| Author | Message | ||
     Jim2 |
First start after top-end refresh on '00 M2. Had a blown rear head gasket so I replaced complete top end gaskets from base up, including intake and exhaust gaskets. Had an independent shop do spec. checks, clean carbon from heads, replace valve seals grind seats and hone cylinders. I installed new rings and put it all back together. Checked carb diaphram/seals and cleaned jets. They seemed nice and clean to begin with. Did the breather re-route to a catch can. New plugs. Started right up and idled great. A little tapping noise from the lifters but it settled down after a minute. Some smoke which I think is normal after doing a bunch of work. Almost fully warmed-up I got off to look around just to make sure the smoke wasn't my breather hose or anything else it shouldn't be. That's when I noticed the rear header was glowing red hot but the front one wasn't!!! I shut it down and here I am, not sure what to think? Any ideas? | ||
| Phelan |
Break in procedure? How hard are you running it? | ||
| Jim2 |
It was the first start after putting it back together. Just chock out warm-up at idle, 1900 rpm. Chock in and idle adjust as it warmed up. Didn't ride at all. | ||
| Rocket_in_uk |
Three things. Either..... 1. The rear cylinder is running lean. Not enough fuel. Which seems unlikely if the carb is good and the heads be rebuilt with no issues in the valve train. Did you seat the inlet manifold correctly? A air leak will lean the cylinder off. I would however check the carb again, as a lean mixture might not be immediately obvious on the front cylinder (though you'd expect this to apply when riding, not stationary) but the rear cylinder would be the obvious choice to get hot first / quicker. Thus if you have a lean mixture cause, the front cylinder appearing to run ok when running stationary, such could be masking BOTH cylinders running lean. Get a infrared thermometer and take temp's in same place for both cylinders/heads/headers etc. 2. Ignition timing is out on the rear cylinder. If so it's likely retarded and the spark/bang is too late thus causing heat to quickly build without time for the exhaust to evacuate hot gasses efficiently enough. 3. Mechanical issue. Given you've had the head done, honed the bore, replaced rings, if you have no issues here it's possible to have a slightly bent rod or a problematic cylinder/piston issue though does sound unlikely. I'd expect scenario 1. the most likely cause for concern. An ignition issue I'd expect you might hear it running unevenly at the very least. Mechanical unlikely if it all went well at rebuild stage. Rocket in England | ||
| General_ulysses |
+1 on the rear manifold air leak theory. | ||
| Reepicheep |
My M2 did that after doing rocker boxes. Actually, it did it all the time, but I only noticed it when I did the rocker box, it was idling at night, and I went looking for problems. Some glowing is normal. | ||
| Jim2 |
Thanks for the help. I will get ir heat gun, go through carb again, inspect intake manifold seals, reseat/remount, fire back up and measure temps. What could possibly cause timing out on rear cylinder only as rocket suggest in #2? | ||
| Rocket_in_uk |
What could possibly cause timing out on rear cylinder only as rocket suggest in #2? On an 00 M2, nothing really, unless the timing is likely out (equally) for both cylinders, both cylinders running somewhat hotter but the rear cylinder showing such at the header. You could of course have an exhaust valve issue. Such could cause excess heat in the header area dependent on the type of exhaust valve problem. Seating, burning, clearance issues most favourable. Rocket in England | ||
| Jim2 |
Thanks again for info. I'll let you know what I find, if anything. | ||
| Jim2 |
A small change in timing made a huge difference in the heat at the top of the header. I bought an infrared thermometer gun and made some measures as suggested. I had the timing a bit off and found that that can make a difference of up to 300 degrees F. I still have to time properly which will require that I mark the flywheel so I can see the marks. I can't see them at all with timing light on. Have ridden much since top-end refresh and it's a big improvement. First time ever to have zero oil leaks  Starts better, idles better, warms up easier and have not been able to see any sign of oil consumption after the first 300 miles up to now (been about 800 now). Thanks all. |
