Lifan 150cc 162MJ - Low Compression. Where to go next?

[kurboy]

G'day everyone!

I was given a chinese ATV's a few months back and I've been trying to get the motor to fire without luck.

The Motor is a 150cc water cooled Lifan (162MHJ). Motor Specs here ->http://www.lifan.com/English/Mall/MotorEngineView.aspx?d9df3d75-77ef-4579-b429-8223c08fd0b9 I don't really know much about this motor (it kinda looks similar to an old Honda?) or if its even worthwhile fixing.

Couple of photos of the motor below.



Spark and fuel are ok and I've fixed the electric gremlins and rebuilt the Carby.

Valves have been checked and adjusted. (Set valve clearances to 0.1mm & 0.13mm (0.004" & 0.005") @ TDC on the compression stroke.) Not sure if the valve timing is adjustable (Push rod engine), however the valves appear to be doing the correct thing at about the right time.

I threw a (diesel) compression tester on it tonight and while it built up a small amount of pressure it wasn't enough to register on the gauge. (usually needs around 50psi to register). I'm not sure what the compression should be in this motor, however I would have expected 100+.

Is there anything else I can/should check while the engine is still on the bike or is it time to bite the bullet and pull it out and put it on my workbench? Or is a water cooled ATV engine just a bad idea in general and perhaps I should just dump the motor and cannibalise the ATV for parts.

Any suggestions welcome!

Cheers

Mick

 

[locko90]

Are u sure that there the right valve clearance? When I adjusted the valves on my bike I made the clearance a bit larger then it was and it had more compresion. Different motor to yours though

 

[my67xr]

Did you put a bit of oil down the spark plug hole before kicking it over with the compression gauge in?

Welcome to Minirider's

Drop in and say hello in our Introduce Yourself thread too.


Most of the vertical engine's run .004" on both the inlet and exhaust, with just a little bit of resistance/drag.

How many turn's out is your mixture screw?
And how far off the bottom is your slide sitting in the bore of the carb ?

Is your spark plug getting wet after a few kick's trying to start it ?

 

[kurboy]

Thanks guys. The valves were at 0.003" & 0.004" before I started. I increased the gap a little in case they were staying open. I haven't tried oil in the cylinder. Can give that a shot tomorrow night after work.

Mix screw 1.5 turns out and the idle screw is a fair way out so the slide is pretty low. Should have been ok to get it started and then I could tune it from there. Also the needle is in the 4th position (slightly rich)

Spark plug was completely dry when I took it out, so it doesn't look like fuel is getting into the cylinder.
I took the intake pipework and carby off tonight. Will strip it down and double check everything again tomorrow.

Cheers

Mick

 

[my67xr]

The needle and seat may be blocked with dirt or might just be stuck ?
Is there a chance you bent the float arm's ?

Try turning the idle speed screw in until you see the slide start to lift, adjust it so it's about 1-2mm off the bottom of the carby bore.
Also check at the bottom of the thread's where the pilot jet screw's into, take the pilot jet out, and make sure that you can see light through the hole into the carby bore, it may be gummed up there too ?

 

[kurboy]

Carby is good. All jets and passages are clear. Washed everything down again in metho and blew it out with compressed air just in case. Once I get the compression sorted she should be good to go.

Put a teaspoon of oil in the cylinder, turned the motor over a couple of times by hand (to distribute the oil) and retested the compression. It hit a 100 PSI with the oil in the cylinder so it looks like its leaking past the rings when its dry. Guess its time to pull the motor out the bike and tear it down.

Thanks for your help guys!

Cheers

Mick