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Sr125pos

Yamaha Sr 125 Siezed

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Hello everybody, so today was on my 2nd time riding on the road, after passing my cbt, all was going well until I noticed It had no power in 5th and as I went to change to 4th as the clutch was In the engine cutout, pulled over at the side of the road and the top end was smoking engine doesn't want to start, got it home, took the tappet covers off and its all solid nothing moves and it stunk when we removed the covers, just wondering if anybody had any ideas as to what needs to be done and what caused it. Spark plug was an okay colour  milage is 16k.

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Did it have any oil in it?

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Sorry but why do 4 oil changes?

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Didnt do them all in one go did them over course of about 3 months for different reasons, had to take casings off etc, sorry but whats that got to do with my original question. 

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Well I think we were all wondering why, next question would be why did you have the casings off, cos if it had oil in maybe it's something you done when the casings were off :wacko:

Edited by Tommy xs
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What we need to know really is 1 Is there still oil in it? 2 What was the reason for you removing the cases before it locked up? 3 The reason Cynic asked the question was there has to be a reason for doing 4 oil changes and it might help if you told us why, You see it's really difficult to say what the problem NOW is if you don't tell us what you needed to do to it that meant you had to change the oil 4 times..!

PS the engine will only lock up for a few good reasons, No oil (lubrication) No water (cooling) broken component. Lots of other reasons lead up to a failure but none of them start without the first 3.

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Sump  plug not tightened ,  and oil ran out,   -  

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There was oil in the bike, I can assure you all that, the reason we did so many oil changes during the course of about 2-3 months is because, of the following, first time we did it was because the person we Baught it from said it was standing for a while, second time was because we took the ride casing off because we had to change the starter motor, then the third time we did it well tbh I can't remember, now yes there is still lots of oil in the engine the sump plug is done up, It ran fine all day yesterday, the  today was going along at 50 noticed it spluttered a few times, then the speed started to drop so as I changed into 4th while I was holding the clutch the engine died, pulled over and the head was smoking, got it home took the the inlet and outlet covers off underneath looked fine  but was just siezed solid no movement whatsoever, and it had a rank smell when the covers were removed, could it be the oil pump.? 

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Yeah that would be my best guess as to the problem, it sounds like a lack of oil to the head which has caused your problem, you might be lucky and save the head and valve gear but if it's really badly scored then you might be looking at a replacement head and valve gear. Your only option now is to take the motor apart and check the oil pump and gears, sorry mate but it does sound like your in for a major overhaul of the motor. Where are you in the world? we might have someone near who can help..!

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Hi

With the bike in gear and the clutch lever pulled back to the bars can you push the bike, I.e. is the gearbox locked up or is it definitely the engine locked up?

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Yeah that's what I'm worried about, I am in Norwich I've manged to source an engine for 50 quid the guy says it has good compression but is an unknown runner but for 50 quid it's worth a shot, yeah the bike rolls In gear the clutch in,, going to pick the engine up tomorrow and hopefully have it in and see if it runs Wednesday. 

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Oh well done on getting an engine really quick, sounds like you had this idea it was toast before you asked. Anyway in your position I would just check that the oil pump on your original engine is in fact the problem, you might just have to swap out the oil pump rather than trash the whole engine and then you will not need to change the V5 and docs. It sometimes makes sense to do a bit more work and get it right rather than rush at it and regret it later. Just sayin..!

A top end swap and oil pump change should be about the same as taking the whole thing out and replacing it.

By the way just check on your original engine that the oil-ways from the pump to the head aren't blocked by old oil and crud, it might be an easy fix and not the pump at all. Some folks (especially the younger ones) don't change the oil as often as they should and 125s are likely to be hammered by their owners.

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Being true to my screen name:

50 quid is awful cheap for a running sr engine. Buyer be VERY aware.... :ninja:

They don't die, they can take biblical amounts of abuse and keep running and can cover truly ridiculous mileages for such a small bike. 100000 miles is by no means impossible.

Ball bearing crank so that is near indestructible, similar bearings to my TDR and that makes 5X the hp at higher rpm. Not sure on the head, they may be white metal.

Did you ever clean/check the oil filter while you were messing, something is wierd here.

Unless you have found the holy grail of an unreliable sr.

 

Even Grouch couldn't kill one of these engines.

 

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25 minutes ago, Cynic said:

Even Grouch couldn't kill one of these engines

Hehehe 

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Oh yes he could  :P

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Yeah we changed the oil filter, there was a few shavings and bits of crap in there, when we the took the casing off to change starter motor, there was a lot of sludgy crud in the bottom, cleaned it as best we could, have decided to leave the 50 quid engine, have a found a whole bike for 200 engine runs nicely, rest of the bike isn't the best. 

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