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Hey guys, I got out my 92 200 with full rebuilt engine, fired it up, got it nice and warm and was riding it in the sand. Was a little loud, but running good. Then it shut off. I held the clutch in, coasted to a stop. Too hot to check coolant level, but a little test on the kick starter and the engine won't turn. Rolling in gear won't turn it either.
I'm walking home now to get the truck. In the meanwhile, I'm still pretty new to 2 strokes. Am I in for another rebuild? Top end kit? Let it cool and work it loose? What are the implications here?

FWIW, total rebuild by millenium tech, new plating, BDK valves, wiseco top end. Less than 10 hrs.


Thanks,
Fried


"Good job, guys. "

you should of broke the engine in correctly.
take it all apart and use fine sandpaper to get the aluminum streaks off the cylinder.
If the rings aren't grooved then you can still use them.
Make sure they can slide around freely within the ring grooves.
What color is the spark plug?

Just out of curiosity, what oil and ratio were you using?

Friedom wrote:...was riding it in the sand.

Any chance it was too lean? Too lean in sand can be a recipe for disaster.

Did you check/set the ring end gap?

Jaguar wrote:you should of broke the engine in correctly.
take it all apart and use fine sandpaper to get the aluminum streaks off the cylinder.
If the rings aren't grooved then you can still use them.
Make sure they can slide around freely within the ring grooves.
What color is the spark plug?

Everyone breaks it in correctly, since there are so many "correct" ways to break in a top end. :)

"Good job, guys. "

Jim B wrote:Just out of curiosity, what oil and ratio were you using?

Maxima 40:1

"Good job, guys. "

Jim B wrote:

Friedom wrote:...was riding it in the sand.

Any chance it was too lean? Too lean in sand can be a recipe for disaster.

Did you check/set the ring end gap?

Millenium tech did the engine build. I assume they gapped it correctly.

The ratio I run is from ss109's recommendation. He lives a few miles away and ran an E series here for awhile without issue.
I wasn't flogging it, but it was getting a workout I guess.

I'll check out the plug color, that should be helpful.

"Good job, guys. "

Something was out of spec ,,ring gap , jetting , air box seal ,base gasket, ect,,,, shd never happen with that oil.

Like you said,, " I'm new to 2-strokes "

Jim B wrote:

Friedom wrote:...was riding it in the sand.

Any chance it was too lean? Too lean in sand can be a recipe for disaster.

I think this is it. 40:1 isnt going to completely protect you if you are too lean on the main and putting a heavy load on the engine.

When you pull the to end off be sure to check if there is any residual oil in the bottm end.

I agree with C George, something is out of spec. Assuming the bike was running when you had it rebuilt, I would doubt jetting. More likely something on reassembly like an air gap at the carb boot that let it run really lean IMO. I don't ride sand dunes though and understand they put an especially heavy load on the engine. You said Millenium did the rebuild, did they do the reassembly or just recoat the cylinder and send you a piston and rings? If the latter, it is risky to assume they checked the ring gap, although they should. If the top seized you're definately in for a top rebuild at best. Open it up and take a look. You might be lucky and can smooth out the cylinder with a Scotch Brite pad or very fine wet/dry sandpaper. I'd put in new rings as a minimum, new gaskets and check all torque values.

Really sorry you had this experience. Especially timely as my newly recoated cylinder from Millenium is in a box in my shop waiting for me to reassemble the top end. I'll be doubly careful checking stuff now!

They did full assembly and sent me the engine shiny and ready to install on the bike.
I think I know what happened, to some degree:

Then I drained all of the coolant out:


I don't think this is the fault of MT..
Where did all my coolant go? The oil is clean, so not a waterpump seal issue.

I'll post up more findings as they come along, but definitely overheated the ol' girl. Guess I wasn't paying enough attention to that, as I come from airheads. But still, have to find why it lost all that coolant. It's probably been 4 hrs of riding time since I last topped it off.

"Good job, guys. "

Ouch! Yep, overheated and now you know why.

That explains why it melted my glove print onto the cylinder when I touched it to check heat.. heh

"Good job, guys. "

Well boys, here's our chance to see just how good the legendary millenium tech lifetime nicasil lining holds up under abuse!

"Good job, guys. "

Digging further:







Engine turns freely.
I probably won't reuse that piston or the rings..
I see lots of oil in the bottom!

Also, 2 or 3 cylinder nuts were finger loose. Spark plug was also. I re torqued those after breakin, I believe.

Cylinder looks pretty good. We'll see after some scotch Brite. Head looks good too. Hopefully nothing warped.


"Good job, guys. "

Engine is coming off the frame, and I'll flush out the bottom end with older premix fuel, then lune up the bearings again and see how it feels. Good sources on top end kits, anyone?

"Good job, guys. "

That's a lot of metal that ran through the bottom end. I would be rebuilding it as well. If it let's go you will lose the top end for a second time.

Yeah, I just spent $1000 rebuilding the bottom and top end, new crank, new seals and bearings all around. I think I'll clean it out good, oil the bearings, check for smooth operation and put it all back together with a new top end.

"Good job, guys. "

WOW.

Muriatic acid to remove any aluminum streaking

Sorry to hear of your troubles.

Did you have the overflow catch tank underneath the left side panel?

Jason wrote:WOW.

Muriatic acid to remove any aluminum streaking

Sorry to hear of your troubles.

Did you have the overflow catch tank underneath the left side panel?

Thanks, I've got some MA around for the pool so that should be handy. Application tips?
No reservoir on either of my E bikes. Didn't know there ever was one until today.

"Good job, guys. "