Help with a Kawasaki

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samyguy

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Sep 19, 2011
Messages
167
Location
74FL Monticello FL.
Have Kawasaki 440A in a Dream Classic strut.
I was doing ground testing, the jetting was spot on, by EGT/CHT gauges.
Was starting hop testing, Getting 6250rpm ground on run up.
Went to go an died off would not make more than 2850rpm.
Hmm I get new plugs again, so I push back to hanger, and install plugs,
and try it while still hot, starts up but still won't more than 2850rpm.
Wait till next morning, fires right up, runs like a champ! 6250 rpm
I'm thinking maybe a coil opened up when it got run long enough to get hot.

I don't have a manual, so anybody know these motors ??
any help would be great thanks
 

delta

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May 26, 2011
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Location
Brookside Utah
Check your fuel delivery too, and make sure the tank's vented. You can check your coils (cold then hot) with an ohm meter for changes. A bad condenser will act like that too if you have points ignition. Think snowmobile for parts.
 

TFF

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Apr 28, 2010
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Memphis, TN
Start checking fuel system. Fuel lines, carb, anything and everything. It might not be as clean as you want. Age of diaphragms? Make sure the ignition isn’t partially grounded somewhere along with just bad parts. Make sure there are no air leaks on the engine. Make sure the fuel is good too.

Did it act like it was throttled or struggling to run?
 

samyguy

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Sep 19, 2011
Messages
167
Location
74FL Monticello FL.
CDI ignition, so no condenser.
Just went thru fuel lines and filter, good flow. Running good for several different taxi runs/test and run ups.
Just all shorter run times up to failure. Then struggling to make 2840rpm, changed plugs same thing.
Waited over night to cool off, starts up fine runs fine. Full RPM 6250

I'll check out the facebutt site.
 

TFF

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Apr 28, 2010
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Fuel tank vent clogged? Can you run it with the cap off and not create a hazard, or at least very loose?
 

Dana

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What do the EGT and CHT look like when the problem is occurring? Heat related ignition failures tend to come on gradually as a misfire, not a sudden hard rpm limit. What you have sounds more like a fuel flow issue, though it's hard to see how it could be temperature related. Do check the fuel cap, run it open as TFF suggested or just loosen it after it fails, if air rushes in and you can restart it and get full rpm, there;s your trouble. Try operating the choke or enrichener and see what happens. Check the fuel pump pulse line if you have one, it could soften or expand with heat and/or start leaking, But hmmm... CDI with two coils? A bad circuit in one coil or its associated wiring that opens with heat and then you're running on only one cylinder? Check if one exhaust is colder than the other once it's failed.
 

Ken Powell

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Dec 8, 2020
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90
Location
Bryant, AR
Make sure the engine is sound. Run a compression test on the top end (not a leak down test as on 4-strokes). You may also need to run a leak town test on the bottom end. You want to start at 7 psi and lose no more than 2 psi over 5 minutes. But my bet is on a failing CDI.
 

Donald

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Feb 21, 2022
Messages
13
I've used a standard timing light on each spark plug lead in turn tracking down if a poor run is fuel or ignition by observing the timing light to see if it cuts out or stays strong when the miss occurs.
 

proppastie

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NJ
hopefully you do not have an air leak and one cylinder over heating, expanding and almost seizing, slowing down the engine. check your plug color
 

Ken Powell

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Dec 8, 2020
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90
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Bryant, AR
I say again... Make sure the engine is sound before chasing herrings. See my post above. And yes, reading the plugs is the first step. If you have had a partial seizure your compression will probably be low. If compression is OK you can feel relatively sure the top end is ok. Next, do you have a leaking crankcase seal? Run a leak down test on the bottom end. If it passes, THEN start checking the other stuff. Don't forget to check for a defective kill switch - not likely a problem but easy to check. My bets are still on a defective CDI. Also check for bad grounds - happens all the time. Incidentally, I have been racing 2-strokes since 1971.
 

Lucky Dog

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Aug 4, 2021
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@Ken Powell is offering good advice.

Before you pull out the ohm-meter or go crazy with compression tests, recheck the fuel system, because every symptom points to this for the cause. First, check the color of the spark plug electrodes (light to medium brown is in the proper range - dark brown is probably okay). That will check off any jetting issues. All two strokes will run well with a too-rich main jet when they are cold, but most will then fail to reach full rpm when warm. Turning off the fuel valve while the engine is struggling to gain RPM will reveal an over rich mixture if the engine roars to life just before it runs out of fuel.

Faulty gas cap vents are common - and the "running fine before your engine RPM suddenly drops off" is the exact result. Drill clean through the center of the cap with a 3/32" bit to eliminate that one (most of us do this before our first flight).

Is your gas tank on the root tube, or is it behind the seat? If it's at the seat, you'll probably need an electric booster pump (Facet is the one most of us use).

Lastly, if you're using a looped vent tube between the carburetor's float vents, switch to two separate tubes. I've seen four engines this year exhibit these same symptoms due to sealed vent holes where looped tubes have been drilled per Rotax instructions. A curious development that makes me think a new additive has been introduced to pump gas. Good luck, and post some pics of your plane, I've always been a fan of that ship!
 
Last edited:

samyguy

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Joined
Sep 19, 2011
Messages
167
Location
74FL Monticello FL.
plugs look good , I'll open up the vent hole in the cap some more.
I'll try Donald's timing light test, sounds like a good one.
I got ohm spec's from J-Bird , Chuck also said to pull exhaust and check piston/cylinder visually

thanks Guys
 
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