jetting question

[NetBSD]

im getting confused here about jetting and stuff, i have this carbs101.pdf and its showing this...



now when im crusing at 65mph in 6th gear about 5,000RPM it acts like its starving for fuel, this is around 1.4 throttle, if i go full throttle it is fine or if i back it down to 1.8 throttle (like 3,000RPM). so what do i change? do i raise the needle? the way it looks i can only do the needle or the valve cutaway. lets hear what you guys have

btw this is on a 1980 gs450l with pods, PO put the pods on and the jetting is damn close. i did plug chops and its always gray, even when just crusing around id check them and they are gray.

btw heres the pdf http://imnotmark.zapto.org:3030/gs450/carbs101.pdf


EDIT: i have the air/fuel mixture screws out 3 1/2turns, trying to figure this out and it still acts up.

[tkent02]

Try raising the needles, if you don't like it put them back.
Much harder to undo a slide cutout change.

[trippivot]

the next larger pilot jet and /or needle adjustment
maybe both do 1 thing at a time and you'll get there. you are on the right track,and almost there.


Gray is cool but chocolate brown is better (plug color)

[NetBSD]

ill give it a shot next nice day. been raining the past 3 days


thanks for the help

[don_gibb6512]

Raise the needle. You'll probably need to shim it using small washers. Don't turn the air/fuel mixture screws out any more. If it's idling ok and running good around town on the 1/8 - 1/4 throttle, they're fine.

[NetBSD]

Raise the needle. You'll probably need to shim it using small washers. Don't turn the air/fuel mixture screws out any more. If it's idling ok and running good around town on the 1/8 - 1/4 throttle, they're fine.

yeah ive been told anything past 2 1/2 turns you need to change stuff but i was trying to temp fix this till the winter but its really ****ing me off.

ive never had this style carb apart before, im used to working on offroad carbs that have the cable down thru the top of the carb and into the slide, and those have notches in the needles for this sort of thing. how far would you guys say i should shim the needles? i know im gunna have to play a bit but whats a good starting point

[don_gibb6512]

SMALL increments. I think about 1 mm. You can buy needles with notches but do your research first. The taper of the needle also has a big input on how the bike responds. The guys at www.carbparts.com are good as are www.sudco.com

Normally, if you're turning out past 2.5 turns on the air/fuel mixture screws you should consider increasing the pilot jet size one step but I've learned that that may not be the case on all sets of carbs. My experience has only been with the Mikuni BS34SS and 34mm RS Flatslides.

I do think that raising the needle will fix your problem. No matter what changes you make to the carbs, stick with the rule of "make only ONE change at a time". It can be real nightmare but with some persistence, you can make it work. The GSR is a great resource.

[NetBSD]

well i got it fixed, raised the needle with a few washer/shims i got from a hardware store and backed up the mixture screw to 2 turns out, idles great, all positions of the throttle is perfect and multiple plug chops show a nice gray/brownish burn on the plugs.

also when ripping into the bike i noticed the one filter (these are foam uni filters) was ripped so it was getting alot of air flow on the right cyl. orderd up some universal 48mm pods to toss on it and then gunna play with the jetting if it isnt right. thanks for the help guys

[don_gibb6512]

Excellent !! Thanks for letting us know how it worked out.

Don