Frustration!!!

[scottessex]

I was running the gyro today trying to get the jetting and the prop pitched.
found out the Dual EGT gauge doesn't work! I checked the probe with another single gauge, the dual gauge is junk.

The engine was running fine then all of a sudden slowed down and quit.
I fired it up again, same thing.

So I hooked up the elctric fuel pump in conjunction with the pulse pumps and it seemend to run fine, and then quit.

I even went back and installed larger jets and it ran for a few minutes and then quit. WTF!?? I even changed the plugs, same thing. Any help or suggestions would be appreciated!

[GyroRon]

wish I could help more. If it is the carbs then when it quits does the carb still have gas in the float chambers? If it does then it may be a igntion problem

[scottessex]

Yes the float bowls are full, but the engine starts right back up.???

[GyroRon]

your guess is as good as mine then. If it has fuel and spark it should run. 2 strokes are as simple as they come.....

Could it be a problem with a reed valve? or rotary valve?

Did you take off the exhaust and inspect the insides of the cylinders?

I am sure you already checked it, but what do the plugs look like after you kill the engine?

[Ron Marlett]

What throttle position was it at when it died? Fuel starvation will effect lower throttle settings first as the pilot fuel(0-1/4 throttle) is drawn from near the top of the float bowl and needle jet fuel(1/4-3/4 throttle) and main jet fuel(3/4-full throttle) is drawn thru the mainjet from low down in the bowl. If you can catch it when it dies(before it stops rotating) and open the throtle quickly it may re-fire. If it will do this, then you most likley have a fuel flow problem or the fuel level in the float bowl could be too low which could cause the same type of problem. Have you checked your float height?

[Friendly]

Scott, I would check to fuel lines closely to see if it is sucking air anywhere or cripping somewhere after start up. You probably have already done this. A coil will heat up and break down just like a fuel problem. The engine quits and then it cools off. You pull the rope and it starts backup because it has cooled down. Then it heats up again and breaks down again. This is the only clues I can give you at the moment. YOU have probably already checked your fuel for water or trash .fuel filters? Good luck, that is worst than eating out and forgetting your wallet at home. You could at least wash dishes. Maybe Mike Gaspard with jump in here. He does amazing stuff with just a few words.

[Friendly]

Ron made a good point as well, if it has any spark arresters in the exhaust they can carbon up. The ports do also right at the cylinder.

[barnstorm2]

Scott, I have no mechanical advice for you but I wanted to post that I empathize completely!!

[scottessex]

Hmm lets see here,
I rebuilt the engine, new reed valves, rings gaskets etc.
I did check the float height, one was high and dumping fuel out the vent when it shut down, I re set the height, It seems to be at any throttle position, I was suspecting the coil as well. It acts like it is running out of fuel, but when the throttle is brought back to idle it does not recover, It starts back up, but is hard to start.
Plugs looked wet. I hate to start trouble shooting with parts, I wish the EGT gauge was working as I might have more info.

Could the squeeze bulb be collapsing? It didn't look like it but I know some people have had problems with them.

I'm having Arrow Engine flashbacks!!!!!Oh NO!

[Friendly]

Scott , look at the bright side, if it is mechanical it is fixable.

[scottessex]

I won't let it kick my butt!

[Gordon Gibson]

Scott

What type of engine is this that's giving you trouble? It wouldn't be a Black Max would it?

Gordon Gibson

[GyroRon]

you may be over propped and are over jetted causing a overly rich mixture to foul the plugs? Or else I suspect a ignition problem

[Screw]

Screw-In

Sorry your having problems man. Get a good nights sleep on it, and I'm sure the problem and cure will come to you. The rows of Christmas trees and I have faith in you. :D

Screw-Out

[gyromike]

Thanks for the plug Mark, but I don't know much about the Rotax engines. I don't even know how the carbs/jets/needles work.

Without an EGT, it's hard to tell if it's too rich/too lean, but the plugs shouldn't be wet. At least I don't think so.

On my Mac, when I pull a plug, they're light brown/dark tan in color, and dry.

Based on what I have read, I would look at the fuel system.
Sounds like an excessively rich mixture (from the wet plugs).

[birdy]

Gees Mike,did you have to scare the crap outa me like that :eek: ,there should be a ban on close up shots of peoples faces on the forum.[especialy ugly ones.] ;) :D


Scott mate,put a few valves init and have it fire on every 4th stroke,problem solved.[solong as its still got ROTAX onit.] ;) :D

Sorry.................wasn't funny I know. :(

[mceagle]

Scott, it is obviously not a Rotax because they do not have a reed valve. What engine is it and does it have dual ignition?

[scottessex]

Ooops sorry, It is a 1989 Arctic cat (suzuki) 530 liquid cooled 2 cyl. With Mikuni VM-38 carbs and single ignition. Rotax A box 2:00-1 ratio, warp drive 3 blade 60 inch.
one facet electric pump and 2 mikuni pulse pumps.

[Brent_Brown]

Stop and get the EGT gauge working before you damage the motor. bypass the bulb.

[scottessex]

Roger, Brent, I am stopping by Acft Spruce after work today to get a new gauge.


