Exactly what does doing this require? Just scraping off the gasket under the cylinder? Or is it something entirely different?
Base gasket delete.
- Thread starter Jason Pitcher
- Start date
Help Support Arborist Forum:
That and then you have to check the Squish with thin solder and a caliper . It cant be too tight. You need specs for that saw.
The whole operation is a quick modification that increases compression and changes port timing. Especially for high altitudes it can be a big plus. Thanks
Mike Gudgeon
This One Works Great On Fingernails
Lol. I did this once on a CB 175 twin cyl. bike. The increased compression may not have been entirely responsible but it shot the RH sparker into the never never! Never again for me!
Measure squish (minimum distance between piston & top of cylinder). For most saws it's ideally around .020". If it's over then remove or reduce gasket to achieve appropriate squish. This will alter port timing fractionally but gains from improved squish will outweigh any potential timing related losses.
If you remove or replace the gasket with a thinner material you must ensure the cylinder is properly sealed to the case using a petrol rated sealant like threebond or something similar & should ideally vac/pressure test the saw to confirm it has sealed too
If you remove or replace the gasket with a thinner material you must ensure the cylinder is properly sealed to the case using a petrol rated sealant like threebond or something similar & should ideally vac/pressure test the saw to confirm it has sealed too
Anyone here actually gone through the procedure and realised deleting the gasket would result in piston being too close to the cylinder?
Yup, you get pretty good at judging it... I did one not long ago that I knew would be borderline so made a super thin gasket, put it together without it & sure enough it was down to .016" so cracked it apart again & dropped the gasket in. It was a bit of a flustered rush but I just managed to do it before the sealant (threebond) set up to the point of having to clean it all off & start again
Certain saws are notorious for this...
Best bet is to measure squish before pulling it apart... then pull cylinder & measure existing gasket to get an idea of where things are at
The older CB Hondas were not any kind of high performance platform. I did mod a few with OK results. However no one can compare the Honda with a chainsaw motor completely different kind of animal. Deleting chainsaw cylinder gaskets can reward OP with a more potent unit. Thanks
Sounds like this might be out my wheel house.
Mike Gudgeon
This One Works Great On Fingernails
Stock chainsaws are also pretty tame. They have to be in order to be robust enough to handle the abuse and wide range of conditions thrown at them. As a result there is, as is mentioned in this thread, a lot of extra power to be had with fairly minimal work, assuming it's done properly - I'm certainly not disputing that.
Have fun!
It's really quite straight forward, & you'll find plenty of helpful advice here if you need it.
Start by measuring your squish & go from there... Get hold of some solder (the softer tin/lead stuff works best but any will do), you want it to be about .050" thick. Remove the plug & poke the solder in the cylinder so the end goes right to the side of the cylinder then pull the engine over slowly (you should feel a little resistance as the piston comes up & "squishes" the end of the solder). Remove the solder & carefully measure the squashed end (ideally with a micrometer but a good set of verniers will do).
Repeat this a couple of times on each side of the cylinder to ensure consistency
