Where’s the best place or way to increase performance with a chainsaw.

[John_Mc]

Re: Where痴 the best place or way to increase performance with a chainsaw.

Which brings me back to chainsaws and tweaking. I see folks commenting about porting saws. I wonder what it will do in the long run, if you run ported hot saws for things like firewood production? How long will the saw last? Will the cost of modifiying the saw cost you in the long run with shortening the life of the saw? Will it really produce that much more wood VS a stock saw over time? Etc.... why not just by a bit larger saw and run it in stock form?

There are race ports, and there are "woods ports"... and then there are guys who think they are porting geniuses who just know how to screw up a saw. A race port is designed to get the absolute maximum our of the saw almost without regard to longevity. These guys are happy if they can get a few races out of the saw without a rebuild. A well done Woods Port adds some power and can have no adverse effect on a saw's life (in some cases, they can help the saw run cooler, extending its life). These are generally sought by guys who are looking for a bit more power without increasing the weight.

 

[newbury]

Re: Where痴 the best place or way to increase performance with a chainsaw.

<snip>
Which brings me back to chainsaws and tweaking. I see folks commenting about porting saws. I wonder what it will do in the long run, if you run ported hot saws for things like firewood production? How long will the saw last? Will the cost of modifiying the saw cost you in the long run with shortening the life of the saw? Will it really produce that much more wood VS a stock saw over time? Etc.... why not just by a bit larger saw and run it in stock form?

My understanding of "saws" is that there are stock, "woods" port and "hot saw" port.

A good "woods" port should not ruin the saw, but will boost the HP.

For instance I've 2 Stihl 660's. One I bought as a used saw and it ran fine. But then I put a DP muffler on it and seemed to notice significantly more power. Then I bought another 660 which had been "woods" ported with NO muffler mod by Brad Snelling (blsnelling over on Arboristsite.com). The "snellerized" 660 ran a little more powerful than the the stock with a DP muffler. Until I swapped the DP muffler onto the "snellerized" 660. LOTS more power. But I chickened out and decided to just have two really fast saws. My primary use at the time was CSM and I could envision burning a hole in the piston to run the snellerized with a DP muffler.

 

[MossRoad]

I have never seen an RZ500. Is it a 2-cyl like the RZ/RD350?

I also bought an RD400 back in the 70s. I bought it, but it was for a friend, and it was quick and fun. Never a problem, tho keeping the
front wheel down was difficult under acceleration.

I have a network of folks who bring me bikes, quads, and chainsaws to fix or modify. Recently got a Yamaha Banshee 350, my first one. Wow. I
get why they are popular. Only the Yamaha 660R I had seemed quicker.

As to chainsaws, other than a sharp chain, there are lots of mods that can make them more powerful. But more practical? Maybe not. My biggest
modification success was a 70s Mac SuperPro 125C, which I converted to electronic ignition from points. If all you did was put on a bigger muffler/expansion
chamber, you could double the power. Of, course you would want a bigger carb, too. And so it begins....

The RD500LC is kind of a V4 two stroke. I say kind of, because it's got two crankshafts, not one crankshaft.

Yamaha RD5LC - Wikipedia

 

[Kyle_in_Tex]

I had an RZ500 back when they were relatively affordable and not super rare like they are now. It was a fun bike but a pain to work on compared to an RZ350. The underseat pipes would roast your butt in traffic on a hot day. Mine was close to stock but they were greatly overbuilt and could be modified to make a lot more power. I could order parts if the part # was common with a Yamaha that was imported to the US (Yamaha was good about using the same parts on multiple bikes unlike Honda). 500-specific parts I had to mail order from Canada. I was afraid to take the bike on the track in case I crashed it. I used 350s for the track. Yamaha shipped the 500s with mismarked main jets- they were marked with a larger number than they were. Yam did that so they would not see as many seized bikes for warranty claims when people bought them and immediately leaned them out for more power.

The pipes made a huge difference in the powerband. Toomey RZ350 pipes were super high rpm screamers. That combined with their overly rich jetting recommendations made for a bike with poor low end and midrange. I much preferred Lassak pipes. They did not have quite the top end as the Toomeys but much more mid range and were easier to ride on the street or a road course. Spec II street pipes were also good. The Lassak pipes would peak at about 10.5 and the Toomeys 11.5 while stock redline was 9.5. For track use on a highly modified 350 you had to turn down the ignition rotor to lighten it up so it would not come off the crank at high rpms. Even then it needed to be lapped to the crank and loctited. I knew RZ350 racers who lost rotors on the track.

I still have my last 350 track bike and a ton of parts. One of these days I'll restore it and make a street bike out of it.

My current FJ-09 is a mildly tuned touring bike and makes 115 hp out of 850cc with not much more weight than the RZ500 that only made 85hp or so stock. I still love two strokes but bikes sure have come a long ways.

Sounds like you really know your stuff... I agree about the modern bikes. It's hard to believe but it's coming up on the 20th anniversary of me buying the first R1 Yamaha back in March 1998. It was the first one to get to Austin Texas. For months, sport bikes would see me pass by (going the opposite direction), turn around and catch up to me just to get a closer look. I would usually pull over for them to drool if I had time.

Yamaha YZF-R1 - Wikipedia

The most fun I had on my 71 H1 was watching some on on a Sportster kicking like crazy trying to start it and then I would lean over and kick start the Kawa with my hand. Then leave him in a cloud of two stroke.