Just another thing I thought of, The original engine had dual tuned pipes, I am running a single rotax style exhaust. I may be loading up the engine untill it messes up the mixture?

[gyromike]

Birdy,

If you think that's bad, you oughta hear me sing!
Sounds like a bunch of cats gargling.
Being a gyro pilot is my only redeeming quality. :)

Scott,

I had forgotten that you were using the Arctic Cat.
Shouldn't matter, since I know even less about them than the Rotax!

I agree with Brent, get the EGT working and take it from there.
It shouldn't be too hard to figure out. It's just another engine, right? :D

The exhaust may have something to do with it. Exhausts/tuned pipes are designed according to cylinder displacement, port timing, exhaust port area, RPM, etc. The Suzuki is probably different enough from the Rotax exhaust that the jetting will need to be changed.

I wish I had some definite answers for you. I'm curious to see how it will perform.

[Ron Marlett]

Scott
If it has VM carbs on it then it most likley has a bowl drain screw and drain/overflow hosebarbed port at the bottom of each floatbowl right? If so, a good way to put the question of fuel level/starvation to bed is to take a short piece of clear tube and attach it to the bowl drain/overflow pipe at the bottom of the bowl. Route the tube up alongside the carb and attach it in place there. Open the drainscrew at the bottom of the bowl and the fuel will find it's own level in the clear tube and you can use that to determine actual fuel level in the bowl(much better than just setting the float height). On the VM series of carbs, Fuel height should be around 1-2 MM below the carb body(point where floatbowl meets the main carb body). If this level is dropping while running, then you have a fuel feed problem.

[Gordon Gibson]

Scott

I have owned not one but two of those very engines. My initial experiences with it (them) were very bad. But after I did one or two certain things, I got them going very well. As far as I know they are both going still, or at least capable of running because a guy bought one off me and had several years of good running on his Dom before wrecking the gyro due to a totally unrelated incident (unrelated to the engine).

If you want to know more let me know. ;)

Thanks, Gordon Gibson.

[birdy]

At least I wouldn't be able to SEE you if you sang Mike. :D

Scott,Mike reminded me of sumth'n,when I was useing a 462 Rotax it started to gradualy loose top rpms,and I got the exhaust/muffler acid bathed.This cleaned and amaz'n amount of crap out ofit,and did the trick.All that crap was slowly choke'n it. :mad:

[Brent_Brown]

Scott I don't think it is the pipe unless it is blocked somehow. That bulb is my guess I don't use them just for that type of thing I use the push pull type.

[scottessex]

Well boys and girls, I think I figured this bad boy out. I took off a couple of hours early today because the weather was fairly nice. I went by aircraft spruce and got a new gauge. I messed with the gyro for about 2 hours, re jetting, running it with the pipe off, and on, repitched the prop again, bla bla bla,
It looks like I am really close to getting it dialed in. I was able to let it run and it did not die. I was able to see 6500 RPM for a few seconds, then it started to sputter so I backed off the throttle and it kept running. I ended up so far with 320 jets, I took 1 1/2 degrees out of the prop. As far as I can tell the fuel squeeze bulb is collapsing over 5000 rpm and shutting off the fuel. When I run the electric pump it causes the engine to burble, like there is too much fuel pressure and it is overcoming the needle/ seat. I also dropped the main jet needles by raising the clip to the top position instead of in the middle, starts alot easier too.

Temps were 170 water temp and 1000 EGT@ 6000.

I am getting close.

Much better day today. thanks for all the help and suggestions. :) :)

[Brent_Brown]

By pass the squeeze bulb. and it should run.

[Screw]

Screw-In

That's Great! What color are we gonna paint it? :D

Screw-Out

[ben]

way to go scott make that cat purrrrrrrrrrrrrrrr lol

[scottessex]

Thanks Brent, That is exactly what I am going to do.

And John, I think Blue metal flake on the pod and tail.
Not sure on the frame color yet.

[scottessex]

Well I got a change to bypass the fuel bulb and got a chance to run it between rain showers. It ran great, other than being a little rich at idle (2000 rpm) I still have some tuning to do, but it seems to be going in the right direction.

[gyrodude]

Scott, I ran one Mikuni dual port pump on my Suzuki. Maybe the three pumps are too much fuel pressure.

[Rick Whittridge]

Scott remember the fuel is your friend.Put the new EGT`S on it & tune from your temp readings.You can install a small inline fuel pressure gauge on the fuel line to ck your pressure at the carbs.

Fat is good -Lean is BAD (EGT tells the REAL STORY) Don`t guess!

[scottessex]

Gary, I was wondering the same thing. about the fuel pressure.

And Rick, Yes I fixed the gauge, (bought a new one) and I am running 1100 degrees EGT@ 6500 rpm @170 degree water temp.

[kieran12]

clean the idle jet -

take down the bowl and its easy to see and remove-

[Brent_Brown]

Sounds like your ready for paint. I hope to get my motor soon getting the need to fly now.

[Doug Riley]

Mike Gaspard, was that SINGING? I thought you were SNORING there at B-Days. My mistake.

[gyromike]

Doug,

My singing sounds like my snoring, just a higher pitch. :D