Jony's in the house!

[Mastermind]

Those numbers are actually lower than what's in my 390, and with the same long intake duration. It's a fantastic runner, even without any timing advance. If it doesn't run well, it won't be those numbers. I know of one other person that did this same build, only they used a 395 piston. It was strong, but couldn't get the RPMs out of it he wanted.

BTW, which numbers were you referring too, specifically? Intake?

The numbers I was looking at the most were the transfers. The intake won't really hurt anything my being a little too long but if the transfers are too high on a quad port saw like the 390 they start going backward in power IMHO.

This 2188 I just finished is at 99, 122, 78. With 6 degrees of advance and 205psi. Torque out the ass.

 

[blsnelling]

I have staggered transfer ports on my 390, and they're at 18° & 20° of blowdown. It has RPMs and fantastic torque. It's exhaust is higher, at 96°. Compression isn't quite as high on it either. I forget exactly what it is, but I'm thinking maybe 190. I appreciate the feedback.

[video=youtube;iPwhrWGAYOc]http://www.youtube.com/watch?v=iPwhrWGAYOc&feature=share&list=UUozS9yJ1nl6HXekd0tV3tRg[/video]

 

[blsnelling]

These numbers are the result of not being happy with RPMs of the 390. These numbers will give you torque and RPMs in a 390. I'm anxious to see how much more some timing advance will buy me.

 

[Mastermind]

These numbers are the result of not being happy with RPMs of the 390. These numbers will give you torque and RPMs in a 390. I'm anxious to see how much more some timing advance will buy me.

I remember a builder telling me he "over ported" a 390 looking for that rpm. Then figured out the timing advance is what was needed.

 

[blsnelling]

That's what excites me about this. I'm already getting the RPMs I'm after, without timing advance. That should just be more icing on the cake.

 

[Trx250r180]

sounds like it pulls pretty good :msp_thumbup:

who got to drop that tree ?

 

[blsnelling]

sounds like it pulls pretty good :msp_thumbup:

And that's with a buried 36" full-comp RSC chain with aggressive rakers.

 

[blsnelling]

who got to drop that tree ?

That was one of 7 that I dropped a week ago last Saturday. There was an Oak that was quite a bit bigger.

[video=youtube;CTI8v5qHpik]http://www.youtube.com/watch?v=CTI8v5qHpik&feature=share&list=UUozS9yJ1nl6HXekd0tV3tRg[/video]

 

[Trx250r180]

seems like dropping the bigguns never gets old does it ,big cedars here with lot of branches make a lot of wind coming down

 

[mdavlee]

What kind of rpm are you planning on tuning it to? I've replaced a crank in one that was used around 13.8k and was limbing with it when it came apart.

 

[blsnelling]

That sounds like a defective crank or bearings to me. My 084 turns more than that, but not in use. I hope to see at least 14K @ WOT, and hopefully 12K in the cut.

 

[mdavlee]

It was used for a month falling timber when it let go. So it had a decent amount of run time on it. Seems there's quite a few of the 385/390s that end up needing cranks if you watch the part saws on ebay sell all the time. I would probably try to run it under 13.5k wot and build for torque.

 

[Mastermind]

That sounds like a defective crank or bearings to me. My 084 turns more than that, but not in use. I hope to see at least 14K @ WOT, and hopefully 12K in the cut.

The one I just built Spike60 easily will hit 14,500 but there's now way in hell I would tune it that fast.

 

[blsnelling]

It was used for a month falling timber when it let go. So it had a decent amount of run time on it. Seems there's quite a few of the 385/390s that end up needing cranks if you watch the part saws on ebay sell all the time. I would probably try to run it under 13.5k wot and build for torque.

They have known crank bearing issues prior to 2005.

 

[parrisw]

I tune mine to 16k for limbing, are you guys saying thats bad?

 

[blsnelling]

What kind of compression was that saw running?

 

[mdavlee]

What kind of compression was that saw running?

The one I put a crank in or randys?

The one I put the crank in just had the squish tightened up. Probably 170 at the most.

 

[blsnelling]

The one I put a crank in or randys?

The one I put the crank in just had the squish tightened up. Probably 170 at the most.

I was referring to the one you put a crank in.

 

[mdavlee]

It was a 2009 or 2010 saw.

 

[Mastermind]

That's one thing I like about the 395XP and most Stihl saws........they don't puke the crank out the exhaust.

These last two I built are more toys than actual work for a living saws......but I'll still ask the owners to keep them tuned to 13,200.....