High rpm problems
 

I have some problems at higher rpm:s on my -97 Hawk. The bike just wont rev more than 6500rpm before it looses all power. I have checked the carbs for clogged jets but they seem ok. The spark plugs looks like it runs a bit rich. The set up of the bike is: Dynojet, KN-filter, Arrow slipons (originally from a -05 Suzuki gsxr 1000), modifyed airbox (Burnie Morgan). Main jets are #200, pilot jet #45. According to previous owner it ran just perfect with this set up. Any suggestions what it could be?

Have a look at THIS THREAD. You seem to be experiencing the exact same conditions. The "previous owner" is not always a trustworthy source for reliable information.

Yeah, for the mods listed the 200 main jet seems way big. Maybe the PO had a Harley and didn't realize motorcycles revved beyond 6000?

Well, it was actually the guy who built the bike from the start that told me that it ran ok with the set up used today. I wouldnt trust the PO even if it was a friend of mine. Anyway, I have ordered new main jets in a range of #175 to #185 so hopefully this will help. I have learned that the Dynojet needles wear out the jets which could cause my problems. The Dyno jet kit was mounted 8 years ago so....If that doesnt help I am thinkin of ordering new needles and main jet holders.

Got to run pig rich at WOT, I run 180/185
I don't see how it could run with a 200 unless there a supercharger hidden somewhere :D

I had the same issue on my bike when I got it. 2000 SHawk. Check all of the wires under the seat to the ecu. Check the battery Wires and Get some Sea Foam. Dump that stuff in your tank and say goodbye to the stumbles at high rpms. You can get it at any auto parts store for less than $10.00

If that doesnt work..the dude that jetted it did it wrong...

I had the same issure when I got my first VTR. It had a 198/200 main jet combo. returned it to stock and all was well.

Got the ordered jets today so hopefully I'll find some time to mount them tonight. I've seached the bike looking for a super charger but so far I havent found any :D

I have drained the fuel tank this winter so it shouldnt be any water in there, but I guess it wount hurt to put in some carb cleaner or Sea foam.

Thanks for all help, I'll get back with the results as soon as the jets are mounted!

supercharger...its in there some where right next to the loads of torque and hp!!!

ok, got the 180/185 jets installed and the bike runs much better but it still hesitates and studder at WOT. I'll try the stock jets today, getting really tired of taking the bike apart every second day!

Do you guys use the Dyno jet needles or the stock ones?

Stock

I run a DJ kit, needle installed @ 4th notch, You are running the same jets as mine but I don't have a K&N filter, witch improve breathing a lot, maybe your best setup is 185/190
Check your plugs to see if the carbon turned white, give it a few WOT pulls and it should put you on the right track.
Soot black too rich
Carbon that turned white, too lean.

I run 2 1/2 turn of idle screw and stock pilots, 48 I think, not quite sure

Went back to stock jets 175/178 and it runs better than with 180/185. It is now possible to rev it until it hits the rev limiter, but it still takes some convincing to get there. This has not been possible with the other settings. The idle screws are 2 1/2, pilot is #48 and needle on 4th notch, but these wount influence the high rpm, right? I've just ordered a stock air filter so I'll se if that helps.

You should try the stock needles if you have those as well.

Is it possible that you have flip-flopped the emulsion tubes?

What brand of jets you have, are they factory jets ?? It should like a bit more fuel than this, but you seem to go the right way tough.

Nope, I dubble checked the emulsion tubes (found a picture of them on this forum). Unfortunately the stock needles were lost some where in the chain of PO:s. Ordering new stock needles will be the next step if the new air filter doesn't help.

The #200 jets are Dynojets and the #185, #180, #178 and #175 are Honda factory jets. I'm getting quite confused that the bike runs better with the stock jets than 185/185 with the modifications done. When seaching the forums for suggested settings, the 185/180 seems to be the best. Might be that the Dynojet needles are worn out? The air/fuel mixture should be different with dynojet needles than with stock needles since the dynojet needles have a "neck" at the tip, right?

What is this "modified air box (Burnie Morgan)" that you speak of in your first post. From my experience, there is a lot of r&d into late model motorcycle air boxes and they are better left alone.

Well it is actually the air filter rather than the air box that has been modified, http://www.burniemorgan.com/firestorm/airfilter.html

This was done by the PO so I can't say if it had any effect or not. I've just picked up a stock air filter so hopefully I will find some time to install it before the weekend, than I can tell you if the mod did any difference.

Ok, it wasn't really clear what I ment. What I was trying to say is that the ammount of fuel thru the jet should increase if Dynojet needles are used since the diameter is smaller than on the stock needles, meaning that the jetting is depending on the type of needles used, correct or not? Someone?

Keihin jets are designed to work with Keihin needles. Dynojet jets are designed to work with Dynojet needles. Mixing jets of one make with needles of another is asking for a headache. Also, Keihin jets and Dynojets with the same number are NOT the same size and do not flow the same volume of mixture.

My advice based on personal experience? Use the OEM air filter, Dynojet 175/180 mains, Dynojet needles on 5th position.

Maybe the guy choked the airflow, reducing the need for fuel and believed that his 20hp air filter mod was in need of big fuel :lol:

That makes sense to me 'cause, 1) there's been such thing as a 20 hp filter mod since about 1986, and 2) #200 mains don't make sense at all without major engine mods, a race air filter and free flowing full exhaust system.