so i bought the bike about 2 weeks ago. guy said it ran horrible at low rpms, and thought it was dirty carbs. i cleaned the carbs, and after fixing the vacuum lines to the correct factory way, and finding that the spark plugs were wired up wrong (what a douche), it finally started up for the first time that i had it. idle was horrible, sounded like it was missing alot. i gave it gas and above 3k, it sounded like a charm. was music. i let it run for a couple min thinking it would burn out any crud in the lines/cylinders... then i got a hair in my *** and wound it up to about 11-12k. it died. started it back up, and it would half *** idle, and die if i gave any gas.

that leads me to believe that the air/fuel mixture is wrong right now and the plugs are fouled.

would vacuum leaks cause it to run like sh*t to 3k, then by the shear force of it sucking air in, it sealed the leaks itself by sucking on the lines/boots to a tight posistion and to run normal above 3k?

 

nice signature ;P

I would pull your plugs and see if they're worn and/or gunked up. And did you synchronize the throttle bodies after you re-installed the carbs?

Did you adjust the pilot screws (air/fuel ratio)?

 

hey. the plugs are brand new, only started the bike on them one time. i had 2 different tutorials that i was referring to while cleaning the carbs and neither of them said anything about sync'ing the carbs after i got done cleaning them. i guess i will research that and the pilot screws now. thanks for the info, will do that this weekend and post back on here.

 

Yeah, a horrible carb sync would cause improper firing, but an "ok" sync should be, well, OK. Did you eyeball the "butterfly" valves movement before reassembly? If they all *appeared* to be working in unison, you shouldn't be getting that bad of a reaction from the lack of sync. Of course, there are always exceptions.

Did you remember to REMOVE *all* of the jets, slow AND main, clean them, and visually inspect them? I've found most people get lazy, and just shoot some carb cleaner through them and call it a day. The slow jets especially have these incredibly tiny holes in them, and can get totally clogged even from a tiny spec of debris, or gummed up gas. Given that your problem happens at low RPMs (low throttle), I'd look at those slow jets. Make sure you can see stright down through them, and also through all the little holes on the sides. It helps to look at a bright light source through them to confirm, as the holes are that tiny. If you're unsure, soak them overnight in carb cleaner (buy one of the "paint can" gallons, and drop the parts inside, don't just spray them and let them sit.), and run some fishing line or welding torch cleaners through the centers.

Watch out when you're unscrewing the jets, as it's easy to crack them. Also remember not to get carb cleaner on any of the rubber pieces, as it'll eat right through them. While you're in there, inspect the bowl gaskets for breakeage or wear. This is a prime area for vacuum leak. Also check your float valves. Make sure that little needle comes all the way out with the bowl attached. Remove the bowl to determine where this point is. Make sure all the float needles do that. They should snap right back out, not slowly slide.

Also, since you've got it all out, check the airbox. Is the gasket OK? Is the little foam baffle behind the air intakes intact \ in place? Replace your air filter. Even if it doesn't look that bad, it's cheap and a pain in butt to have to do later. Get a nice K&N one. Also, replace the fuel filter (don't clean it). They're like $10. Check your fuel pump, as well.

Once you've got it all back together again, make sure all the bowls are getting fuel in them (open the drain screws). You shuold see a steady stream of gasoline come out.

 

hey johnny...I've read that the fuel pump doesn't pump until the engine starts, how do you fill the bowls after a carb clean?

 

cranking

 

Yea, what he said...

As for the slow jets, I don't think you're going to be able to get a piece of fishing line to go through them. The hole is smaller than the line and it's not going to be stiff enough for you to push it through.

 

wow 3 month old post getting replies

btw, i'm on my 3rd set of carbs now

 

3 sets of carbs in 3 months? Um, please tell me that your normal cruising RPMs are just past the redline

Why?

 

1st set was from the PO, they were F2 carbs which i learned have smaller jets, and dont have a throttle posistion sensor. So i ordered a 2nd set off ebay (big no-no) to which the seller lost them in a warehouse for 2 weeks, and ended up sending me a set that was different from what I had won on the auction... upon receiving them (a month after i won the auction) i found it had broken parts, and when I took them apart to clean them, dirt and powder came out the float bowls. So i start taking the jets out, and broke 3 within 5 minutes because they were so stuck / gunked up with this **** that was in there. So my 3rd set is now in the mail and will be here in a couple days. Praying that 3rd time is a charm!