I've got an 04 Ds650 with a 15r front sprocket, k&n air filter w/ pre-filter, pro circuit exhaust,stage one jetting, and a dyna ignition cdi. it only tops out at about 70-74mph and i'm looking for a little bit more top end, is there any way i can do that without changing my sprocket back??

 

Maybe 22inch rear tires would help for a couple mph's...

 

are you hitting the rev. at 74mph or are you running out of power? I would guess its the rev limiter. If thats it go to 22s like baja said and ron woods cdi and some head work with cams then ............ the list goes on and on

 

I've already got 23inch bearclaws in the back. and stock z400s are keeping up with me on the top end. i think im just going to switch my sprocket back to a 16t. the 15t seemed to have slowed me down alot.

 

The 15 tooth will give you more out of the hole but will hurt top speed. if you are running a 23" rear tire, I would keep 15 tooth on the front but change the rear sprocket to a 38 tooth. that will put you very close back to the stock ratio and should bring up you top speed.

 

you're running heavyass utility tires on a sport bike. if you put utility tires on your ds it must be because you ride trails and get into mud. if that is the case then top end really shouldnt matter. but if it does matter, then you need to go back to a sport tire and shed some pounds off your rotating mass on the back end.

also if your jetting is off it will rob you, make sure you have the correct main jet in by trying different sizes and comparing results against your buddies, if you got a jet kit that's telling you what size to use experiment anyway, you may be surprised what you gain.

 

+1 for reducing that heavy rotating mass! Plus, re-gear and/or add some more power!

Gearing chart puts you at 94mph with 15/40, 23's and the DYNA's 8900 limiter. You've basically lost the use of 5th gear. I'd say he's running out of power. There is plenty gear there and going back to the 16 will make it worse.

You need to run a 14/44 (or the like) with that set-up to bring 5th back into a usable range again with those tires and rev limit.

Chris

 

Thank you for the advice on the rear tires and re-jet. but I dont understand how a 14/44 will help my 5th gear power. wont that drop my top end speed like 10 mph?

 

Your 23" tires are making your gearing to tall and out of your power range to pull it.

As its set up - 15/40, 23's and the DYNA's 8900 limiter = top speed of 94mph topped in 5th. The top of fourth with this set up is 79mph. Your not even pulling all of 4th as you said you can only pull 70-74mph.

Same as above but putting the 16 front back on = top speed of 101mph (maybe with hurricane force winds at your back going downhill)

shortening your gearing with a 14/44 (or the like) with your set up = top speed of 80mph, bringing 5th gear back into play and more than likely it will actually be able to pull with your set up.

Chris

 

would 22 inch sport tires fix my problem before i change my gearing to 14/44?