064/066 BB hybrid

[stihlboy]

Wierd, I wonder if it's due to the location of it.

actually i think its because of the high compression, my 084 is the same way

 

[parrisw]

actually i think its because of the high compression, my 084 is the same way

Not likely. Like I said, I have 2 very high compression huskies 395's, higher compression then his 064, and mine don't pop the comp release. Its due to the location. Huskies is in the side of the cylinder below the top of the combustion chamber the Stihl's are right in the top.

 

[mtngun]

I have 2 very high compression huskies 395's, higher compression then his 064, and mine don't pop the comp release. Its due to the location. Huskies is in the side of the cylinder below the top of the combustion chamber the Stihl's are right in the top.

My Efcos decomps are located on the side, through a small vent hole, similar to a Husky, yet they pop the decomp on almost every pull.

Speaking of which, I broke the starter cord on my Oly again today -- twice. That makes three times the starter cord has broken since doing the woods port.

And that's using the decomp. Problem is, the decomp pops almost as soon as you pull on the cord. I see an Elasto-start in my Oly's future.

 

[mtngun]

it was interesting that the 064BB was about 30% faster. we cut and timed about 10 cookies with each saw and the results were very consistant. this is a very powerful saw.

Thanks for that data. I thought you would be pleased with the BB power.

i only wish there were more meat left in the ports so that i could tweak it a bit.

as someone (it may have been you) said, this particular BB is basically ported as it comes from the factory.

I think its best quality is the torque and the broad powerband, and that's hard to improve upon, given the radical port timing.

 

[Zombiechopper]

Not likely. Like I said, I have 2 very high compression huskies 395's, higher compression then his 064, and mine don't pop the comp release. Its due to the location. Huskies is in the side of the cylinder below the top of the combustion chamber the Stihl's are right in the top.

its the location I think. My newly ported 460 pops every pull now that I lowered the jug. It's only at .025" so not super high comp by any means. Maybe the Stihl's have weaker decomp's?

 

[parrisw]

My Efcos decomps are located on the side, through a small vent hole, similar to a Husky, yet they pop the decomp on almost every pull.

Speaking of which, I broke the starter cord on my Oly again today -- twice. That makes three times the starter cord has broken since doing the woods port.

And that's using the decomp. Problem is, the decomp pops almost as soon as you pull on the cord. I see an Elasto-start in my Oly's future.

Hmm interesting. Is the decomp the same as the husky type?

 

[mtngun]

Hmm interesting. Is the decomp the same as the husky type?

I dunno, explain the difference between Stihl and Husky decomps ?

The Oly has a Bailey's decomp while the CS62 has the OEM decomp. They both pop out on almost every pull, especially if the engine pops even faintly.

 

[parrisw]

I dunno, explain the difference between Stihl and Husky decomps ?

The Oly has a Bailey's decomp while the CS62 has the OEM decomp. They both pop out on almost every pull, especially if the engine pops even faintly.

Well, ya if the engine fires at all it will pop the decomp, but say kill switch on so engine wont start, mine will not pop the decomp.

 

[AUSSIE1]

I assume the aftermarket are a copy of the OEM's.

The blue husky one has one large hole.

The black Stihl one had two very small holes. This one still showed a lot more Resistance compared to a Husky decomp so I drilled and blew out with compressed air, one of the holes and now works fine (in a 288).

The Stihl decomp must run a weaker spring (or whatever you call it). The low hour MS460 I used at work had to have the decomp pressed after every pull. The Husky one will fit.

 

[nmurph]

the decomp on the 064BB is a bailey's. it pops off with each pull. i also have 4 7900's. three are stock 79cc and one is a BB. all are running stock compression. two hold as they should and only have to be reset when the engine pops. one requires resetting after each pull. and the other one pops sometimes even when the engine doesn't.

 

[Adam_MA]

Good thread, nicely done. As for the decomp, I have a stock 460 that pulls 185psi cold. The decomp doesn't disengage until the engine fires. Wonder if it may be a combination of multiple things causing the decomp to have to be pushed after every pull?

 

[nmurph]

compression is one part of the equation. but the volume of air being moved with a large cylinder is another factor.

 

[mtngun]

The Stihl decomp must run a weaker spring (or whatever you call it). The low hour MS460 I used at work had to have the decomp pressed after every pull. The Husky one will fit.

