Splitting the case - '69 Yamaha DT1

Succubus

Member
Mar 6, 2005
99
0
OK, first gear on this old 2500cc bike is shot. It goes into gear but won't grab at any RPM over, say, 4. But I got lucky and found a free '70 DT1 behind a barn about a mile from my house. The bike is junk, but extremely free, and it has a few good parts incuding the trannt, which was supposed to be good. I tore it down tonight and the guy was right - the tranny looks pretty clean. Anyway, Tearing down the old bike showed me where the trouble spots would be when I tear down the good one. One of those problems will involve splitting the case. On the grungy, rusty old gimme I had to pry it apart with a fly pry bar. I wasn't caring much about leaving clean edges or saving anything but the tranny. When I tear down the good bike I want to be a lot more persuasive and significantly less forceful. The donor case was very tight and it wasn't coming apart any other way. It had been sitting exposed to the elements for an untold number of years. The cylinder, for instance, is absolutely frozen and nothing short of a nuclear strike is ever going to move the piston again. Only five of the crankcase bolts moved with my impact driver. The rest I had to drill out. The shifter was also frozen at the case. So I expect this was tighter than the case on the other, running bike, case will be. Anyway, I expect it will still be tight, since the bike doesn't rattle. Does anyone have any tricks for getting these little cases open without damage? I don't have the fancy Yamaha case splitting tool. Thanks in advance.

Pat
 

sunnyboy

Member
Feb 24, 2003
98
0
the fancy case splitting tool is the only way--it is just a puller with properly sized bolts to fit the case--also use a soft hammer to tap on the safts as you start pulling-- they are very tight
 

THREADLOCK

Member
Mar 30, 2005
37
0
I've done 2 of these old yamaha's. I use a $9 puller I bought from autozone. I think it's
an a/c wheel puller. It has a horisontal bar with an opened slot on each side and a long screw in the middle. I had to go to a hardware store to get the proper bolts. 6 or 8mm threads and the bolts were about 3in long. I have redone a 75 dt100 and a 73 dt250. This puller worked very well. You will need a rubber malled to tap the case on the oppsite side of the puller. Be sure to pull the case apart evenly. If the puller side comes up faster tap it down and tap the other side up. The sides will come apart with a loud pop. Have fun!!!!
 

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