kviper
VIP Member
Ok, I run. The same belt and have been through a couple clutch kits trying to ballance clutching to flatten wot shift rpm. Just put a TAPP primary on and dialing that in but still seem to have the rpm drop. I'm seeing a 25 to 30° iat temp increase that is consistent with the rpm drop. My thought at this point is that even 25° iat increase is enough to drop power off peak.
1nc 2000
Lifetime Member Tim
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- Marquette, MI
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- Snowmobile
- Yamaha FX Nytro RTX SE
For me after switching to xs825 belt and adjusting clutching for it my rpm's were more consistent after that.
kviper
VIP Member
Interesting! Seems to be a big variable from sled to sled.
When is the last time any of you guys put in a new set of plugs gapped to .020"? If the answer is not within the last year, I'd suggest you give it a try.
kviper
VIP Member
1900 miles on my sled with original plugs. I guess it would be worth a try. Have you seen this go away with a plug change?
Yes, multiple times.
kviper
VIP Member
I will give it a try. Thanks!
yamahahaapex
TY 4 Stroke Master
I'll be trying plugs next. Picking them up today. My RPMS seem to drop as well but Im just chasing this damn boost issue
1nc 2000
Lifetime Member Tim
- Joined
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- 3,210
- Location
- Marquette, MI
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- USA
- Snowmobile
- Yamaha FX Nytro RTX SE
8800 miles on the original plugs. Guess I'll put in a set and gap them to .020".
Couple of logs to illustrate this. First is 2 weekends ago, pulled out onto the lake after a 20 minutes trail ride and gave it a pull. No rpm, didn't stay in it long. Tried another pull, same result:
Yesterday - same sled, same clutching, very similar temp/snow conditions:
Only change to the sled was a set of new plugs...
Yesterday - same sled, same clutching, very similar temp/snow conditions:
Only change to the sled was a set of new plugs...
All i can say is....I'm glad i'm not the only one seeing some timing pulled and a spike in afr's when the throttle is wacked! What were the outdoor temps during that second screen shot?
Second screen shot was yesterday. Temp was -1c. First screen shot was about -6c. Just checked the log for the 1st screen shot and IAT was 73 at time = 1217.
My AFR's were high until the sled got moving at anything below 15F. I just noticed this was a roll on so i'm kinda surprised to see that 1 + degree pull on timing.
You can see that it correlates to a lean spike if a/f, which I assume is the reason it pulled timing. Why, I don't know, but it's an outlier in my logs so not too concerned about it.
