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Rosie
10th June 2006, 12:28
I took the bike out today, and about 1.5k's from home, the engine cut out while I was riding along at 70 (2nd gear, about 9000 revs). The bike started again fine, but cut out again about 500m down the road. Thereafter cutting out about every 100m for the trip home. I got fed up, and pushed it most of the way.

A mechanic mate had a look at it on Thursday because it wasn't starting well on cold mornings, he put a new spark plug in it, gave it a thrashing, and said it was running sweet. I'd had the carb overflow a couple of times a while ago, so he checked the fuel system, and everything was fine.

Any ideas what the problem might be? I'm just at work collecting some tools to have a look and see if I can see any obvious problems (spark plug, battery terminals, fuses etc)

Useful information:
The bike has a full tank of fuel, and an almost full tank of oil.
The fuel tap is on
The spark plug was brand new on Thursday
I cleaned and tightened the battery terminals last week (but will check them again today)
I'd left the choke on for the first couple of minutes the bike was running, and turned it off not long before the first cut out. It didn't need the choke to start again after the engine had cut out.
This was at 11.30am and the bike had been in the sun for 1/2 an hour or so, so wasn't exceptionally cold.

paturoa
10th June 2006, 12:32
swap the plug back to the old one and see what happens

Ixion
10th June 2006, 13:10
What happens when it stops. Does it just stop like you truned the key off. Or splutter and cough for a few moments. When you start it, does it start up "cleanly"? or backfire and splutter?

Doesn't sound like plug, sounds more like fuel blockage of some sort. First thing though check everything especially plug lead for being tight, no loose connections.

Magua
10th June 2006, 13:26
I had a similar problem with cutting out, change of a sparkplug and draining the carb seemed to sort it. Though it seems you've allready done those.

stunz
10th June 2006, 14:03
My p.o.s played up like this last week, kept cutting out. Started fine, change gears ok, 1/2 kay down the road it stops. Turned out it was the side-stand cut out switch not completely in the off position. Had me sweating at the time cos I was miles from home.

Ixion
10th June 2006, 14:05
Ah yes. Those damn switches. Ms Rosie does your mount have a side stand switch (ie can you ride away with the side stand down)? Thye are notorious for giving trouble. (Personally I disconnect all such idiot devices, but that's just me)

stunz
10th June 2006, 14:07
Ah yes. Those damn switches. Ms Rosie does your mount have a side stand switch (ie can you ride away with the side stand down)? Thye are notorious for giving trouble. (Personally I disconnect all such idiot devices, but that's just me)
good plan...

Clivoris
10th June 2006, 15:01
I've also heard of kinked or blocked fuel tank breather hoses causing this type of problem by creating a vacuum in the tank. Just a thought.

Sketchy_Racer
10th June 2006, 15:34
Mine did that when i first got it.

I would ride along at 100kph and it would cough splutter then die.

Brand new plug - it still did it.

What it was in my case was that the cooling system does not have a thermostat in it. It was running to cold and wasn't able to burn the two stroke oil.

I blanked off half of my radiator and teh problem went away ;)

hope this helps.

(ps, it won't be your batt. They run without them :niceone:

Rosie
10th June 2006, 17:17
What happens when it stops. Does it just stop like you truned the key off. Or splutter and cough for a few moments. When you start it, does it start up "cleanly"? or backfire and splutter?

Doesn't sound like plug, sounds more like fuel blockage of some sort. First thing though check everything especially plug lead for being tight, no loose connections.

It stops really suddenly, like you hit the kill switch. And starts again cleanly. Which makes something electrical/ignition related like a dodgy switch seem like a possibility. I don't remember ever trying to ride away with the side stand down, so I don't know if it has a side stand switch. I will test that tomorrow and report back. And check for kinks in hoses etc.

The plug lead is nice and tight, but haven't checked further upstream yet. Although the battery looks like it could do with topping up.

Titanium
10th June 2006, 17:25
Could be crap in your tank, carb, fuel system, vacuum ? draining the carb / fuel bowl quicker than filling it up. Bad fuel fill.

Cheers

Peter

sefer
11th June 2006, 00:04
No sidestand switch (unless I'm blind ;) ), doesn't really need one as the stand tends to go up on it's own if you do leave it down.

Unlikely to be a kink in the fuel line, as there isn't really anywhere for it to kink since it's a pretty straight run to the carb (of course it's still worth checking) .

