Evan
08-05-2002, 01:06 AM
Ok, this is kinda a technical question, if somebody can help me Id appreciate it. I have a 425 (88mm piston) 13:1 JE. I bought the piston from Legacy. John at Legacy seemed like a real nice guy, I explained to him what I wanted. My 416 floated a valve and went all to peices, so I wanted another 416 at 12.5 comp. I got the piston and sleeve from Sparks, took it to Legacy and he ended up talking me into just boring to the next size(425) Along with bumping the compression to 13:1. This seeemd to be ok since I returned the Sparks piston and got my outrageous price back and bought practically the same piston from Legacy for about 40 bucks less and didnt have to pay 150 or whatever to have it sleeved. Well I broke it in ok nice and easy on a tank of gas then ran it kinda hard, varying the throttle but never holding it for a long time. Then I did proably the unthinkable, I raced it. After the race, I adjusted the valves, changed the oil and rode it normal. Well after about 2 hrs or so it started smoking, BAD, like a 2stroke. Somebody sayd I had a cracked ring, I didnt have time to mess with it so I parked it for awhile. Now I have it torn aprt and the rings are fine. It has a whole new head, the gaskets are fine(head) new valve seal, new valves, cam chain etc. When I tore it apart I noticed 2 things, one of the exhuast valves was not adjusted right, had too much play, I dont know how it happended, I must have goofed, but I could have swore...... two, there was more than enough oil in the oil tank, I had put some in after riding one day, b/c I checked it and it was about1/4 above low, now it was above full.(Does checking it hot have anything to do with the oil level in the tank?) After an nspection of just about everything, I looked at the piston, there seems to be some wear marks on one skirt, and the opposite side above the skirt and at the top, and some faint minor scraching like from pinging or from dirt. Now I am pretty sure that no dirt could have got in since I put a new filter on when I rebuilt it, and oiled it good, an there was no sign of dirt in the carb(intake or exhaust bell) So I decided to check the piston in the cyl, wow seems like alot of play. Got a freind to mic it, heres what I found,
Piston
3.432 Top
3.462 Bottom
Bore 3.465
Ring Gap .029
Would this be the cause of the oil burning? Its really loose at the top and about right at the bottom. Rings seem to be wrongly gapped also. John said he would take care of everything. Heres what I am wondering if by chance I somehow got the wrong piston. If so what should I do now? Call them up and get them to find me the right size piston? Or go resleeve and start over with a 416? If I have to buy a new piston I am going with a 11:1 To me its not worth it to run race gas year round, and put the stress on the motor. There was hardly any difference if any between the 12.5 416 and the 13:1 425. Any suggestions, besides taking up reading as a hobby.
Piston
3.432 Top
3.462 Bottom
Bore 3.465
Ring Gap .029
Would this be the cause of the oil burning? Its really loose at the top and about right at the bottom. Rings seem to be wrongly gapped also. John said he would take care of everything. Heres what I am wondering if by chance I somehow got the wrong piston. If so what should I do now? Call them up and get them to find me the right size piston? Or go resleeve and start over with a 416? If I have to buy a new piston I am going with a 11:1 To me its not worth it to run race gas year round, and put the stress on the motor. There was hardly any difference if any between the 12.5 416 and the 13:1 425. Any suggestions, besides taking up reading as a hobby.