Topic: exhaust on #'s 1 and 4 hot?

[neckyzips]

ok,
so i have this old header for the project bike, took it out sanded it down painted it with that high temp stuff, yata yata yata. ok, i was doing a valve job on the daily rider (500) and noticed that the pipes were rusted on the down curve coming off the head, bottom side, (now this really pissed me off because these are imaculate and the stock pipes) so i thought id take them off give em a good cleaning and run the old 4 into 1 while i was doing this. well tonight after the first long ride i noticed that 1 and 4 pipes were bubbling the paint? but not 2 and 3??? now before you start saying i didnt let the paint cure right... it has had several heat cycles before tonight. what ever the problem is it appears to have not changed with the valve job, could i have an oil passage blocked?

[TwoTired]

Maybe 1 and 4 ARE running hotter.   Different exhaust systems often need different jetting or carb set ups due to different restrictive flow charateristics.  Do all the spark plug tips look the same?

How's your carb sync?  All the pilot screws adjusted in the same position?  Are the slide needles clipped in the same position for each carb?  Are the spark plugs all the same heat range?  What are their numbers?

If you are worried about oiling, check the valve train through the tappet adjustment covers.  If it's all still oiled you're okay.  If things look dried out, well...

You probably need carb adjustments, though.  The plugs should tell a story.

Cheers,

[neckyzips]

ok,
everything is stock on the bike still dotted with the yellow check paint, i havent checked the needles, but the plugs are a bit leaner ont the outside cyls... so i will check the carbs, but they should still be factory set up. hmmm. i dont remember what the plugs are, but i remember going one hotter last spring, whatever, as long as its not doing any damage, im ok with it... but ill check it out a bit more and post the findings.

[TwoTired]

Well, the bike isn't stock if you put 4 into 1 pipes on it, now, is it?

Also, just because the carbs were syncronized by the factory 30 years ago, doesn't mean they are still in sync today.  The yellow inspector paint was just a quality assurance marking that verified someone checked it before it left the factory.  And, the Honda shops could then tell if it was messed with during warranty if the paint was disturbed.  They are adjustable because things can change with wear, vibration and time.  You might just have to chip that yellow paint.  But, 4 manometers will tell you for sure.

If they are out of sync, you're really gonna be pleased with idle smoothness, when they are put into sync.

Cheers,

[Terry in Australia]

1 and 4? Ignition timing, I reckon. I won't bet Raul's testicle (cos I wanna keep it) but I remember watching my BMW R100RS pipes glowing in the dark when I retarded the ignition timing once, and as 1 & 4 are on the same points/coil, that's my guess. Cheers, Terry (three balls) 

[dpen]

This is off the topic but-welcome back Lloyd, I missed your melancholic meanderings

[Raul CB750K1]

Some people thint that it is good that cyl. 2 and 3 run richer, so they also run cooler to compensate the better cooling in the outside cylinders.

Raul

[TwoTired]

Yep, Terry's probably right.  And, timing is easier to check than the carbs, too?

Melancholic meanderings?  Now there's a welcome I'm not often given.
Er,   ... Thanks?