I know I keep harping on this but did you do another plug read after you did your adjustments? Last I heard the front was rich and the rear was lean, is this still the case?

 

Same as above reg. the current plug read. Also, are the reads being done after idle, or after an actual run. From what I understand the best way to do a read is to run to full throttle and kill the engine while you're moving. Otherwise you'll learn your idle characteristics. At your elevation a 142/145 should be slightly lean. Have you checked the ignition system? Plug wires etc. You say that the front is running really rich. Have you checked to make sure your float isn't sticking and dumping raw fuel into the carb? Find a nice long straight area and do a run with everything pulled from the airbox so you can look inside the carb while it's running. You should have a nice atomized effect from the carbs, not drips and streams.

Did you do all the listed mods at the same time, or did you space them out with test runs in between? How did it run before any mods were done?

You're not going to like this, but I think your best bet is to do the 1st step in troubleshooting a problem like this. Return everything you can to stock form. Everything related to power delivery that is, I wouldn't worry about the springs. The muffler can't be helped, but put everything else back to stock and really check out how it runs/performs. If it seems better, then make 1 change like the snorkle. Thourough test again. Then jets, thourough test... The absolute last thing I would play with is shimming the needles. Odds are you won't need to adjust the needles.

 

I agree. Its always best to do one mod at a time, then test after each. Then when you have a problem you will know just where to look. But get your plug read as aj650 said and let us know how it looks.

 

plug read stayed much the same with the front now being alittle rich and the back being lean. I will start returning it to stock this week and start over. The mods were done 1 at a time over the winter (not the best time I guess) and I thought I was getting good resolts. OH well back to step one.
One more thing is it normal for a 650 to backfire in the exaust when deaccelerating from high speeds.
all your ideas are very much aprecated.

 

Disme: backfiring on decel is a lean condition usually fixed by readjusting your idle mixture. This wont affect your top end power loss though.

 

I wanna ask a few dumb questions:

1. Are the lights on dash flashing? Probably not, you would have said so.

2. Is the rubber shield partially blocking the airbox inlet? That causes popping like you descibe at high throttle.

3. Are you sure you have the needles, needle holders, shims and springs in right?


Any chance some of those jets are dynojet and others are Kehin?

Backfiiiiiring is more or less normal with a modified exhaust. Richening the idle mixture may reduce or eliminate it.

 

Last night I returned my bike to stock, except the mufler. Still had a problem with rear cylinder quite lean. Checked coils (good),timing (good), carb sync (very close), compression (good), valves (good), clutches (again good). MY question is what have I missed, or should I just go up 1 or 2 more jet sizes on the rear cylinder.

 

woot, I think I found the problem. The spring in the top of the rear was broken and short by 3/4". Where the piece went is beond me but there is 2 small holes in the diaphram. Could this be the source of the problem? Should I be conserned with the missing piece of spring? Ouch $150.00 cdn. for a new spring and plunger hope this is the fix.

 

Crap that's expensive. I don't think the spring could have gotten inside the carb. Yeah, that probably will fix the prob.

However, the last guy that took those off probably busted the spring. [img]i/expressions/face-icon-small-blush.gif[/img]

Glad you found the problem, makes perfect sense. Too bad no one though of that earlier.