Cleaning out the carb could be an idea, as that could be an issue, I've heard of this being a pretty common problem from some Thai krr owners on another forum, but don't know how valid that is as it seems to be some guy's idea for solving everything! :D (again, worth trying)

I'd look into the over cooling idea, as this seems to be my issue since it's gotten colder, but I've never cut out while actually moving, but it's been pretty hard to keep running when stopped, even after running to 10 min or so (not including the 5min or so I usually warm-up in the mornings)

nadroj
11th June 2006, 07:08
Water in the bowl or bowl float height needs adjusting.

Mr. Peanut
11th June 2006, 07:11
Check for ignition/CDI cables close to moving parts (i.e. suspension) you'd be surprised... (STUPID SJ125)

Racey Rider
11th June 2006, 07:13
One of my fuel tanks was doing this the other day.

I found if I rode with the tank filler open, it would keep running fine. The tank vent was blocked which stops the fuel getting to the carb as it should.

Try that to at least rule it out as a issue.

ajturbo
11th June 2006, 07:27
Water in the bowl or bowl float height needs adjusting.

had this very problem with luke's bike yesterday!!!.. wouldn't go on full throtle....

found water in bowl!......ummmmm i also found out that you have to replace the oil feed hose onto the carby:innocent: ... just don't tell luke it was off for a bit.......:nono:

Rosie
11th June 2006, 15:01
The bike will take off with the side stand down, so a dodgy side stand switch isn't the problem.
Will look at kinks in fuel lines, wiring etc tonight.

The tank was drained a couple of weeks ago, and I'm pretty sure the carb etc got checked when it was being looked over last week, but I'll check on that.
When it cuts out, it's very different to what happens when the bike runs out of fuel, which gives me the feeling that it isn't related to fuel supply.

The idea of blocking off part of the radiator appeals to me. I might tape over the front of part of the radiator, to see if that makes any difference, before I go all out and get it modified.

Mr. Peanut
11th June 2006, 15:16
Probably something to do with this.

http://video.google.com/videoplay?docid=-3111473682011187743

Rosie
11th June 2006, 15:33
?? I'm at work, so am suspicious of opening links to videos.

Mr. Peanut
11th June 2006, 15:37
Not very WS

SwanTiger
11th June 2006, 15:53
Ah yes. Those damn switches. Ms Rosie does your mount have a side stand switch (ie can you ride away with the side stand down)? Thye are notorious for giving trouble. (Personally I disconnect all such idiot devices, but that's just me)

Yep, certainly is an idiot device.

I've experienced problems with mine over the last few days and will be disconnecting it tonight after it played up on my all day.

sefer
11th June 2006, 18:14
The idea of blocking off part of the radiator appeals to me. I might tape over the front of part of the radiator, to see if that makes any difference, before I go all out and get it modified.

After doing a bit of a service today I decided that using tinfoil (possibly wrapped around card) attached to the screen that screws to the front of the radiator is probably the easist, lightest way to achieve blocking off. But since I didn't have any tinfoil I'll have to keep you posted on how it works :)

After thinking about it I remembered one of the reasons the carbs were giving those Thai guys problems, some of the earlier models had issues with the fuel cap seal melting when the bike was left in the sun, then leaking when it rained (water into the tank).

Checked the fuel filter lately? That could be an issue as well, prehaps as suggested the carbs not filling fast enough to keep up with fuel use, yet by the time you've stopped and kicked her back over it's filled again, only to run out again pretty soon. Experiment if it's still doing the exact same thing (ie stopping every 100m or so), start up, turn your fuel tap off and see how far you get. If it's about the same distance then it makes that a lot more likely :)

race_demon
5th July 2006, 12:36
is it 2 stroke or 4 stroke? i had a ped that did that and it ended up beign a blowign exhaust so ti didnt have enough back pressure, also check the coil etc if tis not grounded it coudl build up static or summin and in effect short it out (ok i dunno this but its betetr to check) basicly check all connectiosn otut hink why it could stop sparkign after a short time or riding then fire back up (does that sound like a fuel blockage to you?)

race_demon
5th July 2006, 12:38
sorry havent been on the forums lately...well in ages ill do some research for ya

Ivan
5th July 2006, 13:25
have you cheeked the air vent for the tanks is not blocked

Motig
5th July 2006, 18:48
With you on that idea Ivan. Check petrol cap vent if it has one or if you had the tank off has a hose/breather been been kinked or something.