I keep having these little annoying carb problems. Some days she runs great and some days she don't. I have (actually bob) has taken it apart 2 times. Once we just pulled the diaphams out of it and blew air thru it. Ran great!! Then it went back to its old evil ways right before a dragrace. Runs strong on the bottom but does not like to rev out. Took apart again and replaced the choke cable and spring assembly. The spring was corroded up and the choke would stick part way open. I can stay in a gear and run at a steady mid rpm and after a short while it will start sputtering and bucking. At that point it can increase the throtle and she will clear up. Any ideas???? I see the day that my baby loses a drag race to a common DS because of this. Makes me nervous around DS's. I do not mind losing to the raptors! LOl

 

try cleaning the pilot circut, this overlaps in the midrange,
also see if the needles have become disloged in the slides..
if you had crud in the choke, chances are there is some in the pilots as well..
the hole sizes are a LOT smaller in them than the mains..
('course, I'm not a wrench..but iff'n it were mine I'd check that, as well as air leaks in the intake.)

 

The very bottom of the hole in the slide where the needle goes is actually D-shaped, there is a flat on one side, in all the BSR carbs I've had apart (assuming you're still stock on carbs here). I've never had a Raptor carb apart, but I'd guess its the same as the others. This makes the needle sit a little crooked unless the bottom spacer under the clip gets a flat ground on it to fit the shape. With the needle crooked, it barely rubs the inside of the needle jet, causing a wear mark on the needle over time. This may have a small effect on fuel/air atomization, not really sure, but both of the carbs I've done this too seem to be a little more crisp now.

Not saying this is your trouble, but it might possibly be of help. If nothing else, its an improvement after you find another potential problem. I don't know why this flat is down there - they surely don't intend for the needle to sit crooked and wear on the side like that - My guess is that its shaped to accomidate the shape of the clip, and maybe the bike manufacturers add spacers instead of changing to a longer needle, in turn causing it to be crooked. My DS carb and two Cat carbs were like this.

Get her tuned and then we'll race - just wait for my mods to catch up with your first...I'm still a little old 653cc with stock compression.

 

Thanks for the replies so far. My baby has always had a fuel filter on it from day 1. That was the first modd. I love taken the plastic off my baby.

 

first off i would toss the fuel filter.they are junk and worthless.your gas tank already has a filter in it, why do you think the factiry don't put inline filters on the machines?
then i would go through the carb thoroughly,be sure that the needles are seated tight and make sure your mains are tight.it almost sounds like your loading up in the midrange.

 

I had that problem once. I noticed that my plastic cap that holds the needle in place wasnt seated all the way down allowing the needle to bob a little bit. My Rap was running like crap, I opened the tops of the carbs and checked them out, it cleared up. Awhile later it was doing the same thing. I tried the topside of the carbs again and noticed one cap was a bit higher than the other. After pushing them in with needle nose pliers I havent had the problem since. Hopefully that's the trouble you're experiencing.

 

Have you changed your needle settings? Are you running no lid? For a mere $60, you should really try the Dyno-Jet kit.

 

Gary- i had the dyno kit in at one time. My jet size is now a 180 and a 187.5 I should get the dyno jets for that size and try it again. Thanks everyone for the suggestions.

 

14mins. as time passes, I think you'll find many people have a 1/4-1/2 throttle problem but just don't know it. Moose & myself have the same problem & I have replied to it in the post "Raptor,Yoshi Competition FS TEC pipe,K&N,and Proflow" -that title was definitely too long! Anyway, there you will see that the common thread is that taking the lid off opens up a can of worms & may require changing carb parameters other than the clip position,pilot size, fuel screw, Dynojet vs Mikuni, etc. Changing things like, slide cutaway may be necessary, if anybody makes different sized slides that is. See the other post & you'll see what I am rambling about... I certainly haven't perfected the jetting with no lid but I am tired of peopel telling me 1/4 turn of the fuel screws should do it-not!

 

Chimmer- thanks. Bob and i are going to try a few different ideas out. Don't get the wrong impression here, the quad runs great, but could be a little better.