One cylinder running hot

[MotoMartin]

One of my cylinders (#3) appears to be running hotter than the others, because one of my new head pipes is turning a light yellow color, while the rest of them remain chrome colored. I sprayed the inside of the pipes with hi-temp resistant paint prior to installation to help prevent bluing of the pipes. What concerns me more is that this cylinder is hotter than the others. I imagine this is due to lean carb settings or an air leak. Any ideas on how to make this make this one cylinder run cooler?

[mro]

due to lean carb settings or an air leak

Would check for a vac leak first, boots and around where they attach to the head. Would also check the vac cap or petcock vac hose on 3 is good.

Should that not be it...
Under 3000 rpm pilot screw is still in play. Would check em all same as when you tune the carbs.

Float level effects all RPM ranges on the BS34 carbs.
Would first check if it is set to 25.7mm. (and all the others too)
Can lower a float .5mm (raises fuel level) and will still run good but will allow more fuel to flow in that carb which will "richen" it some.

Can be lowered even a full 1mm, SOME times you will run into other issuse from 24mm and less.
(book says in speck 25.7mm + / - 1mm)


mro

[prometheus578]

A jet in the one carb might be starting to plug, or the float setting could be off in reference to the others.
Also check for an exhaust leak at that header pipe.
You may want to go up another jet size across the board, aftermarket exhaust systems often cause the bike to run lean.

[prometheus578]

'Nice going, MRO..."

Beat me by 2 minutes.

[mro]

Beat me by 2 minutes.

starting to plug
aftermarket exhaust
________
Yea, but I did'nt mention those


mro

[MotoMartin]

Thanks for the replies guys.
I have now done much of what has been suggested. I tightened intake boots and exhaust, checked plug gap, adjusted float level. Hard to tell now without somehow removing the yellow, now turning blue, marks on the exhaust if it is still doing it. It may be possible that I forgot to paint the inside of this particular exhaust head pipe but it seems unlikely as it is attached to the headpipe next to it. Maybe I'll take it off and have a look, although the pipes are easy to scratch and taking it off and on again will probably result in another mark.

[prometheus578]

Aftermarket pipes are notorious for turning colors. Thinner, cheaper metal, etc.
Really, not much one can do about it other than rejetting to keep the color change to a minimum.

[MotoMartin]

Right about the quality of after-market pipes for older bikes.
What is annoying is that only one pipe is discolored, which probably indicates some problem or I failed to paint the inside of that header.

[prometheus578]

which probably indicates some problem or I failed to paint the inside of that header.

Hard to really say for sure.
Just do what I do (when some event happens that I have no control over.)
Act like it's not important... or... that you happen to like it that way.
Makes life a little less stressful.

[MotoMartin]

Yeah, it's not a concours condition bike or anything.
The discoloration did disappear with chrome cleaner, so tomorrow I'll take it out and see if the changes made any difference.

[TomB]

Hi MotoMartin

All the after-market exhausts I've had arn't double skinned on the headers so they discolour if the bike is ridden right (like you stole it)

I'd be more worried about the other three pipes not discolouring

[MotoMartin]

I read in a thread here, that if you coat the inside pipe walls with hi-temp paint they won't discolor. Have you ever tried that? Although, it seems like it would be temporary, I could't imagine a paint coating lasting a long time in the exhaust headpipe under those conditions.

[TomB]

Have you ever tried that?

Nope, couldn't see it lasting either

I quite like the coloured pipes

I know all cylinders are running good if I get 1 inch of blue and 2-3 inch of yellow, that'll probably differ on different quality exhausts.

[MotoMartin]

Along with the things I did yesterday, float level, etc., I also took the pipes off and resprayed more of the heat resistant paint. I took it out for a spin and it's still doing it. I now think the exhaust valve clearance on this particular cylinder is too tight. That is the next thing I am going to check.
Hopefully this picture attachment works,
http://s81.photobucket.com/albums/j2...t=P1090828.jpg
Here's a picture of the bike.
http://s81.photobucket.com/albums/j2...t=P1090827.jpg

[TomB]

Very nice bike, just my style

Your pipe thats coloured looks like all four of mine, looks like its running perfect.

Its always worth checking the valve clearances though, at least its something else off your mind.