trappermike
ArboristSite Guru
I'm almost finished building a 395 Husky for the "100cc stock appearing with a pipe" class. I've built quite a few of these saws for the class,but since I was sponsered by Stihl for many years I never built a Husky for this class.
As many of you know the saw really does have to appear stock,any little discrepincy can get you disqualified from running.
Also you cannot exceed the 100cc limit, ex.-100.06 cc is illegal. So the 58mm oversize cyl. kit (100.4 cc)is illegal. So I have modified the crank for a 2.5mm longer stroke which makes a 99.75 cc motor-perfect.Stroking stock V-8 cranks has been done for 50 years,by welding on the crank journal and regrinding to the new desired stroke.In the case of the saw crank I had to have the holes in each side of the 2 crank counterwieght halves(Where the rod big-end pin fits)welded in some and the holes remachined,this was actually pretty straightforward and easy,making a jig to press the crank apart was harder!
So I had to jiggle the cylinder height a bit for the new stroke,the best part is I had to raise the transfer ports(Enlarging them!)to re-obtain my transfer port timing. Intake and Exhaust port timing is basicly normal race specs,I didn't go max.specs on the intake,and held it to 189 degrees but widened the port to max. possible,leaving only 1mm piston skirt sealing on each side of the port,and squared ot out as much as possible for max. area,same as i did on the ex.port.The transfer ports I pushed the duration to 134 degrees,this was in combination with the intake and ex. timing(192 degrees) which I have used before successfully,the specs come from a factory Kawasaki road racer engine,I have used these specs many times on different type engines with great success.
The pipe's tuned length is for max. power at 14,900 rpm with a 21 degree convergent cone,I will try 22 degrees later to try to gain a little more power,at the expense of peak rpms.
With the extra 6 cc's more compression was pretty easy to obtain,sitting perfectly at 220 psi.
Not much for piston mods,but as often I use only 1 ring for decreased friction and more rpms. Also I made a titanium wrist pin from grade 5 titanium,and counter-bored.I first made them 25 years a go for a 2095 Jonsered(Exact same specs as 395),I wieghed it compared to a stock pin and it was almost exactly half the wieght. I have used ti wrist pins for many race motors but they are not for extended use,never put one in a work saw.
All ports were polished,finishing up with metal polishing compound on cloth in the dremel(slow speed).
I have experimented with anti-friction additives,the only one I find usefull is Slick 50 because of it's teflon content. they used to make a small pouch for use in 2-stroke motors,but not anymore,however I add 10-15 ml to a gallon of gas and you can really feel the difference, rpms increase. I had an 090 in a competition that was trying to sieze in the second cut,it was really slowing down and I should have stopped,but I managed to force it thru. On teardown there was only a tiny score on the exaust side that was almost polished,it seems the teflon saved the motor...
Last thing is the carb,unfortunately I have run out of the Bing model carb Stihl used briefly on the 064,It's the last thing I need to complete the motor,if someone has one in decent shape please let me know!! The Bing was of outstanding quality and workmanship,it also had much thinner shafts and butterflys. Used on race motors it does not suffer from unstable high speed mixture as others will. Remove the choke assy and polish the bore well for racing,also recess the brass high-speed nozzle,remove it and re-install it but do not drive it back in flush with the chamber floor,have it sticking up .060"(1.5 mm) so it is not sticking out in the bore of the carb so far,this trick works with Walbros and Tillotsons too.
Soon as I find a carb I will finish and test it,if I can't find a decent Bing,then I will use a modified WJ....
As many of you know the saw really does have to appear stock,any little discrepincy can get you disqualified from running.
Also you cannot exceed the 100cc limit, ex.-100.06 cc is illegal. So the 58mm oversize cyl. kit (100.4 cc)is illegal. So I have modified the crank for a 2.5mm longer stroke which makes a 99.75 cc motor-perfect.Stroking stock V-8 cranks has been done for 50 years,by welding on the crank journal and regrinding to the new desired stroke.In the case of the saw crank I had to have the holes in each side of the 2 crank counterwieght halves(Where the rod big-end pin fits)welded in some and the holes remachined,this was actually pretty straightforward and easy,making a jig to press the crank apart was harder!
So I had to jiggle the cylinder height a bit for the new stroke,the best part is I had to raise the transfer ports(Enlarging them!)to re-obtain my transfer port timing. Intake and Exhaust port timing is basicly normal race specs,I didn't go max.specs on the intake,and held it to 189 degrees but widened the port to max. possible,leaving only 1mm piston skirt sealing on each side of the port,and squared ot out as much as possible for max. area,same as i did on the ex.port.The transfer ports I pushed the duration to 134 degrees,this was in combination with the intake and ex. timing(192 degrees) which I have used before successfully,the specs come from a factory Kawasaki road racer engine,I have used these specs many times on different type engines with great success.
The pipe's tuned length is for max. power at 14,900 rpm with a 21 degree convergent cone,I will try 22 degrees later to try to gain a little more power,at the expense of peak rpms.
With the extra 6 cc's more compression was pretty easy to obtain,sitting perfectly at 220 psi.
Not much for piston mods,but as often I use only 1 ring for decreased friction and more rpms. Also I made a titanium wrist pin from grade 5 titanium,and counter-bored.I first made them 25 years a go for a 2095 Jonsered(Exact same specs as 395),I wieghed it compared to a stock pin and it was almost exactly half the wieght. I have used ti wrist pins for many race motors but they are not for extended use,never put one in a work saw.
All ports were polished,finishing up with metal polishing compound on cloth in the dremel(slow speed).
I have experimented with anti-friction additives,the only one I find usefull is Slick 50 because of it's teflon content. they used to make a small pouch for use in 2-stroke motors,but not anymore,however I add 10-15 ml to a gallon of gas and you can really feel the difference, rpms increase. I had an 090 in a competition that was trying to sieze in the second cut,it was really slowing down and I should have stopped,but I managed to force it thru. On teardown there was only a tiny score on the exaust side that was almost polished,it seems the teflon saved the motor...
Last thing is the carb,unfortunately I have run out of the Bing model carb Stihl used briefly on the 064,It's the last thing I need to complete the motor,if someone has one in decent shape please let me know!! The Bing was of outstanding quality and workmanship,it also had much thinner shafts and butterflys. Used on race motors it does not suffer from unstable high speed mixture as others will. Remove the choke assy and polish the bore well for racing,also recess the brass high-speed nozzle,remove it and re-install it but do not drive it back in flush with the chamber floor,have it sticking up .060"(1.5 mm) so it is not sticking out in the bore of the carb so far,this trick works with Walbros and Tillotsons too.
Soon as I find a carb I will finish and test it,if I can't find a decent Bing,then I will use a modified WJ....
