For those of you who haven't experienced replacing chains &/or sprockets, here's some info that may help...
Before I go into the instructions, here's some background:
For our slow ground speed "around the house" and trail conditions, I wanted to lower the ground speed & top end speed of our '03 Pred-90, yet still give it high rev RPMs (more power and for our stator system to pump out higher watts). Changing its sprockets is a "no brainer" way of doing this. There are other ways, but I picked sprocket and chain replacements method, since our factory chain was worn out anyway...
To view how to determine customized sprocket sizes for your mini, surf: http://atvfrontier.com/ftopict-10066.html
We replaced front factory 19T sprocket with a '01 Scram-50 18T sprocket. Once the paint was removed from its inner groves, this Scram-50 sprocket slid right on.
Replace the rear factory 35T sprocket with a 39T sprocket from Billy Holt @ WRH Racing. Could have also purchased the customized rear sprocket from Rebel Gears [email protected]
Now the chain. Boy, talk about "which type to pick for our unique riding conditions?" confusions. Long and the short... If you are racing then you may want to go with a standard non O-Ring chain. Many say there is less drag / friction with a non O-Ring chain. If you are looking for long term usage, less maintenance and not worried about HP drain, then go with an O-Ring chain. Common brands are DID but they aren't the best. And, they only make a standard O-Ring chain for my needed 428 size. For our trail only riding with slow ground speed and "too much crud" riding conditions, I decided to go one quality higher then DID. I went with an RK O-Ring 428 HO chain as seen in: http://community.webshots.com/photo/...59301449flvBHa
* Note: Since I didn't purchase a chain break tool, I saved the dollars for this tool and spent it on the higher quality chain. What ever works best for you..
To install a new chain, a chain break tool would be nice. Since we have a limited budget in our family, I couldn't afford to purchase this customized tool. Beside that, I spend its reserved dollars on a higher quality chain. To remove our old chain, I simply removed the clip and the master link on our factory 428 chain. Our worn out chain almost fell apart. To install our new chain, I loosened the chain tightening bolts (and adjuster) on the rear axle assembly, pushed the rear assembly all the way forward, threaded the new chain around the sprockets and our HPD spring loaded chain tensioner and while pressing down on the chain tensioner (only 3/4 way down), I fitted the chain sit on its rear sprocket. Measured where the 120 link chain needed to be cut (had to move the chain forward one sprocket tooth for splicing alignment), then used my hand grinder to grind the rivets FLAT - where the chain needed to be shortened. I then removed the chain, took it to my work bench and using a flat screw driver, pried the side of the O-Ring chain link off. With O-Ring design, it was very easy to get a flat screw driver behind the link wall. I then re-installed the chain to double check its new length. Then, I removed the chain from its sprockets and pulled the chain all the way back of our Pre-90. Then, installed the master link and its side plate. Using a car jack, I then held a heavy sludge hammer on the one side of the master link. Using a normal hammer, I then pounded the other end of the master link. Its edges then mushroomed out - holding the side plate on. One final inspection on the master link. Then, I reinstalled the chain back onto the sprockets, adjusted the tension using the chain adjustment's 10mm nuts, then tightened the rear assembly bolts. All done. Bottom line is... I changed my chain without the need for a chain break tool. The above might work for you too...
To install the sprockets, I applied thread tightener liquid (glue) on the threads of the front sprocket and on the small threads of the rear sprocket bolts. Then, I tightened them - snug as a bug. It's also much easier to hand tighten the large nut on the front sprocket, install the new chain, then hold the rear tire while wrench tightening the large nut on the front sprocket.
For the test run.... It's been -26s to -45s in my woods for the last few weeks. Too darn cold to take a long term test run. Besides that, our Pred-90 doesn't have its jets tweaked for extreme cold weather. Thus, it gave me constant hesitations / flat sports when above 3/4 throttle. Sure hope it warms up in my area soon.... For the short term test run & few donuts, its back wheels spin very nicely. Especially in our iced up driveway. Once we get warmer weather, the pre-lube O-Ring chain will also loosen up and less frozen. Hence, it should have much less resistance / friction on its chain.
And from a safety perspective, be very careful when performing maitenance and/or testing the tension of your chain. For details, surf:
Hope this helps others....