I did the same exact thing with my RZ 350. Hand crank it. Then out run them. My buddy had an 84 1340 harley that he put a bunch of money into the engine. On top end, flat out, if we were going INTO the wind, he could go past me by about 1 mph. If we turned around and went WITH the wind, I'd leave him behind. Pretty much the same thing with a Honda 500 interpestor.

Good times.....glad to have survived them.

 

[ericm979]

The RZ500 was a kinda copy of the GP racing bikes of the time. I say kinda because while it was a twin crank V 4 two stroke like the Yamaha GP bikes from '84 on it differed in all the details. In the '80s Yamaha had some disc valve GP 500s and then went to case reeds with custom compact carbs in the center of the vee. The RZ500 had cylinder reeds on the rear cylinders and case reeds on the front and both used the tiny RD400/RZ350 reeds. The carbs were normal Mikuni round slide (26mm like on a RZ350). They wouldn't fit in the vee so Yamaha used 90 degree intake boots and hung them off to the side. The airbox had thin ears that went inside the fairing to feed the carbs sticking out. The engine and rear pipes (under the seat) took up all the room where the rear shock would normally go so they put a pull shock under the engine (like Harley did later with the SoftGlide). The whole thing was very compact and all the space was filled with something. That made it much harder to work on than the relatively open RZ350. The 500 was a little smaller physically than the 350.

Stock the 500 made about 85hp and weighed about 400 lbs. It was mildly tuned with a broad powerband- real power starting at about 5k rpms and signing off around 10. The clutch was 750 sized and the gearbox was hefty too. (the Suzuki RG500 street bike of the same era was known to break 2nd gear). It could be tuned for 110hp with pipes and porting, more for racing. The close range gearbox made 1st pretty tall so you had to rev it and slip the clutch to get moving.

Modern four strokes make so much power with a more rideable powerband but there's nothing like the feel and sound of a well tuned two stroke coming on the pipe.

Chainsaws make so much less power per CC than bikes- they're really not stressed that hard. Part of that is due to the exhaust which for space reasons has to be a small box instead of a proper pipe (race saws excepted of course). I see a lot of saw porting that makes me shake my head and wonder what they're thinking. But there's a lot of people who know their stuff too. I mostly leave mine stock as they're just tools for me.

 

[Kyle_in_Tex]

The RZ500 was a kinda copy of the GP racing bikes of the time. I say kinda because while it was a twin crank V 4 two stroke like the Yamaha GP bikes from '84 on it differed in all the details. In the '80s Yamaha had some disc valve GP 500s and then went to case reeds with custom compact carbs in the center of the vee. The RZ500 had cylinder reeds on the rear cylinders and case reeds on the front and both used the tiny RD400/RZ350 reeds. The carbs were normal Mikuni round slide (26mm like on a RZ350). They wouldn't fit in the vee so Yamaha used 90 degree intake boots and hung them off to the side. The airbox had thin ears that went inside the fairing to feed the carbs sticking out. The engine and rear pipes (under the seat) took up all the room where the rear shock would normally go so they put a pull shock under the engine (like Harley did later with the SoftGlide). The whole thing was very compact and all the space was filled with something. That made it much harder to work on than the relatively open RZ350. The 500 was a little smaller physically than the 350.

Stock the 500 made about 85hp and weighed about 400 lbs. It was mildly tuned with a broad powerband- real power starting at about 5k rpms and signing off around 10. The clutch was 750 sized and the gearbox was hefty too. (the Suzuki RG500 street bike of the same era was known to break 2nd gear). It could be tuned for 110hp with pipes and porting, more for racing. The close range gearbox made 1st pretty tall so you had to rev it and slip the clutch to get moving.

Modern four strokes make so much power with a more rideable powerband but there's nothing like the feel and sound of a well tuned two stroke coming on the pipe.

Chainsaws make so much less power per CC than bikes- they're really not stressed that hard. Part of that is due to the exhaust which for space reasons has to be a small box instead of a proper pipe (race saws excepted of course). I see a lot of saw porting that makes me shake my head and wonder what they're thinking. But there's a lot of people who know their stuff too. I mostly leave mine stock as they're just tools for me.

KISS, (Keep it stock...stupid)....

 

[MossRoad]

More Power!!!

 

[Kyle_in_Tex]

More Power!!!

Eric is right, the RZ 500's are difficult and time consuming to work on vs the RZ 350

The RZ 350's powervalves would get carboned up and need cleaning (by disassembling) but it was relatively straightforward process. Just needed some new gaskets and hopefully your cylinders looked good. You could stick new rings in if you felt compelled. But I was a cheap college student and made sure not to move them when disassembled. Just shove them back up in the cylinders.

 

[MossRoad]

Eric is right, the RZ 500's are difficult and time consuming to work on vs the RZ 350

The RZ 350's powervalves would get carboned up and need cleaning (by disassembling) but it was relatively straightforward process. Just needed some new gaskets and hopefully your cylinders looked good. You could stick new rings in if you felt compelled. But I was a cheap college student and made sure not to move them when disassembled. Just shove them back up in the cylinders.

I was thinking more on the lines of Tim Taylor..... more power!!

 

[John_Mc]

So if I need to get more power out of my chainsaw, I should get a motorcycle?