K8DTG
L plate rider.
Posts: 29
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Post by K8DTG on Mar 20, 2013 21:16:20 GMT 1
I have a Yamaha RD125LC that is running poor when cold, once it starts it will cut out after a few seconds, when the throttle is opened the sound of the engine changes but doesn’t increase rpm, each time it starts it gets better and better until the engine is warm and runs perfect.
The carb has been stripped and cleaned.
Could any one tell me what part of the carb I should be looking at the cause?
before i end i should state it has got a cone airfilter fitted and micron exhaust, the bike has been of the road for about 16 years hand engine has been rebuilt, problem only happpens when tghe engine is cold so guessing carb fault
Thank you for your time
Danny
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Post by raven13 on Mar 20, 2013 21:30:54 GMT 1
bin the cone filter to start with. go to a standard air box
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Post by broughton5 on Mar 20, 2013 21:53:31 GMT 1
after the carb was stripped and cleaned did it start fine then ? the reason i ask is ive had same prob with mine left for a week or so in damp conditions it gets moisture in carb must be condensation forming.
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K8DTG
L plate rider.
Posts: 29
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Post by K8DTG on Mar 20, 2013 22:13:07 GMT 1
the last time it was started it had problems with other areas and hasnt been run for a few months, will retry tomorrow, I haven’t got the original air filter housing. to swap back. the only problem i have got aswell as breathers on the carb and gear box there are no tubes, will take photos tomorrow
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K8DTG
L plate rider.
Posts: 29
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Post by K8DTG on Mar 22, 2013 9:46:51 GMT 1
Tried to start bike last night, the engine was easy to start but still cut out after a few seconds until it was warm, the bike started every time first kick but fails to stay running. The cab on the bike is a 12A does this sound right? I have attached a few pics as I am also having problems with a few locations I am unsure about I have labeled them 1 2 3 to make things easier. Also there is a fitting on the top of the crank case is this just a breather to atmosphere? Attachments:
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K8DTG
L plate rider.
Posts: 29
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Post by K8DTG on Mar 22, 2013 9:48:09 GMT 1
Sorry only let me post one pic so i have attached 2nd one to this message, also what neddle and jets and settings should i have in a 12A carb with a standered engine with micron exust and k and n style filter Attachments:
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Post by dippydave on Mar 22, 2013 18:11:19 GMT 1
go on ebay and find a original yamaha airbox, it will be worth every penny and is a much better starting point to begin to fiddle with ya carb.
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K8DTG
L plate rider.
Posts: 29
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Post by K8DTG on Mar 22, 2013 19:12:43 GMT 1
Ok how much would a reasonable one cost? Also I would prefer to keep the k&n air filter on and tinkle with the carb (as a diesel engineer I’m not sacred of playing) just not sure of settings. As i brought the bike for repairs i don’t actually know if the carb has been adjusted yes but wanted the specs that someone else with a micron and k&n filer is running, also not sure if any of the fittings on the car bi haven’t got hoses on could cause the issue.ok how much would a resonable one cost? also i would prefer to ket the air filter on and tinkle with the carb (as a diesel enginner
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Post by mellow on Mar 24, 2013 13:22:25 GMT 1
2+3 should have pipe on them which goes down through little bracket on float screws,number one is breather which goes under a metal lug on the top frame tube under seat  |
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Post by raven13 on Mar 24, 2013 13:57:34 GMT 1
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K8DTG
L plate rider.
Posts: 29
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Post by K8DTG on Mar 24, 2013 15:24:52 GMT 1
2+3 should have pipe on them which goes down through little bracket on float screws,number one is breather which goes under a metal lug on the top frame tube under seat Thank you do you know where the connection on the gear box should go? Will a new air filter really make a difference to the starting when cold? |
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Post by noelrdlc on Mar 24, 2013 23:59:24 GMT 1
If you mean the pipe on the top of the crank case, its just a breather and will just go at the back of the engine and hang down between swinging arm towards the ground.
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K8DTG
L plate rider.
Posts: 29
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Post by K8DTG on Mar 25, 2013 0:01:16 GMT 1
that's grate thanks
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K8DTG
L plate rider.
Posts: 29
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Post by K8DTG on Apr 5, 2013 21:52:50 GMT 1
update- ordered and fitted filter today, forget to mention only way i could get it to run before was by having the needle set to the 5th clip position so that was reset to the 3rd clip position kicked and vroom and didn't even cut out, still not running right as the tick over wont drop below 3000rpm when the screw is slacked it cuts out screw in a fraction and it idles at 3k but going for MOT in morning so least if it passes i can run it on road to test save driving 10 foot then stopping.
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Post by danrdlc on Apr 5, 2013 22:01:20 GMT 1
About to go out my my 125lc and see if i can track down some boy racers  Cant remember how to add a photo!! And i had same problem with my bike, They dont really like k & n, when mine kept cutting out i changed plug gave it a good thrashing, Seemed to help |
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Post by danrdlc on Apr 5, 2013 22:04:29 GMT 1
and got stand air box back on it ( snorkal removed ) and cleaned tank out,
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K8DTG
L plate rider.
Posts: 29
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Post by K8DTG on Apr 6, 2013 11:44:04 GMT 1
it really improved the starting but i also this the crank seals are shot, dose any one know if they can be changed without splitting the crankcase?
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Post by broughton5 on Apr 6, 2013 12:41:56 GMT 1
left side can definitly, not sure about right, but if seals are shot bearings prob worn aswell causing seals to leak.
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K8DTG
L plate rider.
Posts: 29
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Post by K8DTG on Apr 6, 2013 15:33:02 GMT 1
hmmm im not sure I think its more the fact it hasn't been on the road for the last 16 years but could check bearings first.
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Post by broughton5 on Apr 6, 2013 19:45:17 GMT 1
could be right mate, if bearings are shot you will get a rumbling from bottom end thats what happend with mine.
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K8DTG
L plate rider.
Posts: 29
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Post by K8DTG on Apr 6, 2013 19:51:27 GMT 1
just found some on the bay and the bearings are cheap so will replace the lot. fun times but in a better note it passed the mot  |
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Cant remember how to add a photo!! And i had same problem with my bike, They dont really like k & n, when mine kept cutting out i changed plug gave it a good thrashing, Seemed to help