cool cylinder?

Hellboy · Sep 3, 2014

Does anyone check or notice if your cylinders heat up equally after a cold start? My bike is running like a race horse goanna (very strong and fast). I do notice though that the right rear cylinder takes much longer to get warm than the other 3. After a cold start, within 30 seconds or so 3 of the cylinders are warm to the touch and the pipes are getting hot soon after. The right rear however seems to take several minutes to develop any heat to speak of and I can touch the exhaust manifold from it a couple of minutes later without being burnt. After that it heats up like the rest and all seems fine. Carbs are synched, spark good, gaps good, runs smooth???

Matt

jethrobolas · Sep 3, 2014

Just a guess, I bet the cool cylinder is a bit leaner on the pilot circut. Do you use the choke for cold starts? If not, try using it on the next cold start and see if the cylinder in question heats up quicker. If it does, then you know it is running leaner than the other three.
That would mean the pilot in that carb could be partially or completely blocked. Or it could be leaner on the mixture screw.

Hellboy · Sep 3, 2014

Thanks, I'll check that in the morning. I do use the choke but not much, I'll try full choke, if it will start that way.

davesax36 · Nov 29, 2014

I've got a cold cylinder today, too. I have spark. I'm going to fiddle with the mixture screw to see if that helps. I thought lean was hot, but I've been wrong a lot.

wildweasel_pt · Nov 29, 2014

the spark plug may spark outside the cylinder but when under compression it may behave differently. I had that problem before and it was driving me nuts as i saw it spark outside but it wouldn't spark (enough) inside, plug gap may also be a factor.

alorio1 · Nov 29, 2014

davesax36 said:
I've got a cold cylinder today, too. I have spark. I'm going to fiddle with the mixture screw to see if that helps. I thought lean was hot, but I've been wrong a lot.

Lean is hotter, but if it's too lean the cylinder in question is not getting fuel to burn at idle. I suggest backing the A/F mixture screw out maybe a half turn so the cylinder can get some fuel to burn when cold........