This is obviously not Zed related but my dad has a motorbike that is very poorley.

So all you bikers on here what do ya reckon to this problem?

 

Twin cylinder yamaha TZR 250 F reg.

Its got a 10mm hole in one piston which has only done 1000miles...(carefully run in)

 

engine previously sezied due to broken oil pump but had been completely re-built.

 

Fully synthetic oil....used for last 50miles.

Previosly used part synthetic.

 

80mph in fifth gear 8000rpm and lost power.

He then looked at temperature gauge and saw that it had risen to max but i reckon this had overheated before he lost power.

 

Can a weak mixture cause this?

The plug was not white ...looked the same as the other plug that was fine.

It has no tail baffles in pipes and has carbon reed valves which have been fitted for the last 1000 miles

The carbs have never been touched and had always run very nice.

 

no signs of melted metal...looks like a punch from underneath has gone through and left a crater like effect from the top.

there is a 7mm hole in bottom and 10mm top.

 

Any guesses please chaps ;)

This is obviously not Zed related but my dad has a motorbike that is very poorley.

So all you bikers on here what do ya reckon to this problem?

 

Twin cylinder yamaha TZR 250 F reg.

Its got a 10mm hole in one piston which has only done 1000miles...(carefully run in)

 

engine previously sezied due to broken oil pump but had been completely re-built.

 

Fully synthetic oil....used for last 50miles.

Previosly used part synthetic.

 

80mph in fifth gear 8000rpm and lost power.

He then looked at temperature gauge and saw that it had risen to max but i reckon this had overheated before he lost power.

 

Can a weak mixture cause this?

The plug was not white ...looked the same as the other plug that was fine.

It has no tail baffles in pipes and has carbon reed valves which have been fitted for the last 1000 miles

The carbs have never been touched and had always run very nice.

 

no signs of melted metal...looks like a punch from underneath has gone through and left a crater like effect from the top.

there is a 7mm hole in bottom and 10mm top.

 

Any guesses please chaps ;)

 

 

is it black!if so theres your problem

is it black!if so theres your problem

 

lol..... :mad:

 

Thanks for the help greg.... :smash: not

 

Actually i did say it went into the red which means its gona go slower :D

He did remember to put 2 stroke in, didn't he?

Running lean can cause a piston to hole.

 

I dunno why it would - air leak in a carb stub or something?

Running lean can cause a piston to hole.

 

I dunno why it would - air leak in a carb stub or something?

 

CheerZ peeps

 

HHHHMMmmmmm...

 

I think im gonna have to go n have a look at his bike myself n see what turns up :smash:

 

Might have a blocked fuel jet possibly :confused:

 

Any more ideas then please post....Ive got to rebuild my motoXer as well so looks like im gonna be busy next month :mad:

 

Adios Fellas :cool:

Almost certainly detonation.

Unlike this which was poor oil supply !

Hmmmmm, how many strokers have i seen like that!

 

Id say 99% detonation aswell!

just my 2p, but if the hole is smaller in the bottom than the top, surely that implies (as said in the post) that something has come from underneath. I was under the impresion that det would, if anywhere) hole ift from the combustion chamber or one of the upper ring lands? or do i not know what i'm talking about??:)

nah! detonation would create a hole like that. It burns a bigger area on the crown surface. You say it has no baffles and reeds? I presume the jets have been upped to compensate for this? If not then its running seriously weak at the top end, you wouldnt notice to ride it. I love and hate 2 strokes and this is one of those hate me moments:D

Ill get my coat :(

Almost certainly detonation.

Unlike this which was poor oil supply !

 

Blimey andy....thats one melted mofo u got there.... :eek:

nah! detonation would create a hole like that. It burns a bigger area on the crown surface. You say it has no baffles and reeds? I presume the jets have been upped to compensate for this? If not then its running seriously weak at the top end, you wouldnt notice to ride it. I love and hate 2 strokes and this is one of those hate me moments:D

 

 

He never changed his fuel jets :nelson:

Think he was hoping that the removed baffles would compensate for the carbon reeds :headvswal

 

Sound like hes gonna need some bigger jets then.

 

Strange how the other piston is perfect though and one is fooked :confused:

 

 

Thanks to all help...

 

:bow:

He did remember to put 2 stroke in, didn't he?

 

 

LOL... :rofl:

 

I do hope so... :smw:

Blimey andy....thats one melted mofo u got there.... :eek:

 

Nope, not melted at all. As I said it was poor oil supply, one of the valves (yes those lumps were valves!) seized open, piston comes up and shears it off, rattle, crunch etc. Happened at about 9000rpm, when engines only revved to 9000 rpm .....

This was the culprite:-

 

 

no way near as bad as andys.

 

Ill get my coat

 

FPMSL :rofl: ...cheerz mate ;)