Top end damaged, need help!

[MathGSR98]

Hi folks,
I just got my 85/86 atc 250r disassembled for inspection... (When you have the feeling that it's time to invest before everything breaks...). I removed my cylinder and I had a bad surprise: A big scratch from the top to almost the bottom. My crank also seems to have some damage.

My piston is a wiseco 526p2 0.50mm over. I'm wondering how much oversizes left I have (86 cylinder)? Here is a pic or my piston, what is the cause for all the small holes on it?
http://i9.photobucket.com/albums/a60/MathGSR/Piston.jpg

The cylinder... we can see the large scratch in the middle. I don't know what got blasted in it... Is it possible that it will need to be bored 2 sizes over the get rid of it?
http://i9.photobucket.com/albums/a60/MathGSR/Cylinder1.jpg


Here is my crank. It is just in that position that I can see it's damaged. My bike was running fine though. The rod has no play up and down and a slight play left/right, is it normal?
http://i9.photobucket.com/albums/a60/MathGSR/Crank1.jpg
http://i9.photobucket.com/albums/a60/MathGSR/Crank2.jpg


My head seems ok excepted for the carbon... What is the cause for such accumulation?
http://i9.photobucket.com/albums/a60/MathGSR/Head.jpg


The previous owner had grinded the inside of the intake as you can see. Is it a good idea, should I grind it more?
http://i9.photobucket.com/albums/a60/MathGSR/Intake.jpg


Thank you so much for any help and sorry for my bad english.

[SYKO]

play on the rod left to right some is ok, but up in down its doen for! somehow it looks liek soemthing broke somewhere causing all the piston damage, rings still good?

[Somekindofjerk]

Looks like your preivous owner had a bearing spin in the bottom end or maybe a piston come appart. Did you put that piston in? Carbon is usually running rich or cheap two stroke oil.

[tyman]

well i'm no 250r expert but i think you could get away with only one bore over... you don't want to go too far.. incase something breaks again, you have room for another bore... i'd try to bore it out one (ofcourse after you get everything else straightened up) and see what it looks like... good luck with it...

[Somekindofjerk]

Is that rod and piston pin blued? It looks like that R got really really really hot

[Erics350x]

Post a pick of the spark plug . Is it melted ? What about the needle bearing ?

[MathGSR98]

play on the rod left to right some is ok, but up in down its doen for! somehow it looks liek soemthing broke somewhere causing all the piston damage, rings still good?

The rings seemed to be good enough. Before I disassembled the trike, it was running well so I didn't blew it up.
I made a compression test and I got 160-163lbs but my tester is kinda cheap...

[MathGSR98]

Looks like your preivous owner had a bearing spin in the bottom end or maybe a piston come appart. Did you put that piston in? Carbon is usually running rich or cheap two stroke oil.

No it's the previous owner who put the piston in and it's my cousin who made the job. I trust him, he rebuilt my old 97 cr250r and 86 trx250r...

I guess the crank damage is caused by the previous piston come appart like you said or the bearing spin. So I guess I can go ahead without a new crank...
Thanks

[MathGSR98]

Is that rod and piston pin blued? It looks like that R got really really really hot

I'm not sure about the rod and piston being blued but I can say that it has ran hot. I rode it the last winter (I'm in Quebec, Canada) without jetting it richer... I could feel like 25% more power but It was certainly running lean as hell... My fault... I don't have my piston/rod and pin in hand, so I can't say much.
Thanks

[MathGSR98]

Post a pick of the spark plug . Is it melted ? What about the needle bearing ?

I don't have my sparkplug to take a pic but it is not melted, it is just black with some carbon deposit on it. The needle bearing is fine. I can't detect almost any radial play if I try to move the pin.

[Erics350x]

maybe it sucked in some sand or mud?

[MTS]

Both the Circlips in the piston still? if so the dammage was Probably from running it so Hot,,,,,Aluminum melts at 1400 And it aint hard to get the motor that Hot when its running lean........or the bottem end wasnt flushed out properly when it was last rebuilt. could also be from not Cleaning the cylinder Properly From the last bore job/rebuild

[Unclediezel]

The "DINGS" in the piston are from detonation...Either too hot or too lean..Not bad enough for Replacement IMO....Wiseco pistons are common for "Scratching cylinder walls....Cant tell how deep that is from the pic, but if it isnt too deep, It may be normal. ANyone else , verify this for me?

[Somekindofjerk]

Wiesco pistons tend to need a little more clearance than a normal piston. Being more heavilly constructed they expand further than the specs in the book say. I have been told to add and extra thousands of an inch to the clearance to keep the scraping from happening. Allso, that piston retainer pin looks horribly blued, i would try to get a new one, or use an old one thats in decent shape. I had one but cant seem to find it....

***edit*** a nice new reed cage might be nice too, bring back some life:Bounce

[jason 32]

hone the cylinder ,and check the clearances
clean the head and piston with a soft wire wheel / dremal tool / or sand paper ,and polish it see if they are still in it.
they are so minimal i dont think it will matter,
it ran ok? - it looks like mabe ya didnt warm it up,rings are good? , if it would have been a pin or something like that from the crank it would be bad, my suzuki was
so was the head
did the reeds break and get burnt in the cylinder???

wisco pistons are great pistons follow the instructions -- relieve the exhaust bridge and what ever else they say to do

[TimSr]

The dings in the piston are from good old fashioned debris smacking into it. Nothing more. My first guess is chunks of carbon coming loose from the head. The marks on the crank are from something major coming apart at one time, but who knows when. If it just happened there would be shrapnal inside, and something wouldnt be moving right.

There are absolutely no signs whatsoever this was running lean or hot. Just the opposite. You dont get excessive black carbon buildup from a machine running lean. You dont get black carbon on the top of the piston. When a piston melts, it looks like its been sandblasted away, you dont get dings in it. It typically starts at the exhaust side of the piston.

