1992 SR125 Help naaded.

gary-postman

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Hi I have a 1992 Yamaha SR125 that has developed an intermittent fault. The bike will start and run on tickover, but when revved it will cough and splutter and stop running.
The handle bar switches have all been thoroughly cleaned. The carb has, also, been cleaned. The problem is still there. The bike has completed under 30000 miles. It has not been used since November and left in the open. I'm open suggestions as to what is causing the problem.
I've looked on a Yamaha owners site and there are posts with the same problems.
I hope one of you knowledgeable people will be able to help solving this frustrating problem.

Thanks Gary
 
check....

plug cap ,spark plug , main jet ( yes i know you have , now do it again ) pilot jet , slide and needle , mixture screw , fuel supply ...empty the tank, with the fuel tap removed. bypass the sidestand switch.

cos it sounds like a fueling problem .
 
Hi

Could water have got in the fuel over winter?

Unleaded 'goes off' as well, so as stated, drain the tank and carb, flush through and try with fresh fuel would be a first step.

Bill
 
Coil / Condenser fubarred,

change the plug as well


cheap fixes
 
Hi

Could water have got in the fuel over winter?

Unleaded 'goes off' as well, so as stated, drain the tank and carb, flush through and try with fresh fuel would be a first step.

Bill

Change the fuel first before you start pulling it asunder.
Bf.
 
Have you tried bypassing the ignition switch?
 
Hi folks
News relating to the bike. We've put new fuel in. Tried two different carbs, still no joy. Today, thanks to the advice from guys and deciding that the problem may be related to either the coil or the CDI unit. We tried a different coil with the same results, This has left the CDI being at fault. Having taken the CDI off and cleaned the terminals, reinstalled the bike ran perfect. We've decided that this is the faulty item. We are now looking for a CDI unit for the bike. We've found that Electrex World Ltd near Reading may be able to repair the unit. I'll let you know how we get on.
Thanks for your help.
Cheers
Gary
 
Good luck. Keep us posted.

My money would have been on the carb TBH. It's nearly 30 Y/O & would need a full ultrasonic bath & rebuild.

Failing that, the alternator & reg/rec are weak areas on early SRs, leading to a lack of sparks once the battery (often tired) is depleted.
 
Hi folks
News relating to the bike. We've put new fuel in. Tried two different carbs, still no joy. Today, thanks to the advice from guys and deciding that the problem may be related to either the coil or the CDI unit. We tried a different coil with the same results, This has left the CDI being at fault. Having taken the CDI off and cleaned the terminals, reinstalled the bike ran perfect. We've decided that this is the faulty item. We are now looking for a CDI unit for the bike. We've found that Electrex World Ltd near Reading may be able to repair the unit. I'll let you know how we get on.
Thanks for your help.
Cheers
Gary

Did you try bypassing the ignition switch?
It can give many "electrical fault" symptoms.
 
Further information????

Hi
More info as to how we are progressing with the SR.
I've been in contact with Electrex, They told me that they don't do any thing, repair wise to CDI units. They did say that they recommend a company in Holland. I've emailed them, their reply was that they are willing to take on the repair for £175. We have been unable to find a company that will look at the repair to date.
We did locate a new unit in France for 385 Euros, The cost from Yamaha, when they supplied them was £85.
Getting back to the bike and reinstated the CDI. The bike started and ran perfect. The following day I was going to take it for a run. The problem reared itself again. Getting frustrated with the problem, the unit was tapped with a rubber mallet, guess what it started running perfect again. We are now of the opinion that the problem may be as simple as a dry solder joint or a faulty item on the unit.
We have now managed to locate a CDI unit on ebay, and will try that to see if that cures the problem?
We are also hoping that one of you may be able to answer a few questions.
The CDI unit on the bike is a 5HO-MO. The unit has 8 wires coming from it to two terminal plugs, one white and one blue.
Would it have been possible to use a CDI unit from a later model bike, or a different unit from a different bike?
Looking forward to your input.
Thanks
Gary
 


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