Mastermind Meets The MS661 C-M
- Thread starter Mastermind
- Start date
Help Support Arborist Forum:
Mastermind
Work Saw Specialist
Most of us here are counting on you unlocking the secrets to the 661, and since I have one in my crosshairs when you do figure it out.... I'd like to send a little something ($) towards your endeavor. Your research benefits those in particular that are following this thread, myself included. Check or Paypal bro?opcorn:
While I truly appreciate the offer, I feel that I should take care of this myself. I also should say that Chad and I have worked out a deal that we both think is fair for the parts. In other words, Chad is helping with the cost of these parts in a big way.
Locust Cutter
Sawing for Sanity
Pretty sure I saw some Bacon in one of the pics... Maybe it was cooking on the muffler after the improved cut time?
Been there!! will be there again! It sucks I surly know. Sometimes the only way to learn how to standup. One must first fall down.
Everyone have a Merry Christmas.
Andre.
HuskStihl
Chairin'em for the sound
If the technological advances in 2 strokes parallels cars it will be harder and harder to pull big gains out of these engines with modifications. Before everything became turbocharged a few years ago, a lot of the non-pushrods engines were putting out 100hp/liter. Just not much room for improvement. Us car guys are at a disadvantage in that you face bigger penalties for running "dirty" in a car
CR500
Diesel, Snowmobile, & Chainsaw Technician
I'm still waiting for some company to put an exhaust valve on a saw. To me that will be the next step in performance. Rotax motors have had those for years and they operated by pressure inside the cylinder.
Lark-o
ArboristSite Operative
there would need to be more of a tuned expansion chamber type of pipe/muffler to make it worth while to use a exhaust valve.
MasterMech
ArboristSite Operative
Are you kidding me? Listen to how folks gripe now about m-tronic/AutoTune adding complexity to their saws.....
Officer's Match
Addicted to ArboristSite
I'm still waiting for a model with a flippy-throttle.
komatsuvarna
Arboristsite MVP
Makita EK7651H
Metals406
Granfodder Runningsaw
Or a flippy-filter.
Metals406
Granfodder Runningsaw
Yeah, but to be a true flippy-filter, it would all have to come off as a unit. ;-)
Dieselshawn
ArboristSite Operative
CR500: exhaust valves only benefit for 2 strokes that operate at all rpms while a saw runs at top rpms while cutting.
It will just be dead weight added.
With today's advances in technology, any saw manufacturer would've added a exhaust valve if it did improve performance.
It's only benefit is to make the power band broader, more crisper throttle response across all rpms and varying throttle positions.
With a saw, just hit the throttle, cut a piece of pie off, all done.
Even hot saws don't have them.
It will just be dead weight added.
With today's advances in technology, any saw manufacturer would've added a exhaust valve if it did improve performance.
It's only benefit is to make the power band broader, more crisper throttle response across all rpms and varying throttle positions.
With a saw, just hit the throttle, cut a piece of pie off, all done.
Even hot saws don't have them.
CR500
Diesel, Snowmobile, & Chainsaw Technician
CR500: exhaust valves only benefit for 2 strokes that operate at all rpms while a saw runs at top rpms while cutting.
It will just be dead weight added.
With today's advances in technology, any saw manufacturer would've added a exhaust valve if it did improve performance.
It's only benefit is to make the power band broader, more crisper throttle response across all rpms and varying throttle positions.
With a saw, just hit the throttle, cut a piece of pie off, all done.
Even hot saws don't have them.
Low end response would greatly be improved, I'm willing to bet lol
Dieselshawn
ArboristSite Operative
Cr500: the chain would likely land on the moon if the saw has too much throttle response. 
Dieselshawn
ArboristSite Operative
Rogue60: in a snowmobile where power valves are common, they give better midrange response without taking away top end power.
Yes the power valves tame the hit of the 2 stroke.
As snowmobiles evolved, power has gone up and it's difficult to control a high strung 2 stroke and hard on the belts.
My snowmobile won't make near the power of a power valve engine of equal cc unless I raise the exhaust port but doing so makes the engine harder to work with.
So power valves allow better power and smoother response at all rpms.
You would be correct as the valves tames the peaky power or increase the power of a 2 stroke without sacrificing bottom end power.
Yes the power valves tame the hit of the 2 stroke.
As snowmobiles evolved, power has gone up and it's difficult to control a high strung 2 stroke and hard on the belts.
My snowmobile won't make near the power of a power valve engine of equal cc unless I raise the exhaust port but doing so makes the engine harder to work with.
So power valves allow better power and smoother response at all rpms.
You would be correct as the valves tames the peaky power or increase the power of a 2 stroke without sacrificing bottom end power.
Dieselshawn
ArboristSite Operative
Rogue60: yes, be good for nothing on a saw. There is a Polaris 600 triple back in 1997 that was over ported from factory, it needed a heavy spring loaded clutch to keep the power in the top end. It works well for some people but was hard on belts and not as much fun going slow. If that model had power valves it would run better and have a better setup clutch.
Yes a well tuned carb and properly setup clutch or transmission will work well and make lots of power.
Grass drag sleds don't use power valves as they're only going 500-1,000 ft in the top class.
Hit the throttle, hang on!
Yes a well tuned carb and properly setup clutch or transmission will work well and make lots of power.
Grass drag sleds don't use power valves as they're only going 500-1,000 ft in the top class.
Hit the throttle, hang on!
What it would do is have a nice quiet idle and allow for more radical porting for top end. Just speaking from two stroke off road motorcycle experience the kind with a centrifugal governor for the power valve. I suspect similar would hold true for other designs more likely to be applied to a chainsaw. The powervalve when closed puts the top of the exhaust essentially even with the top of the transfer ports so the shock wave when it is in the lowered position is less.
Dieselshawn
ArboristSite Operative
Let's picture this: let's use skidoo tech stuff on lets say stihl 662 for example if they were building this.
Stihl puts power valves on, direct fuel injection, computers to run the system, and all other fancy stuff that I probably missed.
I'm sure it'll be one big pig of a saw. But it'll be clean, powerful, oil efficient as well and pretty much no emissions.
Then if we want more power, give the 662 to mastermind.
While out in the bush cutting wood, the saw cuts out on power with engine light flashing. Call stihl service to come out to jobsite with a laptop to verify the issue and fix or send to dealer. Meanwhile, I'll take the mooberized 661 and go back to work.
We all want powerful saws but it has to be lightweight, simple and reliable.
All the manufacturers come out with very good units and with a little porting or timing, that machine becomes much better yet.
They're also expensive enough as it is.
Stihl puts power valves on, direct fuel injection, computers to run the system, and all other fancy stuff that I probably missed.
I'm sure it'll be one big pig of a saw. But it'll be clean, powerful, oil efficient as well and pretty much no emissions.
Then if we want more power, give the 662 to mastermind.
While out in the bush cutting wood, the saw cuts out on power with engine light flashing. Call stihl service to come out to jobsite with a laptop to verify the issue and fix or send to dealer. Meanwhile, I'll take the mooberized 661 and go back to work.
We all want powerful saws but it has to be lightweight, simple and reliable.
All the manufacturers come out with very good units and with a little porting or timing, that machine becomes much better yet.
They're also expensive enough as it is.
