dangerdave
Ex Member
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So my saga continues....
After some adjustments to the top end of my bike, including sealing the head cover plug leak, retorquing the cylinder head nuts, and rebuilding the carburetor, the bike seemed to be cured of its ailments. After a few weeks, with the weather getting colder, I decided to go ahead with rejetting and a Sportster muffler installation. The muffler installation was a breeze, sounds good, and seems to be free of leaks (I replace all gaskets and torqued everything correctly).
Rejetted to a 152.5 main, shaved the white spacer to half of its original thickness, and adjusted the idle screw as much as I could (the idle screw was stripped by a previous owner; am waiting for a replacement one--currently on infinite backorder). I have a 55 pilot jet on order as well, and had planned to move up to that when it arrived.
Took the bike out for its first run yesterday: everything seemed great, the bike had a nice mellow sound, and a nice shot of midrange power (no more lean surging at mid-RPM in second/third gear!). I did maybe 10 minutes of stop and go riding around town (it was reasonably cool, in the high 40s) before heading home.
When I pulled into my driveway, I listened to the idle for the first time and noticed that it seemed to be loping a little. Pulled on up, parked the bike in neutral and let it idle: the idle became increasingly slow, until it seemed certain that it would die (interestingly, it never did), and the bike had a new backfire/pop when the throttle was blipped.
After listening for a few minutes, I shut the bike off, and noticed the amount of heat that seemed to be rising off the engine and exhaust. Coming from the world of liquid-cooled bikes, I was, needless to say, alarmed to see heat rippling off the engine block after such a short ride, and to hear the ticking/hissing/squeaking noises that the engine made as it cooled (I guess, with this being a relatively new bike to me, I had never spent much time laying on the ground with my ear near the engine after I shut it off before now).
Of course, I immediately became concerned that the bike was, for some reason, overheating, causing it to run poorly. My mind raced to the recent resealing of the head cover, and then to stealership urban legends about Permatex clogging oil journals/pumps, and then to bad experiences (years ago on dirtbikes) with gas getting into the oil and causing myriad lubrication/cooling problems. I pulled the plug on the airbox drain (which I had been checking regularly after my carb rebuild) and observed that, after weeks of being dry, the airbox had a significant quantity of gas in it once again. Also, I noticed gas running down the side of carb float bowl--I may have not seated the bowl correctly after rejetting, but it was hard to tell if the gas was leaking around the bowl gasket or from somewhere higher up on the carb.
So what think ye? Obviously, it would be wise to check the oil for gas and change it, but there's clearly something going on here. Is this overheating, or am I being paranoid due to a lack of experience (in other words, does anyone elses bike visibly radiate heat)? Given that the stock carb was, as far as I can tell, fairly thoroughly mutilated by the previous owner, I've been thinking a new Mikuni VM from Lancer will be on the agenda as soon as I can scrape the cash together. But I can't put out of my mind that the bike may be overheating.
Can any one put all of this together into some kind of consistent theory? If the bike runs significantly worse when it gets hot, and the problem is not overheating, am I right to think that this points to an excessively rich mixture? What about the backfiring? Where to go next?
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