SR125 Won't rev above about 2000rpm

craptiger · L Plate Warrior Joined: 19 Aug 2008 Karma :

Hi,

My girlfriends SR125 has suddenly developed a problem where it won't rev above about 2000rpm. If you open the throttle the engine actually dies. We've tried with choke in, out, halfway. It'll idle with the choke partly out, but as soon as you increase the revs it dies. We've left it to warm up, then tried again, to no avail.

Any ideas?

Thanks

chillpill · World Chat Champion Joined: 12 Aug 2008 Karma :

clean you carb-o-rama , whack in a new plug, give the air filter a wash then hey presto Razz

alex

L3G3ND_MTX · Spanner Monkey Joined: 13 Feb 2008 Karma :

Tried looking at the carb/Plug? could be flooding itself when your revving which means too much petrol getting in which is genrally something to do with the carb or just check the plug to see if its burning fuel properly and not flooding?

Just some ideas, im sure someone will come and correct me.

Also how do you know what its revving to? i thaught sr 125's were scooters? unless im mistaken and thats only the sr 50's Confused

ms51ves3 · Super Spammer Joined: 07 Jun 2007 Karma :

craptiger · L Plate Warrior Joined: 19 Aug 2008 Karma :

Hi,

Thanks for the tips. I don't know exactly what it's revving to at all, 2000 was a rough guess based on my experience of bikes as a whole!! Basically it won't rev anywhere near half way, and not a great deal above idle speed.

The weird thing is how it's suddenly happened, but I'll clean the air filter, change the plug and try it again. Might drain the fuel out and change that too - would water in the fuel cause these symptoms? Or possibly a piece of grit? Surely that would cause it to not run at all though?

My 1950 land rover once actually had a problem where a vacuum was being created in the fuel line so once it sucked a certain amount of fuel in it stalled - anyone know if there's a breather on the fuel tank on an SR125?

p.s. I'm fairly certain it's not flooding because I've tried increasing the revs really really slowly and it still cuts out at about the same point

Cigaro · World Chat Champion Joined: 28 Mar 2007 Karma :

Blocked air filter?

prawny1 · World Chat Champion Joined: 28 Jun 2005 Karma :

The cdi may not be advancing or not sparking at higher rpm, Iknow they are usless for on the road but i have found that light up sparkplug caps help to eliminate the not sparking at higher revs question as you will see the sparking stop or not as the case may be.

yen_powell · World Chat Champion Joined: 22 Jun 2008 Karma :

Most likely a bit of dirt has blocked one of your jets in the carb, maybe the multi holed emulsion tube. This means the bike will start and tickover, but try and die when you rev it.

Give the carb a strip and clean (don't change any settings) and fit a fuel filter to stop it happening again.

Had the same on an SR125 I looked after for a friend.
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FerretFing · World Chat Champion Joined: 11 Nov 2007 Karma :

the air filter on the SR is very sensitive to being "over oiled" - use something thinner like wd40 as opposed to engine oil & make sure it`s well squeezed (gently!). Check condition of plug for clues Thumbs Up

craptiger · L Plate Warrior Joined: 19 Aug 2008 Karma :

Well I found the problem!!

I took the air filter out and having no handy containers of petrol, ran it for a second without it and it still ran badly. So I changed the plug, to no avail.

I then took the carb off, dismantled it and put it back together again after a clean and hey presto - she ran like a beaut.

It might have had something to do with the large piece of gravel that fell out when I opened it up!!

Thanks for all the help everyone.
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1997 Honda VFR750 (for fast fun) : 1995 Suzuki GS500 (boring commuting) : 1950 Land Rover (muddy fun) : 10.5 metre kite (scary aerial fun)