Basic top end swap /Solo 665 becomes Solo 681

Dex did I notice the decomp on the 681 is on left side of cylinder and decomp for the 665 was top of cylinder to the rightish?

 

Least the solo cover gives you a CUT HERE hint.

1 of the 505 I had needed a cover. I put a 475 cover with no hole. I lined up measured cut and was still off some. Had to go bigger then oem hole but it works.

 

Maybe some Stihl serrated type cylinders bolts would work in lieu of loctite...

 

Thanks for the thread Dexter, well done.

 

My 665 has the decomp on the side.

 

Dex,
Thanks for taking the time and sharing! Really cool to see that for somebody like me who has never taken apart a chainsaw. I've done my share of fixing motors, cars, boats, tools... but never a chainsaw. So it's nice to see what's in there.

In the pic under this description, there is a fuel hose coming out of carb (still attached) and a nipple it obviously attaches to on the base of the head. What is that fuel line for? Is it a a vacuum line to act as a "fuel pump" possibly?

Now that is really amazing to see! I always wonder "does the oil we mix into the fuel "really" coat the motor, or does it just end up burning off.... that really shows how it works.

So, how much (roughly) did the parts cost you on this? AND, is the saw no only 3.3 oz's heavier in total?

 

The 65cc version is the heavier of the two. The 681 ends up lighter by 3.3oz because of the additional material removed from the jug to accommodate the 52mm bore. The cylinders are still available but must be ordered special direct from Solo Germany. It is possible to use a Dolmar 7900 jug and a spacer to achieve nearly the same result for less $.

The line you see going from the base of the cylinder to the carb is the impulse line and yes it does feed the pump section of the carb to move fuel from the tank to the engine. If not done this way you would not be able to run the saw at odd angles.

 

Wow, that's amazing.

 

Dex, you never cease to amaze me! Really nice job!

 

Both Dex and Dewey did a GREAT job!

 

Got me curious now. The 681 lighter 3.3oz cylinder

Did you weigh the pistons to see how much the bigger 681 piston weighed more compared to the smaller 665 piston? Know it wont be much but hey lets put all that info out there. I'm wondering myself.

They are a set and weigh together in the saw.

 

I didn't do any weights or timed cuts or anything technical like Dex....it's just not my thang.

I did, however, just put mine in wood for the first time since the conversion. It was stout before....it's a beast now. I like it a lot!!!! Hopefully I'll be cutting a tree down this weekend. The Solo will get a nice little workout.

 

I don't think that Dex weighed the pistons individually and I believe he only weighed the jugs. See post #3. Kevin, I think you are correct the 52mm piston would add some weight back into the over-all weight of the saw.

Since Dex weighed the jugs, I know I have a 665 P/C that I got from Shep, so I can weigh that as a unit, and I think I have a n OEM new 681 piston which I could weigh along with just the 665 piston, so we could sort of back into the total 681 P/C weight.

681 P/C complete 1lb 7oz, slug alone with ring 2.5oz. Don't have a digital scale used my wife's Dualit baking scale. Subtract the 2.5oz piston from the total of the P&C 1lb 7oz, you are left with 1lb, 4.5oz. Dex got 1lb 4.9oz jug alone using his number plus my 2.5oz piston and ring, you get 1 pound 7.9oz total weight.

 

OBTW, the weights above are a new OEM 681 P/C.

665 P/C complete with ring 1lb 9.5oz, 47mm 665 piston only with ring is 2oz. (.5oz less than the 681) So subtract the 2oz piston from the total you have 1lb 7.5 oz. Which justifies Dexters numbers.

So, now it is ALL out there, is everybody happy?

 

I see it now total weights. LOL I need to go back to bed today.

 

665 P/C including ring is 1lb 9.5oz. That is complete, cylinder, piston and ring, subtract from that the 2oz piston and ring you get 1lb 7.5oz.

681 P/C complete with ring is 1lb 7oz. That is complete cylinder, piston and ring. Subtract from that the 2.5oz piston and ring and you get 1lb 4.5oz.

As far as total weight goes when on the saw the 665 setup adds 1lb 9.5oz, the 681 setup adds 1lb 7oz. The 681 setup is 2.5oz lighter than the 665. Not going to go back and mess with weighing the piston pins impact.

 

Cool, some days I feel the same way. Like yesterday messed around far to long trying to find out why a blower had no spark! Only to read the manual to find that there were two switches. one to make it child proof (hidden) and the regular switch. I hate blowers!!!

 

I'm running back and forth coating frame for plow season. I'm just out of it today. Cant think straight for some reason.

Never heard of child proof switch.