Question on poulan compression

[bigbadbowtie]

I was asked to look at a Poulan Pro PP4218AVX. Brother-in-law said it worked great for 2 years and then would not idle. 1st thing I did was check cranking compression. I tied the throttle open and with 5 full pulls Im only getting about 75 PSI. Everything I have read on here says they usually need 100 to 110 lbs of compression.


Im a drag racer and know very little about the 2 strokers. Does this saw have any sort of compression release?? My guess is no and its toast....

Thanks
Ray

 

[scottr]

The PP4218AVX does not have a compression release. Does your compression gauge have a shrader valve at the input?

 

[bigbadbowtie]

Hi Scott,

It does have a schrader valve at the inlet. Do you think that is affecting my reading?

I have used this on cars over the years and allways thought it was accurate.

I took the carb back to 1-1/4 turns on LS and HS settings and went from there. I just can't seem to get it adjusted right. I have tweaked on it until I'm blue in the face. I can get it to idle but it bogs with any throttle. Once I get it to run at WOT it dies as soon as you let off the throttle.
I consider myself a decent tuner on a holley but can't get this one down.

any suggestions???

Ray

 

[doc874]

Hi Scott,

It does have a schrader valve at the inlet. Do you think that is affecting my reading?

I have used this on cars over the years and allways thought it was accurate.

I took the carb back to 1-1/4 turns on LS and HS settings and went from there. I just can't seem to get it adjusted right. I have tweaked on it until I'm blue in the face. I can get it to idle but it bogs with any throttle. Once I get it to run at WOT it dies as soon as you let off the throttle.
I consider myself a decent tuner on a holley but can't get this one down.

any suggestions???

Ray

Pull the muffler, look for scoring ( gouging ) on the piston, as with most two strokers they go bad at the exhaust port area. I wouldn' t run it again until pulling th muffler, if its scored you'd only be adding to the damage and possibly creating more. It may be repairable.

 

[Scooterbum]

I don't know about yours but the last 4218 I looked at had an aluminum bore with no plating.The piston was plated instead.P&C is the only fix.About $90 shipped.Better off just buying a new one.

 

[scottr]

Hi Scott,

It does have a schrader valve at the inlet. Do you think that is affecting my reading?

I have used this on cars over the years and allways thought it was accurate.

I took the carb back to 1-1/4 turns on LS and HS settings and went from there. I just can't seem to get it adjusted right. I have tweaked on it until I'm blue in the face. I can get it to idle but it bogs with any throttle. Once I get it to run at WOT it dies as soon as you let off the throttle.
I consider myself a decent tuner on a holley but can't get this one down.

any suggestions???

Ray

That's the correct compression gauge. Is the screen behind the front cover of the muffler carbon fouled ? Here is an IPL http://72.3.225.179/manuals/545103408.pdf

 

[bigbadbowtie]

Thanks for the help guys. I'll pull the muffler tonight and see what I find.

Scott.. Thanks for the parts list!!!