Did I measure this squish correctly?
- Thread starter paul hill
- Start date
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Please tell us what you charge to machine the base. Thanks. Don
paul hill
ArboristSite Operative
I ended up using Hondabond 4. Seemed to work just fine.
Maybe next time I'll take the cylinder to a machine shop and have it milled. The sealant was more of a pain in the ass than a gasket.
I got the saw back together and did my first muffler mod. The 357 mufflers with that baffle suck! I got it opened up and braised back together. It won't win a
beauty contest but it works.
Filled it up with gas and it started in a few pulls. Got the carb adjusted so it tuns right but I know it needs a little fine tuning. Cut some hard 18-20 inch oak and it ran well.
I learned a lot on this project. I'd never had a saw apart like this before. Changed the ingition module to an unlimited one, modded the muffler, replaced the entire intake system including the carb, and removed the base gasket. Got some new tools along the way too.
Thank you to all the folks who answered my questions and that have posted great info to research.
Maybe next time I'll take the cylinder to a machine shop and have it milled. The sealant was more of a pain in the ass than a gasket.
I got the saw back together and did my first muffler mod. The 357 mufflers with that baffle suck! I got it opened up and braised back together. It won't win a
beauty contest but it works.
Filled it up with gas and it started in a few pulls. Got the carb adjusted so it tuns right but I know it needs a little fine tuning. Cut some hard 18-20 inch oak and it ran well.
I learned a lot on this project. I'd never had a saw apart like this before. Changed the ingition module to an unlimited one, modded the muffler, replaced the entire intake system including the carb, and removed the base gasket. Got some new tools along the way too.
Thank you to all the folks who answered my questions and that have posted great info to research.
If someone carries it into mu shop and I don't have to pack it and ship it. I charge 25.00
Later
Dan
Good to know, since I am kind of in the neighborhood. But its probably not "while-you-wait" service, I guess. Don
Big_Wood
westcoast dweller
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Big_Wood
westcoast dweller
Not everyone has a dozerdan buddy down the street though. I've tried every machine shop within 5hrs of me and they all just look at me like i'm crazy. Although i'm trying to get my buddy dave who owns an automotive machine shop to get setup to do smaller stuff. The chuck on his lathe is way to large for a mandrel the size of a chainsaw cylinder bore.
Way kool. I like the gasket better than the goo goo.
nmurph
ArboristSite.com Sponsor
Liquid gasket is used extensively in the motorcycles, etc...
I measure squish without the rings on the piston and I only tighten two bolts, catty-cornered from each other. I've checked again after I assemble the saw and this method yields the same measurement when it's ready to cut.
I use a thin layer of sealant applied to both the cylinder base and crankcase with a putty knife and give it a little twist after I seat the cylinder.
I measure squish without the rings on the piston and I only tighten two bolts, catty-cornered from each other. I've checked again after I assemble the saw and this method yields the same measurement when it's ready to cut.
I use a thin layer of sealant applied to both the cylinder base and crankcase with a putty knife and give it a little twist after I seat the cylinder.
Nmurph, I have found neat application difficult, especially with a two-ring piston when I need a ring compressor. Do you have a special technique, special coordination, or just practice practice practice?
Yes, I have used the sealer on cycle cases halves. Most of the cycles that I worked on still use a base gasket.
Later
Dan
WHSH
ArboristSite.com Sponsor
I think a good compromise for the gasket no gasket debate is a piece of .003-.005 paper stock with the selant of your choice. I put very thin bit of sealer to the mid and outside of the gasket so when it compresses is less likely to creep into the crank case. It won't ruin your saw but may disrupt the flow of the charge from the case into the transfers a some. I like a squish of .030 - .025 on 70-80cc saw, I save . 020 for smaller saws. You should think of squish band shape, piston crown cooling and flame front and turbulance, when considering squish. Thats a a topic I am still learning about so I don't have the prefect answer. I just know too little squish you get hot piston crown and there is no value in that. You could mill the base .020 then replace with a gasket but this would all depend on how thick the base is to start with. A saw like the 372xp has a thin base to start with so I go sealer only if I do milling on those bases. This is just my opinion, so take what you want and leave the rest.
I have never considered the 372 base as being thin. There are many 372 cylinders that have the base machined its not an issue. I do try to keep as much metal on the 385 and 390 cylinders as I can. Many of those break in stock form.
Later
Dan
WHSH
ArboristSite.com Sponsor
Well thin might not be the correct term. They don't have as much as other saws do so if you cut the base I like to preserve as much metal as I can on that saw. Thus I run them gasketless with goo. I broke the base on a ported 372xp with 210psi that I used a .020 gasket on. Now I know that nothing above 190psi on a 372 is better for the crank and base. With having no gasket and cutting .010 less from the base i now have .030 more for strength in the base. Just my experience, not everyones.
