Huztl bb 660 free porting but great comp.

[Brianlol]

Got a new huztl bb kit for a 660 decked it for 20 thou. but got 17 thou. Gave me great comp at 195 without braking in yet !!!! But it free ports at 26 thou.. I have to open the low screw out a full turn it get it to level out but she responds great. Can't wait to cut this weekend and I will make a video lol But my question is am I losing power cause of the free port or am I going to feel everything this girl can put out?
I know u dogs know this lolol

 

[Ozhoo]

My understanding of free-porting is that it raises max rpm at the expense of torque. If you think about it that makes sense since you're effectively lowering case pressure.

 

[blsnelling]

While not ideal, that amount of free porting won't hurt a thing.

 

[Brianlol]

While not ideal, that amount of free porting won't hurt a thing.

My worry is that I'll lose vacuum to draw fuel and lose fuel through the gap.
And if this situations causes higher RPM then I can't set the carb with confidence.
Thank u for ur feed back

 

[drf255]

I doubt it will do anything, some postulate it helps-you get a bit of Venturi effect from the exhaust flow to pull even more charge into the case.

Whatever gas you suck into that space should be the same as what's pushed out. Should occupy the same physical area.

I bet you're just fine.

 

[Brianlol]

I doubt it will do anything, some postulate it helps-you get a bit of Venturi effect from the exhaust flow to pull even more charge into the case.

Whatever gas you suck into that space should be the same as what's pushed out. Should occupy the same physical area.

I bet you're just fine.

Thank u for ur experience and knowledge. At what point does free porting start to become an issue?
And I would also like to add that I am very happy with huztl' customers service. Their working with me to find a piston for longer skirts. I'm putting it together tonight to see it's performance
With the one I have now. Here's a pic of the one I have now

 

[drf255]

Thank u for ur experience and knowledge. At what point does free porting start to become an issue?
And I would also like to add that I am very happy with huztl' customers service. Their working with me to find a piston for longer skirts. I'm putting it together tonight to see it's performance
With the one I have now. Here's a pic of the one I have now View attachment 527423

Experience and knowledge? You talking to me?

In most cases, free porting is a byproduct of a saw that was built with a lot of detail for performance. It's the rate limiting step in many builds and some is accepted in trade off for increased performance elsewhere.

I don't think it's ever a "good thing". Every PRO that ever commented on one of my anxiety ridden posts about it have said "it will be fine".

Not sure when it starts to be bad, cause most try not to have any at all.

 

[trboxman]

My worry is that I'll lose vacuum to draw fuel and lose fuel through the gap.
And if this situations causes higher RPM then I can't set the carb with confidence.
Thank u for ur feed back

There's more to fuel getting to the carb than just vacuum. That dogleg in the fuel intake pipe from the tank to the carb acts a bit like a gravity/siphon pump. Don't believe me? Fill your tank less than 1/2 full so that you can open the cap without spillage. Fire up the saw for 30 seconds. Open and close the tank cap to make sure that you don't have pressure in the tank. Take the fuel line off of the carb and see if it doesn't just about drain the tank dry from that hose outlet that's well above the fuel level. Slosh the fuel back and forth and it'll drain even faster...

 

[blsnelling]

Read the old threads about 066/660 BB kits. This is not a new issue.

 

[pioneerguy600]

There's more to fuel getting to the carb than just vacuum. That dogleg in the fuel intake pipe from the tank to the carb acts a bit like a gravity/siphon pump. Don't believe me? Fill your tank less than 1/2 full so that you can open the cap without spillage. Fire up the saw for 30 seconds. Open and close the tank cap to make sure that you don't have pressure in the tank. Take the fuel line off of the carb and see if it doesn't just about drain the tank dry from that hose outlet that's well above the fuel level. Slosh the fuel back and forth and it'll drain even faster...

Take the impulse hose off the carb and then see how long the saw will run properly. Fuel getting to the carb does not mean fuel flowing through the carb properly or at all.

 

[Brianlol]

Experience and knowledge? You talking to me?

In most cases, free porting is a byproduct of a saw that was built with a lot of detail for performance. It's the rate limiting step in many builds and some is accepted in trade off for increased performance elsewhere.

I don't think it's ever a "good thing". Every PRO that ever commented on one of my anxiety ridden posts about it have said "it will be fine".

Not sure when it starts to be bad, cause most try not to have any at all.

Lolol YES YOU lol
That's what I wanted to know about the affects of the free porting. How it would effect the RPM's, torque and hp.
Did I lose the gains I was after in the first place with the bb kit. After cutting the squish to get a good comp. to have the free porting did I lose what I wanted to gain?

 

[trboxman]

Take the impulse hose off the carb and then see how long the saw will run properly. Fuel getting to the carb does not mean fuel flowing through the carb properly or at all.

Absolutely agree that there's more to it than just getting in there, but it certainly makes the diaphragm have to work less.

 

[pioneerguy600]

Absolutely agree that there's more to it than just getting in there, but it certainly makes the diaphragm have to work less.

Hmm, just what does the diaphragm in the carb do to make it work hard?

 

[Ozhoo]

Hmm, just what does the diaphragm in the carb do to make it work hard?

Round here they whistle Dixie along with a few lesser known local hits

 

[trboxman]

I'm not going to try and give lessons to folks who don't need lessons...in fact to folks who likely have forgotten more about carbs that I'll bother to ever learn.

Reed valves, one way flap valves, diaphragm..whatever... The shape of the intake fuel line assists with getting fuel to and through the carb. Exact flow path etc. I can't diagram. Forget I said diaphragm, forget I tried to add to the discussion 'cause clearly I didn't...

 

[pioneerguy600]

I'm not going to try and give lessons to folks who don't need lessons...in fact to folks who likely have forgotten more about carbs that I'll bother to ever learn.

Reed valves, one way flap valves, diaphragm..whatever... The shape of the intake fuel line assists with getting fuel to and through the carb. Exact flow path etc. I can't diagram. Forget I said diaphragm, forget I tried to add to the discussion 'cause clearly I didn't...

No worries old son, just trying to decipher a post I didn`t fully understand...

 

[Brianlol]

I'll have to post the video later. For some reason I'm having a hard time doing so. But she's broken in and I just took another comp. test
That's the highest I've ever gotten on a 660 comp.
she eats wood and want more when she dives in

 

[drf255]

Is that with oiled rings or after running it?

Ideally, you want around 190-200 psi on a saw of that displacement. 225, which still may rise, is a bit too much.

Make sure you keep an eye on tune when you're doing a lot of cutting. It's gonna run on the hotter side.

 

[Little Al]

Round here they whistle Dixie along with a few lesser known local hits

Where I am they mostly run of to the Tyrol to join the " Umpah bands" after all they're good at "wheezing" in & out

 

[Brianlol]

Is that with oiled rings or after running it?

Ideally, you want around 190-200 psi on a saw of that displacement. 225, which still may rise, is a bit too much.

Make sure you keep an eye on tune when you're doing a lot of cutting. It's gonna run on the hotter side.

That's after braking her in. I was shocked to see such a high comp. .
She didn't seam to run hot though.