Hello everyone. I am working on my 1972 Jackpiner and have a question about the plastic chain guide. I purchased a new one from Al B. but didn't pay any attention to how the old one was installed before removing it. One side is thicker than the other and has a square relief cut into it. My first question is , how is it supposed to be installed? Also , is it normal for the chain to rub on the bottom of the plastic guide ,when the bike is on a work stand with the rear wheel hanging in the air? I have the guide adjusted down to the limits of the slotted holes in the chain guard and the frame bracket and it still rubs. Am I correct to assume the amount the chain rubs on the guide will decrease as the wheel travels up as the supension is compressed? If so, should the chain tension be adjusted with the bike on the ground and with the riders weight on the suspension?
It has been a long time since I worked on one of these bikes.Thank you for any help you might be able to provide.
Randy Lamp
Massillon ,Ohio
Can't help you with the orientation, Randy, except to say that it would probably be thick-side-down due to wear considerations.
But I can tell you, the chain should always be adjusted at the tighest position, which may be with you on it, but definitely with the c/s, swingarm pivot and rear axle aligned.
John
Hi Randy, I'm not sure, but the new style does have a relief cut into it and it faces in towards the tire. The old ones on my 6 day and Piner dont have that relief cut into it,[?] but the new ones do.
I have my chain guide adjusted all the way to the bottom, but theres little mileage on the Piner to tell how its wearing.
Raymond
Down East Pentons
I also installed a guide that I purchased from Al. To allign with the chain, the thin side went to the outside. The guide also is adjusted all the way to the bottom and still is rubbed slightly by the chain using a 65 tooth rear sprocket. Good luck.
Nelson Lingle
Thank you for the input. I will install the guide as suggested in your responses. I have got myself convinced that the chain rubbing the bottom of the plastic guide will diminish when the bike is on the ground with weight on it. With plenty of chain lube it should be ok.Might chew up some plastic but that is inevitable.
Randy
Randy,
Just a little follow up. If you want to find out the entire range of the chain on your bike just do this little test if you have time. Take the spring off one shock and mount it to the bike. With your chain on the bike you can observe the tight and looseness of the chain by moving the swing arm up and down. Sounds simple, but in the old days when we first started experimenting with long travel I used this method to develope chain tensioners and set the bike up for the long motos.
I hope this helps. Oh, and by the way I always had a (old)spare shock around the shop that had the spring remeoved for a quick check.
Ron Carbaugh
Ron, thank you for the tip. It is a very good idea. I think I have an old shock to use and if nothing else ,I will feel better knowing I did everything I could to do this aspect of the assembly right. It is great to have the combined knowlege of individules like yourself and the others, on this site.
Randy
Randy,
Thanks for complimenting this group. Everyone really helps each other and it makes for good and new information for all of us. One other tip to do while you are playing with the chain alignment is not trust your marks on the adjustment for the axle bolt. Measure from the center of your swingarm piviot bolt to the center of your rear axle to be sure your rear wheel, and chain, are tracking straight with your engine. The reason I say with your engine is the engine is in line with your swing arm and this keeps the chain hopefully as close to 90 degree angle from your engine....these are all just fun and games, but during the early days of developing long travel I (we) learned a lot of things about trying to keep chains on our bikes. Sorry for th long text, but it seemed like a good time to relive the past.[:p]
Ron Carbaugh
Ron, Thanks again. I was going to go with the old sight down the chain and see if it was straight methode. Not the best way to check the alignment. I went as far as putting a straight edge on the rear and front sprockets to see if they were in line but the small front sprocket made it hard to tell how close it was. Measuring from the swing arm pivot point to the axle is the right thing to do.