Another SP-125/101b build

[Brian13]

I love that sound!! I am no tuning master so take this with a grain of salt, but sounds like its lean on the low side. Looked like it may be starving for fuel when you got on it. That is definitely one mean say, I would saw it was well worth the work!! Looks like its a bear to start too. I use loose grip too. Seems to hurt a little less when it yanks back, and by the looks of it I would say it yanks back pretty good.

If you ever get down here to Fla. you should probably bring it with you:hmm3grin2orange:.

 

[leeha]

Thanks Lee. I'm anxious to see yours and Brad's.

The Mac carbs get a bad rap and I'm not sure it's deserved. This BDC was surprisingly easy to work with once I understood it and it's really just a supersize flatback.

I'd like to get mine done one of these days, But
i dropped the ball and gave up for a few.
Having a very hard time with the new HL360 carb.
Had it on my other 101 Geardrive and had the same
problem. Runs out of fuel at an idle. Like the fuel
pump is not pumping. Iv'e tried everything and still
no go. I'll get back on it soon. Yours gave me a bit
of ambition.



Lee

 

[cpr]

No worries, Brian. I'm all ears, what's left of 'em, anyway. I have the carb manual out right now. I have a lot to learn.

Go get 'em Lee!!!

 

[Dennis Cahoon]

I'm still jittery. You saw racers have my respect! It honestly scares me and it doesn't even have a good tune in it or fast chain yet.

[video=youtube_share;4Xkb6DSA7h4]http://youtu.be/4Xkb6DSA7h4[/video]


It sounds to lean on the low speed. You can hear it buwah, buwah when you give it throttle. Try richning it up on the low end. Should help the high end when you do.

 

[promac850]

Where do I find a bar like that? Price? I'm sitting down right now, so don't worry about me falling over and cracking me skull open on something...

 

[blsnelling]

I agree on the lean L. But WOW! I wasn't expecting that kind of performance! That isn'y anything like a 797 or 125!

 

[cpr]

Thanks guys.

Any input on the carb settings? The book says start from 1 out on both. I'm at 1 1/4 on both, maybe a little more on the high.

I'll check it all out. I had a thought that I may have shaken something loose and there's some crud plugging a jet now. I want to play with it more today, but my whole right arm is killing me. More than a decomp, I wish there was a way to put a 5-10 deg. timing retard in for starting.

 

[Jacob J.]

Having a very hard time with the new HL360 carb.
Had it on my other 101 Geardrive and had the same
problem. Runs out of fuel at an idle. Like the fuel
pump is not pumping.

Have you adjusted the pop-off pressure? It sounds like it might be too high.

Also, they've been having trouble with the ball and check valve in some of the newer carburetors.
Fortunately those are replaceable parts.

 

[Dennis Cahoon]

Thanks guys.

Any input on the carb settings? The book says start from 1 out on both. I'm at 1 1/4 on both, maybe a little more on the high.

The book says!......Hahahahahahaha!

1&1 is just a rule of thumb starting point. You've modified things, so you'll have to play with the adjustments. You need more fuel on the Low Speed. Set your low speed just like a regular saw, while leaving your high speed rich, back off the idle and get it quick reving off the bottom with the low speed needle. If it has any hesititation(boowah,boowah) it's still to lean. Now re-adjust the high to a comfortable richness, then set idle. Piece of cake!

 

[rwoods]

Where do I find a bar like that? Price? I'm sitting down right now, so don't worry about me falling over and cracking me skull open on something...

It's on Baileys' site, so I don't mind saying. 30", $239+ shipping.

Ron

 

[Eccentric]

That thing's a beast Charles. Good job.


I agree with the others. Way too lean on the low side. Possibly on the high side as well (harder to hear on the video). If I ever build one of those, I'm fitting a decomp valve. My fingers have had enough abuse already....

 

[wendell]

My fingers have had enough abuse already....

:msp_scared: :taped: :msp_sad:

 

[cpr]

Thanks for the input on the lean idle. Thankfully I'm not a tuning idiot (well, not a complete one anyway :msp_biggrin. Turns out I was right. Piece of crap partially blocking the idle jet.

I love this carb. No welch plugs!

 

[RandyMac]

Time to filter the fuel before putting it in the tank.

 

[cpr]

And the air... In the previous carb photos, you can see the atomization air bleed hole right at the bottom of the venturi. It goes right to that chamber. It could have huffed it as easily as drank it. I may have to visit a craft store and see what kinds of foam are out there. The gas-resistant part could be tough.

 

[Eccentric]

:msp_scared: :taped: :msp_sad:

Figured somebody'd have some fun with that one....

 

[cpr]

Idle's working great again, but now the main's not flowing.

Screw it. 85 and humid, I give up for the day...

I did fish 2 more suitable test oak logs out of the pile though. The bigger one is over 25" and about 8 feet long. The other is over 20" and about 10'+. Not enough to really challenge these, but they're the biggest I have here and bigger really isn't practical for my intended use of it.

 

[cpr]

Had a major, month-long fight with this carb. Mitch (stinkbait) turned me on to an idea about the metering diaphram that I think would work great on the standard flatback kit with the glued on metal disk. This one won't respond to heating and stretching the diaphram as it is identical to what you would see in an HL kit and is plenty pliable enough. I reckoned I could simulate the effect of more flexibility in the diaphram by raising the metering lever. Recall I had lowered it to flush before due to flooding.

In the course of testing tonight, I had the fuel line out of the tank and was force feeding the line with a medical plunger. In so doing, I briefly got it visibly pumping (throttle open, plug out, pulling rope). Then it dawned on me... Film on the shroud, back to pumping back up the line. I had a leak at the carb. I hose clamped the line at the carb and within 5 pulls was back to the flooding condition I started with. I reckon tomorrow I can go back in and lower the lever and it should run as before.

Doggone air leaks... They'll get you every time. Here's hoping I cracked the riddle.

 

[1375619cm3]

Doggone air leaks... They'll get you every time. Here's hoping I cracked the riddle.[/QUOTE]

Well "Crack" a PBR in anticipated celebration and hope it don't bite ya in the "Handle Bar" lol

Good Job n Good Luck

Cody McM

 

[leeha]

Hope ya get it sorted out Charles.
I'm still fighting with mine.




Lee