When is saw compression too high?

[aldo]

I picked up a Homelite Super Mini, two tone paint red and white.

I have had half a look at it so far (not running) and tried a compression gauge on it. It registered 205 psi. I haven't had a saw register that high before.

The exhaust port is pretty choked up. Looking through the plug hole and the piston top is very clean. Would you go to the trouble of pulling it down to see if carbon build up is the culprit or are those figures ok to go?

 

[67L36Driver]

Cleaning it won't hurt unless you mess something up.

Check your gauge against one know for accuracy. Little red Homies don't normally have that much compression.:msp_scared:


Sudden thought: Engine has sucked in bar oil. Check the duckbill in the oil tank. (Also explains the carbon build up.)

 

[aldo]

Thanks. Pretty sure gauge is accurate as I gave tested a few machines over time and it has given me expected values.

I've had a quick look at the saw and it doesn't look like the simplest thing to pull down.

 

[Eightweight]

unless you nervous start it up !!!

 

[67L36Driver]

Thanks. Pretty sure gauge is accurate as I gave tested a few machines over time and it has given me expected values.

I've had a quick look at the saw and it doesn't look like the simplest thing to pull down.

Little red Homies actually come apart quite easily. Once the recoil cover and wrap handle are off, four screws secure the engine in the shell. Then you can learn the 'tip & slide' dance to get it out and back in.

Watch the throttle link. It is a tiny bit different one end to the other.

 

[aldo]

There is a heap of carbon in the exhaust port. I would like to remove a bit of it first. It would have to be 25% blocked I reckon unless there is a significant taper on the port. Lastly I'm waiting on some parts from Canada to arrive to make it complete.

 

[brokenbudget]

unless you nervous start it up !!!

it would be wise to postpone starting it until he has the oil issue fixed first. that much comp will tear the pullstarter up on these little saws.


dump a buch of fuel into it and flush the chain/bar oil out and let it sit for awhile to 'dry out' a bit before tugging on the rope.

 

[aldo]

Little red Homies actually come apart quite easily. Once the recoil cover and wrap handle are off, four screws secure the engine in the shell. Then you can learn the 'tip & slide' dance to get it out and back in.

Watch the throttle link. It is a tiny bit different one end to the other.

Cheers for that

 

[ernurse]

Compression is too high when there isn't a high enough octane fuel to run it on making it a diesel....so IMHO never. Compression = HP and heat.

 

[wyk]

I didn't see detonation in my 444SE until I had her at 245psi cold. That was with 94 octane non ethanol at 40:1. I recontoured the piston and got her down to 220-225psi cold and haven't had a problem.

 

[brokenbudget]

the fact of the matter is these little saws DO NOT have 205psi. the pull start WILL NOT handle that. it will either split/crack the plactic pulley, chew the cogs up fast or the cord will let go. weather a saw will run with high comp isn't the topic.
the oiler 'system' needs to be looked at and the engine flushed out before i would run it. the carbon in the exhaust is a clear sign this saw has been burning chain oil for a while.

 

[nmurph]

I didn't see detonation in my 444SE until I had her at 245psi cold. That was with 94 octane non ethanol at 40:1. I recontoured the piston and got her down to 220-225psi cold and haven't had a problem.

So, I take it you are still happy with that saw?:msp_biggrin:

 

[aldo]

Excuse the ignorance but I would have thought that the oil tank was entirely separate and run by a crank driven pump then out onto the bar mount.
This particular saw has a manual oiler too by the looks so where does the oil make its way to the crankcase?

 

[brokenbudget]

Excuse the ignorance but I would have thought that the oil tank was entirely separate and run by a crank driven pump then out onto the bar mount.
This particular saw has a manual oiler too by the looks so where does the oil make its way to the crankcase?

it is, however it still can leak oil into the crankcase. it's also possible that the gasket is leaking past into the case.

 

[67L36Driver]

Excuse the ignorance but I would have thought that the oil tank was entirely separate and run by a crank driven pump then out onto the bar mount.
This particular saw has a manual oiler too by the looks so where does the oil make its way to the crankcase?

No.:msp_rolleyes:

Line from crankcase w/duckbill in oil tank.

O.P.'s duckbill has gone to tar or fallin off end of the line.

 

[lesorubcheek]

Super Mini's were (pretty sure) the Canadian version of the EZ/SuperEZ. If this is the case, then no duck (other than breather on oil cap).

Dan

 

[brokenbudget]

Super Mini's were (pretty sure) the Canadian version of the EZ/SuperEZ. If this is the case, then no duck (other than breather on oil cap).

Dan

correct. we're not talking about the little 'top handle' super2's or the xl's or whatever other designation they used.

 

[aldo]

That's right Lesorubcheek. It's Canadian built and it does look like the models you mention.

Does that mean I'm still searching for chain oil getting into the engine?

 

[brokenbudget]

is it possible somebody "fogged" it before storage? maybe somebody sprayed oil in there.
flush it out, let it dry for a while and retry the comp test.

 

[67L36Driver]

correct. we're not talking about the little 'top handle' super2's or the xl's or whatever other designation they used.

Oh crap.

Forget everything I posted................................................................

darn canuks. Always skewing the discussion.