MS250-Too Much Compression?

[AKDoug]

I'm not even sure you will get it started. I also suspect that the base pan won't hold at these pressures if it does start.

 

[drf255]

Just to play devil's advocate - so he's got an extra 60 or 70psi at cranking speeds. How much extra cylinder pressure does it have at 10,000rpm under load, and how much more load is this going to put on the bearings? I'm not sure one can make a direct correlation between these two vastly different conditions.

I'm thinking the same.

It's at 230 with no oil in cylinder and no ring breakin.

At rpm, it's not gonna fill the cylinder all the way.

Phuck it, I'm running it.

Modding the muffler now. Hopefully run by Sunday.

I have no idea how to post a video to YouTube or any other place.

 

[Red97]

Detonation is going to be the number 1 issue. the bearings might be ok for a minute if it doesn't detonate, which it will. If you are truly going for broke and going to run it try cutting your mix 50/50 with diesel It will help lube the piston if nothing else.

 

[R DeLawter]

You asked for help but are not listening to what the experts are saying.

 

[drf255]

If your all saying that at 230 psi it won't hold together, I will take it apart and grind the dome down.

If there's a chance it will run like a raped ape, it woulda been fun to try.

I do respect what the experts are saying.

I'm not looking to grenade the saw. It was just my intention to get more power out of this compact saw.

 

[sunfish]

I have 5 ported pro saws and not one over 200 psi... Just sayin.

 

[drf255]

Why will a masterminded pro saw run at 230 psi but this one won't?

 

[bayard]

boom

 

[sunfish]

Why will a masterminded pro saw run at 230 psi but this one won't?

Well, cause mastermind is an awesome dude.

 

[Red97]

Why will a masterminded pro saw run at 230 psi but this one won't?

Your saw Will have closer to the 270 mark after it first fires, the cyl will be wet from the fuel/oil mix sealing it even better. That is the issue, Much over 220is psi detonation becomes real. Mastermind cuts the squish/base to create a tighter quench area, to increase the compression.

The large dome you have impedes the flame travel and will create hot spots ontop of the piston, causing preigniton of the fuel charge. meaning the fuel charge ignites while the piston is still traveling up. not a good thing to have.

Or you could have enough compression to diesel the engine. Ignite the fuel charge by compression alone before the sparkplug even hits.

Both very bad for a engine not designed for it.

 

[Chris-PA]

Why will a masterminded pro saw run at 230 psi but this one won't?

I think the cut squish band will give a better combustion chamber geometry for resistance to detonation. I doubt there is much other reason.

I doubt having compression that high will be much benefit, but I'm interested to see what happens. It's free for me!

 

[HarleyT]

Doesn't really matter much, the EZ starter won't allow all of that redneck crap.....

 

[Deleted member 83629]

Put a bit of oil in the cylinder.

View attachment 389618


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[Deleted member 83629]

i would run 130 octane in that.

 

[hseII]

you have to make a video of it running

Yes

Proof Is Absolutely Necessary.

Might wanna build a plexiglass box around the camera first

 

[1Alpha1]

Everybody run and duck for cover.

She's gonna blow.................

 

[Deleted member 83629]

this is very interesting with compression that high you almost don't need a ignition coil.

 

[chris zautner]

Yes

Proof Is Absolutely Necessary.

Might wanna build a plexiglass box around the camera first

more like a bomb shelter for it haha

 

[drf255]

Gonna run some Cam2.

 

[Red97]

Good luck my friend, I am going to join the band wagon on this. My last note Oil content in the fuel alters the octane rating.