Slow lately - time for a new oil thread - I have Castor questions

[Little Al]

Blowing the top end is usually a tuning problem, oil issues would be deposits (too much) or scored cyclinders (too little). A blown top end, or at least what I think, is when there is a hole in the top of the piston. This is mostly caused by heat due to a very lean fuel mix. I'm guessing the group of guys that has suzi's and use 927 were all friends, and they all leaned out the carbs to get more power until, ummm, piston blowout!

Agree with this entirely, & if it was the same as towards the end that I spent road racing 2 smokes, it seemed to be more important & to gain bragging right in the paddock as to who was using the least amount of oil in their fuel mix I can remember one (plonker) boasting his mix was some where in the region of120/1as he was using some all singing/dancing snake oil. IIRC he did a least half a lap before it locked up, some folk think they know best & won"t listen to the folks that really know.

 

[wyk]

I spoke with Danny Massie at Maxima. He shared a few insights with me. One of which was the fact you need to make sure you do not run 927 rich like you would most esters when milling. He informed me it was formulated to burn well both at high and low temp operations when jetted correctly. Many motorbikes and chainsaws err on the side of being rich. Set your jets right, and pay attention to the burn(checking plugs, adjusting the carb as needed) and you won't have deposit issues. I am gonna test this shortly here in a 'full ported' saw from Randy(vs a 'woods port'). So we'll see how it goes.

 

[wyk]

OK, as I said, I am gonna post an update. I ran out of my usual full synth(castor racing 2t pro something or other) which can make my eyes bleed if I get a full whiff of it, and I went to a 32:1 Maxima 927 mix with 95 octane fuel(the minimum available locally here in Ireland). The saw is a MasterMind ported 044R with bridge ports and ridiculous compression and timing advance(it bites every single time you start it - I always wear gloves), tuned for 14,200 RPMish. It has seen most of it's use on wood larger than 24", a 4' DBH beech, a 4' dbh chestnut, a few 2' dbh spruce, and some random mix. So, not an easy life. I have recently added a TTO gauge to the saw itself to make sure she stays in tune as well. These are the pics after two US gallons of the stuff:

The spark screen(which is now permanently removed):

The piston:

Sort of difficult to see here, but the top of the piston is very shiny with a coat of oil on it.

Almost forgot the plug(Bosch are made in China now?! Ugh!):

The stuff smells great, too. When you cut Beech or Chestnut with it, it smells of doughnuts! A confection difficult to find in these parts, btw.
Overall, I'm impressed.

 

[Vintage Engine Repairs]

Hey WYK, sorry to bring this thread up, but I’m curious to see if you still have the pics of the 927 maxima piston? I have recently gotten 500mls to experiment. I ran it for about an hour total, it made quite the mess. It was tuned correctly, cleaned up under load, a slight 4 stroking out of load. This is in a strimmer so won’t see the loads a chainsaw would. Are you still running it? Noticed you are still around as you logged in today so had to ask!

 

[bwalker]

Hey WYK, sorry to bring this thread up, but I’m curious to see if you still have the pics of the 927 maxima piston? I have recently gotten 500mls to experiment. I ran it for about an hour total, it made quite the mess. It was tuned correctly, cleaned up under load, a slight 4 stroking out of load. This is in a strimmer so won’t see the loads a chainsaw would. Are you still running it? Noticed you are still around as you logged in today so had to ask!

927 in a saw is a fools errand for a variety of reasons.