up late thinkong 046/440 BB

[Evan]

Okay
so im up late thinkn about what to do with my preoject 440 i have to get going. i guess i should start this with question. how amny ccs is the 54mm 046 big bore kit. id touch up the the ports alittle like usual saw will get modded muffler. well maybe full out port it , ill have to see how much time i have when it comes time

would this 046 be worth it compared to the 52mm 440 044 bb kit. this kit will bolt on it would get ported aswell. but this 52mm is lacking the coolness apeal to me.
partly why i like the 046bb kit is because it doesnt just bolt on and is im guessn 80 something ccs its just plain cool. and i like the challenge of it

so what would you guys do. i dont need the saw i have plenty its just hobby thing for me though i will use it cutn fire wood and the odball tree removal job. been getn a few calls latley on tree removals. looked at job just today open prperty lots of space. probly just the push the trees over without the saw.

or in the back of my head there keeps being that nagging voice that says your an idiot youve got perfectly clean and ported 044 cylinder why dont you just order a piston and be done with it and have it running alot cheaper and way less time consumeing

yes it is way late ive got be up in about 4 hours
ohhhhhh this guy i know used to cut firewood for his father. he has cabin by here. he told me if i cut fire wood for his dad and split it that hell give me his log splitter. i told him id do it. all i have to do is fall some pine trees cut split and then take my splitter home he said i wouldnt even have to haul the wood.

nota bad deal fora fire wood cutn cadder

 

[dragrcr]

SWEET DEAL on the splitter, i thought my 200 bone running splitter was a good deal,

i think you should put a 046 BB kit on it, and send my that 044 cyl for "long term testing" that way if you dont like the 46 BB I can tell you how the ported cyl would have worked for you.

 

[timberwolf]

Works out to just shy of 82.5cc.

Fun project no real complicated machien work required. In terms of gains the 046bb is an extra 8% displacement, but you should not expect to see 8% more power. Inefficiencies of going way over square on the bore to stroke creep in and things like the extra piston weight and increases in cylinder volume to port area ratios will trim the gains to closer to 5%.

 

[Evan]

timberwolf
talkn gains over 52mm or over 50mm.


dragrcr
ill hang on to the cylinder, ive got another 10mm 044 i could build if i have some money and its real slow this winter i stumbled across 3 of these saws this summer. only have one up and running so far

 

[timberwolf]

I was talking the difference between 044BB @ 52mm and 046BB @ 54mm.

But ist about the same again (just very slightly more % wise) going from 50mm to 52mm.

 

[Bowtie]

Thats the killer Evan, you have to decide, lol. I been there a lot of times. You DO have a good cylinder already for the 044. Hope that helps, lol.

Im building a nice 10mm 044 right now as well, it is getting an OEM new piston and seals.

 

[blsnelling]

I'm guessing the CC will require some relieving for the 046BB piston to clear at BDC. No? The OEM 046 P&C I put on my 440 did not require any mods to the CC.

 

[Meadow Beaver]

I'm guessing the CC will require some relieving for the 046BB piston to clear at BDC. No? The OEM 046 P&C I put on my 440 did not require any mods to the CC.

No it shouldn't need any modding for BDC. I got a new port 460BB on my 440, the piston skirt is 3mm shorter than the old one. I almost free ports so you'll probably need an 066 piston.

 

[blsnelling]

No it shouldn't need any modding for BDC. I got a new port 460BB on my 440, the piston skirt is 3mm shorter than the old one. I almost free ports so you'll probably need an 066 piston.

The current gen of 066BB does free port at BDC. So that's not a deal breaker. No reason to lower the port floor any further anyway unless you're doing a popup and the whole jug has to come down.

 

[Meadow Beaver]

The current gen of 066BB does free port at BDC. So that's not a deal breaker. No reason to lower the port floor any further anyway unless you're doing a popup and the whole jug has to come down.

You make a good point

 

[blsnelling]

I know that free porting at BDC is something to avoid, but you'd probably still be fine even if you did want to go with a popup, based on my experience with the current 066BB.

 

[mtfallsmikey]

I know that free porting at BDC is something to avoid, but you'd probably still be fine even if you did want to go with a popup, based on my experience with the current 066BB.

Dumb azz question 'o the day:...what is free porting?

 

[blsnelling]

Dumb azz question 'o the day:...what is free porting?

When the edges of the piston open up the port to the crankcase. In this case, we're talking about the piston skirt being a little too short and opening up the bottom of the exhaust port when the piston is at TDC. This situation can also happen if you widen a port to far and the skirt of the piston is no longer wide enough to cover the edges of the port.

 

[timberwolf]

Having the port to wide is more a problem than free porting at TDC, for one the piton can start to fall into the open port and get jammed and two you lose the seal that builds base compression and end up blowing new charge out into the exhaust.

Quite often going to a BB stihl will require some grinding in the case, going from 50mm to 54mm will almost certainly require making some room in the case for the larger piston.

 

[Meadow Beaver]

Having the port to wide is more a problem than free porting at TDC, for one the piton can start to fall into the open port and get jammed and two you lose the seal that builds base compression and end up blowing new charge out into the exhaust.

Quite often going to a BB stihl will require some grinding in the case, going from 50mm to 54mm will almost certainly require making some room in the case for the larger piston.

You can also break a ring or two and destroy the top end if you go too wide.

 

[Evan]

man thats a good bit of info you guys just dropped in here. thanks

 

[blsnelling]

Just a FYI for you guys, you can take anything Timberwolf says to the bank. I've learned a ton from him myself. Great guy!