Yesterday I was at the local rubbish tip when the supervisor, who knows I'm a bike nut, came up to me and told me that there was an old Yamaha trailbike with gold rims down at the Rynie tip (another sit operated by the local council 30km away). My thoughts were that it would be the ultimate in good luck for it to be a late model XT500, but more likely that it would be an early 80's XT250. So I was at the gate waiting for Rynie tip to open this morning, and here it is;
Yep, it's a 1981 XT250H and it cost me $20, which was what supervisor and I agreed would be it's scrap value. Except the picture does lie, there were no front forks with it. The forks that are fitted are a pair of XT250 forks that I happened to pick up from my younger brother a few years ago. I knew they would come in handy one day!
The engine would not turn more than about 300 degrees, and we all know what that generally means. Yes, a bent valve. So, it was off with the head, and this is what I found;
So the question is what to do with it? Well I can probably get a seat, tank and some guards from the wreckers that I frequent. The engine is repairable, it needs the head fixed, new piston and camchain. The camshaft and exhaust rockers are worn but thats not a real problem, and I also have a 34mm Mikuni Carbie that I can fit. My thoughts at present are to make it into an enduro bike to replace the XT500 that I currently race. With a bit of head work, a hot cam, maybe a big bore kit and the 34mm Mikuni from my parts box, I should be able to extract a bit more go from the engine.
When I pulled the top end off, I found that the camshaft looks to be the same as the XT/TT/SR 500 camshaft. I don't know if they actually are and will have to do a bit of research. If it is the same came I will be in luck as I have a few spares, including some hot ones.
Has anyone had any experience of hotting up one of these engines? Are big bore kits, available, and what cams do people use / recommend?
CJ
