Lack of fuel in one way or another will do it, especially if it happens
suddenly at WOT under a hard pull down a straight.
Typically a popped c-clip and a dropped needle will do what you describe,
but you seem to be able to get it running again after motor repairs. A
dropped needle would put you out of business until you fixed the carb.
Look for vacuum leaks at the carb rubber mounts. Carb to mount and mount to
barrel.
You won't pull any fuel from the carb if you have a leak that opens up
sometimes.
Make sure the jet sizes and needle drops are equal. Float levels are OK and
no ocassional sticking closed of float valve.
There are othe more subtle things, like the crank throws being off from each
other and consequently the ignition timing being off.
Detonation:
Look for pepper specs on one ceramic insulator vs the other. The ceramic
insulator is an indicator mostly of detonation and plug heat range not fuel
mixture. Mixture is shown more by the color of the plug ground electrode
and plug metal base exposed in the chamber below the threads.
Chuck
From: "John Vriesinga" <[EMAIL PROTECTED]>
Reply-To: [email protected]
To: <[email protected]>
Subject: [F500] Help I don't know what to do anymore
Date: Sun, 24 Sep 2006 15:16:53 -0400
I've got GM Harmuth's old Red Devil. I have yet to get a full event running
with it. It has been to a professional engine builder who is known around
North America for the engines he builds for drag racing snow mobiles. He
knows his stuff. Problem is, it will run great for a while especially when
cold, but then it just dies.
Today was the same as usual. My son and I went to the local autox. We both
got 4 runs of roughly seventy secs. Throughout this time, I pulled the
plugs twice, and each time they looked beautiful with a nice clean, dry,
brownish burn. The car ran good and felt strong then suddenly it stopped
running on one cylinder. We limped the car into the pit area and pulled the
plugs, and found the tip literally fused to the ground; it looked like it
was welded. This cylinder has been the source of trouble from the get go in
April. I've changed heads on it twice. I've tried different jetting and
different heat range plugs. Now I don't know what to do. I have no idea
what sort of intermittent problem will cause this.
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