cooked the top end, now what ?

[diymirage]

hey guys

went for a good ride today (will try to upload videos later) and the bike ran strong all day long
at one point I noticed there was a ticking noise to the engine, almost like piston slap
when I stopped for a second the bike would not rev down and smelled weird

as I headed back to the parking lot the ticking started to sound more like knocking (specially in low RPM) and power was way down
at about a mile from the parking lot I had to stop to cross a road and there she died
I tried kicking her over but compression was non existent

that was the end of the ride for me
I hauled the bike back home and started tearing into her
as soon as I removed the pipe I noticed the problem, the lower radiator hose had come loose and so I basically ran her in AC...not good
I tore the jug off and this is what I found



















so im guessing the piston is pretty well shot but what about the cylinder ?
can I hone it and be good ?
(its already bored 3 MM over and that's about the max so boring and replating it isn't an option

should I worry about the head ?
does it warp like car heads that overheat?

[Julien D]

Replating does not require boring. Can't tell from pics, are you running a sleeve? If so, hone it. If not, scrub it down with scotchbrite and have a closer look. Doesn't look damaged to me from what I can see here.

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[diymirage]

that sounds promising

no sleeve, just stock material

I guess if it isn't too gouged up a replate wouldn't require a bore, but when I got it was wore down so bad it had to be bored over 3 MM

I don't "feel" anything in there so it doenst look like the bore is too bad
the lack of compression tell me something isn't right though...piston ?

[KDXohio]

you can use a ball hone on it lightly

[diymirage]

is that something that autozone lends out or should I take it to a shop to have that done ?

[royadams]

When the rings get stuck in the piston they can no longer seal against the cylinder. Clean up the cylinder real good if there is any small bits of aluminum left behind you will stick it again in short order. The plating is pretty tough I think the cylinder will be fine.

[royadams]

I would not use a ball hone on it. If you read up on it it will cause your rings to wear out faster. If it needs it its best to have it done with a diamond hone, that's what there done with when you get them replayed. I would use scotchbrite and soap. If there is small bits of aluminum left use a little muratic acid on a qtip and disolve it.

[KDXohio]

The ball hone is what's used to break the glaze and bring back the proper cross hatching without removing much material it won't make you're rings wear out faster if done correct correctly and a ball hone is what the pros use for ring changes. The hones you're referring to are used after replating to gain the correct piston clearance. You can't rent them have to buy one. A scotch brute pad and acid doesn't always bring back the proper cross hatching which is necessary for full ring seal for your highest possible compression

[KDXohio]

Ball hones do come in different grits which after rereading your post may be more along the lines of what you were talking about

[rbates9]

It does look like the rings might be stuck in the piston and that could be where the compression would have gone.

So, any thoughts on a little better pre ride inspection routine?

[KDXohio]

Would be better to triple check fluids and hoses rather than find out the hard way

[Postigo]

Clean your cylinder with a scotchbrite and soapy water then inspect the cylinder with your finger nail and look for groves if you find at least one you are in need of a replate or a sleeve. Good luck bro.

[KDXGarage]

OUCH!! Sorry to see it!

Green Scotch-Brite pad and muriatic acid to get the aluminum off.

If it still looks like it was scraped too bad, maybe a replate will do.

[diymirage]

ill bust out the scotchbrite pad in the morning

thanks for all the advise guys


I checked the rings, they move freely in their grooves

[Gotanubike]

I rode my 89 around the sand pits all day without water the first couple times...that was before I discovered the crack under the KIPS cover and had it welded.

I recall the overheating knock and fluctuating throttle at low rpm, as you described. Luckily I never had a seizure but it would not idle..

My top end looked a lot like that, as in the plating wasn't exactly perfect with one somewhat considerable score line up the cylinder wall near the exhaust side. The piston looked like that too...the rings were fine and it is running great now that it is not inhaling antifreeze through the resonator chamber.

Can't really say considering you bored over but might have something to do with it...if you're going for a new piston, personally I'd have it replated back to stock if that's even possible and buy the OEM spec wiseco piston.

[KDXohio]

Its likely the exhaust side of the rings are worn thinner than the intake

[Roadhazardguy]

I wouldn't use a ball hone on a two stroke because of all the ports in the cylinder, the three stone hone is a better choice.

[Julien D]

Either hone can catch the plating at the port openings and flake it off. A few things, crosshatch is really not necessary on plated bores. If the plating is worn thin or gouged, a hone would do you no good anyway. Best to stick with the scothbrite and clean any aluminum residue from the piston off with muriatic, as mentioned above. Not that you can't use a hone on a plated cylinder, I have, but it's more likely to hurt than help.

[diymirage]

thanks for all the advise guys

ill pick up a scotchbrite and some acid and hopefully the bore is still good
gotanewbike, the original bore was wore out so bad in order to get it round and true again it had to be bored over by 3 MM, no chance of returning to the stock bore short of sleeving it
did you reuse your old piston ?

the rings are free but there was no compression so I don't think im willing to try that anyway

I send the pictures to langcourt (they did the overbore and replate) to see what they think the best course of action is

for what it is worth, here are the last few minutes of it running


[youtube][/youtube]

[youtube][/youtube]

[Julien D]

I really think your plating will be fine once you get it cleaned up. Pop in a new top end kit, and give it hell. Side note, if you go with the muriatic, apply sparingly and ONLY to the plating. It will eat away at the aluminum portions of the cylinder if you get any on there. Do not let it sit for long, flush with plenty of water, and you can neutralize it with a baking soda/water solution to be safe once it's clean.