High Quality Chainsaw Bars Husqvarna Toys

Ported 036 Squish

drf256

Dr. Richard Cranium
GoldMember
Local time
10:24 AM
User ID
319
Joined
Dec 29, 2015
Messages
9,356
Reaction score
61,530
Location
Strong Island NY
Country flag
So I had some case and piston variation between my builder case and the actual saw I'm building.

Using my builder case, I got a perfect 020 squish, but there were no rings on the piston.

The jug has .040 out of the band. Exhaust is 103.

I'm using .023 solder for measurements.

I'm at .015-.017 across the band right now. I'm using a caliper and my mic usually reads .001 bigger, so maybe I'm at .016 minimum.

Run it, or sand the band?
 

Savage Saws

kangawallaroo!
Local time
12:24 AM
User ID
562
Joined
Jan 17, 2016
Messages
48
Reaction score
227
Location
Cockatoo, Australia
I found this little formula on the other site long ago and has worked well for me. (Stroke x .0125 ÷ 25.4) gives you the minimum squish clerance for that stroke. I.e 395xp has 38mm stroke: 38 × .0125 = .0475 ÷ 25.4 =.0187. So .018 is closest you should safely go. Could be absolute hokum but, i haven't built a head slapper yet! (Prbably means i'm not pushing the envelope far enough:cool:)
 

drf256

Dr. Richard Cranium
GoldMember
Local time
10:24 AM
User ID
319
Joined
Dec 29, 2015
Messages
9,356
Reaction score
61,530
Location
Strong Island NY
Country flag
Sounds like it's coming apart for a sanding.

Was my plan anyway, do it right once.

Figured I'd throw it out there.
 

Keith Gandy

Maxima K2 40:1 87 Pump Gas
Local time
9:24 AM
User ID
341
Joined
Dec 30, 2015
Messages
6,207
Reaction score
16,189
Location
Provencal, Louisiana
Country flag
I found this little formula on the other site long ago and has worked well for me. (Stroke x .0125 ÷ 25.4) gives you the minimum squish clerance for that stroke. I.e 395xp has 38mm stroke: 38 × .0125 = .0475 ÷ 25.4 =.0187. So .018 is closest you should safely go. Could be absolute hokum but, i haven't built a head slapper yet! (Prbably means i'm not pushing the envelope far enough:cool:)
What was the source of this formula? Thats interesting and would be nice to calculate from if it has a creditable source?
 

Keith Gandy

Maxima K2 40:1 87 Pump Gas
Local time
9:24 AM
User ID
341
Joined
Dec 30, 2015
Messages
6,207
Reaction score
16,189
Location
Provencal, Louisiana
Country flag
Sounds like it's coming apart for a sanding.

Was my plan anyway, do it right once.

Figured I'd throw it out there.
I like .018 to . 022. Ive seen alota ported saws Ive been in around .026 but I think that will also depend on the amount taken out of the top as to whether u need a tighter squish?
 

Savage Saws

kangawallaroo!
Local time
12:24 AM
User ID
562
Joined
Jan 17, 2016
Messages
48
Reaction score
227
Location
Cockatoo, Australia
I honestly can't remember Keith??? Its probably lost in the waste land of the pre-linkbuks A.S.

I'm sure it was a side note from one of the old time builders. Posibly Romeo, used to build bike saws i think.
 

Keith Gandy

Maxima K2 40:1 87 Pump Gas
Local time
9:24 AM
User ID
341
Joined
Dec 30, 2015
Messages
6,207
Reaction score
16,189
Location
Provencal, Louisiana
Country flag
I guess if the port timing was near where it needed to be from factory ,taking more out the top and deleting gasket and lil off base would make more sense than cutting the base first then the squish? I may be wrong but taking more out of the top will require less of a tight squish to gain psi?
 

Keith Gandy

Maxima K2 40:1 87 Pump Gas
Local time
9:24 AM
User ID
341
Joined
Dec 30, 2015
Messages
6,207
Reaction score
16,189
Location
Provencal, Louisiana
Country flag
I honestly can't remember Keith??? Its probably lost in the waste land of the pre-linkbuks A.S.

I'm sure it was a side note from one of the old time builders. Posibly Romeo, used to build bike saws i think.
Ya there was a load of info lost as well as pics. Discouraging when a man starts using the search function
 

Moparmyway

Its just a saw
GoldMember
Local time
10:24 AM
User ID
21
Joined
Dec 4, 2015
Messages
5,237
Reaction score
28,046
Location
In a meeting
Country flag
So I had some case and piston variation between my builder case and the actual saw I'm building.

Using my builder case, I got a perfect 020 squish, but there were no rings on the piston.

The jug has .040 out of the band. Exhaust is 103.

I'm using .023 solder for measurements.

I'm at .015-.017 across the band right now. I'm using a caliper and my mic usually reads .001 bigger, so maybe I'm at .016 minimum.

Run it, or sand the band?
With that tiny chamber, it probably is best to sand a little. Youre going to have pretty high compression anyway
 
Top