This isn't exactly about boats, but a similar engine.
Up here in the northwest we're haveing a snow and ice storm.
Brought my chain saw in, just in case these big firs come down and lock me in.
There has to be some of you guys out there who have tried coleman fuel in your saw.
don't see why it would hurt my Stihl. Mentioned running coleman in my zens to the saw shop guy,
his eyes got big and he threw me out.
Pat

Don't !!! ..... you will fry your engine

I agree with Scott - been a Northern Boy for 55 + years - do not use in ANY chainsaw

I'm curious! Why not? Why is it ok in the Zenoah in our boats and not in a chainsaw?


www.modelgasboats.com

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I would think it's low octane fuels tendency to detonate in higher compression air cooled engines under load. I know low octane fuels will burn pistons in liquid cooled outboards in a heartbeat. In both a fuel that resists exploding under heat and pressure is key. I think Zenoahs and RCMK's are considered low pressure low volume engines that are tolerant to this problem

All I know is I used to used Coleman and tried it in Weed trimmer - trimmer was smoking hot within couple minutes and seized when I turned off. I spoke with service gun at small engine shop (buying new trimmer) and he said white gas will seize air cooled small engines, mine just did so I left it at that. Yes the gas and oil were mixed right.

I think it's octane too but not sure ........ I don't use Coleman anymore I use 97 O Marine gas with no ethonal

RD

A few reasons ...
because of the much higher operating temperature of an air cooled engine the Detonation threshold is much lower.
The AREA within a larger chainsaw cylinder simply does not offer the ability to control flame propagation with fuel that is of such low octane.

We get away using it in the mod Zenoahs / Rcmk's etc only by virtue of fairly low compression ratios, small combustion chamber area and cooler operating temperatures.
* You CAN'T use it in Quick Draws or J&G's either without possible engine damage !!

Scott, have you seen any problems with Zen/RCMK engines with advanced timing or increased compression running on white gas? Don't want to try it but curious where that threshold is?

Being it is pretty well known advancing timing really does little if anything for power gains, can't say heard much from those doing so. That said tho, advancing ignition timing while using a fast burning low octane fuel would be IMO asking for trouble

As for increases in compression with modified Zenoah or RCMK engines, those who claim such things are clueless !! ( It is a sales gimmick )
* Few things going on here ... We cut exhaust ports HIGHER increasing open duration that also REDUCES captive compression.
* Then we drop the cylinder closer to piston for a tighter fit at TDC ... this DECREASES squish clearance and EVER SO SLIGHTLY increases compression.
** Sadly the amount taken in most cases off the roof of exhaust port is GREATER than distance squish clearance is reduced has a MODIFIED ENGINE HAVING LOWER COMPRESSION than it had when stock.

Another reason we get away running Camp fuel in them

I was told to run 100 LL from the airport. Will start eaiser, also keep in generator also. Was told sometimes it sets in planes for a few years and they stsrt right up' The gentlman at the local airpoRT TOLD ME THIS, HE SAYS ALOT OF PEOPLE DO THIS.