Chainsaw Repair

I put the older 365/372 rod on some of the 272's race saws , if its stroked to 38 mm you pretty much have to run the longer rod , Aclarke is correct to what I have found from putting a longer rod on , it does make the motor produce more torque and helps not kicking the hell out of the intake skirt , On a small intake port its not a huge thing but on a saw the port is widen to the max this longer rod is huge , I have seen racesaws that you can see the shape of the intake port pushed on the intake skirt on the piston, As far as crankcase pressure , yes you are loosing some BUT you can gain some of that back by changing your blowdown timing . If it was me I might think about doing this on a racesaw but if its just a worksaw I would say no to that . Main reason is I just never seem to have crank bearing problems in any of my worksaws . Main thing is oil in the gas

I put the older 365/372 rod on some of the 272's race saws , if its stroked to 38 mm you pretty much have to run the longer rod , Aclarke is correct to what I have found from putting a longer rod on , it does make the motor produce more torque and helps not kicking the hell out of the intake skirt , On a small intake port its not a huge thing but on a saw the port is widen to the max this longer rod is huge , I have seen racesaws that you can see the shape of the intake port pushed on the intake skirt on the piston, As far as crankcase pressure , yes you are loosing some BUT you can gain some of that back by changing your blowdown timing . If it was me I might think about doing this on a racesaw but if its just a worksaw I would say no to that . Main reason is I just never seem to have crank bearing problems in any of my worksaws . Main thing is oil in the gas

would enjoy talking motors w/you sometime.

.....benefit would be that trans lowers un-shrouded a bit.  gotta go. good thread.

Can't think of any pistons much shorter?


Joe, with the dwell time increase is it at TDC and BDC ?   Confused....

Ok, that what I thought

Gate your thinking pretty good , if your building a saw for any of these GTG's and want to build a saw that is what some guys do , put a longer rod on it and you look like you did less cutting on base of jug or crankcase but you still end up with more compression and make the bigger power so everyone thinks you did some kind of magic to it . You can hide a ton of work in a motor that looks pretty stock but along ways from it  . Biggest thing is you have to build the motor around the fuel your running and the jone it has to do , the shorter the run time  the hotter you can build the motor