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My bike seems like it could run a little better across the board. When I turn the throttle wide open really fast, it will miss before reving, but only when I do it really fast. Also, I have trouble maintaining a good idle speed between when the bike is cold and when it is hot. It will run fine when cold, but when hot, it wants to die. If I turn my idle up to make it idle when hot, then when it's cold, it runs too fast. Any suggestions? Do I need to do some tuning? The carb, head, airbox, and exhaust are all stock.

Thanks,

Nick

Is your miss while the bike is on the stand? If so, quit worrying. That is totally normal for this carb. If it is when riding, then it may be that you need to jet your machine. Give us the altitude and temps where you normally ride.
Joe

The bike misses on the stand. I'll quit worrying because it doesn't do it when I'm riding. I am in the very northeast corner of Mississippi. My altitude is between 350 and 400 feet above sea level. I've been down here for 8 months and am from Illinois. I ride in Missouri too, and the bike doesn't seem to run much different in any of those three locations. I have 40 hours on my current top end and valves are all within spec, too. What can I do to get it to idle well across a range of operating temperatures?

Actually, the altitude here in Mississippi is closer to 500. Where I'm from, in Illinois, it's actually about 812.

Ooops, forgot the tempurature. It ranges from 70s to 100+ during the summer months.

When you are starting and the bike is cold are you using the choke when the idle is too high?
Joe

I choke the bike to start it when it is cold. It idles high enough that this time of year (when it's warm out) I can immediately turn the choke off. It will continue to idle at about the same speed, though. Then if I bump the choke half on a few times I can get it to idle down. At this point it purrs like a kitten. However, once the bike becomes hot, it no longer wants to idle; it wants to die.

Nick

What have you done to the bike? Jetting, Pipe? etc? What is the position of your fuel screw? What does your plug look like?
Joe

Everything is stock except for top end. It has 40 hours on it and has kibblewhite springs and valves. No jetting. Plug is normal, not sure where fuel screw is at now. I will have to check. The difference, however, when I tune it on the stand and when I ride is the tempurature. Obviously I let it warm up on the stand, but it still is not as hot as it gets when you are riding in 100 degree weather. Do I need to tune it during a ride or something? I haven't done it since my top end, but I feel fairly confident that adjusting the fuel screw may smooth things out...?

Your fuel screw should be around 1-3/4 out or so. I am going to ask another more R oriented guy to get into this conversation.
Joe

Sounds like an air leak to me guys. If you set the idle cold and it varies as the bikes warms up, it almost always points towards an air leak. Also check your exhaust flange bolts at the head, make sure they're tight.

Check the valve cover rubber gasket. Make sure that thing is fully seated and in the groove.

Thanks, 124, I was kinda leaning that way too. Check the carb boots for tightness as well.
Joe

Exhaust flange bolts should be tight, fuel screw is about 1-3/4 turns out, but an air leak is definitely possible. I had a similar issue on another bike and it seemed to be an air leak as well, but didn't even think about it. As far as the valve cover goes, I check my valve clearances about every 15 hours. Every time I do, I have the darndest time getting that valve cover to sit on the top of the head right. The main problem is the seal around the spark plug tube. Is the seal/cover supposed to go around the spark plug tube, or mate up flat against it? It's difficult to get around if so. This may be my problem.

Thanks, guys.

nicksumm1983 wrote:Exhaust flange bolts should be tight....

Check them to be sure!

The main problem is the seal around the spark plug tube. Is the seal/cover supposed to go around the spark plug tube, or mate up flat against it? It's difficult to get around if so. This may be my problem.

It fits over the tube. Agreed, this could be your issue.

I replaced the seals on my valve cover under each bolt and the spark plug tube seal and tightened the carb boots on both sides. It seems to have helped a lot. Thanks for your help, guys!