blew it up again, no good!

[factoryX]

Maybe he's not, but maybe his dad is? At this point there are 3 possibilities:
1. He truly blew up the bike, but not from the reeds breaking.
2. The mechanic is screwing him over.
3. His dad is trying to convince him  to move on to 4 strokes.
 

[ACMX]

It's a game of clue. Someone is framing the reeds. It's up to us to find out who the real culprit is.

[2T Institute]

Have broken reed petals while the engine is turning over at 12,500 rpm, back of the piston munches the reed to carbon powder and disappears out the exhaust. But for the missing reed you will never know.
Maxima 927 is good oil , no problems with that.On a hard ridden 125  25:1 would be the very minimum of oil I would run. Remember "Nobody killed a 2 stroke with too much oil" (sic 'Spanky') 
I see this as a straight mantenance issue, a 125 will usualy need 2 rings to every piston and a new piston would be needed after 15-20 hours on a track as a general rule.If your lifting the top end after season end your asking for trouble.
I would seek a reputable tuner rather than the one your persisting with.
Cranks and big end bearing failures are caused soley by the lack of lubrication.
Learn how to do a plug chop and how to read a plug(you will find you don need your 'tuner' then)
As mentioned cylinders can be replated for about $200 +piston no need to buy a new cylinder.

[factoryX]

it happened to his 250, not his 125...

[VintageBlueSmoke]

Remember "Nobody killed a 2 stroke with too much oil"

I get your point and I am not flaming you but actually, too much oil in the fuel causes a lean situation and generates heat in a 2 stroke.

You may also want to check your intake manifold real good. Maybe the carb was not put on correctly and well seated or the manifold is cracked? That would cause it to lean out as well and might even generate the sucking noise that you heard.

[msmola2002]

Yes, if you add more oil it will run leaner, so you jet accordingly - hence the talk of checking the jetting with a plug chop etc.

[2T Institute]

Remember "Nobody killed a 2 stroke with too much oil"

I get your point and I am not flaming you but actually, too much oil in the fuel causes a lean situation and generates heat in a 2 stroke.

You may also want to check your intake manifold real good. Maybe the carb was not put on correctly and well seated or the manifold is cracked? That would cause it to lean out as well and might even generate the sucking noise that you heard.

Ah well 250 my mistake.

At 50:1 your running 2% oil and 25:1 4% oil how many engines are jetted within 2% of a seizure? To little fuel causes seizure faster than anything, without oil a engine will go for half a lap.

[factoryX]

Well, any updates?

[TotalNZ]

Remember "Nobody killed a 2 stroke with too much oil"

I get your point and I am not flaming you but actually, too much oil in the fuel causes a lean situation and generates heat in a 2 stroke.

You may also want to check your intake manifold real good. Maybe the carb was not put on correctly and well seated or the manifold is cracked? That would cause it to lean out as well and might even generate the sucking noise that you heard.

The lean situation you talk about is still a jetting issue, as always.
Jet to suit the mix.

[Super Trucker]

Too Lean, chamfer cylinder wrong, for replating  I would only use Milenium technologys , I used another plater and it costed me a riding season. A  1,000 bucks on a engine is a bummer, but it,s 25-28,000 for engine rebuild on a big truck engine.

[luthier269]

You can send your motor to Eric Gorr and they will diagnose the problem and recommend changes

[Mountain Goat]

Looks like Gorr will save you money:

http://www.eric-gorr.com/cylinder%20repairs.html

We offer 4 types of repairs;

1)     Honing of plated cylinders to clean-up minor seizures $20
2)   Boring and honing to the next oversized piston for cast-iron sleeved cylinders $50
3)   Replating with nickel silicon-carbide composite plating to stock size and up to 2mm oversize $250

[snip]

FAQs on 2-Stroke Cylinder Repairs

If the piston breaks can I just powerwash the crankcase and change the oil to get out the broken pieces?
The crankcase on 2-stroke engines is sealed so draining the transmission oil won't help. Most likely the metal particles will contaminate the bottom end to the extreme that you'll need to rebuild the bottom end with a new crankshaft, bearings, and seals. We offer that service and it averages $500 parts and labor. Additionally you'll need to powerwash the exhaust pipe (not silencer) because metal may be trapped in there and re-enter the cylinder once you restart the freshly rebuilt engine.

If I send my old piston with the cylinder can you tell me what the original failure was caused from and recommend repairs to keep it from happening again?
Yes, we recommend that you send any and all damaged parts, especially if you've had repeated failures. Also you should check out the tech article (PDF format) from Eric's book titled Piston Diagnostic Guide (on our home page). We'll diagnose your mechanical problem and recommend action solutions.

[smoke229]

Guys, on the first page he says his mechanic found dirt - right there is the start of the problem. Take any newer 2 stroke (or 4 stroke if your really brave) and throw some dirt down the intake and see how it works out for you!! You can say he needs to run X brand of oil or Y jetting with Z fuel , add some dirt and nothing matters LOL.....
2nd if your bike is trying to sieze, bog, and sounding wierd - quit riding it until you can properly investigate the problem