Big Bore 064 / I need Help

[Logger4Life]

So I am trying to put a big bore kit on my Bother's 064 and the piston is hitting the case, Now I am a very capable machinists as well as a Logger but I thought that one of you Stihl guys out there could throw me a bone and tell me exactly what has to be done. I have built few saws for myself and the peoplr in town but they have all been Huskys, Dolmars, Makitas, and Jonsreds . This is my first Sthil and it,s for my Brother and I do not want to mess it up so any help would be appreciated. Thank you for your time

 

[nmurph]

Jay, it sounds like you have an older kit. Most of the newer ones have a shorter skirt and don't hit the case. You can trim the skirt enough to give the piston clearance without hurting anything.

If you got that kit from Baileys or Weedeaterman, I would let them know. I know Grande Dog has replaced kits with similar problems in the past.

 

[Logger4Life]

Thanks I appreciate the advice. Now how much shorter because I measured the pistons and the BB piston is a half mm shorter already . The 064 piston is 43mm and the bb piston is 42.5mm . I have the bolt holes and everything all lined up and everything put together and rotated it over at first I thought I was hitting the top of the cylinder but it wasn't . when I took it back apart the piston is hitting the case and not just a little bit a lot. Was there any 064's made with a shorter connecting rod. I don't know I just know it isn't right. I did get the kit from Bailey's about a year ago. But it was suppose to be the 3rd gen kit so I do not know.

 

[gulity1]

Is the piston on correctly? arrow should point to the exhaust Pictures might help?

 

[Logger4Life]

Yes the piston is on correctly and all I don't have a camera so no pics or a cell it won't work where I live so sorry . But when it gets to the bottom of the stroke the skirt hits the case on both sides and either way you rotate the engine it is like the wrist pin is to close the top of the piston or something. Like I said before this piston is about .020 shorter than the stock one.

 

[herkomer]

if you have the case apart id suggest laying the base gasket down then scribe around the inside of it. a little clearance never hurts and increasing the lower volume of the case means more room for fuel/air charge = more potential power to be made. cutting the bottom of the skirt can lead to free porting.

 

[Grande Dog]

Howdy,
The BB kit should have had a piston that is 39mm. The exhaust ports on the kits have been modified so that they won't free port. I sent you a PM, and we'll get you fixed up.
Regards
Gregg

 

[Logger4Life]

That's what the problem was had the 43mm piston. now does the 39mm piston change the intake timing at all and if so would it be benifical to to change the EX timing and transfers or is all made to work together?

Thanks Grande Dog I really Appreciate it. Thank you for your time
Jay

 

[chadihman]

That's what the problem was had the 43mm piston. now does the 39mm piston change the intake timing at all and if so would it be benifical to to change the EX timing and transfers or is all made to work together?

Thanks Grande Dog I really Appreciate it. Thank you for your time
Jay

That Gregg guy really rocks. Great guy and business he runs.

 

[Grande Dog]

Howdy,
There's no doubt that port work would enhance performance. I was a little surprised at the minimal difference there was when cylinder free ports. The difference was fuel consumption. The exhaust port was raised 2mm to close the opening on the bottom. There was a net loss in displacement by doing this. We moved to a smaller combustion chamber at the same time.
Regards
Gregg

 

[Red Amor]

Gday fellers
Im down in Tasmainia lill Island state under Australia and I need a set of rings al least and base gasket for an 064, or better a piston m ring set for same , Its standard bore and the bore look good , would master mind or weedeater man or anyone Ive come to respect on here please advise me as to which brand to but and where from or help by providing a kit asap , as Id like to get this saw going for the up coming season , I cut fire wood for all my family three house holds not a pro but anymeans just enjoy my saws and wood hooking , thankyou for all your help these forums have given me more help that you,ll all ever know thanks guys ay
The Redfella