What this looks like to me is somebody ran a 20:1 mix for a long time, and never got it hot enough to burn off, and never set it lean enough to burn off. I agree the piston is probably okay to use, but my guess is youre going to need a bore job, because those carbon chunks rubbing the clylinder walls have probably formed some grooves too deep to hone. It wont hurt to try a mild hone job first, but Id be surprised if that takes care of it. Youve got plenty of room to bore as I think that goes up to 3.0mm oversize (.120") if I remember right. Then get a good high performance 2 cycle oil, and mix it up at 50:1, and adjust carb accordingly.

[jason 32]

i wouldnt go 50 i use klotz at 40 - burns clean and smells good 2 lol
depends if you use racing fuel too

[MathGSR98]

The dings in the piston are from good old fashioned debris smacking into it. Nothing more. My first guess is chunks of carbon coming loose from the head. The marks on the crank are from something major coming apart at one time, but who knows when. If it just happened there would be shrapnal inside, and something wouldnt be moving right.

There are absolutely no signs whatsoever this was running lean or hot. Just the opposite. You dont get excessive black carbon buildup from a machine running lean. You dont get black carbon on the top of the piston. When a piston melts, it looks like its been sandblasted away, you dont get dings in it. It typically starts at the exhaust side of the piston.

What this looks like to me is somebody ran a 20:1 mix for a long time, and never got it hot enough to burn off, and never set it lean enough to burn off. I agree the piston is probably okay to use, but my guess is youre going to need a bore job, because those carbon chunks rubbing the clylinder walls have probably formed some grooves too deep to hone. It wont hurt to try a mild hone job first, but Id be surprised if that takes care of it. Youve got plenty of room to bore as I think that goes up to 3.0mm oversize (.120") if I remember right. Then get a good high performance 2 cycle oil, and mix it up at 50:1, and adjust carb accordingly.

Wow dude, you rock big time! The previous owner did run it 20:1 with probably barely cheap oil. I used klotz super techniplate at 45:1 and at the end Sinto Racing performa (40:1) which is semi synthetic (http://www.sinto.ca/). I liked more the klotz but it's harder to get it in Quebec, Canada...

I don't think I would be able to hone it because the scratch that you can see on one pic is really deep. What tool you use to hone it and clean the carbon deposit?

Now for a 66.75mm piston, what bore size I have to ask to a mecanic. I mean, he will have to do it larger than 66.75mm because of the rings?

Some other guys in this thread told me that my pin is blued. Does it means that the pin is more fragile?

[jason 32]

a 3 blade, flex hone - i used a soft wire wheel on a dremel to remove the carbon
it will kinda polish the head , did it to the piston too
check the piston to cylinder clearance and the ring clearance after honeing it lightly
if you use a ball type hone- it is supposed to be ? like 10 % smaller than the cylinder- so it will not catch the ports
i dont like them!! if they catch they can do damage / and break your wrists ouch!!
use warm soapy water and i like dawn dish soap its 1 of the best soaps out there
rince throughly and lightly oil

[MathGSR98]

Thanks man and thank everybody. This forum is very helpful and I'm very proud riding a TRIKE! even if it's not running now :(
hehe

[MTS]

a 3 blade, flex hone - i used a soft wire wheel on a dremel to remove the carbon
it will kinda polish the head , did it to the piston too
check the piston to cylinder clearance and the ring clearance after honeing it lightly
if you use a ball type hone- it is supposed to be ? like 10 % smaller than the cylinder- so it will not catch the ports
i dont like them!! if they catch they can do damage / and break your wrists ouch!!
use warm soapy water and i like dawn dish soap its 1 of the best soaps out there
rince throughly and lightly oil
Are you nuts, 3 blade flex hone WILL catch ports and do dammage, Ball hone all the way...

[TimSr]

Are you nuts, 3 blade flex hone WILL catch ports and do dammage, Ball hone all the way...

I agree, but if you dont already have a hone, Id just send it out for a bore and save the expense of buying something thats not going to fix it anyways.

[Bryan Raffa]

Are you nuts, 3 blade flex hone WILL catch ports and do dammage, Ball hone all the way...

I agree also,,,, ball hone all the way..3 blade flex hones are a thing of past and suck.. I would bore the next size up,,and take that plastic right out of the reed cage! more air = faster..

[MathGSR98]

Now what bore size I need for a wiseco 66.75mm (.75 over)? I assume I have to tell the size I want to the machine shop dude?
Thanks

[MTS]

Now what bore size I need for a wiseco 66.75mm (.75 over)? I assume I have to tell the size I want to the machine shop dude?
Thanks
Bring the Piston and cylinder to the machine shop....make sure its a reputble one that Know's how to bore a 2 stroke cylinder properly, Heck i would Shove it in the mail and Send it Right to Wiseco....do belive they do boring, and its For Damn Sure proper.....:TrikesOwn :beer

[Bryan Raffa]

yes thats what you need.. check ebay you might find one cheeper that what a shop will carge you. and dont for get the top rod bearing they dont come with a kit.

[hrc85250r]

um, it looks like you need a whole rebuild, the dings on the crank are from someone using a metal hammer to true it, you're supposed to use a lead hammer, and the pitting is a peice of metal bouncing around, and wiseco pistons dont need extra clearance because they are "heavy duty" they expand slightly more because they are forged, not cast like the ghetto pistons like pro-x. and you can take the reed stuffer right out of that cage, it just snaps in, it will give you a little better top end, i dont know if you would be able to feel it on a stock bike though.....i say bore it with a new piston and do a new rod kit and main bearings/seals, if not a brand new crank and mains/seals...