billdapart

Thanks for the replies guys. I have decided not to powdercoat for a couple reasons. First to save some money and second because I do plan on taking this bike offroad just as much as I plan on riding it on the road (not very much actually) Actually the money is a very important thing since the guy who rebuilt the crank used a YZ250 connecting rod as well and the crank that I had rebuilt is completely useless. The piston might actually be ok, but it's a moot point.. I guess I have a second crank to send out at least... As far as the seat goes, the bike originally had the really big seat option, which I've heard came on the "CAT" version of the TY. Anybody have any more info. on this? Got a line on a brand new seat cover and still have the original base, but would need to source some foams to rebuild the seat and that will be a new experience which should be fun. Thanks again guys, looks like the bike won't run until after the new year now but coming on here and reading these threads keeps me motivated.

WoW! Alan and Tony283 thanks for the links, as Tony27 pointed out those links wont help me much with a piston but for the rest of the build they are an absolute god-send! They look to use the exact same microfiche applet so I'm willing to bet they have the same supplier and prices on the available NOS parts. I'll have to try both and see who ships faster. Tony27 thanks for the heads up, I actually had the wossner site up already when you posted that and will be the place that I go to in for the piston. I've already had REALLY great dealings with them and their VW pistons even back when I had to get them shipped across the pond. So now that I am pulling the cases apart again and putting new bearings in and a new piston I think I'm good to go with the motor. I'm currently looking at two things in the next part of the project. Fuel tank/seat and powdercoat/paint What are you guys thoughts on this? I have an old tank which is in fair shape (one small ding) and has some rust inside. I also have no seat. I was thinking of either cleaning the tank with electrolosis and buying the majesty replica seat and making brackets or purchasing the sammy miller seat/tank combo. As I will be using this as a commuter part time to and from work and teaching my wife to ride motorcycles on it what do you think the more comfortable seat (to actually sit on ) would be? Then what do you guys think about paint vs. powdercoat? I'm leaning towards powdercoat right now. Also I know i have to cut the swingarm away from the frame and I'm really not sure where to cut. Do I have to pry the frame away from the swingarm to get the blade in to cut the bolt? Or do i cut through the spacer/sleeve/bolt? Thanks again all and sorry for my ridiculous posts.

Wow, this project just went from fun to ARGH!! So as I pointed out in that last picture the kickstart return spring was missing.. DOH! I used a puller and pulled the left side of the case off and threw the kick start spring in there, double checking I had everything inside that needed to be inside I welded up a tool for cold-pressing the case halves together. (thanks again Rich!) The tool was made out of an old VW wheel bearing tool and and old VW widow maker (i'll post some pictures tomorrow). The case went together great and I got the cylinder put on with my fresh spankin' new Wiseco piston and installed the cylinder head. Turned her over and clunk.. clunk.. clunk.. The piston was hitting at top dead center. I used a mirror through the exhaust port and couldnt see anything wrong so I begrudgingly tore the cylinder head off again (is that copper head gasket re-usable at all or is it now junk?) Rotated it over with the head off and pow! The piston comes right out the top of the jug and the top ring popped out and sat on top of the cylinder! So sadly I had this crankshaft rebuilt about 9 years ago by a friend of a friend.. who also supplied the piston.. After checking the piston number come to find out it's for a 76-79 YZ250.. If he got this wrong there's no telling what the shape of the crankshaft is.. So I have a useless shiny 70.50 wiseco piston and a brand spanking new std ty250 piston that i found among the drift.. money is scarce but where would you guys recommend a 1st oversize piston set from? Time to go get

What I've found to work really well on all sorts of plastics (from car bumpers to interior pieces), as well as vinyl and rubber is SEM colorcoat. Comes in a variety of colors and actually dyes the part. SEM also makes a prep solvent which makes the piece a little more porous and rough and allows the dye to seep in better. Just my .02c

I believe Bob and Peewee over at BJracing.com still have them. They may be available from sammymillerproducts.co.uk also depending where you're located.

Thanks so much Rich! I do happen to have that stuff sitting around and will be making myself that tool in the next couple days. I may just need it in the next couple days as well. Maybe you can tell me if there is something wrong with my engine as I have it pictured here.. I may be wrong as it has been over 10 years.. but I feel I may have left something out of the internals and will have to crack the case again....

So after I re-taught myself how to use a set of calipers.. My work has me constantly using metric but whenever I get a measurement tool in my hands I think in standard (thanks to my time working at the machine shop). In short, the bearing i.d. and crank journal difference was within .005" which apparently is ok.. I froze the crank and heated up the case halves on the stove top (didn't make my wife too happy with the smell.. oh and the very small kitchen fire which freaked her out made me laugh... uh.. yeah) While heating up the case halves the tranny bearings fell out so I figured now or never! I slapped the tranny bearings back in lickity-split. Threw in the crank and tranny components and applied a very thin layer of yamabond to the other case half. Crank fell into the first case half so then I placed those on end and put the other case half on top and with a few taps from my 13oz dead blow it was within a couple mm's of together.. then it wouldn't budge. I placed my tongue fairly outside my lips and clenched by teeth.. installed the new stainless case bolts and tightened them in crisscross fashion first around the crank, then around the tranny in 3 stages.. She went together really easily and after wiping away the excess silicone and securing the con-rod everything spins really smoothly. I think this thing is gonna run just fine! Just gotta slap in the new clutch assembly and the electronic ignition and she'll be ready for a carb and exhaust! It's not the prettiest engine but it should do the job for a little while and it's not too bad for something I took apart more than 10 years ago and let rust in the flooded garage! Now I can move on to powdercoating the frame and fork chambers. Thanks everybody for your help, I'll be sure to post up some more follow up here as I get further down the road. (no pun intended)

Thank you guys for your help! I actually went about measuring this morning and as far as I can tell something is off. The crank which is out of a different set of case halves (thus probably explaining my problem) measures about 30mm give or take a couple thousandths. The bearing I.D.s that I measure are anywhere from 29.93 to 29.85 (seems like one side is much smaller than the other). At this point I am splurging for some new bearings (even though these feel like they are perfectly good) Any suggestions on the best place to purchase crank bearings? Then I'll probably take the suggestion of freezing the crank assembly and try to heat up the case halves. Thanks again gang, hopefully this won't hold me back too much more.

Hello All, This is my first post on this forum so please bear with me. I have a74 ty250a that I am currently restoring. I am an automotive technician of 6 years and have my basics covered but this is really my first embarkation into the world of motorcycle mechanics. I have the cases split and had the crank assembly professionally rebuilt and I'm looking to re-assemble and having a hard time with the crank. As far as I can tell the crank will have to be pressed into the bearing, correct? I assume a pipe approximately equal to the inner race of the crank bearing should be used to support the case half and the crank should be pressed in one side first. What would I use to press against the crank assembly and where? Also once I have the crank assembly securely in one half, how would you go about pressing the second half onto the other? I am sorry if this is a very broad question, I admit this may be a bit over my head but I refuse to give up. I have or am willing to get whatever tools are necessary to do this correctly, and if it means watching over the shoulder of an experienced hand I will do whatever it takes to do so. Thanks for any help and glad to be a part of such a great forum. Bill