Optimal track run-out

Hbmtr · Feb 14, 2015

So i got my 1st real ride on my 14 MH ST mounted to a 07 crf 488 couple of days ago out here in the driest winter the CA Sierras have seen in years,but was riding @8500ft to 10,000ft off of MT.Rose Hwy.

Bike had good power and snow was starting to transition to spring time conditions on south exsposures but east and North faces still had decent snow.So ichecked my run out after a post ride inspection and tightening primary chain plus chaincase chain.I measured 12.75 inches.1st gear is a crawl and 5th is maybe 40mph at the most.I have stock chaincase gearing and a 13 counter shaft sprocket.

I know this is a compramise but i get to 5th in a heart beat what are your recomondations.

Cvbracing · Feb 14, 2015

Track run out

I'm far from an expert but I had the same problem on my YZ. I swapped the sprockets in the chain case and love it. Just put the small sprocket on the bottom and the large on top. Makes it feel almost like the bike did with wheels.
Good luck

CATSLEDMAN1 · Feb 14, 2015

gear'n fur success

the issue with the sno bikes is the extremely wide snow conditions and how those conditions affect performance on any given day. We need about 8 or 9 speed tranny's to maintain as good as performance. Ride that bike some more, snow and terrain will dictate your best compromise, you are pretty close to ideal for a kit like yours in West Mt vertical tree hugging.

Hbmtr · Feb 14, 2015

CATSLEDMAN1 said:
the issue with the sno bikes is the extremely wide snow conditions and how those conditions affect performance on any given day. We need about 8 or 9 speed tranny's to maintain as good as performance. Ride that bike some more, snow and terrain will dictate your best compromise, you are pretty close to ideal for a kit like yours in West Mt vertical tree hugging.

completely agree on the wide variety of snow conditions that are out there on any given day.I weight 155 w/no gear so pulling 3rd gear is not a problem on good climbs.If i wanted slightly taller gearing would you rec.going to a 18 on top gear of chaincase?

kylerf150 · Feb 15, 2015

I don't Know if you have read this but there is allot of info in this link.
http://www.snowest.com/forum/showthread.php?p=3403001&mode=linear&highlight=gearing#post3403001

I dont have any recommendations for you right now. I am running 15 kits and am pretty happy with the stock gearing. The 500xcw could use a change but im going to live with it for now i find myself jumping from 2nd to 3rd constantly. Let me know if you want runout numbers i can go out and get them for ya.

I would personally try just swapping the gears around in the chaincase and see what it does for ya.

PST · Feb 15, 2015

Gear

I had a 06 and 07 Crf450 and ran a 16 top and 17 bottom with a 13t counter and loved it. First gear is useful and 5th was high enough for down the trail. Rode at 8000" to 10000'. Engine had 13:1 piston, stage 2 cam and Dr D exhaust exhaust. I weigh 175 lbs. You should have no problem pulling this gearing at 155 lbs.

CATSLEDMAN1 · Feb 15, 2015

gear head

I need to check my runout, I just regeared. 2.5" lug track and lots of wet snow this winter, so I dropped. I'll go check my track movement. I like it for now.

3" of cold dry snow though and I would be in 5th zinging right now. Last week it was tough to pull and 4th on a flat, mush.

CATSLEDMAN1 · Feb 15, 2015

I checked

My bike is WR450 with timbersled clone with tweaks. but a whole lot the same.
144" 2.5 track.
14 tooth bike to 18 driven
16 top 18 bottom in my chain case
results in 14" Track run out

checked Dan's 450 ktm 6 speed bike has same kit as mine
I didn't count his sprockets I know is runs a 15 on the bike
He remembered his run out from last year at 15 or so.
However it turned out to be 14" when we measured.

Down a flat road my wr450 seems a little higher geared..........because of the 1/2" taller track. But on a run for home down a sled trail, he can always hit 6th gear and leaves me if the running is that good. I would guess about 50mph cook'n along.

Hbmtr · Feb 15, 2015

Great info! thanks for your replies.I rode today in true spring conditions in hilly woods with constant direction change and found the lower gearing helped.Go figure.:bowl:

As i ride more and start to carry more speed i will probaly gear up.Once again thanks guys

Hbmtr · Feb 15, 2015

PST said:
I had a 06 and 07 Crf450 and ran a 16 top and 17 bottom with a 13t counter and loved it. First gear is useful and 5th was high enough for down the trail. Rode at 8000" to 10000'. Engine had 13:1 piston, stage 2 cam and Dr D exhaust exhaust. I weigh 175 lbs. You should have no problem pulling this gearing at 155 lbs.

On your 07 crf did you ever try running a 14 countershaft sprocket.would it fit?

Curt_T · Feb 15, 2015

03 525sx with gears at 13-17 and 17-16 I can pull 55-60 mph in fourth gear on the trail. Or that's what the guys on the sleds say. No gps verification. I can check roll out tomorrow. But I have plenty of power for everything. Run 4th gear almost all the time and bang third to climb.

kevinhoglund · Feb 16, 2015

I have a 15 LT Stock Gearing.
04 525 EXC with 13 tooth sprocket -13-1/4" run out
14 tooth sprocket- 14 1/4" run out

I run the 14 tooth sprocket.

3rd and 4th gear hill pulls. 5th gear trails very fast.

Hbmtr · Feb 16, 2015

Ok just so we are clear,roll-out is being checked in 1st gear. If thats the case then my 12.75 inches is pretty low gearing wise.

After breaking both of my legs last year motocrossing top speed should not be a priority,but being able to properly use my available torque from my 488cc.:face-icon-small-coo

mrquick68 · Feb 16, 2015

rollout is not effected by what gear you are in. Its just how far the track rolls-out per countersprocket rotation.

It's a rule of thumb anyway, as each bike model's given internal gearing is different than the next. So, get close to 13.5" or so and make small adjustments from there up or down depending on your bike, your weight, your snow type, your track, and your elevation.

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Optimal track run-out

Hbmtr

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PST

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