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11800 rpm (to high?)

dookiller

Guest
Joined
Nov 4, 2009
Messages
11
I notice that on average cruising in the field at 60 km/h this thing revs just around 10 000 rpm and when I nail it it gets up around 11800. Isn't that a bit much. (08 mtx) Top speed is 114 km/h on hard pack. Should I be upping the flyweights in this thing or where is the optimal rpm? I think it is geared a bit low for flat land riding. Lots of low end torque though is nice but would like to see 125 km/h. I this attainable? I bought it used so I don't know what the guy used it for. Thanks for any info guys! :-o
 

Ideally you want to be in the 11000-11500 range. I'm still going through the break in process and I'm going to have to add weight again to mine. I currently have the stock flat lander weight setup in mine which is 13.3 steel rivets in both holes. I noticed quite a big loss in top end speed with it over reving to 11800. I've seen 82mph on the dream meter which is 73mph GPS or 117kph and thats as fast as it would go pulling up to the rev limiter with the clutches fully shifted out. I have a 19 tooth gear I'm going to put in when I change the oil at 500 miles. Running the numbers a 18 tooth will allow another 4mph/6kph over the stock 17 tooth and going to 19 tooth will allow 8mph/13kph over the stock 17 tooth but that depends on if the sled has enough power to pull those gears all the way up.
 
JUST changed my 17 tooth for a 19 tooth and it didn't do much to pull down the RPMs. It only lost ~100rpms. It DID gain top end speed and pulls harder from 70-80mph on the dream-o-meter. Top end went from 82 to 87mph, on the speedo, on the same stretch of hardpack only 1 hour apart. GPS confirms about 4mph extra speed with no over rev on top as the sled didn't have the power to fully shift out the clutches anymore. Once I get the RPM's down to around 11,100 where I want them I think that the 19 tooth will be perfect, just hitting full shift out as the sled hits top speed. I also tried softening up the secondary clutch spring from 55* to 45* (B1 to A1) which resulted in bringing down the rpms by around 200 and no ill effects on backshifting.
 
check to make sure you are running an 8gs belt i was overreving on my 09 with the old red letter belt, changed to the 8 gs and i dropped about 400 rpm at wot
 
backcountrymafia said:
check to make sure you are running an 8gs belt i was overreving on my 09 with the old red letter belt, changed to the 8 gs and i dropped about 400 rpm at wot
did you notice any preformace increase?
 
picked up some top end and it pulled like it should have from day one. the best part was getting the revs down tho. i dont like to see 11, 8 to to 12k 0n this thing your not gaining anything over 11,600 but increased wear in my opinion. dosent feel like it makes any more power at 12k
 
I dont want to steal the thread, but since its on clutches I need a little guidence. Ive always been into the rev limiter at WOT. So I adjusted my secondary from stock 60% to 40% (not sure on what position just remembered the percent but its wrote down in my toolbox) I still fine the limiter frequently so I think I should put more weight on the primary? Just wondering if I'm going in the right direction and what weights I should put where. Also its stock gearing stock clutches.

Interested in gearing too, are you guys just replacing the top gear then, keeping the same chain?

Thanks
Joe
 
ThatOneGuy said:
I dont want to steal the thread, but since its on clutches I need a little guidence. Ive always been into the rev limiter at WOT. So I adjusted my secondary from stock 60% to 40% (not sure on what position just remembered the percent but its wrote down in my toolbox) I still fine the limiter frequently so I think I should put more weight on the primary? Just wondering if I'm going in the right direction and what weights I should put where. Also its stock gearing stock clutches.

Interested in gearing too, are you guys just replacing the top gear then, keeping the same chain?

Thanks
Joe
How many miles on belt,what belt are you running, and do you mainly ride on or off trail?
 
last season i had really good early morning snow conditions and i had just finished breaking in spare belt on my sled which come to find out is different than the belt the sled came factory with. i hit 92 on the speedo
keep in mind very good snow conditions, but i could frequent the high 80's with my mtx on the new belt. when i was stuck at about 82 with the original belt, my dealer took real good care of me on this one, as usual.
running this belt brought the full shift rpms into the 11,400-11600 range the sled seems like it loses power anywhere past 11,600.
 
last season i had really good early morning snow conditions and i had just finished breaking in spare belt on my sled which come to find out is different than the belt the sled came factory with. i hit 92 on the speedo
keep in mind very good snow conditions, but i could frequent the high 80's with my mtx on the new belt. when i was stuck at about 82 with the original belt, my dealer took real good care of me on this one, as usual.
running this belt brought the full shift rpms into the 11,400-11600 range the sled seems like it loses power anywhere past 11,600.
 
Its the 8gs belt, I did that last season, swaped used belt with spare that measured out exactly the same, and no results so I figured I got it narrowed down to clutching. I ride pretty much all trail but I will still mess around in friends hilly pastures jumping and hitting drifts every now and then or whenever I get a chance. Any time I punch the throttle its into the 12s if not the limiter, pretty much all conditions. I loosed the seconday last year 60% to 50% now this year 40% and it helped but not enough.

Thanks
Joe
 
You can try heavier wieghts in your tips in primary. it will bring it down 200-800 rpm. I believe the shorty's were set up with 10.3mm rivets on the inner and center position and 13.3mm outer, both steel. Yami sells a 13.9 and 17.2 steel you could try in the tip? I may be way off base here but I did it for my mnt lite and it did the trick.
 
I'm running the 17.2 in my tips. put me rite where i want to be when the track hooks up but will still over rev when it slips. 17 tooth top gear at sea level rinning 151 2.3 challenger
 


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