Ok so I just had my 89 lt250r port and polished, head milled, bore over, new wiesco piston. Just had it running good then one of my cylinder studs stripped which caused antifreeze to leak so I helicoiled the cylinder and reinstalled. It ran good but I couldnt get rid of a bog, I check my antifreeze a few times after the helicoil and it didnt lose any. Then today i rode it hard for about 20 minutes and was on my way home and it shut off and wouldn't start back up. I let it cool and checked my antifreesze and it had lost alot of antifreeze. So I try to retourque the head to 20 ft and a different stud kept turning and was loose. So I took it home pulled it apart helicoiled the stud. And now my piston and head look like the something broke and was bouncing between them and obviously needs to be replaced as it will not even run. My cylinder has no damage but my piston is beat and I can not figure out what could have been bouncing around on the piston? Also my head looks like it is being hit by my piston. Any idea what could have cause the head and piston to be damaged?
cheak and see if your thrush washers are still there
tear down the top end lol !
i connot see through the cylinder.
It may be down in the crank or could of blown out the pipe.
Most likely the trust washers especially if they're stockers.
There is a washer on each side of the small end of the connecting rod where the piston pin is.The washers go between the pist0n and con rod and the stock ones are stepped and break...The upgrade is to use the RM bearing and aluminum thrust washers.Do you have any pics of the head and piston?
My thrust washers seem to be in good shape. i do not have a picture right now but i can take some
Post some pics.I,m no expect but I,m wondering if you had some pre detonation issues if it got really hot due to the lost antifreeze?I,m sure motorgeek may have some input if you can post some pics.
Heres be for and after of the head
Sorry I realise that this is over a month old but my cousin had a similar thing happen to his rm250 recently after he changed the pipe on his bike and didn't bother to tune it. It caused the same symptoms as your bike, with the bogging feeling being caused by the piston expanding too much and trying to stop in the bore, and the same marks appeared on the head from detonation or pre ignition(I don't know which is which). If it were me I would check everything to do with the coolant, combustion and timing in the engine, including the compression and doing a leak test once it is reassembled.
I notice you had the head milled and port work done...maybe the compression ratio has been messed up.
Thanks everyone. I had alot of shavings in my oil. I split the cases and inspected everything very closely and there is nothing broke or out of place. Im lost now. Im thinking just clean it up andput it back together and see what happens. Any suggestions?
Read up on how to do a compression ratio calculation (it's not hard at all) and check what your motor comes out with against with other 250 owners compression ratios and what a stock 250 is. If its too high then it is likely that that's the problem, otherwise check it for air leaks by doing a leak test (I think a lot of people do this every time they rebuild their engine). Detonation can cause those marks on the piston and head-look up 'two stroke detonation piston' on google images.
So my compression ratio is off?
So what causes detonation? Also I was running 93 octane, is that too low of octane?
Detonation info:
http://www.2strokeheads.com/tech-octane-detonation.htmI have no idea if your compression ratio is off as I cannot measure it. I'm also in New Zealand so I cannot tell you about octane as our measuring system is slightly different to yours. Lots of things can cause detonation, its just that your motor has recently been worked on so I would check the compression ratio first as it is relatively easy to do. I'm just trying to point you in the right direction... but all the answers can be found on this site and others like macdizzy with a butload of reading.
Ok thanks man. Would detonation leave any metal in the engine?
If it melted a piece off it could. I had that happen to my old rgv250...but I think that it might be quite unlikely for that to happen