I call B.S. on Stihl. My dyno doesn't lie. MS 461 is king over MS 660

[Trx250r180]

I would slow it down with more fuel Brian. Part throttle scares me.

with the stock muffler cover on it was dryer inside vs the dual port cover ,maybe from running hotter not letting it breathe ,i was trying to quiet it down some at that time ,i put the dual cover back on and with no carb adjustments it is wetter inside the muffler ,piston is nice and oily also,does not feel the slightest bit lean in the cut when i am milling ,but i let the chain feed itself and i have an aux oiler so the chain stays wet ,cutting rounds i go wide open ,milling it does not seem to need to be wide open in the stuff i cut ,just makes more noise and the cut is not as smooth ,trust me i was worried about the part throttle too lean ,maybe the rich oil mix makes up for it

 

[Mastermind]

Sounds like you have it covered Brian.

Experience is our best teacher.

 

[chadihman]

I'm going to do some more break in on the dyno as i want to save the wood for timed testing. I'm thinking now I'll load it to 9000 and let it run till the tank is out. Seems to me it wouldn't be any harder on it than milling till it runs out.

 

[blsnelling]

I'm going to do some more break in on the dyno as i want to save the wood for timed testing. I'm thinking now I'll load it to 9000 and let it run till the tank is out. Seems to me it wouldn't be any harder on it than milling till it runs out.

With a brand new saw?!!! I sure hope you at least richen it up a LOT! You do realize that a chainsaw is not designed for that kind of use, right? Even when milling with a well broken in saw tuned rich, I'd never run it that hard that long.

 

[chadihman]

With a brand new saw?!!! I sure hope you at least richen it up a LOT! You do realize that a chainsaw is not designed for that kind of use, right? Even when milling with a well broken in saw tuned rich, I'd never run it that hard that long.

9000 seems better than 10 or 11k. Guys take em right out of the box and run em hard and have no trouble. It has some time on it now

 

[mdavlee]

I've run them for a tank, stop refuel and finish the milling cut. I don't think a tank lasted more than 7-10 minutes that way on a ported saw. If I can I refuel them running if I catch it before it runs out. After tank 2 I've been milling with the 046 like that. It seems to be fine with 200 lbs of compression.

 

[Haywire Haywood]

When I was milling this last time, I ran it wot 2 minutes and then let it idle for 1 minute. A bit of overkill maybe, but better safe than sorry.

 

[chadihman]

I'm just taking a guess here but I'm thinking a saw reaches its max temp in a minute when it's under a load wot. Probably reaches a certain temp then stops climbing. If that's the case what does it matter if it runs 1 minute or 10 minutes under load?

 

[Haywire Haywood]

I'd guess that depends on ambient temperature. Cool and dry vs hot and humid.

 

[wyk]

9000 seems better than 10 or 11k. Guys take em right out of the box and run em hard and have no trouble. It has some time on it now

Even in milling, you rarely do a full cut on a whole tank at 9K or so unless you hate your saw. Brad is warning you about loading that saw for so much for so long. Saws aren't generators, they aren't designed to run under load for hours. Give the thing SOME rest between loading it.

 

[redfin]

What's the difference between a saw running wot under load for extended periods or a 2 stroke lawn mower cutting the grass?

I do understand the lawn moweres run at a much lower rpm but each is designed for their rpm and heat tolerance.

 

[mdavlee]

Even in milling, you rarely do a full cut on a whole tank at 9K or so unless you hate your saw. Brad is warning you about loading that saw for so much for so long. Saws aren't generators, they aren't designed to run under load for hours. Give the thing SOME rest between loading it.

The last outing one cut was almost 2 whole tanks for my 390. The first time it ran out and died 5' into a 9' long cut. I didn't know what happened and then checked the tank and it was dry. I started stopping in the middle and refueling with it running after that.

 

[wyk]

The last outing one cut was almost 2 whole tanks for my 390. The first time it ran out and died 5' into a 9' long cut. I didn't know what happened and then checked the tank and it was dry. I started stopping in the middle and refueling with it running after that.

Is that how you broke your 390 in?

 

[chadihman]

OK guys I like #'s so I'll share some more. I just finished running a tank through the 660. This time I used an inferred temp gun and took temps from the front muffler cover and the jug at the opening in the shroud above the clutch cover.
First 1 min idle. 198°f at the muffler and 164 on the cylinder. Then 1 min under load at 9k.. Muffler 720 cylinder 315. After 2 min under load at 9k. Muffler 770 cylinder 330. 3 min muffler 765 cylinder 295. After 4 min muffler 768 cylinder 305 and the same patter for the remaining time under load. I then idled it for 1 min and the muffler was back to 326 and the cylinder 250°f. So it does reach a Max temp and stay there. Pretty close to my guess. I should play the lottery.

 

[wyk]

OK guys I like #'s so I'll share some more. I just finished running a tank through the 660. This time I used an inferred temp gun and took temps from the front muffler cover and the jug at the opening in the shroud above the clutch cover.
First 1 min idle. 198°f at the muffler and 164 on the cylinder. Then 1 min under load at 9k.. Muffler 720 cylinder 315. After 2 min under load at 9k. Muffler 770 cylinder 330. 3 min muffler 765 cylinder 295. After 4 min muffler 768 cylinder 305 and the same patter for the remaining time under load. I then idled it for 1 min and the muffler was back to 326 and the cylinder 250°f. So it does reach a Max temp and stay there. Pretty close to my guess. I should play the lottery.

Does the sprocket reach a max temp and stay there? Steel is a very poor insulator, and the chain heat goes to the sprocket, goes to the, uh, other sprocket/clutch housing, goes to the bearing, goes to the PTO side shaft...

Pain in the ass to get that temp, tho.

 

[mdavlee]

Is that how you broke your 390 in?

It's got about 15 tanks through it now so yeah sort of. It was ported and had one tank on it before milling the other day after machine work.

 

[chadihman]

Does the sprocket reach a max temp and stay there? Steel is a very poor insulator, and the chain heat goes to the sprocket, goes to the, uh, other sprocket/clutch housing, goes to the bearing, goes to the PTO side shaft...

Pain in the ass to get that temp, tho.

Didn't get those temps. I could probably leave the clutch cover off and get a temp of the clutch and sprocket. Now just ran another thank through. I'm doing one or to more tanks and calling it broken in. Then I'll test again against the 461. Then I have a special front muffler cover for testing different opening sizes and how it affects power and fuel consumption.

 

[chadihman]

Here's a video. It's sunny and beautiful here in Pa today.

 

[Haywire Haywood]

Interesting setup. How are you getting your numbers from that? I see some kind of electronic piece in front of the oil tank

 

[chadihman]

Interesting setup. How are you getting your numbers from that? I see some kind of electronic piece in front of the oil tank

Scale goes on the platform that reads torque from the twisting action of the hydraulic pump. The hydraulic pump is a variable brake controlled by a needle flow valve. Electronic box is just a shaft rpm sensor. I spent a lot if time and effort making sure the shafts were lined up just right and it payed off because this dyno is smooth running.