Transfer port back flow

[CR888]

I hoped Terry would chime in here to quash a few of the 'ideas' floating around.

 

[Bigmac]

I understand what your saying, I was asking your opinion on carbon build in the transfers to help answer the op’s question.
I agree that carbon under the crown is heat cooking and have seen what I feel Is heat cooking it in reed valve tuned pipe motors as well in the crankcase and transfers, and it is mainly oil related, the caster base oils are magnified or accelerated results, switch oil and it goes away, similar to piston crown carbon and different oils. Idk, just throwing it out there. I have never had transfers carbon in my saws of other Mx bikes/quads, it’s always other people’s stuff, but most of the time even low hour stuff had burnt oil stains with some brands, same customers different oils no staining. Not trying to sound like a..., It’s just what I have observed, if the staining/carbon was universal then I would feel it to be design issues/normal two stoke positions. Like the 461 pics the fan side was cleaner than the pto side, to me that’s a heat issue.

 

[CR888]

Yeah the carbon under the crown is a good way to verify things are getting hot. When its becomes white its referred to as the dreaded 'death ash'.

 

[Deets066]

Yeah the carbon under the crown is a good way to verify things are getting hot. When its becomes white its referred to as the dreaded 'death ash'.

I usually melt the exhaust side of the crown off by the time the death ash comes. Lol

 

[Bigmac]

I usually melt the exhaust side of the crown off by the time the death ash comes. Lol

Back in my younger days I used fuel/mix from other people twice, it was the only times I put a hole in pistons , couldn’t believe how fast it happened both times...didn’t make it 100 yards out of the parking lot! I thought the fluke the first time, both people said they used the same oil and mix, well that was the last time I ever did that! Lol

 

[Bigmac]

Yeah the carbon under the crown is a good way to verify things are getting hot. When its becomes white its referred to as the dreaded 'death ash'.

Ya but some oils will do that without getting that hot, were other will burn the exhaust side off and have zero build up under the crown

 

[Terry Syd]

Like the 461 pics the fan side was cleaner than the pto side, to me that’s a heat issue.

I agree. The PTO side just doesn't get the airflow of the fan side. That's one of the reason I spend some time cleaning up the cylinder casting from the manufacturing process. Lots of times it is relatively easy to increase the air flow on the PTO side of the jug. I've even drilled a hole on the top fin on the PTO side so that the air flow could drop down and cool the underside of the top fin and the top of the second fin.

 

[Deets066]

Back in my younger days I used fuel/mix from other people twice, it was the only times I put a hole in pistons , couldn’t believe how fast it happened both times...didn’t make it 100 yards out of the parking lot! I thought the fluke the first time, both people said they used the same oil and mix, well that was the last time I ever did that! Lol

I got 7 pistons in my sled. Expensive jetting learning curve. Lol

 

[Al Smith]

----sacrifices to the piston god ----- .

 

[Al Smith]

Now this Art Martin deal with the reeds in the transfers also used windows in the piston if memory serves . I've only seen less than a dozen of these big old saws in my lifetime and ran maybe three at best . One was owned by Larry S ,another buckeye from up around Cleveland had one reworked by Ken Dunn I believe and it would scoot .The rest were not overly fast just pulled like Georgia mules .Weather the Ken Dunn example had reeds or not I cannot say .

 

[Nc grease monkey]

I love this forum. Always good discussions and brainstorming with different ideas. Taking a break from making bushings and pin for the front of dads tractor. Hard to take round rolls of hay to feed cows without. I’ve got some catching up on reading to do though. Lol