I have a 94 600 F2 I am making into a streetfighter/stunt bike. When I purchased the bike it had a KN filter and full V&H supersport system. Of course it ran like crap. So I put in a new OEM filter and it still ran like crab, but slightly better, so I know it’s lean. (Carbs are full cleaned.) I spent $110 on a stage one dynojet kit. It says that the kit is for stock bikes with slip-on or aftermarket exhaust system. Great, should work great! Wrong! The largest jets it comes with is a DJ126 which is = to the stock 135 Jet. Crap! So in a pinch I drill the jet out to a DJ132 jet with a #54 drill bit. Runs much better but still needs a little more fuel I think. I do not believe in drilling jets, I only did it in a pinch. I have two questions. First does anyone have a good idea where an F2 should be jetting with a full exhaust system? Also if I call dyno jet can I harass them for some new jets? I spent all this money for the kit and it doesn't even have the right jets!! Please let me know your thoughts.

 

Its very hard to say what the problem is since you are just now starting to work on the bike.. You didnt mention what the Eclip position is. usually, with a dynojet kit, they will specify how far to raise the needle. If the needle did not get raised along with the new jet, it will not have the fuel it needs as the needle is still limiting the fuel.

You may also be suffering from a leak somewhere. on a model that old, I would suggest looking towards the carb boots. If they are cracked, it will suck in air and the bike will run very lean. You can do a simple check by starting the bike, get some wd40 and spray all around the carbs and the boots. If the rpms raise or fall, you have an air leak in that area.

As far as the jets go, you are probably SOL since you drilled them out. I believe those are the correct jets for that bike and should work as long as all the other steps are taken.

 

There are no air leaks at all. I have been speaking with a guy online about tuning the F2 and he is telling me if I had a stumble between 7-8K Wide open throttleit’s the needle position. I didn't drill the dynojet jets, just the stock jets, so I still got the 126's. I guess with a CV carb the needle is not fully out of the jet at those RPMS and needle position is more import. After a long ride with the drill jets yesterday I noticed that 1st and 2nd gear would rev past 12K, it would stumble. In 3rd gear it would rev to 13K. It’s probably fat up top, really fat. With the 126 jet it would rev fine after 8K to redline. Looks like bad needle position has tricked me into thinking the main is lean. The guy I am speaking with says 122 should be more of what I need /w my pipe.

 

Go to the Dynojet web page, there you can get specs and pdf files of every kit they make. Look up the stage 2 instructionsfor your bike, get both the proper jet size AND needle position...use that as a jumping off point...while you're on it check the p/n for the needles to make sure you don't need one with a different taper. You can buy just the jets for about $2 a piece from the site, and use whatever new parts were in your stage 1 kit to install them. With aftermarket filters and a full exhaust, you need to be running the stage 2.

 

I don't see anything about syncing the carbs in your original post. My bike also ran like crap until I did this. After I jetted it (I used Keihun jets, $40 total), I resynced them. You can build your own sync tool, buy one of the many on the market, or pay the dealer $100 to do it. Try this before you start throwing more parts at it.

And make sure the idle screws are adjusted correctly. Sounds odd, but it will effect your top end, in my expereince.

 

Remember, even though the jets are equivelent in diameter, the dynojet needles are where the meat and bones of the kit are. The ends of the new needles are thinner allowing more fuel to pass through the main jets than the stock needles did. Right now on my F1, I am running DJ needles with the stock 110 mains. I also have a filter, full exhaust and a 6 degree ignition advancer. With these settings the bike runs great!!

 

Correct! Too much misinformation out there, 95% of people seem to think it is all jets. Unless you are running at wide open throttle, the needle is where most of the fuel is controlled...thinner taper equals more fuel, even with stock jets. Raising the needle (moving the clip towards the pointy end) effectively richens the mixture, lowering the needle leans it out.

 

To stay sort of on topic with this thread, when i first cleaned my carbs there was small pieces of tape on the diaphragm springs. I took them off not knowing what they were for.

Could the person before me tape them up to allow more fuel to pass through? From the posts above i gather that the essentially shorter spring would allow less of a strain on the diaphragm to allow more fuel. Any insight? Should i tape them back up again or should i cut them? Or should i leave it the way it is?

If you could find my other post the bike loses all mid to top end above 65mph