Carb backfiring?
 

So I got the bike jetted and set up and it runs awesome, throttle response is spot-on, it pulls HARD at all rpms....but I noticed the cold idle was only around 750 rpms and the bike kept cutting out even after a few minutes of choking it...and warm idle was about 850, well below spec.

Well, I upped the idle via the little thumbscrew, to about 1100...and now when I'm, say, pulling into a parking lot and I pull the clutch in and give it a blip of the throttle, it keeps backfiring through the carburetors??

Did cranking this screw somehow make the carbs lose their sync maybe? Any ideas?

I think the carbs are loading up at low rpm's and when you goose it, too much gas goes into the chamber and causes it to burp. You might double check your choke cable and make sure everything is clear. If the cable is caught on something it might not be completely clearing when you think it's full open.

I know that he disassembled and cleaned the carbs and since all of that, the choke works quite a bit differently....it's much, much looser on the pull, but it also takes a further pull to work effectively....I'll bet the cable has slack and is binding up, because it doesn't seem to start even choking at all until the cable is 1/3 of an inch out....

Thanks, I'll check it out tomorrow!

Does the choke supposed to stay out when you pull it? I just bought my bike, used with no manual, and you have to hold the choke out?!

When you pull it out it should hold its position. Some will slack off a bit as the bike warms but not much.

Slip the little rubber cover off of the back side of the choke, not the cable itself, but where it's mounted.... You'll see a little nut there, just tighten it up some until the cable stays in place, and slip the cover back over it. Greg's got a write-up on it, it's a common point of confusion

Brooks,

Whenever you rejet you should perform a carb sync. I think that's your problem. What are your mixture screws at?

Here are the notes I got back from the mechanic Greg:

"Cleaned carbs, synchronized carbs. Adjusted mixture screws. Installed factory jet kit, 178 mj front, 180 mj rear, 50 pilot jets, needles in 3 position"

It only started this the other night, after I upped the idle just a hair because it was stalling at idle. It still runs awesome and has great throttle response, even down at 2000 rpms it will make the front end climb up....but it won't take a blip

Mixture screws then. If they did not provide the settings they probably don't even know they're there and didn't touch them...or set them wrong.

So how should I go about correcting this? As I mentioned, the bike runs AWESOME...it just backfires now and then...did it once tonight in a 45 min ride..almost afraid to fix "good"

Take it back to the dealer. Ask them to adjust the mixture screws. The tool required (which they have) makes this a 2 minute job. Shouldn't cost you a penny.

This bike is a 98 and has been modified.... I'd rather be given a link to adjust them myself, for the tool...

And you dont know the dealership here! Scumbags.

What brand jet kit was installed? Factory or Dyno? Factory provides the tool required to adjust mixture screws. Maybe the Dyno kit does too, but I'm not familiar with the Dyno kit.

It was a used Factory kit.. What's the tool look like>? I'll see if it's in what he gave me leftover

SuperHawkins it is the bulkiest thing in the kit, about 3 and a half inches long, one end has a D shaped indentation, which fits the mixture screws, the other end would fit a small ratchet.

I bought the kit used...it had everything else in it but the previous owner must've taken the tool.

I couldn't find the end of the choke cable. Do I have to remove anything to get to it? Where is Gregs link, I did a search and couldnt find it?

What was meant was the end where the knob is. Right behind there is the nut you tighten.