too low compression?

[welle]

I measured the compression on my gasser ec250 today, and got 125psi with cold engine (WOT). The bike is quite difficult too start and runs really rich, though if the petcock is turned off while the engine is running it runs quite well until it runs out of gas ofcourse.

Below are some pictures i took of the piston through the exhaust port. Time for replacement?

 

[GMP]

You should do the test with a warm engine, and kick until the gauge peaks.

What is your altitude? Hours on motor? Pics look normal, actually good as no blowby is evident. If its rich, look at the float hight and jetting first.

 

[welle]

Ah yes.. i guess a warm engine would result in higher readings, but I just wanted to check that the piston wasn't completly bust. Altitude is very close to sea level. Not sure how many hours.

I have checked the float height twice and made sure that the floater isn't twisted or damaged in any way. The jetting should be in order, atleast according to the diagram in the service manual.
I'm using a 180 main jet, and with the low temperatures here in sweden I should actually be using a larger one. But still it just floods the engine at full throttle.
I have also tried setting the needle at it's lowest setting. Replaced air filter, spark plug, HT wire, inspected the killswitch, reed valve, exhaust valve without any improvment.

I'm thinking about pushing it into a lake or something soon

 

[kim]

Has this just started to happened or has been like that for a while ?

What color is the spark plug after a WOT run ?

I'm running a 168 main and a 38 pilot at sea level on a 03 300.

Kim

 

[GMP]

I know it sounds obvious, but last year another guy in Sweden had trouble and turns out he had the restrictor plate still in the airboot. Are you sure the PV is opening completely?

 

[iancp5]

Strange, I'd have thought float height if you hadn't checked.
Is the needle valve ok?

The piston looks in great condition as does the PV.

Jetting seems to vary a lot on Gassers, from bike to bike, for some reason. Think it's like the old quadratic equations, there's always more than one solution with a Gasser.

 

[welle]

Thanks for all the ideas and suggestions!

kim: it has never been running well, I bought the bike just a month ago.

GMP: I have checked the airboot, no restriction. Well i haven't checked the PV with engine running since i can't get it to run right now. I think the spark plug is really fouled.

iancp5
The needle valve is fine, checked for leak by blowing into the fuel inlet with valve closed. No leak.
Yes.. i'm actually thinking about putting a smaller main jet in. The previous owner used the bike in very cold climates so it might need smaller jet ..

 

[jlk_250]

One other thing you can do is baseline your compression tester on a similar bike that is known to be in good condition. You may find that 125 psi is a good reading using your gage and technique at your elevation.

Have you repacked the silencer and checked that the holes are not plugged with carbon?

If everything else checks out you may have to work on the jetting. I have an '01 EC300 that has required much leaner jetting than normal to get it to run right and some other 300 owners have found the same.

 

[welle]

Yes. I may try the compression tester on another bike.
The silencer has been cleaned & repacked. I'm gonna buy some smaller jets and a new spark plug tomorrow. I'll let you know how it works out.

 

[lech]

Hi,
I have a 01 EC250 and using 178 / 38 second clip on needle and it runs quite okay, a little bit to rich and planning to go down on main when it gets a bit warmer.

Lech

 

[welle]

Okay, I tried a 160 main jet and new spark plug. Still runs like crap. But with petcock off it ran OK. I also noticed that the carb is dripping some gas.. I guess that the floater must be the problem! But i have measured the float height (16.5mm) It must be sticking somehow then??

 

[iancp5]

Okay, I tried a 160 main jet and new spark plug. Still runs like crap. But with petcock off it ran OK. I also noticed that the carb is dripping some gas.. I guess that the floater must be the problem! But i have measured the float height (16.5mm) It must be sticking somehow then??

Hmm have a good look at the condition of the float valve as well as if there is anything to cause the float to stick. If all looks ok just try setting the float gap larger and see what happens.

I'm not sure messing with the main is going to be a good test as until you're at 3/4 throttle it'll be masked by needle size and notch. Unless you have a long straight where you just hold it wide open for a long time - in which case I'd be very wary of making a large change in the lean direction!

 

[kim]

Only make ONE size change at the time (ie from 178 to 175) and WRITE down the results.
Float level MUST be done correctly first and use the spark-plug colour as a guide.

It can be a tedious job, especially when changing the pilot jet as you will need to remove the bowl each time. The main jet can be changed by just removing the carb drain plug.

If you remove the chain case saver you quite easily rotate the carb in place.

Kim

 

[welle]

okay, i put in 170 main jet instead and adjusted the float height to about 18mm
Now the top end is good! easy to wheelie
No idle though, gonna look into that now.