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post #1 of 4 (permalink) Old 04-29-2008, 03:59 AM Thread Starter
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Carb advice needed

Since I got my bike (96 Suzuki RF900) and got to know it, I've thought it was running rich.

I think this for a few reasons, people have told me it lets out a puff of black smoke when I really nail it, the midrange seems a little doggy, and when you hold the throttle open in a high gear for a while then roll off a bit, it feels like I actually begin to accelerate faster. Not to mention the heavy soot in the outlet of the muffler.

OK, so I took the carbs off and took the bowl off one of them. The main jet is a 118, which is larger than the largest factory jet which specifies a 115 for the German-spec'ed model.

Mine is the USA spec which I think calls for a 112.5 main jet. I'm not 100% sure of that because for some reason, the Suzuki repair manual I have does not list the USA-spec bike. But, the 112.5 main jet is most common on several models including the Canada spec.

So, it would seem someone has re-jetted the bike, but I don't know if the needle is different, or if the CV slide spring has been changed, etc. I can't ask the previous owner because he's deceased - was when I bought the bike.

The bike's pipe and muffler are stock, afaik, but it does have a K&N filter in the stock, unmodified air box.

The question is, do you think I should just try a smaller main jet (maybe the 115) and put the needle back to the stock-recommended 3rd notch down because it's currently 4th notch, and give it a go?

Or, just get a complete different jet kit (DynoJet?, Factory Pro?, Ivan's?) to put in so I know what I've got for sure?

Last edited by Whoaru99; 04-29-2008 at 04:07 AM.
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post #2 of 4 (permalink) Old 05-07-2008, 04:37 AM
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Dealing with the carbs, for me, has always been a trial-and-error process. Does the service manual offer any guidance?

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post #3 of 4 (permalink) Old 05-07-2008, 12:56 PM
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I agree with your diagnosis, and going back to the 112s and stock needle height may cure the problem. If not it will give you a good baseline from which to begin.
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post #4 of 4 (permalink) Old 05-08-2008, 11:15 AM Thread Starter
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Best I can tell, the rest of the carb parts seem to be stock, although the CV spring remains unknown. At least the CV slides aren't drilled, and the other jets are factory, including the needle jet.

So, parts are on order for 112.5 and 115 main jets, one CV diaphragm, and various o-rings.

Hopefully, the parts will arrive tomorrow...
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