Over-hot cylinder, rpm correct. Ideas?

[riverdog]

Hey.

I picked up an old husky 346xp 'spares and repairs' off ebay as a project.

Stripped it all down, cleaned it up, new sprocket, carb kit, spark plug etc.

The piston was seized so I fitted a new piston and cylinder.

Cylinder/piston is a 44mm "War Tec" non-genuine £48 kit from GHS in Worcester.

Started her up and with a bit of carb fiddling she runs.

I used a Tacho to get 2400rpm at idle and 14,000 at full throttle.

The weird thing is that the cylinder gets VERY hot (you can feel heat coming through casing) within minutes of starting her up! I daren't run her in case I burn up the new piston/cylinder. What's going on???

[riverdog]

p.s. I know cylinders do get hot, I'm comparing this to my newish 346xp silverside model which gets "normal hot", but this is on a whole new level of heat!

[Eddy_t]

Have you checked the cooling parts? Are many fins missing off the flywheel? Are the cylinder fins caked in crap or snapped? Are the air holes on the starter casing blocked?

 

 

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[peatff]

Do you have access to an infrared thermometer to compare the temperature to a known good saw to see how hot it is getting ?

[Ray1]

Characteristic of the cheap metal it's made of?

[peatff]

I'd set it up to four stroke a bit at the top end nearer to 12,000 till it's had a run for a while instead of going for 14,000rpm flat out. It might be heating up because it's lean at the top end. Just guessing as I'm not a saw expert but I've had a few two strokes over the years.

[H-A]

I would run it in rich, not scream the nuts off it to start with, none original pot and piston could be a tad tight perhaps, did you gap the ring in the bore?

 

What is the plug colour like? Did you find any air leaks that would explain the original cylinder and piston failure.

 

H-A

[spudulike]

Do you have access to an infrared thermometer to compare the temperature to a known good saw to see how hot it is getting ?

 

Well I like that idea...nice one:thumbup:

 

It will generate a bit more heat when running in but may be worth dialing it down to 13,500 whilst it is being run in.

 

It may just be the quality of the new kit, time will tell. My ported one pulls 15,000 rpm and gets a tad hot:blushing:

[riverdog]

Alright. Thanks for your help.

All the fins/flywheel etc are clean and sound and I don't have access to an infrared thermometer so I think I'll just tone it down a bit as suggested and then take it into the woods for a few hours and see what happens.

I'll let you know!

I have to say I would never have set the H jet that lean if I'd been tuning it by ear but I just kept going until the Tacho said stop! I'll see if it's happier at 13,500rpm.

Thanks. S.

[riverdog]

I took the rpm down to 13,000 and ran the saw through some seasoned ash roundwood for a couple of hours yesterday. My mate was running his newer edition 346xp for the same period. My 346 got much hotter than his but it actually ran quite nicely with no problems. I reckon Ray1 is probably right and the cheaper cylinder just heats up a bit more for whatever reason but it seems to be staying within it's tolerance limits so who cares?

Thanks for you're help/advice.

S.