Help! melted it down after 2 days of ownership

[nate538]

Hi everyone I just joined here because my friend bought a 2001 srx700. Everything was going great until he called me today from the trail to tell me the motor just seized up . He managed to un-seize it after a few min of turning the primary back and forth. Limped it home, compression was 120,120,30(exhaust side) . Tore the exhaust side down and there was scoring all the way around the piston and the cylinder. We believe the meltdown was caused lean condition due to missing exhaust springs
My question is:

1)Can missing exhaust springs cause the exhaust to blow of during hard acceleration creating a lean condition?

2)Should we replace just the exhaust side cylinder and piston or all three pistons?

3)Should we still split the cases and clean everything since there was minimal metal shrapnel?

 

[amatosrx]

please post your correct location in your info.

 

[j2hizzo]

any pics? that would help, thanks

 

[Whammy]

Sounds like dirty carbs,,,,, Did he clean them before seeing what it would do.......

 

[nate538]

Fixed profile sorry about that
Pics will be coming tomorrow hopefully
Sled ran great for about 3 hours the first day around the yard, brought it out to the trail and started to open it up then it seized
It ran great so we didn't check much Never again!

 

[yamirules]

If the exhaust opened up you would hear it at WOT. If the motor would have been shutdown and not ran you can get by rinsing the bottom end with fuel and cleaning it out. Disassembly and cleaning is the right way to do it. You dont have to, but crud and metal particles are death to crank bearigs.

 

[nate538]

He said that at some point he was playing with the pipes and it quieted down
Could be a clogged carb i will have him check tomarrow

 

[BBlueSRX]

yes if the exhaust comes off there is no back pressure and kaboom

 

[Fardoche]

Same thing happened to a cousin few years back. I think the grafoil gasket had disintegrated.

 

[nate538]

Thanks for the replys guys I haven't seen the damage in person yet because I am away at school. I mostly wanted to make sure the exhaust could be the cause if the carbs look clean
Any opinions on 1 piston vs 3
as soon as I get the pictures I will post them on here

 

[Skydog]

Man sorry to hear that! Yamaha is about as good as it gets for not doing that.......

 

[nate538]

The worst part is this is not the first time this happened to him before this he had a srv 540 that was a total basket case at least that lasted half a season
btw we compression tested the 700 before he bought it checked out fine (120,120,115)

also so far i have only been able to locate the 2000 srx service manual anyone have the 01 version they would like to share thanks in advance

 

[Maim]

2000 and 2001 are the same sled other than the colour. the 00 manual will be the same.

 

[nate538]

Thanks didn't know if any specs for the rebuild changed between the years

 

[Spinner18]

change all 3 pistons. thats the best thing you can do. if your in a pinch with money, you can get by with just one. but the right way to do it is to pull all the pistons, replace with new, and hone all the cylinders to put in a fresh crosshatch so the rings seat properly.

 

[YAMAHIZAL700]

I disagree that the lack of back pressure will cause enough of a lean condition to go kaboom. I would look for an airleek or plugged carb jet. Jmo

 

[BBlueSRX]

Hey Yamahizal you ever blown a hole in the exhaust? Or had a hole rust through? this is exactly what happens. LEAN----> KABOOM. take your exhaust off and go run it down the road if you dont believe me....

 

[nate538]

pics

My friend just sent the pictures of the so called kaboom looks worse than I thought it would

 

[nate538]

Carb is getting pulled apart tomorrow along with other cylinders will let you know what he finds I'm hoping they will be good enough to use
BTW the lighter coloured gouges were caused by my friend somehow not the meltdown

 

[KneeDown]

Looks like a cold sieze to me