390xp

[logger 12345]

nice saw,nice build,best of luck with it!!!
must be heavy beast when it's all set to go...

 

[parrisw]

That's right Willie, I figured you left some tolerance......besides, we'd have to listen to a big crying if you ever traveled to Freeport City!......Hahahahahahaha!

LOL, yup, I've done that on a 395, it sucked but fixed it with a 2101 piston.

 

[parrisw]

nice saw,nice build,best of luck with it!!!
must be heavy beast when it's all set to go...

Thanks.

Supposed to be not too bad in weight for a 90cc saw.

 

[parrisw]

Was powering through some work on this saw today, then got a call from the school, had to go pick up one of my daughters, not feeling well, so had to stop work, oh well, the joys of parenting.

Final smoothing with 320.

Polished up the port a little.

Polished the piston crown.

 

[parrisw]

Carb through the USC, man I love this thing.

And that's it for today folks. Not doing anymore to the cylinder, going to run it now and see what happens.

 

[jropo]

Once again, Nice work!

Why does that piston look like a Popup?

 

[jropo]

P.s. Good luck on the first fire!

 

[parrisw]

Once again, Nice work!

Why does that piston look like a Popup?

Thanks.

Now that you mention it, it does look like a domed piston doesn't it. Its not, I think its just the way the light is reflecting off of it.

 

[RiverRat2]

Thanks.

Now that you mention it, it does look like a domed piston doesn't it. Its not, I think its just the way the light is reflecting off of it.

will what do you use in your cleaner???

 

[parrisw]

will what do you use in your cleaner???

Usually just paint thinner, or mineral spirits is pretty much the same thing, this time I used Lacquer thinner, though its a little more aggressive. That's just for carbs, I put the thinner in a coffee pot and float that in the USC that has just water in it.

 

[jropo]

Thanks.

Now that you mention it, it does look like a domed piston doesn't it. Its not, I think its just the way the light is reflecting off of it.

I was going to say, Where did you get that!!

Another question, is that all the chamfer needed on the exhaust/ intake port?

 

[komatsuvarna]

Looking good Will......The saw I mean :msp_sad:.

I gotta get me an USC before long, Just not sure what Im looking for yet.

 

[parrisw]

I was going to say, Where did you get that!!

Another question, is that all the chamfer needed on the exhaust/ intake port?

Yes, you don't need much. I may actually go a little more near the outside of the port since its a little wider then 65% of bore Dia.

Looking good Will......The saw I mean :msp_sad:.

I gotta get me an USC before long, Just not sure what Im looking for yet.

Thanks.

Yes the USC's are great, got mine from ebay.

 

[young]

Usually just paint thinner, or mineral spirits is pretty much the same thing, this time I used Lacquer thinner, though its a little more aggressive. That's just for carbs, I put the thinner in a coffee pot and float that in the USC that has just water in it.

i like seafoam also.

 

[jropo]

Yes, you don't need much. I may actually go a little more near the outside of the port since its a little wider then 65% of bore Dia.



Thanks.

Yes the USC's are great, got mine from ebay.

O.k. Was not sure. I have seen some pictures on here and every one looks a little different. +/- Chamfer.

Can you have too much chamfer?

 

[mdavlee]

Looks nice Will. How soon til you get to run it?

 

[parrisw]

i like seafoam also.

I've heard that works well. I'll have to try it sometime.

O.k. Was not sure. I have seen some pictures on here and every one looks a little different. +/- Chamfer.

Can you have too much chamfer?

Yes and no. The chamfer will change timing so you have to account for that. Too much wont harm it, to little and you can hang a ring.

Looks nice Will. How soon til you get to run it?

Not sure yet, I got most of the parts now. Still need a tank vent, and I think that's it. Just have to assemble it. Not likely I'll get to cut wood with it until after the beginning of February.

 

[jropo]

I've been trying a lower intake duration than I've used in the past Will. I'm in no way saying that this is the way to go or even that it helps at this point, but my thinking is along these lines....

We talk a lot about intake opening point, but what about the relationship between intake closing and transfer opening? We think about the blowdown time, but never do we mention the amount of time that crankcase pressure is building between intake closing and transfer opening.

I'm seeing a pattern based on the size of the crankcase and this number. As we all have found, some saws "like" more blowdown....some "like" less. I'm thinking that this is because of crankcase volume vs displacement.

The lower the intake and the higher the transfers the less time the pressure builds in the crankcase, so by leaving the intake as is and just raising the transfers.........????

Keep in mind that all this is just me thinking out loud, but I wouldn't lower that intake until I saw how well it pulled a long bar. Sure a high revving saw is a hoot to run, but a saw that has a butt load of torque is a fine thing.

Sorry for the long winded derail.....carry on.

"The lower the intake and the higher the transfers the less time the pressure builds in the crankcase, so by leaving the intake as is and just raising the transfers.........????"

Sorry had to reread, I'm trying not to hound you w/ questions, but did you do this?^ Did you have to raise or lower the Exh./Int. in any way to account for the dropped cylinder? If so how many Deg.'s? Or did you just widen and blend? If so how much? You said that "I may actually go a little more near the outside of the port since its a little wider then 65% of bore Dia." How much is this over stock?

Once again sorry for all the questions.

 

[komatsuvarna]

I hope Will don't care, But this is a 066 cylinder Im getting ready to port.

That upper mark is when the Intake closes, the lower one down next to the lip is when the transfers open.......marked off the bottom of the piston skirt. I laid it out like this because it was easy to tell what was what just by eyeballing it.
Intake is at 160 stock. If ya lower the intake more, its gonna move that upper line closer to the bottom line.

Transfer are at 114. Raise them and its gonna move that bottom line closer to the top line. The closer them lines get, the less case pressure you have. Am I making any sence?


Now I have no idea how much is enough, or how much is not enough.......:msp_confused: But the lower the intake gets, and the higher the transfers get, the less case pressure you have. The area between them 2 lines is what ''Im gonna call" the compression stage for the crank case....which don't look like much anyways.





BTW, all of this is just thinking out loud.

 

[stihl038x2]

So how about this ........... what if you don't raise the uppers to compensate for dropping the jug, widen them towards the intake as much as possible. Does this not help to "save" some c/c pressure & if you raise the ex. up this will increase the blowdown. By widening the uppers only, will this not help in the port/time/area to sweep out the old gasses & fill the cyl. with the extra charge from the added intake dur.

Also just thinkin' through the keys.........

Steve