1988 LT250R Burnt Piston

[fire0501]

Thats weird about the pic I can see it... i dont know.

Yeah the last piston I had was 68.50 I think max your supposed to go is 69mm

I got a lucky break on the piston I bought It was actually $47 including shipping

let me know if the pic is still not showing

[hawaiianbasshead]

you can deck the sleeve and run some yz250 pistons I believe, not sure which year tho or the whole procedure, I'm hoping to find out tho. I'd like to get a zilla motor and start another project really tho lol

[fire0501]

Looks like you have a nice project going and I just read on another forum about the yz250 pistons so you can def do it!

I am now having a problem with the power valve. It doesn't move when revved? Does anyone know which way the actuator rod moves when revved? Up or Down?

[sandman74]

Originally Posted by fire0501

Hello again I just want to update as promised. And thanks for all the replies! I took it to a somewhat local about and hour away but given his quote of $30 for the bore and $60 to resleeve I drove it there and picked it up myself. Here's what he did. He bored the old sleeve out. The new sleeves out diameter was 300,000ths bigger so he bored the cylinder itself to fit the new sleeve in. :-0 I was worried about this and yes he pressed it in cold. He said he does this to big bore harley's all the time. So i figured go for it. I paid $90 for the machine work $50 for the stock Piston and $80 for the sleeve so I got away with $220 for a new top end. Hopefully there wont be any problems lol

At this point I would have found another shop. Air cooled and liquid cooled are 2 entirely different animals.....but nice LT, hope it doesn't give you any problems!

[hawaiianbasshead]

Originally Posted by fire0501

Looks like you have a nice project going and I just read on another forum about the yz250 pistons so you can def do it!

I am now having a problem with the power valve. It doesn't move when revved? Does anyone know which way the actuator rod moves when revved? Up or Down?

it's hard to see it move are you sure it's stuck?

down open, up close, I just did it on my jug that's outside

VIDEO0081.mp4 video by hawaiianbasshead - Photobucket

[fire0501]

Thanks Sandman. thanks basshead I had to take the clutch side cover off because the last person that put the actuator together did it wrong an there was no movement it was stuck so i had to free it and now the power valve works perfect! Now I have another problem lol it seems everytime i turn around with this 250r its something else anyway it keeps flooding itself???? Weird thing is I didnt change anything in the carb or anything so i was thinking the reeds are bad? would bad reeds cause an engine to flood like that? If i take the plug out and dry it and crank it over a few times to clear out the cylinder i can get it to start for one second then it floods itself and wont even attempt to start unless i dry the plug and clear the cylinder. I thought maybe the spark but its a nice blue I changed the coil with another one i had and still the same thing. Im lost...

[fire0501]

I took the carb off after cleaning the plug and cylinder it sat all night so it was clear anyway. so i took the carb off and started it and wham it started and revved high so i shut it off and tried to start it again and nothing. i pulled the plug and it was wet with what looks like oil....yea I think crank seal is bad clutch side but before i get into that does anyone think that the reeds would cause this also??? They are not brand new but they arent that open either please any info would be great!

[jerkin]

Reeds will not cause the issue you are having, sounds like crank seals which is probably a symptom of a bigger problem. Check for play in the crank, if you have any you will need to split the cases and replace the bearings.

[fire0501]

Thanks I have had the clutch side case off multiple times and If I remember correctly I have checked the crank for play and I dont recall any play but I will def check again thanks for the info.I didnt think the reeds would cause this but I wanted to be sure

[fire0501]

Well I pulled the crank seal last night and there doesnt seem to be any play in the crank at least on the wet side. I havent pulled the stator side because i dont believe it to be bad but now I have metal shavings in the bottom end.... prob from the first piston torching lol. I am going to attempt to find the time tonight to pull the engine from the frame and split the case. I believe i can just split the case from the clutch side without pulling anything off of the stator side....? I prob wont get that far tonight anyway but thats the plan. I want to clean out the bottom end as best i can without pulling the crank from the dry side for some reason or another I think that it will pull easier from the clutch side maybe something I read in the manual or somewhere else. guessing the metal ruined the seal... I only found one little chunk of the outer part of the seal missing but the inner was perfect.. Guess i ll find out when she goes back together.. Will keep you posted.

[hawaiianbasshead]

you have to pull the flywheel as there are bolts behind it that hold the cases together.

I had a pita pulling the counter balancer weight on the clutch side lol. I had plenty of problems really getting it apart, now I've been super lazy putting it back together LOL. just wanted to change out my seals/o-rings and now I'm wanting to change crank bearings but didn't order any yet. my motor is split and on the outside table waiting to rust out all the parts LOL

I would say the reeds are probably a bigger issue than the crank seals imo, that and the float valve for the carb sometimes they just go bad letting it just flow and if somehow it overflows down into the reeds which are open it could cause similar problems as well.

my seals were leaking to the point of pumping out plenty of white smoke from the exhaust but the bike still started easy and ran pretty good despite it's burning oil and sucking in air... hell it was auto oiling my chain thru the counter shaft seal as I was pressurizing the clutch side which is open to the trans so oil would spurt out and oil my chain was messy but nice that my chain was auto oiled LMFAO

[fire0501]

Hahaha the auto oiler I had the same issue I just replace the seal its pretty easy. you can do it from the outside. Its easiest to pull the shifter saft out from the clutch side but now she doesnt leak. I cant get the flywheel off I bought the flywheel puller and it just stripped the rusty threads in the flywheel so now......I tired of this thing already lol I just replace the trans side crank seal and im gonna see how it runs from there until i decide to do a full rebuild im just gonna run the P!22 out of it

[hawaiianbasshead]

mine was actually leaking at the case joint too, so I had to pop mine.

as for the stripped flywheel, maybe weld the puller to the flywheel and order another flywheel you can get um cheap on quadracerhq.com I would think. there's always someone parting out motors or bottom end parts.

[fire0501]

i bought another parts quad a while ago and it was a good thing too..so i have another flywheel and clutch and a bunch of motor parts some god some bad i havent looked at it yet though but welding is the best idea..

I put it all back together and wham she fires right up so the crank seal was def bad..

now i have to get her to idle and at the top end it kinda breaks up seems like it should have more scream but it doesnt so now on to the fine tuning lol

[hawaiianbasshead]

sounds like it could be jetting possibly.

gets some vids of it running