OT; 3-wheeler doesn't start

I feel like a fool for posting this since I should be able to fix it in my sleep, but I can't. 1983 Kaweasaki Prairie 3-wheel ATV wouldn't start. After digging into it I found the 3 screws sheared that transmit starter torque to the flywheel. Fixed that; engine turns, has compression (50#, admittedly low, likely dirt on valve seats that would blow out on start since I measures 100# 2 weeks ago). Starter is turning motor in the correct direction, the intake & exhaust valve operate in the correct sequence when I turn the crankshaft by hand, The spark is hot & blue and will jump a .250" gap in air. Timing is not adjustable but a timing light seems to show a flash at the correct 10 deg BTDC.

I put gas or starting fluid in the spark plug hole and NO firing.

If I try it with the plug just out of the hole I get fire about 3 times before it runs out of fuel.

If I crank the engine with the hot wire just off the plug I get fire between the plug & hot wire, so that proves current is flowing thru the plug gap BUT the engine fires on every stroke so I could just be seeing the spark at the top of the exhaust cycle.

I have the feeling I am missing something simple & stupid. Tell me what stupid thing I forgot. Please.

Reply to
Nick Hull
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If you have spart, and you have compression, it's got to be in your carb. If it sat for any amount of time. Pull the carb and clean it spotless, I bet it starts right up.

Reply to
kade

No idea if it'll be any help, but the first thing I would try is replace the plug. Mine deteriorated to where it would not spark under compression. It looked fine and sparked nicely in open air, but not in the cylinder. Cheap fix if your luck's running good lately. :)

Funniest one was one _cold_ day it wouldn't run more than 3-4 seconds. After practically disassembling and reassembling the engine, I found water had frozen in a low part of the exhaust system. First time I had an engine failure from a frozen up exhaust. Solved the problem with a hair dryer and thereafter, making sure to rev the engine to expell the water before shutting down.:)

Reply to
John Husvar

50# ain't gonna get it..... try some oil in the cylinder to maybe increase the compression, then if it starts, you're going to need rings and stuff... I've had a couple that wouldn't fire up even with spinning the engine with a drill motor... low compression. New oversized piston and rings fixed the problem. Ken.
Reply to
Ken Sterling

Agree with all of the preceding. The other thing I have found helpful at times like this is to warm up the head and/or carb with a hot air blower. You're not using old petrol, are you? Over time this loses some of the more volatile components and gives starting problems if the system is marginal.

Reply to
Newshound

Or a gas torch (not oxy acetylene!) if you are away from power.

Reply to
Newshound

If it were a carb problem wouldn't it run a few licks with starting fluid? It doesn't.

Reply to
Nick Hull

The plug is NEW, properly gapped at .030". Also tried plug gapped at .020" and .010". Doesn't light.

Tear it down and look for what? It ran fine until one day it wouldn't start - I thought I fixed THAT problem.

Reply to
Nick Hull

220 0 article Path: finder4.readnews.com!fnd01.iad01.newshosting.com!textbe01-ams!hwmnpeer02.ams!hw-filter.ams!hwmnpeer03.ams!hwmedia!news.highwinds-media.com!feeder.news-service.com!newsfeed.freenet.de!newsfeed00.sul.t-online.de!t-online.de!border2.nntp.dca.giganews.com!nntp.giganews.com!elnk-atl-nf1!newsfeed.earthlink.net!stamper.news.atl.earthlink.net!newsread1.news.atl.earthlink.net.POSTED!e78e3015!not-for-mail From: Nick Hull Newsgroups: rec.crafts.metalworking Subject: Re: OT; 3-wheeler doesn't start Organization: farm References:

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2006 14:10:12 PDT) NNTP-Post> Or a gas torch (not oxy acetylene!) if you are away from power. >

Have tried starting fluid, fresh gasoline, propane, and carb cleaner (usually works best!). No firing on any.

Reply to
Nick Hull

Doesn't mean anything now days unfortunately. It's not unheard of to find 3-4 bad plugs in a box.

I'm betting ignition problem from what you describe. If it fires with the extra gap in the plug that usually indicates a shorted plug but it could be something else nearly shorted. I had a Honda engine one time that drove me nuts. It fired fine with the plug, and it fired fine on my spark checker. The only clue was that it didn't fire fine with my spark checker inline with the plug. Usually I don't have any problems with that. It turned out to be a bad coil.

Reply to
Wayne Cook

Sounds like a bad plug preventing the starting. Low compression is another story.

Reply to
tomcas

Open the gap up on the plug to at least .075 and see if it sparks across the gap. From all the information you gave, it seems that there is no spark inside the cylinder with compression which increases the effective gap. By opening up the gap and looking at the plug firing you can see if there is a breakdown inside the plug.

The old spark plug testers had a ignition coil and a way to presurize the plug and watch the spark under high pressure to see if the plug would break down.

A new sparkplug dropped on a hard surface is likely to be junk, it will still look new though.

John

Reply to
John

Check valve timing; maybe cam belt or chain has lost tension and slipped.

Reply to
Roger_Nickel

Sounds like Valve timing to me. Or something caused the screws to shear and that could have been a backfire which may have caused other damage. A sheared key on the flywheel/magneto or just displacement of the key. Are there timing marks you can look at on the crank and cam?

Reply to
Glenn

I agree it 'looks like' no spark inside the cylinder with compression, yet with a plug outside I can easily get over .200 spark. I can think of no reason why I shouldn't get a spark with a mere .030 gap inside, but I can't actually see it.

Reply to
Nick Hull

I did try it with 2 new plugs, plus some older one I'd cleaned up.

I agree it 'looks' like ignition problems. But I have a NEW coil and it puts out big blue sparks. Tell me about the spark checker you put inline with the plug; is it just another spark gap? I have tried a spark gap in series with the plug, but the engine is designed to fire everytime the piston goes up, wether compression or exhaust, and I cvan't distinguish between the 2.

Reply to
Nick Hull

There is nothing between the coil and plug but 6" of new high voltage cable and the rubber plug cover. It's one cylinder so there is no distributor and the timing is fixed (like a magneto) so I can't change it. A timing light makes it look like the correct timing but at cranking speed it's tough to see well because I lose persistence of vision.

Reply to
Nick Hull

I was so convinced the flywheel key had sheared that I removed the flywheel; the key was perfect, no displacement. At least when I removed the flywheel I could see the problem with the sheared bolts on the starter overrunning clutch.

Reply to
Nick Hull

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