Pioneer 1073... not starting.

[r1stgei]

Well the old story... “take a look at my saw please”. lol. Got this really neat pioneer 1073. It’s getting spark, timing looks good. I’m pretty sure since the compression is around 110 is the reason it’s not starting. Cleaned the carb. Fuel is getting to the cylinder. Any thoughts?

 

[r1stgei]

Asp disabled that auto decomp valve

 

[dougand3]

Debris and light scoring on piston - is exhaust wall scored? Are rings so worn there is a big end ring gap? 110 PSI is really marginal - may run a bit but shut off frequently and be low on power. Try a tsp of 90 wt gear oil in plug hole with piston near TDC - see if PSI jumps to ~150.

 

[HarleyT]

Many of those Pioneers had a compression release button that is automatically depressed when the rope is pulled.

https://www.ebay.com/itm/pioneer-p25-1073-chainsaw-oem-2-lever-/161596585579

 

[r1stgei]

Many of those Pioneers had a compression release button that is automatically depressed when the rope is pulled.

https://www.ebay.com/itm/pioneer-p25-1073-chainsaw-oem-2-lever-/161596585579

Yessir. I disabled it. I’ll try poking around to see . Thanks for the help!

 

[r1stgei]

Debris and light scoring on piston - is exhaust wall scored? Are rings so worn there is a big end ring gap? 110 PSI is really marginal - may run a bit but shut off frequently and be low on power. Try a tsp of 90 wt gear oil in plug hole with piston near TDC - see if PSI jumps to ~150.

I’ll try that tonight. Thanks!

 

[Old2stroke]

Compression may be on the low side but at 110 psi it should still start (with decomp valve disabled) and run well, just not develop the same power as a new saw. Have you tried dribbling some fuel in the spark plug hole to see if it will fire? To test for good spark you have to do it with a plug gap that is opened up to about 1/8" as it takes less energy to fire a plug in atmosphere then under compression in the engine. If dribbling fuel into the top of the engine doesn't get it to fire, then as suggested above, try some heavy oil in the top, work it around a bit then dribble the fuel in and see if it fires. If the heavy oil makes the difference, THEN you do have a compression issue.

 

[r1stgei]

Compression may be on the low side but at 110 psi it should still start (with decomp valve disabled) and run well, just not develop the same power as a new saw. Have you tried dribbling some fuel in the spark plug hole to see if it will fire? To test for good spark you have to do it with a plug gap that is opened up to about 1/8" as it takes less energy to fire a plug in atmosphere then under compression in the engine. If dribbling fuel into the top of the engine doesn't get it to fire, then as suggested above, try some heavy oil in the top, work it around a bit then dribble the fuel in and see if it fires. If the heavy oil makes the difference, THEN you do have a compression issue.

Thank you!