horsepower on climb out. The precise numbers were not important. At the time you were bragging about having the most powerful two place gyroplane.

You should be proud of your accomplishments. You have built a gyroplane that flies with a Yamaha engine.

Fly it more and if it doesn’t break you can be proud of that too.

Your efforts to design and manufacture a PSRU for the Yamaha engine are laudable. In my experience there is a much longer road from proof of concept to having a viable product to sell then you appear to recognize.

In my opinion pretending that dyno numbers are factual because you can only find one dyno chart is not reasonable. Using the highest numbers on the chart that were achieved after tuning is also not reasonable when you haven’t done the same tuning.

Dyno tested horsepower can be a wonderful tool for all kinds of things. Unfortunately it has been so abused that many dyno operators use a BS correction factor relegating most published horsepower numbers to bar talk.

In my experience only those with very little dynamometer experience imagine that published dyno numbers are accurate.

Doug Schwochert’s experience with factory numbers being 15% to 20% higher than actual testing is aligned with mine. I don’t recall ever getting factory published numbers on a certified dynamometer. It sets off my BS detector when I see dyno numbers that are aligned with the factory claims.

I so not anticipate doing further research on Yamaha snowmobile engines.

I went to several Yamaha snowmobile website and they didn’t even quote horsepower numbers.

That might be a good approach for you too Greg if you want people to take you seriously.
 

Zro1

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Looking for Gearbox for 3cyl. Yamaha

Looking for Gearbox for 3cyl. Yamaha

Hello folks.
I recently built a "Dominator" style gyro and put a Yamaha 3 Cylinder Snowmobile engine (120hp), however, the gearbox that is on it is absolute garbage. It keeps tearing up the drive belts.
Ive heard that there are conversion kits available to attach a Rotax C gearbox to this engine.
If anyone out there has any information, please let me know.

Engine: Yamaha 973cc, 3 cylinder, appx. 120hp, 4 stroke.
 

Vance

Gyroplane CFI
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Givens Predator
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Hello folks.
I recently built a "Dominator" style gyro and put a Yamaha 3 Cylinder Snowmobile engine (120hp), however, the gearbox that is on it is absolute garbage. It keeps tearing up the drive belts.
Ive heard that there are conversion kits available to attach a Rotax C gearbox to this engine.
If anyone out there has any information, please let me know.

Engine: Yamaha 973cc, 3 cylinder, appx. 120hp, 4 stroke.

Contact Todd Rieck AKA Racer on the Forum.

He has been managing conversions using the Rotax gearbox for a while with considerable success.

Send him a private message or email.
 

NoWingsAttached

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Hello folks.
I recently built a "Dominator" style gyro and put a Yamaha 3 Cylinder Snowmobile engine (120hp), however, the gearbox that is on it is absolute garbage. It keeps tearing up the drive belts.
Ive heard that there are conversion kits available to attach a Rotax C gearbox to this engine.
If anyone out there has any information, please let me know.

Engine: Yamaha 973cc, 3 cylinder, appx. 120hp, 4 stroke.

I'm confused> Gearbox with belts??? Do you mean a PSRU that is a cog belt drive?

Are you in the (Georgia) Peachstate Rotorcraft Club?

Send an Email to the address below.
 

NoWingsAttached

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My Diamond Drive sprocket arrived this week.

I first ordered this to be cut in January 2014.

When it never arrived I found the shop in Michigan that makes the only gear hob for sprockets to match this particular chain I am using. Bought the tool, sent it to a gear shop out in the plains, and that guy turned an aluminum piece to test match to the chain. When we verified that the hob was correct, we then cut this piece out of 4140 steel and had the finished gear heat treated to Rockwell 60-64. I mean, this is HARD!

I designed it so it can be easily removed from the taper shaft with a simple off-the-shelf bolt. No gear pullers, no beating yourself up to remove it for servicing. Just put your 1/2" pneumatic impact w-r-r-rench to the task and this thing will pull right off of the Yamaha shaft, no prob.

And you DO NOT GRIND THE YG4 SHAFT LENGTH DOWN ~30% to jury rig the PSRU to the engine. You leave it like the Yamaha engineers wanted it in the first place. Not shortened, not compromised in any way, shape or form.
 

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NoWingsAttached

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It rained in Savannah every day for the second half of this past summer. It has been miserable. Every day when I was getting ready to fly, it started to frikkin rain. Or the grass strip was still so soaked I didn't care to take off. It has taken forever to get 20 hours flown off this PSRU, but I finally finished it this Saturday.

The test has been outstanding. Kinda like the Wicked, right outta the gate. I can't say flawless, like that, but for a prototype, and something that is sooo different from anything thing else on the market, anywhere in the entire world, then this has been an astounding success by anyone's measuring stick.

This chain drive PSRU uses no clutch for soft starts. That's the whole idea. Make something that doesn't need an expensive, large, heavy, maintenance-intensive, single-point-of-failure clutch in the power plant.

Done deal, folks.

