Mastermind Ported Dolmar 6100

[Four Paws]

I'm gonna tear this saw in the video back down and map every port. I'm even gonna check the timing on it with an inductive light. I gotta document this one for sure.

It's nice when they come together! Some saws just put a smile on your face!

 

[Duce]

I hope you make that 562 run strong!

 

[Mastermind]

I'll do my very best.

 

[Duce]

I'll do my very best.

Sir, That's all I can ask and your work speaks for itself. Thanks.

 

[ajschainsaws]

P

Like I've said before. I think my new one runs better than my old one did.

Ditto --- My 1st one back when they where launched was.ok but not fantastic
but the one I got here now has been out on demo to potential customers and I never seen it for nearly six months it came back too me a bit used but that saw runs fantastic better than the other one , despite all the abuse from husky and stihl users trying to kill it

 

[166]

There has been some changes to the intake boots.

 

[Terry Syd]

There has been some changes to the intake boots.

It's been a while since I've seen a picture of the reed block on the 6100, the intake boots are attached to the reed block - is that correct?

If so, then there may be a bit more difference to the block than just the boots. Comparing the two might clear up the differences and give us some mods about tuning these saws.

 

[Mastermind]

It's been a while since I've seen a picture of the reed block on the 6100, the intake boots are attached to the reed block - is that correct?

If so, then there may be a bit more difference to the block than just the boots. Comparing the two might clear up the differences and give us some mods about tuning these saws.

I'll do a detailed thread on this saw when I tear it back down Terry.

 

[johnny5ny]

moobs-your skill is unmatched.
Credit where credit due to the saw, coming from a huge 562 fan.
Mines at .010 squish and .71 exhaust/bore now so prob no longer considered a woods port. Fun saw? Yes. Work saw? No. Likely to hang a ring? Time will tell.
Impressive work randy. As always

 

[Terry Syd]

I'll do a detailed thread on this saw when I tear it back down Terry.

I'll be looking forward to it. I'd appreciate it if you pulled the reeds off so they can be measured and a picture of the inside of the reed block, the area under the reeds, to see how it flows. I've never seen a reed block designed that way.

 

[weedkilla]

I haven't even seen one of these in the flesh, let alone pulled one down. And quite frankly with the way makita run part supply for dolmar in Aus I'd be hesitant to run one commercially. They do, however look like an awesome saw.

The reeds are just in the strato feed, right? So how can they have a significant part to play in making more power in a modded saw? What am I not understanding?

 

[Terry Syd]

Air flow - it is real easy to get more fuel in an engine (just tweak the needles), but getting the AIR in there to burn the fuel is the hard part. Think of superchargers and turbos - they are trying to cram extra air into the cylinder to make power.

The strato reeds feed extra air into the cylinder, the more air we can get, the more fuel we can burn.

 

[Mastermind]

I haven't even seen one of these in the flesh, let alone pulled one down. And quite frankly with the way makita run part supply for dolmar in Aus I'd be hesitant to run one commercially. They do, however look like an awesome saw.

The reeds are just in the strato feed, right? So how can they have a significant part to play in making more power in a modded saw? What am I not understanding?

I can't wrap my mind around it either.......but here's what I see.

The reeds allow the strato ports to flow ONLY when there is a low pressure signal in the upper transfer port area. The carb is huge for a 60cc stratified saw.

Maybe Terry can help us both understand how it works better.

 

[Terry Syd]

The reeds allow the strato ports to flow ONLY when there is a low pressure signal in the upper transfer port area. The carb is huge for a 60cc stratified saw.

That upper transfer area is connected to the lower transfer area AND the crankcase. The reeds can start opening as soon as there is a pressure differential, which should occur when the piston moves upwards and closes the transfer port windows. Once the transfer windows are closed, the piston can then create a low pressure in the crankcase as it continues to rise in the cylinder. The reeds allow the engine to start sucking air as soon as that low pressure develops.

In a regular piston-port engine, the flow into the crankcase can't start until the intake opens. The time from the closing of the transfer windows to intake opening is 'dead' time - there is no flow. In fact, there is the increasing low pressure area under the piston trying to pull the piston back down. - That results in more mechanical resistance in the engine.

 

[weedkilla]

Air flow - it is real easy to get more fuel in an engine (just tweak the needles), but getting the AIR in there to burn the fuel is the hard part. Think of superchargers and turbos - they are trying to cram extra air into the cylinder to make power.

The strato reeds feed extra air into the cylinder, the more air we can get, the more fuel we can burn.

So we are talking about increasing cylinder filling, and an appropriate increase in VE?
The mix feed is compressed in the crankcase, and the fresh air feed is just coming in at atmospheric pressure, right? I'm still not seeing the area of improvement being significant. A slight increase in VE is likely by getting strato timing just right to flush the cylinder completely, but that's about all I see.

Honestly not trying to do anything but understand.

Edit - we posted at the same time.

 

[Mastermind]

That upper transfer area is connected to the lower transfer area AND the crankcase. The reeds can start opening as soon as there is a pressure differential, which should occur when the piston moves upwards and closes the transfer port windows. Once the transfer windows are closed, the piston can then create a low pressure in the crankcase as it continues to rise in the cylinder. The reeds allow the engine to start sucking air as soon as that low pressure develops.

In a regular piston-port engine, the flow into the crankcase can't start until the intake opens. The time from the closing of the transfer windows to intake opening is 'dead' time - there is no flow. In fact, there is the increasing low pressure area under the piston trying to pull the piston back down. - That results in more mechanical resistance in the engine.

I get that.......I just don't understand how that pure air layer makes power.

 

[Mastermind]

Honestly not trying to do anything but understand.

Same here.........I just can't see the strats making more power. I can see that may doing it the way Dolmar did allowing us to have a bigger intake than any strat saw I've seen yet.

 

[Terry Syd]

I get that.......I just don't understand how that pure air layer makes power.

That's what I couldn't understand when I first looked at a strato. All the advertising videos showed a 'stratified' charge of clean air pushing out the exhaust.

The reality is by the time of ignition there is a homogeneous mixture in the combustion chamber. All the 'pure air' and mixture from the carb get blended together by all the turbulence. If you get more 'pure air' in there, you just tweak the carb to add a bit more fuel.

 

[Mastermind]

I might buy that.......maybe. lol

 

[Mastermind]

I might buy that.......maybe. lol