Porting an 090

[pioneerguy600]

The lower transfer port bulge extends up for 6 cooling fins from the base, that is one way to determine if a saw is actually an 090 from an 070 if all you have to go on is to look at the number of coolin fins on that bulge.

The decomp valve connected to its offset lever to allow for the push button, you really need the decomp on these saws.

Pioneerguy600

 

[WesternSaw]

Jerry your 090 piston job

Jerry you have probably told me already but is that from the 090 I sent you.?Or is that the piston you got from our friend in Ontario?
Lawrence

 

[Brmorgan]

The decomp valve connected to its offset lever to allow for the push button, you really need the decomp on these saws.

Pioneerguy600

I never have, frankly I've found it a pain to use because it has to be held in. You gettin' old, Jerry?

Of course I wouldn't argue with using one on a ported 090, especially if it's had raised compression.

 

[pioneerguy600]

Jerry you have probably told me already but is that from the 090 I sent you.?Or is that the piston you got from our friend in Ontario?
Lawrence

This one is from my regular and a little older 090 that I had for a couple years now. The P&C that I got from Ontario was new OEM.., that is my backup just in case. LOL.

 

[pioneerguy600]

I never have, frankly I've found it a pain to use because it has to be held in. You gettin' old, Jerry?

Of course I wouldn't argue with using one on a ported 090, especially if it's had raised compression.

You know this is true, it was my birthday yesterday and here I am taking it easy today.LOL
What is your saw running for comp Brad? This saw was very hard to pull over cold, I am sure the pull cord streatched an inch or two on every pull on this one so I admit I used the decomp more than once. Once it warmed up I could drop start it easily enough but when cold it would nearly roll over on its side and hit my right knee a couple times so I gave in and started it on the ground , lean on the front handle with left hand, push the decomp down with my thumb and pull up real sharply with my right. I did a cold comp test one morning on it and it was showing 175-178 on five pulls, did this 4 seperate times to get an average and that is what it showed. I have no idea if this is common or not, the last one that I got with the long bar on it I can start that one without the de comp but its bar is too long to make drop starting easy so I start it while on the ground also.
Pioneerguy600

 

[Brmorgan]

I have no idea what the compression is on mine. Good enough, that's for sure. One time I went to start it on the ground and it pulled back real hard; however rather than sucking my arm back down, the saw jumped up off the ground and kneecapped me on the right knee, kinda like how you described. Bruised my knee all to heck too; I had a hard time standing up at work for a couple days afterwards. Generally, though, I don't have a hard time dropstarting it if I make sure it's in the right position before I give it a good pull.

I should put the tester on it sometime though just to see where it's at.

 

[pioneerguy600]

I have found my older 090 with a 40' bar manage able to start after warming it up but it has capped my knee once too often starting it cold, it has not kicked back on me so far but it would not be pleasant if it did. Limping around with a skinned shin and purple bruises has taught me not to streatch my luck with them. I just completed grinding out a 044 for Bruce + a dual port muffler, now that its done the 090 will be next.
Pioneerguy600

 

[Brmorgan]

Jerry, I went down and put the tester on my 090 this afternoon. It draws almost 100 PSI in ONE pull, but caps out just shy of 160 after 5 or 6. Not quite as strong as yours, but I don't feel the need to spend any money on it just yet! The piston and cylinder are still pretty much mint, so I'd imagine the rings are just a bit worn down.

 

[pioneerguy600]

Jerry, I went down and put the tester on my 090 this afternoon. It draws almost 100 PSI in ONE pull, but caps out just shy of 160 after 5 or 6. Not quite as strong as yours, but I don't feel the need to spend any money on it just yet! The piston and cylinder are still pretty much mint, so I'd imagine the rings are just a bit worn down.

160 sure is fine in my books, that big piston does pump up a tester much quicker than on the smaller bore saws. Your rings won`t have to be replaced for a long while either, we just don`t run these things enough to wear them out. LOL
Pioneerguy600

 

[056kid]

You should not rest until she brakes 200 lbs. Thats when you will see a 090 really wake the #### up!!!

 

[pioneerguy600]

You should not rest until she brakes 200 lbs. Thats when you will see a 090 really wake the #### up!!!

I will see what the comp can be brought up to when the squish is at .025., there is no room for a pop up in this cylinder head.
Pioneerguy600

 

[pioneerguy600]

This is a rough idea of what I have in mind for porting, the broken lines are representing where I intend to cut and extent the ports to.

Sizing to be done and posted later
Pioneerguy600

 

[7oaks]

To my inexperienced eye those look like massive changes.

 

[isaaccarlson]

considering it is mostly opening up TINY transfers....

looks just fine. Most of the lowers will be blending...and the uppers could really use some help.

 

[pioneerguy600]

For the first run at it I will be playing it safe, or at least I think so. The lowers are mostly dropping and blending as stated, it looks like a large area but its not really deep, this is a common change in woods ported cylinders. The stock upper transfers look like they are too small and would be the most restrictive passage in the network for the passage of fuel/air mix. I only plan on opening them over toward the intake side 5-6 mm and just square the top of the ports up with the top of the cylinder, I guess the proper term might be make them parraell to the top. The intake port on the inside does not have any room for widening out but out on the carb side there is some material that can be removed to make the port flow better. The intake side has some more area on the sides that can be removed to make a better flow out of the cylinder, on the muffler side there is some that can be removed to match what is removed from the inside which would be about 1 mm taken from each side. Once I do this and remount the P&C then I will mount a degree wheel and see what the port timing works out at, might be ok as is or it may have some improvements that can be made there also.
I appreciate any and all comments or suggestions, this is my first 090 port job but I have easily done over 50 port jobs on other chainsaw engines along with 40 years of HP automobile engine porting, I can grind but there is always some little things that can be done during any modifing procedure that I might overlook or not even know about, I am no expert by any means. LOL.
Pioneerguy600

 

[nanuk]

Pioneerguy600

How do you know when to stop grinding so you don't create a hole through to the outside of the lower transfer?

 

[isaaccarlson]

you make sure there is enough metal left to start with.

you measure.

 

[blsnelling]

This is a rough idea of what I have in mind for porting, the broken lines are representing where I intend to cut and extent the ports to.

Did you leave enough room for your ring ends when widening the transfers that far?

 

[pioneerguy600]

Did you leave enough room for your ring ends when widening the transfers that far?

Good catch Brad, I actually caught it myself while doing a bit of measurement this evening and did up another map showing the locator pins in relation to the piston skirts and the upper transfers, they are the 2 dots on either side of the intake skirt line.
Pioneerguy600

 

[056kid]

Are you going to hog out the transfer ports after opening up the ends like that? seems like you wouldnt get any gains from the widening untill you opened up the ports..