Here is what I have been finding with the first batch of tensioners delivered.
Most tensioners fitted to MK3 850s have needed a shim behind the tensioner to give clearance between the front of the intermediate gear and the ledge on the tensioner. A shim about .040 in thick seems to do the trick.
I plan on altering my program a bit to make some tensioners to fit without the shim. They will then be specific for the MK3.
Some people have found that with a tight new chain there is interference between the left rear corner of the shoe and the intermediate gear. Rotating and holding the tensioner CCW on the studs before tightening the screws normally solves that. I have altered the build program to rotate the 2nd batch of tensioners for more clearance.
I have 5 new chains here that I have tried.
1. the chain I designed the tensioner around was a NOS Reynolds chain purchased from a dealer several years ago. It just fits.
2. a new chain from Andover norton. It is slightly shorter than the nos chain and usually requires pre-grooving the shoe for the side rails to get enough chain slack. Three hacksaw blades taped together and handheld will cut grooves for the siderails.
3. a new chain purchased from MSC industrial. It is pretty close to the NOS chain in length. It just fits.
4. a new IWIS chain from Andy. It compares pretty close in length to the Andover chain. It required pregrooving the shoe to get clearance.
Any of the above chains will fit with no work if they have some mileage on then. They all stretch quite a bit in the first hundred miles as they are breaking in except possibly the IWIS chain -I have not run it, I just tested it for fit.
5. a superduty IWIS chain. It has considerably larger pins and heavier side links. This chain is very much overkill for the application and should not stretch near as much. To use it requires re-contouring the tensioner shoe along with pre-grooving. I am presently running one on my bike and it has not changed in length at all.
From now on all the tensioners will have a body that is .050 shorter and rotated a few degrees CCW for more clearance. All the shoes will be re-contoured and pre-grooved so they will clear with any chain. I have ordered a stock of heavy duty IWIS chains and can supply them with a tensioner.
It anyone has purchased one of the first batch of tensioners and wants a heavy duty chain I can supply one along with a re-contoured shoe. I would exchange the re-contoured shoe for the one you have. I don't have a solid price yet for the chains.
I am waiting for the order of chains to arrive along with some better tooling for re-contouring the shoes so it will be a week or two before I will be able to fill orders. Then about 25 units will be available. Jim
Jim
