Some may remember this bike from last year, and the trials and tribulations I've experienced with piston seizure. First year I though it was jetting, second year I thought it was oil starvation, last year it happened again, and when I pulled out the galled piston it was dripping with oil and no sign of lean condition on the head. Quite frustrating, to say the least, and my pile of toasted pistons has grown to a depressing level.
This year I've done a lot of looking back at what's happened and what I've done wrong, and possibly done wrong. I came to the conclusion that I started this journey with several problems, everything that I though was a problem in the past actually was, I was only addressing the most obvious things as they appeared, and not looking deeper for other existing conditions.
As you may recall, the engine on this bike is buried inside the body work. It is a 1971 Triumph TR25W, single cylinder 250cc push rod 4 stroke. I'm running 12.5:1 compression with a Megacycle cam retarded for more top end oomph. The engine was initially built with all the tolerances set up tight, this included cylinder clearance. I now believe that this was the last major oversight in my planning, since I failed to take into account that the piston might expand more than the jug due to compromised cooling.
To address this, I've honed the cylinder out to provide .0055 clearance cold, up from the .0030 that I have been running. I've also built some quick and dirty cooling shrouds to direct more of the air flow from the electric fan across the cylinder and head to help prevent overheating. My hope is that these mods will finally kill the gremlin that has been chasing me every since I started running this thing.
One other thing I've done is to add a catch tank to the oil tank vent. Last year I was mortified to get back to impound with the truck and tools and discover that the bike had been dripping oil onto the salt. Some kind person had found a card board box to put under it to catch most of the oil. A major oversight that should not have happened on my part. Belated thanks to who ever it was that took care of the problem and didn't even bother to chew me out for it.
Anyway, due to other obligations and short funds, these are the only mods I'm doing for this year, the wood body work stays for now, no new front fairing, nothing visible and cool looking added. At least the bike proved itself stable and easy to ride last year. The hope is that this year the engine will hold together and I'll be able to get in a lot of good runs, bump the record some more, and not have to do any on the salt McGuyver type repairs to salvage the week. LOL.
Not much new to see, but here's a short vid of the second start up, in case anyone's interested. It sounds much better in person. Pretty good for a 250 I think!
