Problem

How much fuel is draining out? Just a few drops or much more? You might have a problem with your float/float valve. Is your overflow tube routed up or clogged? This combination makes all the excess fuel from a bad seal on float to pour right down the crank case. Kicking it over with lots of fuel in there blows your crank seals. I had this problem on an old Husqvarna, where small grit in the fuel tank slipped by the fuel screens and jammed the float needle open, with a massive fuel overflow as the result. And it blew out my crank seal.
 
the over flow is not blocked its about an egg cup full mabye less depends how long ive been kicking it for.. does anyone know were i can get a new float needle from??? mine has like a ring round it so im guessing its worn..
 
me25690017 thats the gas gas parts number but does anyone know the kheien (carb make) id number? my local gasser dealer wants over 30 quid for one.. bit pricey i reckon
 
Just been out to try her again and she seems to be back firing/missfiring (wooshing from exhaust) any more ideas/help very welcome! Cheers luke
 
After about 20 kicks or so I open the crank drain and a drizzle of fuel poors out.. So theres fuel getting through and a great big blue spark.. The carb has been running fine for the.last year.. Ive not adjusted anything and gave it a good clean/blow out.. Im at my wits end with this now. ive put so much time money and effort into replacing everything that needs doing to my bike but im seriously considering parting it :(
 
Rabbitist said:
Reeds are fine and rings are in tact/no scoring to end is only 12 hours old however I did find fuel in the flywheel case so I'm guessing the crank seal has gone on that side.. Would this cause it to just stop working?
Click to expand...

Did you ever pull the cylinder off to check the piston/rings? My kid stuck his rings running lean. Still had what fealt like good compression but symptoms were identical.
 
With the head off and piston at TDC, push the piston top. It should move a noticeable bit forward and backward in the cylinder bore. If it doesn't move, the rings are stuck out in the grooves. Did the engine make an odd humming/rubbing sound the last time you rode the bike? Stuck rings often sound different.

The only way to really know is to remove the cylinder.

Did you do a compression test? If compression is good, what you are describing sounds like the timing is way off. Can you judge if the spark coincides with top dead center?
 
thanks neil ill have a look at that.. ill pick a compression tester up tomorrow and see if its dropped much.. what pressure am i looking for? also how would i judge the spark? should it spark bang on tdc? how would i adjust the timing if that is out?
thanks luke
 
Compression 150-200 psi (hopefully it's not less than 120).

You could scribe the flywheel to match a spot on the case as a reference when it's at TDC. A timing light should show about 1 mm before your mark (the engine has to be running). You would need to rotate the stator mounting plate in the slots to change the timing (this assumes you have a flywheel puller).

One other thing is the quality of your spark plug connection. Maybe it's got a spark laying on the head, but not when it's installed. You can unscrew the cap from the wire, trim the wire back ~10mm, then screw the cap back on. Sometimes the wire in the high tension lead will corrode.
 
Rabbitist said:
thanks neil ill have a look at that.. ill pick a compression tester up tomorrow and see if its dropped much.. what pressure am i looking for? also how would i judge the spark? should it spark bang on tdc? how would i adjust the timing if that is out?
thanks luke
Click to expand...

I think things might be getting a bit out of hand here. The bike was going fine - you stalled it - it hasn't gone since - it's not like the engine seized on you, eh?. Is this the correct story? If so, you would think it must be something fairly basic. My first pick would be a sheared flywheel key - but you say you have checked. The symptoms you describe and the fact that you stalled are classic "slipped flywheel" to me.
Have you got any way to swap out/check the CDI and coil? coil lead? electrical connections? A spark can sometimes look good with the plug resting on the engine, but sometimes under compression it just doesn't do the job.
Sorry if I'm not being any help, but, I don't think this should require an engine tear down:)

Just saw NeilE's post. Yes, spark quality - just what I was thinking.
 
You have an older engine. Any chance the ignition pickup is out of place? Like bchatt says, if it suddenly developed the problem, a flywheel key would be the culprit. The only other way the timing can be off is if the CDI is bad.

You're not trying to use a Lodge brand spark plug found at the side of the road are you? Been many years since I've seen one, but they are familiar to owners of British bikes made in the 50s. I've had several AJS and Matchless bikes.
 
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