And when I install the new Diamond Drive sprocket, I am going to also install a new prototype chain tensioning system that is designed to absorb the start up shock pulsations and provide a smoother start.
 

teal

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[

"DO NOT GRIND THE YG4 SHAFT LENGTH DOWN ~30% to jury rig the PSRU to the engine".

Did someone come up a way to jury rig a gearbox to this engine by grinding 30% off the shaft? Sorry I haven't been to active with the rotary wing forum in a while, just curious if there were some new adapter out there.
 

Jason O

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Dont take it personally

Dont take it personally

If I was you I wouldn't bother engaging Mr Mills. He is all over the map with his assumptions and things he posts. He is throwing out marketing sh** so fast and hard that he is now used to the smell and doesn't even recognize it. I was curious how many adapters you have shipped and how many different aircraft are flying with them?

Regards
Jason



[

"DO NOT GRIND THE YG4 SHAFT LENGTH DOWN ~30% to jury rig the PSRU to the engine".

Did someone come up a way to jury rig a gearbox to this engine by grinding 30% off the shaft? Sorry I haven't been to active with the rotary wing forum in a while, just curious if there were some new adapter out there.
 

teal

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Thanks for the Heads up. I seriously thought there maybe another new adapter out there where someone was "jury rigging" a gearbox on a engine. I welcome any and all constructive criticism on my adapter especially were I may have a weakness in the design that I have not accounted for or recognized but down right trash talk without basis I will not engage in. I wish anybody luck and will assist if I can if they come up with a design after all if there is a better design out there it will benefit us all. I would be happy buying someone else's adapter if it were better. I have sold 6 adapters 4 of which are flying or can fly based on the engine conversion. Thanks again.
 

NoWingsAttached

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[

"DO NOT GRIND THE YG4 SHAFT LENGTH DOWN ~30% to jury rig the PSRU to the engine".

Did someone come up a way to jury rig a gearbox to this engine by grinding 30% off the shaft? Sorry I haven't been to active with the rotary wing forum in a while, just curious if there were some new adapter out there.


Teal:

I had shortened two YG4 shafts after reading your thread and watching your Youtube installation video showing you doing this to your engines to fit a C Box onto a YG4 with your adapter. I was also aware that Todd Reick's kits require this as well. I figured if it was working for you, it would be OK for me, as I needed to shorten the shaft in order to jury rig a different test gear [after I had already fabricated the PSRU to be built with what is shown above] until I could get the real gear made. I figured there would be no harm in it.

Wrong.

I mentioned elsewhere that I pulled a gear off of a YG4 shaft after 150 hours of operation and found it was scored, indicating that the gear had slipped on the shaft. Manufacturer's spec for torqueing a brand new shaft bolt is 90 PF, and second use of the same bolt is 45 PF. I followed that guideline, definitely. I use a 1/2" impact wrench, and it puts a good 75-90 PF to a tire lug nut at 90-100 PSI in the hose.

This shaft had not even been compromised by shortening it ~5/16" (as you and Todd have required to fit your adapters).

Todd Reick's kit is only 120-130 HP. There may not be any problems in the lower power range, so perhaps your kits will be fine so long as you never run the engine past 135 HP (anything much past 8700 RPM)

I have hit 140 HP with the Arrow PSRU - the gear that got scored inside the hub - and believe that is most likely when the gear twisted on the shaft.

In my experience I have come to determine that anyone intending to use the full power of a stock 140-150HP Yamaha is asking for trouble if they grind off the end of the taper shaft, and thus reduce the friction mating surface significantly - and anything more than 1/8" is definitely significant.

On another note: If you are using Teal's adapter, be sure to re-use the little 1" square, 3-vane, flow vent found in the stock case cover instead of discarding it when you swap out and install your adapter, and you will find that no oil will bubble up through the breather on steep climbs. That's what it's there for.
 
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teal

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buckeye
You must be confused, The part of the shaft that gets ground of is extending out past the Rotax flywheel. I don't put a gear on that shaft. Maybe the gear you had a problem with slipping had a slightly different taper?? On my adapter the entire length of the Taper is in contact with the with the flywheel. Just as Rotax ment it to be. I have ran my engine on the test stand to 10,000 RPM for extended periods of time with Zero slippage. Also I would be cautious about using a impact to get proper torque. I work in a industry where proper torque is very important ( Nuclear Power generation) and we only use a calibrated impact in one place to get fasteners torqued and we try stay away from using it because of the inaccuracies. Please do not put information out about my adapter that you do not know as facts. If you know of someone or you personally had a experience with my adapters slipping then far enough lets talk and tell the world about it but don't hypothesis about your so called "experience" on what you thank could happen. In the beginning you called me about buying some of my adapters if I could modify them for your chain drive when I told to many things would have to be changed you started down a path of talking bad about my adapters and I don't understand why. If I could of helped you I would have I thought we had a good relationship still. If you had a functioning adapter on the market when I started my research I would have just bought one of yours. Please in the future if you have a question about my kit just ask before you post negative assumptions and I will do the same about your product. Teal
 

Jason O

Junior Member
Joined
Jun 13, 2007
Messages
540
Location
Portland
GT Mills,

I know you will never get this but here it goes. The only thing similar between you installation and others is the engine. Everything else is different. How do you know that your scoring is from the shortened shaft? If the shaft was full length, would it have still happened? Did you test it with a long shaft? What kind of torsional dampening is in your system? Could the scores have been caused by a resonance (start up shut down)? In my experience, if a shaft is scored it most likely encountered a one time event. If the event is on going, it will fret. Maybe you did all this testing, my guess is you did not. Instead of considering and testing to find out why the shaft slipped, you made a HUGE assumption and then used it to try to put down another product. Your assumptions of failure are not based on anything but your desire to promote you product. Your marketing smacks of mini 500 all over. There have been many times people have tried to point this out but you just don't hear it.

