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Quick question about drilling decomp valve

stihl livin

stihl livin

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Ryan Browne said:
Hey Ed, I greatly appreciate the offer but knowing my luck with small drill bits, I'd better refrain.

I think I'll pop the decomp out of my 395 and see if that does the trick. If so, I'll think about how to proceed. Might just order another one of those.
Click to expand...

Id grow a set of balls and pull that saw over like a man. Just kidding Ryan. Hope you get the help you need with the decomp from the 395.
 
Backtroller

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My cfb Hybrid did not like Stihl decomps. I tried Two that I had laying around here. I happened to have an extra blue Makita one from a 6421-7910(?) and it has worked great.
 
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Lightning Performance said:
Starting procedure is needed on my 66, no decomp. I believe it is timing advance on the ignition.
Click to expand...

Yeah, I put a 066 coil on my 029/390 as it has a 4 degree retard on starting (Chinese A$19.95). The 390 jug conversion could kick-back pretty bad with a timing advance and the pop-up piston. However, putting the 066 coil and a proper working de-comp on, it is just 'pull and go', no drill is necessary.

I put an AM jug on a 064 that was 92cc and had a de-comp. It took me a while to work out what kind of de-comp it needed. The Stihl type de-comp couldn't be modded as it had a detent to hold the valve open. I had to find a de-comp without the detent and mod that. The bloke that owned the saw loves it, no starting drill, no kick back. Perhaps the same type of jug is available for the 066.
 
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Terry Syd said:
Yeah, I put a 066 coil on my 029/390 as it has a 4 degree retard on starting (Chinese A$19.95). The 390 jug conversion could kick-back pretty bad with a timing advance and the pop-up piston. However, putting the 066 coil and a proper working de-comp on, it is just 'pull and go', no drill is necessary.

I put an AM jug on a 064 that was 92cc and had a de-comp. It took me a while to work out what kind of de-comp it needed. The Stihl type de-comp couldn't be modded as it had a detent to hold the valve open. I had to find a de-comp without the detent and mod that. The bloke that owned the saw loves it, no starting drill, no kick back. Perhaps the same type of jug is available for the 066.
Click to expand...
My jug has a decomp under a flat top cover plugged up. It has no machine work done. Gasket in place. The timing does not appear to be advanced. I have not removed the jug, yet....work/ felling saw bought in a basket. Long block was tight...metal flywheel big bearing saw with red lever and HD filter bone stock. This might be a case of all the right stuff and too much ignition timing. I'm not putting a decomp on this saw unless I can find a decomp flat top cover. Not sure they made them.
 
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I had to put a hole in the top cover to access the de-comp. I went small and kept opening it up. The end of the de-comp just sticks out of the cover. If you end up drilling the cover, use a small drill to start with and drill the hole in line with the angle of the de-comp.
 
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Ryan Browne

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Alright, update time: I swapped the decomp from my 395 onto the 261. By the way, the 395 has 2 holes, each way bigger than 1/16. Like maybe 1/8, they're huge.

So, it was quite a bit different starting. I kinda flooded it, maybe from a cold start, not using it might be the way to go until it fires the first time. Anyway, after it got going, it restarted WAY easier than with the stock decomp. One thing I really like in a small saw is easy restarting. The 261 was awesome for that stock, you could just hit the decomp and pull the rope at whatever speed you liked and it'd come alive. After porting it required some forethought. With the 395 decomp it's much more like when it was stock. So, I'm calling it a success.

After that I put a stihl decomp from a 361 back in my 395 until I order one. I would have used the one from my 261, but I wrecked it by attempting to drill it out. I have the utmost respect for anyone that can use small drill bits! I broke two 1/16 bits in this project, even only having about half an inch sticking out of the chuck.

So, all systems go. Thanks for the help everyone.
 
drf256

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I always use a Husky Decomp when there is an issue, and I drill those also for big saws.

Surprised a 261 is fighting you that bad.
 
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Lightning Performance said:
Was thinking more like 0.020 increments but like Doc said...

Starting procedure is needed on my 66, no decomp. I believe it is timing advance on the ignition. Time to dik with it is coming soon. It must be added or fixed another way. Chews up OE starter parts.

Hey @drf256
Didn't you add a decomp to one of Jacks saw?
Someone did an 064 to a decomp saw. Curious what valve was used for that build.
Click to expand...
That was JMS.
 
Bigmac

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I like the large husky decomps!! There are lifesavers! I prefer them over modifying the small ones! I used one on a Mac and it was a lot better the the oem Mcculloch
 
Lightning Performance

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Bigmac said:
I like the large husky decomps!! There are lifesavers! I prefer them over modifying the small ones! I used one on a Mac and it was a lot better the the oem Mcculloch
Click to expand...
What models had those so I can get a few Makitas, Stihls and maybe a Husky up to par?
 
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Lightning Performance said:
What models had those so I can get a few Makitas, Stihls and maybe a Husky up to par?
Click to expand...
I usually get 390 ones because that’s what they have at the dealer. Not 100% sure if the 372 and 395 are the same, haven’t looked it up.

And Stihl did make a flat top decomp cover for an 066
 
Lightning Performance

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Bigmac said:
I usually get 390 ones because that’s what they have at the dealer. Not 100% sure if the 372 and 395 are the same, haven’t looked it up.

And Stihl did make a flat top decomp cover for an 066
Click to expand...
Who's got a flat top decomp cover.... never thought to check aftermarket, opps.
 
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