logging22
Cuttin to live, livin to cut
Im in.
Mastermind Meets the 562XP
- Thread starter Mastermind
- Start date
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Mastermind
Work Saw Specialist
OK now here's where it gets interesting. 
This saw has a .025 base gasket and with that gasket it has .027 squish. I didn't want to cut the cylinder base and the gasket thickness made this work out great.
I ditched the gasket (which infringed on the transfers a little) and cut a .025 popup.
I did have to cut the cylinder walls but just to allow the flange to sit tight against the case. The base is untouched so with a base gasket a stock piston will fit back in with no worries.
Checking squish.
.027 clearance.
The transfer entrances all cleaned up.
This saw has a .025 base gasket and with that gasket it has .027 squish. I didn't want to cut the cylinder base and the gasket thickness made this work out great.
I ditched the gasket (which infringed on the transfers a little) and cut a .025 popup.
I did have to cut the cylinder walls but just to allow the flange to sit tight against the case. The base is untouched so with a base gasket a stock piston will fit back in with no worries.
Checking squish.
.027 clearance.
The transfer entrances all cleaned up.
Well here we go once again.Mastermind sort of reminding me of a Mr. Jack Rousch.He takes a perfectly good Mustang and completely dismantles it.Now in between bottles of beer Randy makes decisions that will change the performance aspect of the piece involved.What becomes of this?The fuel system is modified, the ignition timing may get tweaked, and in this instance the compression may get raised a tad.OK Jack or Randy lets see what you have for us this time. Sacrificing another perfectly good saw just for the name of performance gained.The audience is now primed and awaiting the final results.Buy the way, has anyone heard jack Rousches P 51 Mustang? Ken
Mastermind
Work Saw Specialist
After dropping the jug the numbers are now....
Ex. Duration: 152° A loss of 2°
In. Duration: 152° For an increase of 6°
Strato Duration: 148° Also a 6° increase.
Blowdown 12°
Just a bit of blending and smoothing here.
I did raise and widen the exhaust.
Check out those stuffers.
Ex. Duration: 152° A loss of 2°
In. Duration: 152° For an increase of 6°
Strato Duration: 148° Also a 6° increase.
Blowdown 12°
Just a bit of blending and smoothing here.
I did raise and widen the exhaust.
Check out those stuffers.
Only 12° of blowdown? Wow! Hope she turns out good for you. Don't be shy
Mastermind
Work Saw Specialist
Welp......I don't drink.
The final port numbers ended up.....
Exhaust Duration: 161°
Blowdown: 17°
Strato Duration: 148°
Intake Duration: 153°
I'll probably end up going back in a time or two before I'm finished. I think that by adding a couple more degrees of intake timing the fuel mixture will overpower the strato event even more and that should add a bit of snot. I just hope the auto tune can make this stuff work out alright.
I cut the muffler in half in order to gut it and open it properly. It's welded back up and repainted. The owner wants a dual port with exhaust tubes. I also ordered a new muffler to go with the saw when it goes back home in case he wants a stock look for any reason.
I should have it wrapped up and running tomorrow.
Mastermind
Work Saw Specialist
Only 12° of blowdown? Wow! Hope she turns out good for you. Don't be shy
It was 12° from the factory. It ended up with 17°
You know I ain't shy Brad.
Mastermind
Work Saw Specialist
I was hoping you would show up Terry. What do you think of the plan?
Of course I have a before video.
sunfish
Fish Head
Great thread Randy!
I am watching closely.
I am watching closely.
Mastermind
Work Saw Specialist
I'm sure they can be.....I've not really looked that closely at it.
Terry Syd
Addicted to ArboristSite
My strato work was limited to that 450 with all the inherent problems of a 'big bore' on a small chassis. However, I did learn a heap by overcoming all the problems.
I did cut my piston to take the blowdown out to 16 degrees, coupled with the notches on the piston to increase the area, the saw flat screamed. Unfortunately, I have a 13,000 limiter on the coil. Hell, with the 14 degree blowdown and the other work, I can hit the limiter quite easily. So, I went conservative for a work saw and stayed with 14 degrees (plus the notches which seem to work like an extra 2 degrees).
If there is no limiter problem on the 562, you should be feeling some serious revs.
