Porting the 361 Big Bore

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He said 11%... not a big gain considering the cc etc. Of couse, I'm not the guy to ask. I could care less if I cut a log in 20 or 22.2 seconds ;)
 
Last edited:
blsnelling said:
WOT is only an indicator. Doesn't mean much if you raised the exhaust roof and killed compression to get them. I don't really think RPMs in the wood counts either. The BB is faster because I can push on it harder than the OEM. The OEM would stall if I pushed as much as I am on the BB. It just like the 7900 Slingr built. If I don't really load it down, I saw >13K in the cut with a square ground chain in a different log last night.



They are screamin'!:) But nothing out of line with other modded saws.
Click to expand...

Actually, the only thing that matters is the rpm in the cut.... What you can maintain at optimal pressure... and that gives the best cut rate and time...

13k not loaded isn't meaningful... what is it "loaded" and cutting best?
 
Lakeside53 said:
Actually, the only thing that matters is the rpm in the cut.... What you can maintain at optimal pressure... and that gives the best cut rate and time...

13k not loaded isn't meaningful... what is it "loaded" and cutting best?
Click to expand...

na andy it is only if your chain is sharp as demonstrated at the GTG
 
yo2001 said:
Right. So what you think of it mr.Snelling? Is it much gain? Narrow powerband or broad? I wanted to know the pros and cons if you don't mind.
Click to expand...

There isn't a hint of peakiness in the powerband. You'll notice several different in the cut RPMs in the video I poseted. I was not only looking to see which would yield the fastest times, but also demonstrating how broad the powerband is. It pulls VERY strong. I'm definately impressed.
 
I just put a 460 carb on the 361BB. It won't idle at all. It's not trying to race like an air leak. It simply won't run that slow and shakes like crazy. Rev it up and it smooths out.

What does the little replaceable jet near the needle valve control? Is that the fixed portion of the high side? I swapped that out with the one from the 361 carb and it got worse. I was only guessing anyway.

I borrowed the choke shaft from the 361 carb to get the correct arm orientation. I had to widen the flat spot for the 460 choke plate to fit in it. I also had to open up the impulse passage and use the bottom plate from the 361 carb. Other than that, it was a direct bolt on.

So what might be the idling problem and how to fix it.
 
The idling problem may due to way too much gas, or an imbalance in the L circuit (pressures, venturi etc.). The L path to the progression bores in late model HD carbs (361, 460, 290 etc) has a check valve, and it's not replaceable.

You might be better trying an early model 044 carb.
 
Lakeside53 said:
The idling problem may due to way too much gas, or an imbalance in the L circuit (pressures, venturi etc.). The L path to the progression bores in late model HD carbs (361, 460, 290 etc) has a check valve, and it's not replaceable.

You might be better trying an early model 044 carb.
Click to expand...

Thanks Andy. This is a HD16 carb. Funny you mention the 044 carb. That's what I put on my 260 and it runs like a dream. No one problem since the first startup with it.
 

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