Yamaha SR 125 Refusing to Start ***UPDATE***

[Adam.I]

Hello all. After much talk, my brother in law finally got his CBT with the view of doing his DAS in April. In the mean time, he wanted a 125 to some experience. I agreed to source him a cheapish one and found one 125 miles away from his house. It is a Yamaha SR 125. I said I would ride it home for him. Checked the bike and it seemed fine; started first time; no knocking; obvious marks of a previous accident etc.

Filled her up and started the long journey home. After about ten miles, I got to the motorway. Again, all was going OK but after about 40 miles of being on the motorway (which was stop/start for last 15 miles) there was a problem.

All of a sudden, the bike cut out with any warning. I immediately pulled the clutch in and got on to the hard shoulder. Tried to start it back up but nothing. All electricals worked fine. I thought that it may be petrol so went and got five litres worth and filled it up but that did not do it.

When attempting to start the bike, it just makes a noise like it is trying to but just cannot. I will be going to his house in a few days and see if I can diagnose it and hopefully repair it, but I am after a few suggestions from you lot. One of the first things I will be doing is fully charging the battery as it was not used for a few months (but regularly started).

So, any ideas?

________ EDIT ___________

The bike is now fixed. Turned out, the inlet valve was knackered. Replaced that and she good as gold.
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Veni Vidi Vici

[N cee thirty]

hmm

just try all the basics first really

oil
carb
air filter
valves
plug

then check over the electrics for any breaks in the wiring
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'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[fiery tupp]

Yeh as rob says & if its the standard sr air filter, an oiled sponge type they clog often & rot if not done regular,
clean that & a new plug , I would renew on any old new bike .
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If you can't fix it with a hammer , use your head .

[Adam.I]

Will do. Just ordered a new spark plug, air filter and oil filter. Will also do an oil change whilst I am there.
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Veni Vidi Vici

[fiery tupp]

If you fancy doing the valve clearances for him while your at it & dont have manual yet ?
By the way how did you get home ?

Inlet. 0.05 - 0.09 m / 0.002-0.003 in

Exh . 0.11-0.15 m / 0.004-0.006 in
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If you can't fix it with a hammer , use your head .

[Adam.I]

I managed to get hold of a 2001+ service manual but his is a 1994 model. However, there are only minor differences between the two.

My insurance policy has breakdown cover with it so a quick call to the RAC and they loaded the bike on a van and drove 70+ miles to his house then I drove the 120 miles north to mine.

I wouldn't mind going over all of the bike making sure that (hopefully) once the problem is fixed it is going to be sound, but I have very limited knowledge on how to preform certain tasks. Only been doing things myself fully since November of last year so not that clued up.
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Veni Vidi Vici

[fiery tupp]

They are very easy to work on & although the 94 model will have a manual cam chain tensioner that, I dont think will be in your manual .
though the carb is very simple , if you need to stip it , with no heater or diaphram etc , like the newer ones .
& I dont think I would be brave enough to try doing 125 miles on a strange old one
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If you can't fix it with a hammer , use your head .

[Adam.I]

I am trying to find a decent guide for striping and cleaning the carb, ideally for the SR.
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Veni Vidi Vici

[N cee thirty]

take the carb apart,all you have to do is unscrew the throttle at the top,
then undo the 2 nuts that connect it to the rubber manifold,then pull the carb out,undo the float chamber (3 scews) and you'll see the jets.

get a flat head to the jets and unscrew them and blow through them,then get a 10mm ? spanner and undo the bits the the jets go in to,blow through all these and clean them up

then do the stuff in reverse order and your bike shall work...hopefully


thats what i wrote for the cg,they can't be that different
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'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[Adam.I]

Tried starting the bike an it weren't havin any of it. The battery wouldn't even make a click noise when the kill switch was moved to on. Turns out, the battery was absolutely knackered. Just bought anew one and whacked it in.

All electricals work fine now, and when the starter is pressed, it just makes like a 'grinding' noise over and over but refuses to actually start.

Changed the oil, spark plug and air filter and had a good look at the carb but nothing. Any ideas?
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Veni Vidi Vici

[weasley]

It has fuel in it? And the tap is on?
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Yamaha XJ600 | Yamaha YZF600R Thundercat | KTM 990 SMT | BMW F900XR TE

[Adam.I]

A full, fresh tank and in th on position.
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Veni Vidi Vici

[Adam.I]

Tried bump starting it and it is like it wants to stet but is lacking something. It makes a deep pop noise as well when bump starting it.
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Veni Vidi Vici

[N cee thirty]

hmm the starter motor could be fubar

before bump starting it,put some petrol down the plug hole
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'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[Adam.I]

Just tried that but it made no difference. It is sparking and the fuel is flowing. I have no idea what is going on.
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Veni Vidi Vici

[N cee thirty]

hmm fuel,spark all you need now is compression

maybe get it compression tested ?
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'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[Adam.I]

It is so frustrating. It is like it is almost there when bump starting it but just cannot hold on to it.
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Veni Vidi Vici

[Adam.I]

I do not understand why it would work for about 50 miles then suddenly cut out.
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Veni Vidi Vici

[mattsprattuk]

apparently they're pretty renowned for rocker problems. see if it's snapped.

I even helped out some kid who'd broken down on an SR125, same problems as you, on inspection after i'd got home, got some tools and come back, it'd dropped an exhaust valve.

good luck.

oh yeah, then someone pulled over at the side of the road, stole his gloves and helmet then fucked off.

lolz
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Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!!
Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[Adam.I]

I have currently got the carb in front of me. There is a little bit of gunk in and around the float bowl. I have some carb clearner so I will get rid of that. What else should I clean? I have no access to compressed air by the way.

I will try the rocker and valves tomorrow.
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Veni Vidi Vici

[N cee thirty]

just take all the jets out and blow through them untill you can see light


imma guessin the rockers come loose
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'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[fiery tupp]

Yes, i'm afraid they are prone to top end failures , when oil changing the check bolt shown ,(*though that woud happen within a very short time after oil change *)
is often missed which dosen't help along with regular oil & filter changing & if the oil's not getting to the cam ..crunch .
I would take the valve inspection covers off & the flywheel cap & turn with a socket anti clockwise , you should be able to tell any damage .
Another thing that I found on this a friends bike , was the fuel pipe routed like shown , slowing flow & cutting out every few miles , had him baffled , simple but easily missed . probably wont help you but worth noting , for anyone with that problem ?
* It sounds like the owner didn't do the oil etc regular it could have sludged up & balls the oil pump up , then just could't cope with a 50 mile run* ?
*Edit*
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If you can't fix it with a hammer , use your head .

[kat250]

[Robg123]

Any updates on this? I have just purchased a sr125 spares repair..Sounds to be a knock when trying to start it, did a quick compression test and was giving 70-80psi , took oil filter off and if full (FULLL!!!) of metallic oil/shavings...so the engine is sick..
what are my steps from here with this engine?

[Suntan Sid]

5 years later, probably rusted away by now!
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