2003 ec300 lean/won't get on pipe

[Thompo]

2003 ec300 seems to be running super lean.

Working at mates bike can't get it to run properly.
Was bought knowing it wasn't right but took a chance. I suspected main jet had fallen out from sellers description.

Pulled the carb, Floats were bent and main jet was rattling around the float bowl! Hoped this was the fix but sadly not...

Carb is pwk38 as1
Jetting is
38 pilot
180main
N1EF 3rd clip
#6 slide
Freshly cleaned and oiled filter.
See level to 300m 10 to 15deg.

Starts and idles ok won't get on the pipe and splutters over half throttle.
After a short run the silencer is too hot to touch. Even the exhaust gas out the silencer at idle is uncomfortably HOT with no smoke. (Silencer freshly packed and not obstructed)
Seems a bit low on compression compared to my 250 but this shouldn't cause lean condition would it?
Checked for air getting in by spraying some carb cleaner around carb, engine and flywheel (cover off) at idle and get no change in engine speed or sound.

Any ideas?

My 2011 250 runs well. Over the same run up and down the road my exhaust is warm to the touch not hot and at idle the exhaust gas is verging on cool with a little smoke. Both bikes are using fuel from the same can.

Cheers

 

[gasgasman]

Check the power valve. Maybe sticking.
Ignition timing could be off too.

 

[Gibnut]

I would check the needle isn?t bent so it?s partially blocking the jet and also you don?t have a kink or crimp in one of the hoses.

Good luck!

 

[Thompo]

Power valve is resting on the stop and seems to move ok, ill maybe pop the cover off and check it operates.


Replaced all the breather hoses and fuel feed

How do you verify ignition timing?

 

[Thompo]

Made a bit of progress last night.

Swapped carb over from my 2011 (AS2), its a good 10mm shorter so I cant get the airbox boot on, just wrapped some inner tube between the carb and boot.

Bike sounds a whole lot better on the stand, seems to takes revs cleanly and I confirmed the powervalve is opening with this carb. Exhaust gas temperature is waaaay down too.

Checked timing and the stator doesn't look like its been off as it has a rounded bolt! the special washer to lock the timing is also fitted.

Hopefully get it out for a run later and see if its working as it should.

Other than swapping all my jets and slide over is there anything can be done to diagnose a worn carb?

Thinking a Chinese copy for 35quid is the way to go rather than something used that could have the same problems....

 

[motopsycho87]

Check the dry side crank seal. Run the bike and spray wd40 or similar behind the stator.

Worn carbs get richer, not leaner!

If it's running fine at low revs but struggles mid way, check for blocked main jet, condition of reeds (unlikely), and air leaks (centre case gasket, left side crank seal etc)

 

[Zman]

If it is running hotter it is likely lean and starving for fuel. I had a 2004 EC250 that would not rev out and it was lean. I needed to increase the main size after I set the float slightly on the high side.

Is it possible the muffler is plugged up or that the air filter is very dirty or over oiled?

 

[Thompo]

Cheers folks,

Ive had the stator cover off and sprayed carb cleaner (and wd40 just incase 1 was better than the other lol) around this was one of my 1st thoughts after finding the main in the float bowl. No change in engine speed or sound.

Carb was well cleaned and all passages and jets are passing air. Although the engine (rounded) side of the slide is quite rough.
Exhaust repacked, clean filter
Cant find any air leaks

Will get it out for a run later today and see if it is actually better and report back.

How would low compression affect it?
It feels easier to kick than my 250 but ive read the 300cylinder has a bleed port to make it easy to kick so not sure if its meant to feel like this.

 

[Thompo]

Confirmed.

Bike runs well with my 2011 250 carb attached.

Not as much power as hoped but gets on the pipe and has some go.
I guess the 300 would be a bit lean on my 250 setup?

Question is what could be away on the standard carb for it to run so bad?

 

[Jacob 'Berg]

Confirmed.

Bike runs well with my 2011 250 carb attached.

Not as much power as hoped but gets on the pipe and has some go.
I guess the 300 would be a bit lean on my 250 setup?

Question is what could be away on the standard carb for it to run so bad?

The slide could be worn, or getting hung up so that it does not seat properly (seems that this would cause a hanging idle..). Float level could be set too low, causing fuel starvation. Jets are cheap, maybe replace them, as blockage may not be visibly noticeable. I would make sure that you also had the air boot fitted properly, as the boot to carb fitment can be a pita, and you could have been drawing air.

 

[Thompo]

Swapped the normal carb back onto the bike last night.
Still not going right so ordered copy pwk38

Decided to check the piston as it felt low on compression as it kicks over like a 125 (although still starts easily) and after checking with my newly acquired cheapanese compression tester it read 115psi

(un)Fortunately I had my other mates 200 in the shed to weld the gear selector fork back on. so I checked it and mine too.

Whilst id take the absolute values with a pinch of salt, comparatively it gives an idea.
Mates Ec200, decent looking cylinder and piston, 145psi
My Ec250, had a top end done around 20hrs ago 165psi

Cylinder is in pretty bad shape.

Obviously it wouldn't help with the running of the bike, but it makes no nasty noises. Will have to see if I can get a quote to get it welded bored and plated or get a replacement cylinder somewhere.

The different coloured bit beside the crack is raised, not chipped. Could it be some piston material?

 

[Zman]

It is probably piston material. On the positive side your bike will run much better after you get this fixed.