99 Rotax 670 Running Poorly under wide open throttle

[josh599903]

I have a 99 Summit 670 rotax. Everything on this motor checks out good..(compression,cylinder leakage, etc.). I've got it jetted with 360's which is right according to the jetting chart, even the plugs are looking great, the power side is a little darker though. This sled is bogging under wide open throttle like its losing a cylinder. Also when I hit like 45 mph even varying the throttle does not seem to gain any more power. I have digital EGT's, the racepak avenger 2, I can't seem to get the display to show both EGT's simultaneously though. Any help would be greatly appreciated.

Josh

 

[Coldfinger]

I forget what it is called, maybe Electronic Control Module, but it by the oil tank and have a lot of wires. Anyway, these were notoriously bad. Everyone I knew with a 670 had to replace these. Mine was done under warranty and has been fine ever since.

 

[josh599903]

also this sled has had the DPM removed from it, so I am manually jetting it.

 

[ak]

If you still have your Dpm? reinstall it if you do. Another thing is to have BR9es plugs gapped propery and to replace the hard rubber sparkplug caps with the plastic style. And make shure the caps are making a good connection. Ar sensor in the Airbox needs to be plugged in are it will run like crap. Bottom Line Put Your DPM back on.

 

[josh599903]

The DPM did not come with this machine when i bought it unfortunateley. but it was running great for the last 4 months or so without it. What about my clutching, coud this be affecting my "bog" situation?

 

[ak]

The DPM did not come with this machine when i bought it unfortunateley. but it was running great for the last 4 months or so without it. What about my clutching, coud this be affecting my "bog" situation?

Your bog could be affected buy clutching but you would notice it more on low end not top end, you dont know whats in the sled for clutching? Check your springs and make shure there not broke its pretty rare for a ski doo spring to break. How have you been riding the sled for the last 4 months There wasnt any snow in september?

 

[ak]

I have seen the electronic modules fail also, Does the sled run good when its cold and bad when it warms up? Also stock Summit X jetting is 350/ 340 with 44 mm carbs, A mxz has no Dpm and 40 mm carbs and runs 290/300 mains You may be jetted real fat if your at high alttitude. What readings is your egt getting for full throttle? And it never hurts to run Isoprophlyne in your tank along with fresh fuel.

 

[winter brew]

Broken primary spring comes to mind.

 

[MountainPowder]

I forget what it is called, maybe Electronic Control Module, but it by the oil tank and have a lot of wires. Anyway, these were notoriously bad. Everyone I knew with a 670 had to replace these. Mine was done under warranty and has been fine ever since.

Yup, replaced one on a 98 Summit X couple years ago, was expensive too, want to say like $500-600. Hope its not that for you.

 

[josh599903]

I am jetted fat at 350's EGT's are around 950 to 1100. Fresh fuel, iso heat, clean tank, dry air box too. Yea I guess there wasnt any snow in september lol. If my secondary clutch is stuck would it affect my top end?

 

[ak]

Yes it could.