I have searched this topic and havent really come up with a clear answer. I would love to put an original 064 bore back on but they are expensive and hard to find. I know I will have to elongate the bolt holes on the 066 cyl but if I do that right is there anything else ill have to worry about? Im thinkin I can come out with a more powerful 064 for way less money than replacing with original parts.
Any problems with 066 cyl on 064 besides holes?
- Thread starter Cgabriel
- Start date
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Bowtie
Gearhead
Search Function is at the top right side of the page. The bottom end is smaller in the 064 if Im not mistaken. Dont know how long it may handle the abuse from the larger top end.
joesawer
Addicted to ArboristSite
IMO the bottom end is more than strong enough if it is in good condition.
You need to make sure the bigger piston has enough room inside the case to travel up and down with out any interference.
You need to make sure the bigger piston has enough room inside the case to travel up and down with out any interference.
slabmaster
ArboristSite Guru
It will swap just fine.You should relieve the case where the piston travels and the muffler might need holes elongated like the cylinder did.Also blend the transfers to the case as that will give you some case volume for power as a 064 has less case volume.
Mark Groza
Mark Groza
slabmaster
ArboristSite Guru
Oh, And now you can have a compression release button if you wish.You can also use the same carb.Just don't over work it and the crank will hold up too.:rockn:
Bowtie
Gearhead
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Lakeside53
Stihl Wrenching
The 066 has 6mm bolts, not 5mm as with the 064... and for good reason. Tap you case out to 6mm... then deal with the various fit issues. If I was doing it, I'd plug the case, redrill and retap to 6mm. Then you can use the stock steel gasket - a great improvement over the paper gaskets...
And.. the 066 case was beefed up in later product. Early production used the same crank as the 064, but due to problems with the cranks breaking, it was changed.
And.. the 066 case was beefed up in later product. Early production used the same crank as the 064, but due to problems with the cranks breaking, it was changed.
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So in other words I should be fine. Can I get away with using the 5mm bolts and the steel gasket? because that sounds like alot of trouble to swap in the 6mm ones. How do the paper and steel gaskets compare in thickness is going to give me less squish? For the compression release I would have to get a new top cover correct?
Slabmaster: I will take your advice and blend the transfers. I also thought about doin a mild port job. I saw your thread on the 064 you were building. How did it turn out/hold up?
Slabmaster: I will take your advice and blend the transfers. I also thought about doin a mild port job. I saw your thread on the 064 you were building. How did it turn out/hold up?
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Lakeside53
Stihl Wrenching
They did upgrade the bolts size for good reason.
The steel and paper will have the same compressed thickness. The steel will not compress and allow the cylinder to loosen.
5mm or 6mm? you know what I'd do... Can't take more than 45 minutes to plug and redrill, and that includes making threaded aluminum plugs, but, I've done it a few times...
There is a difference in what you do and a manf. making thousands. You might get away with it..
If you're reluctant to plug and drill new holes, you really should look at the pistion skirt interference with the case - it might (depends on exactly which case you have) require more work than you want to do.
The steel and paper will have the same compressed thickness. The steel will not compress and allow the cylinder to loosen.
5mm or 6mm? you know what I'd do... Can't take more than 45 minutes to plug and redrill, and that includes making threaded aluminum plugs, but, I've done it a few times...
There is a difference in what you do and a manf. making thousands. You might get away with it..
If you're reluctant to plug and drill new holes, you really should look at the pistion skirt interference with the case - it might (depends on exactly which case you have) require more work than you want to do.
I dont really understand the big deal with the bolts. Was there a problem with them stripping out or breaking or something? But if I did want to change them I would just use the original holes just drill and tap them to 6mm? I dont see the use for the plugs your talking about? Im pretty sure I have a later model saw because i have more than enough clearance for another 2mm. I realized there would be some mods I have just never heard of the cylinder bolt thing.
joesawer
Addicted to ArboristSite
If you plug the holes, you can redrill new hole in the proper location for the 66 cylinder.
I would be very surprised if you have more than enough clearance for an 066 piston. I have put two 66 top ends on 64's and have had to remove material from the case on both of them.
The first saw I used the smaller bolts and had trouble with the base gasket seal. The bolts did not break or strip. The simply stretch more under load and give the base gasket a work out. The 6mm bolts give much better clamping force as they don't stretch nearly as easily or as much as the 5 mm bolts.
Any thing you do to raise the power puts more pressure on the piston, so the equal and opposite pressure on the head of the cylinder loads the bolts more.
Lakeside53
Stihl Wrenching
Said better than I ever could!:rockn: :rockn:
Bowtie
Gearhead
I think this guy is dead set on putting a 066 top end on his 064.
Like I said before if I could find an affordable 064 cylinder I would love to throw it on there. The only reason I am considering this is the price difference. I think im goin to go ahead and order a p and c assembly and go from there. I will probably end up redrilling and tapping the case. Ill let you know how i make out. Thanks guys
Bowtie
Gearhead
Do let us know, and please post pics! I think my 064 top end will outlast me, as Lakeside put it together from NOS parts. Heaven forbid I ever need another top end for it, but ya never know. Dont forget to take plenty of pics!!!
I plan on documenting the whole thing and taking plenty of pics from start til end of the whole process.
One more question though... Can I just use the new steel base gasket as a guide to where the new holes will go?
One more question though... Can I just use the new steel base gasket as a guide to where the new holes will go?
Bowtie
Gearhead
If the gasket is for an 066 I would think so, as long as you make dang sure its centered right. It MIGHT help determine if the case is wide enough for the piston too. Good luck. Again, keep us posted, Im very interested in your project.
slabmaster
ArboristSite Guru
The case is wide enough,as a 064 piston has the same width as a 066 piston at the skirt. They are both 33.8 mm wide.However the case will have to be relieved in front and back side only. Mark
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slabmaster
ArboristSite Guru
If you compare a 064 cylinder gasket to a 066 gasket they are the same except the bolt holes.The inside diameters where the piston passes are the same.
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