iDRY Vacuum Kilns

Sponsors:

Jonsereds 520sp no power under load

Started by sonnyboy53, October 05, 2014, 10:10:57 AM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

sonnyboy53

I can't seem to get my Jonsereds  520sp operating well.  I've rebuilt two carbs (first the Tillotson now Walbro), checked for piston scoring through the exhaust port, replaced fuel lines & filter and although it will start, idle & rev up to high speed,  when the cutting begins, it slows down & would die unless I remove it from the log.  Compression is about 140 psi.  What am I missing?  Should compression be higher?

sawguy21

How are you setting the high speed screw. It should be adjusted so the saw just starts to 'four cycle' out of the cut and smooth out under load.
old age and treachery will always overcome youth and enthusiasm

sablatnic

Did you change the fuel filter in the tank?
How is the pulse line? (The tube running down to the crankcase). It isn't clogged somewhere?

Is it still oiling?

sonnyboy53

It is oiling like crazy; no problem there.  The pulse being clogged is something I haven't checked.  It is intact & in place but clogged; I don't know. Will check it out & report back.
Thanks

sablatnic

The oiling has nothing to do with the lack of power, I just asked because the oiling can be a weak point on that series.

thecfarm

Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

sonnyboy53

I think I've resolved the problem.  More for the experience than anything I tore the saw down & replaced the piston ring.  I reasoned that it was probably original & 30+ years old; it couldn't hurt.  Compression is now 155 psi.  Also replaced the clutch drum & bearing.  The drum had a ridge worn on the inside edge so I reasoned the clutch might not be getting a good grip.  Another spark plug & another fuel filter.  More tuning of the carb.  Anyway, one or the other of those things took care of it.  It starts, runs & cuts well now.  Thanks for the various ideas all. 8)

Thank You Sponsors!