ski-dood
Newbie
I have an '03 mtn with 19/39 gearing w/reverse. The 19 it toast and I have a 21 to swap in.
Q#1: Is 19/39 stock?
My donor sled had 21/40 no reverse. It also had a 70 pin chain where the reverse chain was 68 pin. Here comes the big one.
Q#2: Is it better to have the adjustment bolt way in or backed way out?
Both chains appear to fit but the adjustment bolt moves to both extremes to get proper tension. I am thinking the shorter chain would be better because it will run straighter. If anyone has previous experience/advice when re-gearing please let me know.
Q#3: Does anyone think 21/39 will be too tall with a 159" paddle track?
I will try it out tomorrow for sure but just curious what to expect. The 19/39 like it was geared too low but I don't have a 20 to try. Thanks!
Q#1: Is 19/39 stock?
My donor sled had 21/40 no reverse. It also had a 70 pin chain where the reverse chain was 68 pin. Here comes the big one.
Q#2: Is it better to have the adjustment bolt way in or backed way out?
Both chains appear to fit but the adjustment bolt moves to both extremes to get proper tension. I am thinking the shorter chain would be better because it will run straighter. If anyone has previous experience/advice when re-gearing please let me know.
Q#3: Does anyone think 21/39 will be too tall with a 159" paddle track?
I will try it out tomorrow for sure but just curious what to expect. The 19/39 like it was geared too low but I don't have a 20 to try. Thanks!
kinger
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Use the 68 chain, I used this link which tells you which chain to use:
http://www.ty4stroke.com/viewtopic.php?t=33188
the 21 gear will add about 10mph over the other one, its a fairly large gear change, only way to know if its too big is go ride it. I think your fine I run a 25 on my trail based short track with nitrous.
http://www.ty4stroke.com/viewtopic.php?t=33188
the 21 gear will add about 10mph over the other one, its a fairly large gear change, only way to know if its too big is go ride it. I think your fine I run a 25 on my trail based short track with nitrous.
RedRocket
TY 4 Stroke Junkie
The stock RX-1 gearing is 38/24 and the RX-1 Mtn is 40/21, both have a 70 link chain. If they are both in good condition, I would use the shorter chain so there is more room for stretch.
I would try using the stock 40/21 gearing and 70 link chain with such a long track.
I would try using the stock 40/21 gearing and 70 link chain with such a long track.
ski-dood
Newbie
I wonder if the reverse kit came stock with 39? Online the kit shows a 38 as optional and doesn't say what standard is. Still have a 3rd case to open up and see what that PO might have used for gearing. If nothing else I can take reverse off and try the stock 21/40. Will know more tomorrow. Thanks!!!
suprfst
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The mountain should have 8 tooth drives.I ran 20/39 with 2" track out west seemed to work great with factory 9 tooth drivers.
Shivesy
Expert
Q#2: Is it better to have the adjustment bolt way in or backed way out?
Both chains appear to fit but the adjustment bolt moves to both extremes to get proper tension. I am thinking the shorter chain would be better because it will run straighter. If anyone has previous experience/advice when re-gearing please let me know.
I would think there would be less friction and less heat with the chain runnig straighter. I geared my Apex down last year and noticed less MPG so that is something to take into consideration.
Both chains appear to fit but the adjustment bolt moves to both extremes to get proper tension. I am thinking the shorter chain would be better because it will run straighter. If anyone has previous experience/advice when re-gearing please let me know.
I would think there would be less friction and less heat with the chain runnig straighter. I geared my Apex down last year and noticed less MPG so that is something to take into consideration.
grader
TY 4 Stroke Master
the shorter the chain the better.
race24x
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When I went down 2 teeth on my shorty it ended up the chain was to long and having the adjustment way out to make up for it was bad it snapped the adjuster off and broke a piece of my chaincase off too. Now I have a brand new chain case shorter chain etc. Let me know if you want to trade for some of that reverse stuff I would love to add reverse to my 03 shorty. But as far as longer or shorter chain shorter is better less leverage on the adjuster bolt
ski-dood
Newbie
Oops I forgot about this post...here is my update. The 21/39 gearing is awesome with my 159 track around here. The sled is smoother and more predictable now. However I have a jetting problem that is more noticeable with the taller gearing. The PO cut a big hole in the airbox and I am hoping that is why it's too rich (usually more air in=lean but these carbs are picky). Fortunately I have two spare airboxes but also have the breadbox to try. Once that is fixed it should be a rocket again. Anyway thanks to all who posted as it was a great help!
ski-dood
Newbie
update
Actually found answers to all but Q#3 in the repair manual on page 78 or chapter 2-62. It has stock gearing info along with what length chain is required for each sprocket combo. Turns out the 68 link is the right one for 21/39.
So I have attached that page for future reference.
Actually found answers to all but Q#3 in the repair manual on page 78 or chapter 2-62. It has stock gearing info along with what length chain is required for each sprocket combo. Turns out the 68 link is the right one for 21/39.
So I have attached that page for future reference.
