Monday, May 26, 2014
There are so many, many, many ways to screw this up......
Finally all of the parts have come in from around the world. TY Trials provided most of the smaller pieces as well as a couple of tools and a throttle cable. All Balls Racing (now there's a fun name!) was an excellent source for the main bearings and seals as well as the swing arm pieces. eBay was a source for most of the generic bits like a chain, piston, rings, seals, stainless socket head bolts for the case, etc...Most of this stuff is common with a wide variety of Yamaha MX and trail bikes.
Now I have to put it together in a way which will allow it to run. No guarantees. As I mentioned above, there are so many ways to get it wrong. Fortunately, I've done this before and I have a general idea what to do in what order. Also, there is a lot of helpful literature which makes it almost impossible to get it wrong if you just take your time...resist the urge to rush and double or even triple check your work against the manuals (and common sense). I think that I have found one way to screw it up already....I can not find my 4th oversize rings. They are somewhere, but if they simply can not be found. I will get some new ones. They are not vastly expensive and waiting for them to arrive will give me a chance to go slowly and check my work.
Featured above are the crankcase halves and their respective bearings and seals...which are apparently the same as used on the Yamaha 250 and 350 racing twins. They should be able to hold up to the rigors of the occasional trail ride.
Here are most of the smaller gaskets, seals, lock rings, snap rings and other bits that I received from TY Trials. You really should replace these little buggers while your bike is apart. I have spent a fair amount of time relabeling this stuff as it comes in. These little pieces come with a Yamaha part number, but no further identification. It is easy to forget what is what. Anyhow, take your time and all will be well.
The piston rings found their way back into the fold, which meant that I had to play with them. I checked the end gap on both rings and found them perfect...so I installed them on the piston and did a trial fit. The main thing that I discovered was that the intake and exhaust ports needed to be chamfered. My Dremel tool was perfect. Next up is to install the bearings and seals....Can't wait!