disintergrating base gasket...?

[sydduckett]

Scooter finally packed up after running rough for a while earlier today. Also loads of oil under the bottom of engine and across the pipe under the carb. Dropped the engine and took off the barrel & head and this what i found or more to the point what i didnt find....







Seems as though the gasket has just disolved leaving a gap, quite lucky i didnt blow it up... anyone had similar issues?

Also when i looked through the manifold after taking the carb off i could see somthing sticking across thought it was a buggered petal. Turns out the gasket had perished and worked its way in...?

[lamblast]

is it an mb gasket as there was a problem with them

[camel]

what is the blue sealant on the gasket?could there be a reaction?

[Ian Hepworth]

Scooter finally packed up after running rough for a while earlier today. Also loads of oil under the bottom of engine and across the pipe under the carb. Dropped the engine and took off the barrel & head and this what i found or more to the point what i didnt find....

quite lucky i didnt blow it up...

Did the rough running and oil leak not make you think to check your engine before today?
If the engine hadn't packed up today when would you have looked into the rough running and oil leak?

[Ian Hepworth]

what is the blue sealant on the gasket?could there be a reaction?

looks like it. there may or may not be a problem with a batch of MB base gaskets (5 reported failures out of 1000 sold) but MB don't make RB inlet gaskets so it's looking like the sealant may be the culprit.

Who built the engine? What was the sealant?

[sydduckett]

Scooter finally packed up after running rough for a while earlier today. Also loads of oil under the bottom of engine and across the pipe under the carb. Dropped the engine and took off the barrel & head and this what i found or more to the point what i didnt find....

quite lucky i didnt blow it up...

Did the rough running and oil leak not make you think to check your engine before today?
If the engine hadn't packed up today when would you have looked into the rough running and oil leak?

That is gasket sealer as used on the other gaskets. Prior to taking the cowelling off and the head it looked as though the oil was coming out of the exhaust stub as it was coated in oil, had booked it in to have the stub sleeved beleving this would sort the issue. It was only when i dropped the engine that i found that the oil was iun fact coming out of the base gasket then flowing over the stub.

[navywolf]

Ian, my Ts1 was one of the 5 reported failures (from the speedshop portsmouth).......the base gasket (black type) had all but disintegrated, resulting in cyl head nuts loosening....air leak....bang.....holed mb piston!

Now need a new piston.... not to mention having to strip/clean/new seals/rebuild.

Gutted mate

[Train Driver]

sydduckett sorry to hear of your problems but what is wrong with the base of your cylinder is that rough casting or a hole, it might be my computer but the pictures filled my screen.
With these high performance kits we should look at hours used not miles done before we check them over,
found this on a mx-enduro site
How often do you rebuild your 2 stroke?

I'm kinda new to this sport, but I've pretty much fallen in love with riding. I think I've been out practicing on the bike at least 5 days a week the last two weeks since I got my bike running. As you can imagine the hours are clocking up on that rebuild pretty quickly. Eric Gorr says the 125 two strokes need new bottom ends every 80 hours. I think I'll go through 80 hours within the next year or two!
But I can deal with that, whatever.
But my service manual says i need to replace the piston every 7.5 hours. Do you guys really replace these things that often? I will stretch that out to a few months probably just because I'm learning to ride and I just don't have the guts to hold on and ride the pipe very often so it probably doesn't get beaten as much as some of the race bikes do, but still.
So I wonder... how often are you guys rebuilding your top ends I'm curious about the bottom ends too. I don't think I'll just split the case at 80 hours and replace the crank, but its kind of sobering to think the week I spent learning to rebuild the bottom end may only be good for a year or two.

[yellow peril]

I have just ordered a new 'black' base gasket today from MB, the website quotes 0.5mm but on the phone they said they only have the Graftec type at 0.75mm, which version is this?

[yian-ts1]

Thanks for posting this, checked my ts1 tonight and gasket is knackered, mb have been really helpful as usual.

Lots of hearteache and money saved so once again thanks

Yian