As I mentioned before, I'm in the matched strato/intake timing camp. The crankcase compression can't start until both strato and intake ports are closed. Having one with a shorter duration simply restricts the ability of the engine to flow the 'intake' charge.
As it was on the 450 the intake was 144 and the strato was 154. Further, the strato conduit was 13.5mm and the carburetor intake venturi was 11mm. Now wrap your head around what was going into the cylinder - LOTS OF AIR. Yet, the fuel mixture was just fine at the time of combustion. In other words, when it got down to the moment of ignition, the turbulence of the air and fuel mixture had formed a homogenised air/fuel mixture in the combustion chamber. - When you go back in, if you need any more intake duration, I would go with increasing the strato timing to match the intake. You will still have the same base compression, but will have picked up more flow.
I'd check the strato intake as it comes into the cylinder. I had a flow restriction from the piston at TDC. It didn't take much on my saw to increase the strato flow about 30% just by trimming the piston edges that were in the way.
I'm anal when it comes to flow patterns on pistons. They tell me a lot about what is going on in the cylinder. When you go back in, check that area of the pop-up that sits in front of the transfer flow. I noticed that the 450 had a really nice flow pattern from the way the transfers entered the cylinder. It may be that flow pattern over the pop-up will indicate that you could trim some of the pop-up near the transfers to clean up the flow pattern. You may not need to completely cut down the pop-up at that point, perhaps just smooth out the edges so that you get a clean flow.
The last thread on modding the 562 showed some problems with getting the stock carb to flow enough fuel. I had the same problem on the stock 450 (after boring). It appears the factory is still playing around with keeping the mixture on the lean side. You should check the metering lever height because it in all probability will be set low and you may have to drop the POP to get some more fuel flow.
Nice work by the way, that is one purty engine.
EDIT: When you get a chance, check the size of the venturi on the carb. The 445/450 had a 11mm, the 570/576 has a 13.5mm. I expect that the 562 has something like a 12 or 12.5mm venturi. The C1M carb is on all these models, so the larger 576 carb would fit. Someone may want to swap the carb or bore out the 562 carb.
I did cut my piston to take the blowdown out to 16 degrees, coupled with the notches on the piston to increase the area, the saw flat screamed. Unfortunately, I have a 13,000 limiter on the coil. Hell, with the 14 degree blowdown and the other work, I can hit the limiter quite easily. So, I went conservative for a work saw and stayed with 14 degrees (plus the notches which seem to work like an extra 2 degrees).
If there is no limiter problem on the 562, you should be feeling some serious revs.
As I mentioned before, I'm in the matched strato/intake timing camp. The crankcase compression can't start until both strato and intake ports are closed. Having one with a shorter duration simply restricts the ability of the engine to flow the 'intake' charge.
As it was on the 450 the intake was 144 and the strato was 154. Further, the strato conduit was 13.5mm and the carburetor intake venturi was 11mm. Now wrap your head around what was going into the cylinder - LOTS OF AIR. Yet, the fuel mixture was just fine at the time of combustion. In other words, when it got down to the moment of ignition, the turbulence of the air and fuel mixture had formed a homogenised air/fuel mixture in the combustion chamber. - When you go back in, if you need any more intake duration, I would go with increasing the strato timing to match the intake. You will still have the same base compression, but will have picked up more flow.
I'd check the strato intake as it comes into the cylinder. I had a flow restriction from the piston at TDC. It didn't take much on my saw to increase the strato flow about 30% just by trimming the piston edges that were in the way.
I'm anal when it comes to flow patterns on pistons. They tell me a lot about what is going on in the cylinder. When you go back in, check that area of the pop-up that sits in front of the transfer flow. I noticed that the 450 had a really nice flow pattern from the way the transfers entered the cylinder. It may be that flow pattern over the pop-up will indicate that you could trim some of the pop-up near the transfers to clean up the flow pattern. You may not need to completely cut down the pop-up at that point, perhaps just smooth out the edges so that you get a clean flow.
The last thread on modding the 562 showed some problems with getting the stock carb to flow enough fuel. I had the same problem on the stock 450 (after boring). It appears the factory is still playing around with keeping the mixture on the lean side. You should check the metering lever height because it in all probability will be set low and you may have to drop the POP to get some more fuel flow.
