2 stroke question?

P

parks

Joined Dec 2007

45 Posts | 0+

Vancouver Wa.

Discussion Starter
• Sep 15, 2008

• #1

Brother in law brought home a used but late model yz 250 for my nephew from a dealer. I notices it had a tar like substance dripping from somewhere on the swing-arm and out the tailpipe. I asked him if it was normal and he said the shop he bought it from (Hillsbourogh Oregon)
Had gone completely through it.

Yesterday they went on a ride and it blew up. They are trying to blame it on Nephew revving too hard but I think the tar had more to do with it?

What does the forum think?

 

G

grasstrackpete

Joined Sep 2008

299 Posts | 1+

Up North Uk

• Sep 15, 2008

• #2

whereabouts was the 'tar' from? a leak in the exhaust? if it was before the silencer then its just an exhaust leak, does it smell of petrol? could it have been massivly over fueling, i worked on a kx125 that had the needle stuck open and the mixture screw 4 turns out and it hydraulic'ed its self!! (long shot) some piccy's of spark plug please

 

husabutt

Joined Feb 2003

3K Posts | 384+

Escondido, Ca. USA

• Sep 15, 2008

• #3

parks said:

Brother in law brought home a used but late model yz 250 for my nephew from a dealer. I notices it had a tar like substance dripping from somewhere on the swing-arm and out the tailpipe. I asked him if it was normal and he said the shop he bought it from (Hillsbourogh Oregon)
Had gone completely through it.

Yesterday they went on a ride and it blew up. They are trying to blame it on Nephew revving too hard but I think the tar had more to do with it?

What does the forum think?

Click to expand...

Most two strokes and especially Yamahas are jetted overly rich from the factory which causes oily goo to run down the back of the silencer and drip on to the swingarm. Chances are slim to none that this caused the engine failure.

 

S

Shorty

Joined May 2008

91 Posts | 0+

Saskatoon, SK. Canada

• Sep 15, 2008

• #4

RE: Re: 2 stroke question?

SPOOGE!

 

G

grasstrackpete

Joined Sep 2008

299 Posts | 1+

Up North Uk

• Sep 15, 2008

• #5

RE: Re: 2 stroke question?

eh?

 

S

Shorty

Joined May 2008

91 Posts | 0+

Saskatoon, SK. Canada

• Sep 15, 2008

• #6

RE: Re: 2 stroke question?

thats what people call the sticky tar like stuff associated with 2-strokes when it comes out of the engine.

they call it "spooge".

maybe its a north American thing? maybe not, im not sure where your from.

 

ned37

Joined Dec 2004

2K Posts | 248+

back in cottonwood, az

• Sep 15, 2008

• #7

RE: Re: 2 stroke question?

the spooge is normal, nature of the 2t beast. what blew? what was he doing when it blew?

 

nsman

Joined Oct 2004

1K Posts | 14+

nova scotia

• Sep 15, 2008

• #8

RE: Re: 2 stroke question?

What do you mean by "blew it up"...did it seizethe piston,hole a piston,rod failure or???
The piston will tell most of the story,can you post a pic?

 

P

parks

Joined Dec 2007

45 Posts | 0+

Vancouver Wa.

Discussion Starter
• Sep 15, 2008

• #9

Great feedback as usual.

He is a new rider. It has a recluse clutch and we assume he did not shift out of low gear all day. It is a 2006-7 yz125 We are planning to pull the head tomorrow.

With this new info. What are your opinions we will find when we peel back the onion?

Thanks Mike

 

nsman

Joined Oct 2004

1K Posts | 14+

nova scotia

• Sep 16, 2008

• #10

my crystal ball is broken

 

ned37

Joined Dec 2004

2K Posts | 248+

back in cottonwood, az

• Sep 16, 2008

• #11

scuffed cylinder wall and piston skirt, stuck rings.

 

husabutt

Joined Feb 2003

3K Posts | 384+

Escondido, Ca. USA

• Sep 16, 2008

• #12

I am placing my bet that the top end needle bearing let go. Whats the prize for the correct answer?

 

A

awilksch

Joined Oct 2006

746 Posts | 1+

Kangaroo Island, South Australia

• Sep 16, 2008

• #13

Hi Parks,

My old KX125 'blew up' (hate that term - if it blew up thered be nothing left) it siezed up on a trailride, and I can tell you I wasnt abusing it, rather when I investigated the matter, I found that many MX bikes are only that, designed to go like a shower of **** for 15minutes full noise, when you trailride them, you arent going full noise, especially when you are doing distance at some speed, the cooling system overcools the cyl, and can causethe hot, expanded piston to nip up.

With my KX, after a hefty rebuild with new rod bearings, piston etc, nickasil coated bore (nearly $2000.00) I got the bike back, cut the feed between the cyl head and the radiator and put in a KTM EXC thermostat (open @92deg C) and pit in the digital thermometer wire, and idled it for 25 minutes did some short bursts with it, and kept the temp at approx 100 -110 deg C.

never had a problem after that, sold it, and the two owners since me have never done anything else to it.

I'll bet it is a nip up (cold sieze) and should be a basic top end rebuild, hardest thing will prolly be the power valve dissasembly.

Azza.

 

P

parks

Joined Dec 2007

45 Posts | 0+

Vancouver Wa.

Discussion Starter
• Sep 17, 2008

• #14

Going into shop today I will let the winner know.

Question: Used bike from local dealer. First time out over revved probably. Any recourse or just get her fixed?

Oh Yea, Dealer will not return phone calls and disappears when he goes into shop.

 

ned37

Joined Dec 2004

2K Posts | 248+

back in cottonwood, az

• Sep 17, 2008

• #15

Any recourse or just get her fixed?

Click to expand...

depends on what he finds. if its something he overlooked when he inspected it, maybe he'll cut you some slack. most likely it wasn't.

 

thorzburn

Joined Jul 2007

40 Posts | 0+

Beaverton Oregon USA

• Sep 17, 2008

• #16

Is this "dealer" actually in Hillsboro? Or perhaps in Aloha? Just sounds a little similar to a few personal experiences with a local guy.

 

P

parks

Joined Dec 2007

45 Posts | 0+

Vancouver Wa.

Discussion Starter
• Sep 19, 2008

• #17

Same shop, Bearing froze. Graphit oil mixture found. Boys from you are correct Aloha are not addressing problem. Do not recomend!!!

 

B

BundyBear

Joined Apr 2003

1K Posts | 3+

Newcastle, NSW, Australia

• Sep 22, 2008

• #18

Is it possible it was running on un-oiled fuel? I'd imagine it could take an hour or so for it to give up on petrol only. If it was spitting spooooge when it stopped it would have already been in the silencer packing from previous running.

Did it have coolant water in it OK?

Exactly how new to bikes is he?