Sounds like the Husky OEM decomps are the most desirable. I'll keep that in mind next time. It's a nuisance to reset the decomp on every pull.

 

[fields_mj]

Warning, idiot posting with questions....

I just picked up my 064 a few months ago. It had already been rebuilt with an 066 P&C. I've thought that down the road, if I ever had problems (which will probably never happen), I'd put a BB kit on it. I like the saw now, but I can't imagine the grin on my face if it had a BB kit....

So here's the questions:

1. Since my 064 doesn't have a decomp, is there anything that I would need to do to accomodate the one on the BB cylinder other than make a hole in the top cover for it?


2. I noticed that nmurph reduced his squish. Is this a requirement with the 066 bb kit, or does is it just another upgrade to get even more power? How much is gained by reducing the squish, and if I don't make any other changes to the saw, is there a generally accepted thickness to use for the new gasket?

3. I've already opened the muffler up a little (about like the 066 in the muff mod sticky). How much more would I need to open it with a BB kit, and how much with a BB kit and less squish?

Thanks,
Mark

 

[nmurph]

you can probably sell the 066 OEM P/C for more than the 066BB costs.

the top cover was the only mod i had to do. i did change the cylinder bolts to M6's from M5's. you can leave the smaller bolts, but you will need to get longer ones. i went larger for the extra insurance. it cost me about $10 to buy the tap and bolts.

it is not required to remove the gasket, but it maximizes the gain. the squish was pretty much ideal with only a little gasket-in-a-tube to make a nice seal.

can't help you on #3. my MM is about .75"x1.5". i may look into getting a OEM dual ports setup or adding another deflector and opening to the existing mod.

 

[fields_mj]

Thanks for shareing you're results! I can sure tell a big difference between pulling a few times on the 036 and the 064! A decomp valve would help, especially if it had even more displacement. What's worse is that my 064 feels like the starter rope should be about 6" longer. I'm 6'2" and it feels like I'm short stroking it. Thankfully, it usually fires on the 2nd pull, so right now I'm not going to change a darn thing! lol

I THINK that the shop that put mine together already upgraded the bolts to 6mm. If not, when it comes time I'll make the change. I already have the correct taps and drills so that will be a piece of cake.

I just get nervous at the thought of changing things like timing or squish. I'd like to do a woods port on my 024 and 036, but changing things like that just makes me nervous since I've never done it before. I'm happy with the saw now, so I'll leave it like it is, but this is all good info to have should the P&C some how get messed up. Still, a 15.5 lb powerhead that has 100cc of displacement.... :jawdrop: Maybe next year...

One more question, what did you use to clean the saw up? Other than the expected wear, that thing looks brand new!

Thanks!
Mark

 

[nmurph]

mj,
one of the cylinder bolt holes is a little difficult to access with the t-handle on my T&D set. i ended up using a set of vice-grips on the R,R hole.---no biggie!!
i know what you mean about short stroking. mine has 1/4" rope and it is only about 18" long. i'm 6'4" and had to roll the piston just past TDC and then give it a sharp pull. now that i have a decomp it is a little easier. i am going to install an elasto-start and a longer rope.

don't worry about messing up the timing. the change in squish is small and is off-set with the gains in compression (and freeer (sp) when you port a saw). but this BB is great. it needs nothing out of the box. i had planned to clean it up, but decided to bolt it on and run it. honestly, it only had a couple of very casting lines and some roughness in the ports. i will probably pull it down when i have a couple of hours and smooth things up.

yes, 99cc and 15.5lbs is nice. i have already seen what it will do to a 7900. i have a nice 394 that i have clean up to sell, but i may have to get it dirty and run it against the 064BB.

i cleaned the saw with a purple cleaner (made by Oakite, not which number, i can look) that is similar to Purple Power. i start with an air nozzle, then i spray the cleaner and let it sit. then brush and hose it down.

 

[WidowMaker]

update???

Realizing this is a year old thread I"m wondering if Murph could give us an update on his 100cc 064. I've been bitten by the bug and want one baaaaad, but not if if ain't gonna live...Love my 064, I probaly want to sleep with a 100cc verision....

 

[nmurph]

Love it!!!!! What are you waiting on?????

 

[WidowMaker]

Love it!!!!! What are you waiting on?????

====

Thats the answer I was hoping for...