Nice work by the way, that is one purty engine.
EDIT: When you get a chance, check the size of the venturi on the carb. The 445/450 had a 11mm, the 570/576 has a 13.5mm. I expect that the 562 has something like a 12 or 12.5mm venturi. The C1M carb is on all these models, so the larger 576 carb would fit. Someone may want to swap the carb or bore out the 562 carb.
Last edited:
wigglesworth
Booned
geeze louise....
that saw has a lot goin on under that ramped top, huh?
As usual, your work looks great!!
Really looking forward to the vids. Keeping my fingers crossed its a bit faster in the after vid.
that saw has a lot goin on under that ramped top, huh?
As usual, your work looks great!!
Really looking forward to the vids. Keeping my fingers crossed its a bit faster in the after vid.
Terry Syd
Addicted to ArboristSite
Here's another trick that someone might want to use. When the intake and strato timing are the same, you can widen the intake port so that it will join up with the strato cutaways on the piston.
Since the timing is the same, there won't be the sever compromise of the strato's good fuel economy when running at WOT, but it will give you a tad more 'gulp' (time/area) on the intake port for perhaps a tad bit more power. The compromise of the economy will occur mainly at idle when the intake charge also gets pulled into the transfer ports.
I mentioned the possible larger carburetor. The stratos have a lot of time/area for the intake cycle, the restriction of flow is in the size of the strato butterfly/conduit and the size of the carburetor. I like the idea of running a larger carburetor to get the extra flow rather than to use a bit more intake timing. You can maintain the same base compression, but pick up the extra flow by having less restriction.
You have to remember that the restriction of flow through an orifice is not linear. If you double the flow through an orifice the restriction does not double, but is four times the restriction. Thus, a bigger carb works well for high rpm work. You can tune an engine for a good strong powerband and the bigger carb will give you the extra over-run after the power peak. That combination works well on a small saw that will be used for high speed limbing and for bucking.
Since the timing is the same, there won't be the sever compromise of the strato's good fuel economy when running at WOT, but it will give you a tad more 'gulp' (time/area) on the intake port for perhaps a tad bit more power. The compromise of the economy will occur mainly at idle when the intake charge also gets pulled into the transfer ports.
I mentioned the possible larger carburetor. The stratos have a lot of time/area for the intake cycle, the restriction of flow is in the size of the strato butterfly/conduit and the size of the carburetor. I like the idea of running a larger carburetor to get the extra flow rather than to use a bit more intake timing. You can maintain the same base compression, but pick up the extra flow by having less restriction.
You have to remember that the restriction of flow through an orifice is not linear. If you double the flow through an orifice the restriction does not double, but is four times the restriction. Thus, a bigger carb works well for high rpm work. You can tune an engine for a good strong powerband and the bigger carb will give you the extra over-run after the power peak. That combination works well on a small saw that will be used for high speed limbing and for bucking.
Brendann
ArboristSite Lurker
Terry,
How come you don't open a mod shop, or do you already do that?
How come you don't open a mod shop, or do you already do that?
Terry Syd
Addicted to ArboristSite
I'm a 64 year old retired trial attorney, you sure you want me charging you to work on your saw?
I've been building engines since I was 16 and was the technical editor of a motorcycle magazine. I just like being a petrol head. When I got my first new chainsaw, it only took two days before I had to pull the damn thing apart to see how it worked. I don't race anymore, but nowadays I can get my jollies by paying close attention to how a saw performs as it cuts.
Randy is probably going to bump the speed of this saw fairly high. At that point, he's going to be looking for some more time/area for the transfers - that will be when this thread gets really interesting.
I've been building engines since I was 16 and was the technical editor of a motorcycle magazine. I just like being a petrol head. When I got my first new chainsaw, it only took two days before I had to pull the damn thing apart to see how it worked. I don't race anymore, but nowadays I can get my jollies by paying close attention to how a saw performs as it cuts.
Randy is probably going to bump the speed of this saw fairly high. At that point, he's going to be looking for some more time/area for the transfers - that will be when this thread gets really interesting.
chopperfreak2k1
Addicted to ArboristSite
all in for this one. man did i like that cylnder!
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