Freshen your springs

[sled_guy]

Ok, just a reminder to freshen your springs on your clutches. My 910 has been down on revs a bit... pulling 8100 instead of the 8400 I want to see. I serviced the clutches late last season and they were in great shape, didn't even need button shimming. Spring still 'looked' good so I put it all back together.

Here a week or so ago I serviced them again (yeah, I check them often) and decided to throw new springs in... yesterday was the first ride out on it.

Holy Shnikey... 8600rpm all day long when I got on it hard. Guess the springs were sagged out.

Good news is I get to throw 2grams more weight at it.

So just a reminder, replace those springs periodically.

sled_guy

 

[minus40]

Ok, just a reminder to freshen your springs on your clutches. My 910 has been down on revs a bit... pulling 8100 instead of the 8400 I want to see. I serviced the clutches late last season and they were in great shape, didn't even need button shimming. Spring still 'looked' good so I put it all back together.

Here a week or so ago I serviced them again (yeah, I check them often) and decided to throw new springs in... yesterday was the first ride out on it.

Holy Shnikey... 8600rpm all day long when I got on it hard. Guess the springs were sagged out.

Good news is I get to throw 2grams more weight at it.

So just a reminder, replace those springs periodically.

sled_guy

Do you have a spring tester? I wonder if you got a spring on the high side of the tolerance.

 

[winter brew]

Yep. I check both springs on a lot of the sleds that come through the shop and typically find secondary springs that are supposed to be near 300 at full shift to be down 50-70 lbs at around 1000 miles, sometimes sooner. Primary springs are usually better but down 20-40 lbs is typical.
H5 springs seem to be doing much better.

 

[minus40]

A spring checker is an eye opener that's for sure, taking a new spring and squeeze it in the vise overnight will often tell you if the springs crap.
I liked the old ti springs, will have to try the new stuff, thanks

 

[Thatspec]

Sled guy, you want 8400 out of your 910? You are at 7500' + yes? My 910 info from previous owner is saying 82-8300 (one piece head version). There is a black/green 120/340 in there now and since I've just got the jetting right I'm seeing some 8400's. I'm more 4-6000', today I will know more in some deeper snow. Loving the low/mid grunt

What spring/weights in your primary? Secondary?

 

[sled_guy]

Sled guy, you want 8400 out of your 910? You are at 7500' + yes? My 910 info from previous owner is saying 82-8300 (one piece head version). There is a black/green 120/340 in there now and since I've just got the jetting right I'm seeing some 8400's. I'm more 4-6000', today I will know more in some deeper snow. Loving the low/mid grunt

What spring/weights in your primary? Secondary?

IF you have the reprogrammed CDI from Carl's then you can run 8400rpm without hitting the rev limiter. With 4 degrees of advance and the reprogrammed CDI I run at 8400.

I run slp blue/pink with 10-64s in the primary. 64/40-46 with the slp shim and a black/redstripe secondary spring. 159x2.4 track, 20/43 grearing.

I'm above 7500ft.

sled_guy

 

[Thatspec]

I'm still short on info as I haven't opened up the secondary to see what the spring is but the helix is 66-42-46 er 66-44-46, I think there is a shim in there as there is paperwork on it I received. Today I didn't see over 8300 for some reason, the 84's may have been the track unloading after bouncing off the bottom. Clutches never get very hot and an 080 belt is hanging in there so I'm tempted to not change a thing. Could be that black/green primary is aging and would otherwise be trying to rev higher.

On a tangent for a moment it seems my air screws are 2 1/2 turns out which does seem to be best idle. Fuel screws are 1 1/2, clip is in the middle ('03 needle). Plugs at least look great, just got a bore light for looking at the wash but there's no way really to see to the edge of the piston. Should I go to a larger air jet or does it really matter?

Thanks for the info!

 

[sled_guy]

If its running good I wouldn't touch it.

Are you reading off the stock tach or an Avenger or something? The stock tachs are usually not very accurate to be honest.

sled_guy

 

[Thatspec]

There is an Avenger 3, nothing stock left on the sled but the bulkhead. I've recorded a few mid and wot 25 second runs to look closely. In fact there really is nowhere at my usual spot that you can go wot for more than 10-15 seconds, all trees/boondocking with a few steep larger clear cuts. The clutching seems set up well for that type of riding, it is much different than my other Edge which essentially "freewheels" down a hill while the 910 sled engine brakes down a hill. Not sure if that means it's backshifting instantly or not at all regardless, I prefer the "engaged" all the time clutching, seems always ready to pounce, the throttle response seems very good to me. All that I can tell about the gearing aside from 7 tooth drivers is the lower cog (CMX belt drive) is in excess of 60 teeth, the upper is damn small but it's impossible to count with the belt on, the sled tops out at 70 or so, must be well over 2/1 gearing.

Anyway, thanks for all the info so far. Big snow coming into the NW over the next three days, headed your way

 

[pharotek]

i also have a 910, but i live in New York and ride 0-3000. I have done some head work to the engine suggeted from carls.

turned heads out too 56cc from 50 and squish is 0.72 from 0.50 (was told could run straight 93, though i like to add 1gal to 9gals)
increased jetting to 480's

I am working on a 500' drag setup for this motor currently and my setup is
68g heavy hitters
168/310 TPI spring
red/blk secondary
Helix unknow for i am at work
136"
22/40 gearing with 8tooth driver for stud clearance
8" wheel kit
gutted air box, but for drag i have uni-filters on
This setup seem okay?? hard to see my RPM curve since i cannot log it.

I am at about 8400rpm and based on your statment that is the sweet spot for tourqe? I have the updated CDI and i have one question digatron could not help me with. I have the kit on a 05 rmk 800 bottom end. The tach part of my digatron seems to peak at ~6k. I think it's on the wrong wire, what one should the power be hooked to? it's a DT-33sn?

 

[sled_guy]

Find out what helix you have... 68s seem light unless you are throwing a lot of helix at it, which I would do if I was drag racing the sled.

Mark your clutches and see where they are shifting out to. In a drag race you don't care about backshift so shift that thing out as fast as you can and keep it on the pipe... you might even try gearing it up some more.

Are you asking about what wire on the motor or on the gauge? You want tach pulse from any solid yellow wire that comes from the rectangular 'whitish' colored connector on the motor (some times they are blue by the way). You may have your gauge set to the wrong pulse number. I have an Avenger and in the setup I tell it how many pulses the stator gives out. Its 6 on Polaris big blocks.

sled_guy

 

[pharotek]

Thanks for the info, Since my last post, i have decided not to race the 910 for few reasons, 1. it's is to large for 800 class, 2. i found out lastweekend their is no 900 class anymore 3. i'ts just bit to small for 1000 class. I plan to keep this sled for trail riding and use all the great information i learned this summer at the 4 races i went to and build a pro stock 600 or 800 (depends on what sled i can get). I have heavyier washers on order and few different springs/ helix's after talking to thunder product. Once i get it done i will post back with my final setup. Though not sure if i should post it here or is their and section over in the polaris area for this topic?