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bettyloo

throttle sticking yam sr125

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Hi, my first, but old bike, sr125 1997 has a tendancy to be on full revs when slowing down - standing still, this doesn't happen all the time, mostly when I have been riding for a while, only cure is to slightly release the clutch, cant see anything wrong with the cable..or handle.

Also back brake, when riding I put my foot on to slow down and it doesn't seem to have any effect, so use the front one. It does work when standing still. Lastly, two things happen over 40mph - a slight front end wobble and vibration throughout the bike.

Any suggestions?

Thanks

Liz

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Hi Liz

not familiar with the bike or carb cable mechanisms but if you can improve things by 'releasing the clutch' whatever that means you should investigate this further

back brake...is it a drum brake? perhaps the brake cam spindle has seized in the backplate...quite common. The fix is to remove the brake plate from the wheel and clean up / grease this part

wobble...check for play in the steering head bearings, wheel bearings, swing arm bearings, check tyre pressures

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Hi Mod, thanx for your reply, what I mean by releasing the clutch is this:- If, coming up to a junction say, I slow down to a stop but-the engine is still on full revvs, not just ticking over like it should, if, however I gently release the clutch at this time, the bike will return to idle, this happens frequently.

I will have a look and see if I can find the bearings you were talking about, being a newbie :)

Liz

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Full revs when slowing down

Check the throttle cable is not sticking and that the carb slider is moving freely in the carb.

Back brake

As Airheads comments. Bad set up, contaminated brake shoes, very dirty. Best to clean the brake drum, change the pads and set them up correctly. Cheap to do.

Wobble/vibration

As Airheads comments. Check the head and wheel bearings. The trueness of the rim, the tyre and the tyre air pressure.

Have a look here LINKY

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Hi pro

thats a point, not sure what the tyre pressure should be! :) will check that and the rim, not sure how to check the carb slider, but will check the throttle cable,

cheers

liz

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Click on the work LINKY in my previous post. a SR manual is there that can be downloaded t will help you.

Also each members name on the forum is in the blue strip and not the name under the photo. I am definitely not a Pro. :D

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Oh ok!

haha sorry, thanks for the manual Dirty, (if you think that sounds better!) :)

Liz

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Follow the cable from the thottle back as far as it goes, it will finish at the carburetor. With the bike on its stand and running, open the throttle and watch for something moving on the exteroir of the carb at the same time. Snap the thottle shut quickly and whatever moved when you opened it should move back as you move the throttle back. If its not, then switch off and disconnect the cable at the carb end after measuring distances from nuts to stops/ends etc. Tie up the loose end of the cable so that its higher than the throttle, make a small funnel shape from some blue tack and squeeze it around the loose end of the cable, then pour oil into the funnel and let it drip down overnight and into the cable sleeve until it runs out the other end. Reconnect back up and try again. If it works, its a quick win, if not we''ll try something else.

Rear drum brakes on motorbikes arent particularly efficient

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Hi Never

Thanks for the advise, but not being particular mechanically minded, have decided to give up and take it to the garage, as the vibration and front wobble is getting worse, in fact quite worrying now.

I checked the tyre pressure and topped up the oil (which was low) couldn't see any loose bearings, Not knowing anything about bikes, I don't want to start messing about with it, when I don't really know what I'm doing..I did notice however the other day whilst sitting on it, that the handlebars are not exactly straight, knowing my luck its probably been dropped, could account for the wobble...

Anyway thanks for all your advise, trying to help...will take it to the garage and let you know what was causing the problems, (you can then all laugh at how much they charged me) :hah:

I shall concentrate on maintaining the bike, and then maybe later on be in a position to start 'tinkering' with it.

At the moment am just hoping to be able to ride it! :icon_cry:

Will let you all know the outcome

Cheers

Liz

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Fingers crossed you get it sorted.

My only advice would be to buy a Haynes manual. They are worth their weight in gold. !

I am a complete newbie to all things motorcycles and have so far. with the aid of a Haynes manual and good advice on here, been able to check brakes, sort idle out, change the oil, change to petrol. Ok that all may sound pretty basic stuff but to me its an achievement and he's running !

I know I could have taken him to the garage but hate taking the car to one never mind forking out for the bike too lol

But don't think I'm saying I could have fixed your problem with my manual, but ye never know :)

Fingers crossed they are good to you and your bike is back on the road healthy soon

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