madsledhead
01-30-2002, 09:19 PM
Hi,
I need some help trail tunning a 98 XCR 600.
* * This machine has been great for top end high speed and accelerated real hard - was set up for lake running and hard cross country. But since there isn't a frozen lake this year I have dicided to "tone it down" for trail running through woods and such.
* * The clutching and gearing are now stock, stock reeds, and stock jetting. (except running 360's on all jugs unstead of 380's - top end was way rich)
* * Here is the problem. The pilot stage runs real crips, up to 5000 rpm - then there is a flat spot up to 5600 RPM. After that range - the sled bolts to 7600 RPM and you have to back off the throttle. once backed off, the sled stays in the 5000-5600 range.
* * Plugs check out OK ant this range - light tan. At first I thought it was the transition from pilot to mid-range but when I leaned out my pilots I was getting poor combustion below 5000. And still a flat spot at the same range.
* * I then tried to keep my secondary tighter using different combos but the range is still apparent.
* * After talking to Polaris racing dept. - They say that there is no problem or revised jetting - But my buddies Ultra 680 does the same damn thing. I have read in other posts that most H.O triples do that as well.
* *Leaning out the stock needle did nothing for that problem as well.
* * I sync'd the carbs perfectly using a manometer, EGT is good, Engine temp is good. Plugs look good. But when I crack the throttle from this range I get a small hesitation (not a bog)
* * Could the needle be wrong? How about changing the spark timming? Anybody done these tests?
* *There is absolutely no problem past 5600 - throttle responds on demand and the sled pulls it front end off the snow about 1 foot. But you cannot maintain speed - only accelerate. Once you start to maintain RPM, the secondary opens and you are too fast for the woods.
* * I know this sound like a clutching problem, but I am sure it is combustion, spark timming, Ect. I am concentrating on the engine.
I hope I have given enough info to get help, I can answer anything I have missed if you ask.
I need to fix this problem fast or else I will need to take my wifes "formula DLX" on my next trip and my buddies will laugh at me - so please help.
Thanks in advance
I need some help trail tunning a 98 XCR 600.
* * This machine has been great for top end high speed and accelerated real hard - was set up for lake running and hard cross country. But since there isn't a frozen lake this year I have dicided to "tone it down" for trail running through woods and such.
* * The clutching and gearing are now stock, stock reeds, and stock jetting. (except running 360's on all jugs unstead of 380's - top end was way rich)
* * Here is the problem. The pilot stage runs real crips, up to 5000 rpm - then there is a flat spot up to 5600 RPM. After that range - the sled bolts to 7600 RPM and you have to back off the throttle. once backed off, the sled stays in the 5000-5600 range.
* * Plugs check out OK ant this range - light tan. At first I thought it was the transition from pilot to mid-range but when I leaned out my pilots I was getting poor combustion below 5000. And still a flat spot at the same range.
* * I then tried to keep my secondary tighter using different combos but the range is still apparent.
* * After talking to Polaris racing dept. - They say that there is no problem or revised jetting - But my buddies Ultra 680 does the same damn thing. I have read in other posts that most H.O triples do that as well.
* *Leaning out the stock needle did nothing for that problem as well.
* * I sync'd the carbs perfectly using a manometer, EGT is good, Engine temp is good. Plugs look good. But when I crack the throttle from this range I get a small hesitation (not a bog)
* * Could the needle be wrong? How about changing the spark timming? Anybody done these tests?
* *There is absolutely no problem past 5600 - throttle responds on demand and the sled pulls it front end off the snow about 1 foot. But you cannot maintain speed - only accelerate. Once you start to maintain RPM, the secondary opens and you are too fast for the woods.
* * I know this sound like a clutching problem, but I am sure it is combustion, spark timming, Ect. I am concentrating on the engine.
I hope I have given enough info to get help, I can answer anything I have missed if you ask.
I need to fix this problem fast or else I will need to take my wifes "formula DLX" on my next trip and my buddies will laugh at me - so please help.
Thanks in advance