I purchased the bike with a no spark situation. After buying a new source coil, points, condenser and coil I finally got spark! I then did a compression test @ 120 lbs. the carb was rebuilt by a shop. I then disassembled the top end and ordered new Yamaha replacement 1st over as the piston read .25. Upon arrival they did not fit they were to large to fit the cylinder wall so I put the old ones back in. When kicking it over 0 results and 0 gas on the plug. I tried gas in carb and in plug hole not one pop. Any ideas what to do next?????? I grow very tired of this bike. Shops here are the blind leading the blind. DT

On the old web site, I had a long saga of trying to figure out why my 74Dt100 would not start. Long story short, I did a complete rebuild of everything. Turns out the new coil I bought, although it produced spark, did not produce enough under compression. I put the old coil back on it, it started first kicv k, and I’ve been riding the heck out of it since.

I actually had a CDI coil the last owner put on . LOL I took it to the bike shop and they put this new coil on it. I hope they have the right one I don’t have the original. I have twins two 74 DT 100’s, but I’m afraid to rob parts to check the dead bike from the awsome one. My LT2 runs perfect as do my 175mx and TY250 I can’t beleive this thing is it possible the crank seals are crap is why it won’t start? I’m very confused why my piston is stamped .25 and new Yamaha rings do not fit the hole you would need to grind off 20 thousands to get them in the hole!