Yamaha SR125 problems

[SR125T37]

Hi, I have a 1999 Yamaha SR125 (23,000 miles) I got it as a nonrunner, It had sat in a garage for 5 years not being used.

I have put a new battery in it,

new spark plug,

a oil & filter change,

the air filter looks good,

cleaned the carb,

new fuel,

cleaned the side stand cut off switch.

Wrapped insulating tape round the rubber between the carb and inlet, it's cracking but not all the way thru.

It starts (just, it seems to run better on a warm day, than the cold of night?).

When it's idling,

if I open the throttle normally the engine slows down and dies.

If I open the throttle a fraction the revs pick up a wee bit and the engine dies again.

I can open the throttle a wee bit, the revs pick up and then close the throttle and the bike goes back to idling.

I have the throttle stop screw about 2 full turns out, any more and it doesn't start.

The engine doesn't sound noisy eg. tappets, cam chain. But I'm used to 2 strokes, I wouldn't know what to listen for.

Can anyone help,

thanks Mark

[Derek Herbert]

Mark,

I have an 89 model and I am having very similar problems. I have done all of the stuff you have mentioned. My problem seems to be air getting into the carb inlet rubber due to it being perished. I am trying to get a new one online but finding it very difficult to get. Seems I was going round in circles trying to diagnose the problem. It was not until I looked closely at the inlet rubber (between the carb and inlet manifold pipe) that I noticed there were several cracks in the hose. I applied a little of pressure to pull the hose apart to see if the cracks were bad for the hose to completely come apart in my hands, it seems the hose was a little more perished than I thought.

I hope this helps as I have had many headaches with the idling. Now to try and get a replacement hose.

[SR125T37]

Thanks Derek,

I got it fixed & running. I had cleaned the jets etc. with WD40 twice, petrol then paraffin, and it still didn't work.

I took the carb across to my mates, he has a air hose/compressor, he blasted air thru it, I could see a big difference with the hole in the main jet. I bought a new hose, I fitted them & ajusted the idle screw & the bike runs perfectly.

The hose was cracking on the outside but looked good on the inside, but I thought I would replace it any way.

The hose cost £12.58, it's a Yamaha part that I bought at a Suzuki bike dealers. They said they can get any part for the bike. Any parts that Yamaha sell they can get for me.

There is a jet? in the base of the carb, I didn't notice, my mate cleaned it for me with solder wire, I think it's for the choke.

I also fitted a polisport fuel filter.

I like the bike, it's not as quick/fast as my Kawasaki AR80 but it's more relaxing & it's fun to ride.

Good luck with your bike.

Thanks again.

Mark