FWIW
Jason

Teal:

I had shortened two YG4 shafts after reading your thread and watching your Youtube installation video showing you doing this to your engines to fit a C Box onto a YG4 with your adapter. I was also aware that Todd Reick's kits require this as well. I figured if it was working for you, it would be OK for me, as I needed to shorten the shaft in order to jury rig a different test gear [after I had already fabricated the PSRU to be built with what is shown above] until I could get the real gear made. I figured there would be no harm in it.

Wrong.

I mentioned elsewhere that I pulled a gear off of a YG4 shaft after 150 hours of operation and found it was scored, indicating that the gear had slipped on the shaft. Manufacturer's spec for torqueing a brand new shaft bolt is 90 PF, and second use of the same bolt is 45 PF. I followed that guideline, definitely. I use a 1/2" impact wrench, and it puts a good 75-90 PF to a tire lug nut at 90-100 PSI in the hose.

This shaft had not even been compromised by shortening it ~5/16" (as you and Todd have required to fit your adapters).

Todd Reick's kit is only 120-130 HP. There may not be any problems in the lower power range, so perhaps your kits will be fine so long as you never run the engine past 135 HP (anything much past 8700 RPM)

I have hit 140 HP with the Arrow PSRU - the gear that got scored inside the hub - and believe that is most likely when the gear twisted on the shaft.

In my experience I have come to determine that anyone intending to use the full power of a stock 140-150HP Yamaha is asking for trouble if they grind off the end of the taper shaft, and thus reduce the friction mating surface significantly - and anything more than 1/8" is definitely significant.

On another note: If you are using Teal's adapter, be sure to re-use the little 1" square, 3-vane, flow vent found in the stock case cover instead of discarding it when you swap out and install your adapter, and you will find that no oil will bubble up through the breather on steep climbs. That's what it's there for.
 

NoWingsAttached

Unobtainium Member
Joined
May 21, 2006
Messages
4,871
Location
Columbia, SC
Aircraft
Air Command Tandem w/ Arrow 100hp; GyroBee w/ Hirth 65hp; Air Command Tandem w/ Yamaha 150hp
Total Flight Time
>350
GT Mills,

I know you will never get this but here it goes. The only thing similar between you installation and others is the engine. Everything else is different. How do you know that your scoring is from the shortened shaft? If the shaft was full length, would it have still happened? Did you test it with a long shaft? What kind of torsional dampening is in your system? Could the scores have been caused by a resonance (start up shut down)? In my experience, if a shaft is scored it most likely encountered a one time event. If the event is on going, it will fret. Maybe you did all this testing, my guess is you did not. Instead of considering and testing to find out why the shaft slipped, you made a HUGE assumption and then used it to try to put down another product. Your assumptions of failure are not based on anything but your desire to promote you product. Your marketing smacks of mini 500 all over. There have been many times people have tried to point this out but you just don't hear it.

FWIW
Jason


Jason:


1. The shaft on the engine discussed was FULL LENGTH

2. The drive gear was a perfect fit on the 1:10 taper shaft

3. The drive gear was torqued to spec

4. The gear slipped on the full length shaft

5. By simple math, shortening the shaft 25% (~5/16") makes this type of slipping more likely to happen on any installation, by any builder. (Recall I said I cut down my own shaft on the prototype Silent Drive installation, and was happily reporting here that I had finally received the correct drive gear which would not require cutting the shaft down.)

6. Resonance has nothing to do with it. Unlike the YG3, which delivers crankshaft harmonics to the PSRU coupling, the YG4 engineers at Yamaha spent two full years developing the internal countershaft damper (I have already posted photos of it elsewhere on this thread) which arrests all engine harmonics before they can reach the taper coupling we are talking about. Additionally, the Arrow PSRU has an internal one-way clutch which arrests constructive wave formation of prop harmonic vibration.


One has to wonder: If I discovered cracks on a particular rotor blade - which you also happened to be flying on your gyrocopter - and I reported it here, would you be responding to my posts in the same manner as you have above?
 
Last edited:

JEFF TIPTON

Senior Member
Joined
Feb 17, 2007
Messages
3,029
Location
DICKSON, TN
Aircraft
Grumman AA5
Total Flight Time
1350
Greg; trying to learn and not argumative.

Assuming the installation of a gear or say RK400 clutch and assuming both items are a fixed diameter, taper and length, which to me suggests the same clamping area, what would the difference be as it relates to the length of the shaft?
 
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