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2003 Yz125 Engine Seized on me

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Hey, i was just wondering for advice because i bought a 2003 yz125 and i when i test rode it at the blokes house it sounded mint, it idled perfectly and was real smoothe, the man said that he did the top end rebuilt a couple months ago and it only has 4 hours on the top end, then it sat in his shed for 3 months, when i took it home i really opened it up and gave it a bootful and the engine seized up, the fuel mixture was perfect (30:1 just like the manual said) and it was singing like a birdy but then it made a clunch and it seized up, it wouldnt even kick over, I returned it to the man and he refunded me but i want to know if it was me riding to hard or a dodgy rebuilt as i want to buy another yz125? My dad thought it could be something the man did when he rebuilt it himself but my mate said not to back off quickly and often on 2 strokes because it has the motor running but no oil in it, and I usually ride a kx250f but i've had 2 strokes in the past and it didnt sound like i was overevving it so im thinking dodgy rebuild?

Edited by The man with bike problems

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Describe how & where you were riding when the engine seized, 

during a long stretch of sustained wide open throttle, say like a road or field perhaps?

Edited by mlatour

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3 hours ago, The man with bike problems said:

Hey, i was just wondering for advice because i bought a 2003 yz125 and i when i test rode it at the blokes house it sounded mint, it idled perfectly and was real smoothe, the man said that he did the top end rebuilt a couple months ago and it only has 4 hours on the top end, then it sat in his shed for 3 months, when i took it home i really opened it up and gave it a bootful and the engine seized up, the fuel mixture was perfect (30:1 just like the manual said) and it was singing like a birdy but then it made a clunch and it seized up, it wouldnt even kick over, I returned it to the man and he refunded me but i want to know if it was me riding to hard or a dodgy rebuilt as i want to buy another yz125? My dad thought it could be something the man did when he rebuilt it himself but my mate said not to back off quickly and often on 2 strokes because it has the motor running but no oil in it, and I usually ride a kx250f but i've had 2 strokes in the past and it didnt sound like i was overevving it so im thinking dodgy rebuild?

Cold seizure, you didn't let it warm up proper, than you clubbed it like a baby seal, let off throttle, cold water rushed into the expanded chamber, and locked the cylinder. Bet after it cooled, it started, unless you really spanked the monkey!

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Your damn lucky you got a dollar back. If he truly had 4 hrs on it, I'm going with something you did, but alot of previous owners lie or guess at hrs.

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Indeed lucky to get a refund,

being intended for racing usage in most regions even brand new of the showroom floor MX bikes are sold 'as-is' with no warranty at all or,

a very limited one covering possible defects.

 

No answer from OP but each time I see Australia as the location in a member's profile I think of vast open terrain,

somewhere a high revving, steep final drive ratio YZ125 would no doubt top out and seize if held wide open for too long.

Edited by mlatour
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Yeah thanks for commenting quickly, when i rode it i gave it around 3 mins to warm up and then took it steady on the road (dirt, windy road, also on the farm) then started to open it up and pick up some speed but never held the throttle wide open as it wasnt too straight and kept slowing down for logs and sharp turns, and then after around 10 mins it started losing power, and then all power dropped so i hit the killswitch and my guess is the cylinder is stuck on the inlet or outlet, and even after it cooled down, the compression was tighter than your sister before graduation night, so im thinking maybe the seal has gripped on the exhaust outlet and locked up

Edited by The man with bike problems

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1 hour ago, The man with bike problems said:

tighter than your sister before graduation night

:(

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2 hours ago, The man with bike problems said:

Yeah thanks for commenting quickly, when i rode it i gave it around 3 mins to warm up and then took it steady on the road (dirt, windy road, also on the farm) then started to open it up and pick up some speed but never held the throttle wide open as it wasnt too straight and kept slowing down for logs and sharp turns, and then after around 10 mins it started losing power, and then all power dropped so i hit the killswitch and my guess is the cylinder is stuck on the inlet or outlet, and even after it cooled down, the compression was tighter than MY MOM before I came out, so im thinking maybe the seal has gripped on the exhaust outlet and locked up

 

3 minutes ago, MaybeMe said:

:(

Fixed it! :naughty:

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7 hours ago, The man with bike problems said:

Yeah thanks for commenting quickly, when i rode it i gave it around 3 mins to warm up and then took it steady on the road (dirt, windy road, also on the farm) then started to open it up and pick up some speed but never held the throttle wide open as it wasnt too straight and kept slowing down for logs and sharp turns, and then after around 10 mins it started losing power, and then all power dropped so i hit the killswitch and my guess is the cylinder is stuck on the inlet or outlet, and even after it cooled down, the compression was tighter than your sister before graduation night, so im thinking maybe the seal has gripped on the exhaust outlet and locked up

Tighter than a sister gheesh

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3 hours ago, Smoking 2's said:

Wait what, 2 posts prior "tighter than Monica Lawinskies cigar pu$$" what is happening around here:devil:

You know the quote thread is awesome!

Edited by 2 STOKE YZ DOC

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A YZ125 is designed for MX racing, meaning accelerating hard from corner to corner on relatively short straightaways

where it ideally it 'tops out' at max rpms in top gear for only a brief moment.

 

If your intended usage is more off-road oriented with vast open terrain, fast dirt roads where the bike will

see long straights of sustained high rpms and speeds, a small bore MX'er isn't the right choice for you. (rather look into a 'WR' wide-ratio enduro bike)

 

Also, since 2-strokes are lubricated and internally cooled by the incoming air/fuel/oil mixture,

it is not advisable to excessively 'compression brake' with the engine.

With the engine decelerating yet still turning high rpms,

as the throttle is closed the engine is getting minimal internal cooling effect and risks damages / seizure.

 

You should tell us what type of usage you plan to do, if no MX'ing is anticipated,

there are much better choices than a high strung MX bike for casual off-roading.

 

 

 

Edited by mlatour
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On 9/25/2017 at 8:02 AM, mlatour said:

Indeed lucky to get a refund,

being intended for racing usage in most regions even brand new of the showroom floor MX bikes are sold 'as-is' with no warranty at all or,

a very limited one covering possible defects.

 

No answer from OP but each time I see Australia as the location in a member's profile I think of vast open terrain,

somewhere a high revving, steep final drive ratio YZ125 would no doubt top out and seize if held wide open for too long.

Majority of the places ridden in aus are semi tight to vrry tight single track with tons of connecting fire trails, which are usually not very straight for long.

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Yeah thanks for your help, and dad thought i should get an enduro as well, but pretty much every 2nd weekend we go to a motocross track so that why i was gonna get a yz but I suppose for everyday riding how it is down here i think something like a wr is suitable

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