She seems to drop power above mid-speed...

My 82 650 Maxim sounds like she runs great. Revs fine in neutral. Seems to be firing in all 4. Gets up to speed as one would expect. However, when you are going mid speeds (30 to 50 mph) and you really give her gas, she responds weekly. A long-time rider who rode the bike agrees that it ought to be a lot more punchy and responsive.

It feels like some sort of carburetion issue, but have any of you come across this in your XJs?

Thanks!

 

could be something like needle height or float height...

Needles would affect the midde range... if the floats were set to low it would starve for fuel above a certain rpm range after a little bit of time.

I'd need more info to help... others will be able to help as they arrive

woot.

 

Need to know a litle moe about the bike. Is it stock or are you running a 4 into 1 exhaust ; pod filters; air filter stock? Have you done any tuning to the bike or run any carb cleaners through?

 

Thanks, guys.

The bike is pretty stock, as near as I can tell. Stock exhaust, etc. The air filter is stock, and in tact, although I looked at it in diagnosing this issue, and the gasket foam had disintegrated, and it is possible some portion of this foam was sucked nearer the carbs. I had pulled the carbs out this spring, and completely cleaned them, using Yamaha carb cleaner, and blowing air through all the orifices. The diaphrams looked good, and the carbs cleaned up well (in fact, they were pretty shiny to begin with). I have not done any further tuning. I bought the bike in the fall, and live in Minnesota, so the season is still pretty young...

Woot mentioned needle height. I wondered about needle height, because it does seem to run a little rich when it first starts. I did not change this at all when the carbs were apart this spring. Thanks again, guys for your help.

 

I just saw replacement airfilter seal foam in the new Dennis Kirk catalog. You might wish to invest to help protect from further ingestion of unwanted materials.

 

Sounds like it may be running just a little bit lean. Best thing to do is a sync and colortune. If you don't have the tools for this you could check the float levels with the clear tube method. This entails using clear tubing that will fit over the nipple on the float bowls. Get the bike level on the center stand and attach the tubing. Using a flat blade screwdriver open the float bowl drain screws and leave them open for a while. Place the tubing against the side of the carb and check for the correct fuel level. For the correct level check out the user galleries and look through Nick's photos. He has a photo showing teh tubing against the carb with a slightly low but acceptable level. Let us know if you have any questions!