RENAMED: SR plug fouling

My sr125 is still fouling spark plugs and theres no real pattern to it which makes it even more annoying, altho it generally happens after its been sitting for a couple of hrs.

It starts fine and then eventually cuts out after about 50metres or so, then will turn over but wont start until u put a new spark plug in it and then its fine again.

The mechanic thought it might be dodgy oil pump but its not that, and after checking the bike over he's sure theres nothing mechanically wrong it.

So what could it be?

 

although i agree with the post titles, chill . actually the stock plug for a stock SR is the BR8ES according to the handbook and the NGK book. i run the 8ES without problems.

I think your problem may be water getting somwhere it shouldn't or it could be the ignition coil isn't producing a large enough spark. there is a wire that runs from the CDI (right side of the bike under the belly pan) to the ignition coil (left side under the footboard), check that that is connected properly as it can cause a weak spark.

also i would suspect your auto choke.

EDIT: the 9ES is a colder plug so wouldn't that make it not ignite the fuel as quickly??

 

fair enough. try the 9 before looking elswere, its an easy fix.

 

Cheers for the replies guys. Sorry bout the post title minor.

Ive tried both the br8es and the 9es but it still happens. Would a hotter plug help, 7es?

Its weird tho cos ive used the 8es since ive had the bike and it worked fine for years so would've thought that wld be fine still.

Will check the wire wobbly, cheers. Also, what are the signs of a dodgy auto choke cos my choke is s**t anyhow but its pretty much always been like that, it only idles on its own once its got going for a bit

 

pretty much the symptoms you've given. it will just pour too much fuel into the engine and literally drown the plug.

the best way to check it really is remove it and put another in, possibly a manual one to eliminate the wiring, also check that the rubber isnt damaged on the end of the choke slide, that will make the bike run rich.

oh and if you have a gas cooker, heat the end of your damp plugs up on it to remove fuel then wipe then wih a rag, should work again afterwards.

 

Cheers for the tip about the spark plug, ill be needing that until this prob is sorted!!

If it is the choke would this one do?

http://www.donotlink-pedstop.co.uk/p/MA ... -1479.aspx

My bike is stock so want to check it'll fit on the stock carb

 

nah you actually need the choke slide that goes into the carb.

the best bet is try a different carb as it could be a casting fault too.

 

Should've known it wouldnt be a cheap fix!!!

So id basically need to get a carb that can take a manual choke?

If the choke is at fault, would it happen everytime u start the bike cos sometimes it happens and sometimes it doesnt, its hard to say when it will do it

 

could be a bad wiring connection. its a cheap fix, even if its a carb casting, i'm sure someone on here will sell you s stock carb cheap enough.

 

Gonna check the wiring then and pray that its just something loose!!

Thanks for all the help

 

no problem. do you know if your'e using the mikuni or the dellorto carb (mikuni is metal bowl and dell is plastic)

 

Pretty sure its the dellorto one, at least i assume it is cos it says so on the choke (that is the black plastic bit on the carb isnt it??)

is one worse than the other?

 

not much in it really.

the dellorto is easier to clean out and set up.

 

this might be a stupid question but would not warming the bike up for long enough cause the problem?

the last few days ive used it, ive let it warm up for 2-3mins b4 moving and so far (touch wood) its been alright (it could be coincidence). its a bit annoying cos even if the bikes only been sitting for hour ive gotta wait 3 mins b4 moving but its worth it if it keeps the bike working!!

altho surely the plug shouldnt drown from setting off too soon should it, it never used to

 

sounds like the choke is fucked.

 

get a manual choke on there and test it.

 

yeah i was thinking the same. where can i get one that fits the stock sr125 carb cos wobbly mentioned that i need a choke slide that goes into the carb

 

i got an old polini manual choke in shed bit tatty but will find out if its your problem if you want it.