Revving with no bar/chain on

[livemusic]

Is there any harm to a chainsaw to rev it up without bar/chain on it? And, can you tune one like that or does it need the load of the bar/chain spinning?

 

[Marshy]

Put a bar and chain on it to tune it.
It's possible to break the key on the flywheel if you're reving it hard with no bar and chain.

 

[rogue60]

The clutch bearing is designed to control the clutch drum at idle as soon as you give the saw a rev the clutch shoes engage and the bearing is locked and no longer spinning.
Reving a saw WOT with no bar and chain and then letting off the trigger and shutting the saw off you will still hear the clutch drum spinning at about 20k for a min or two not really what that little bearing was designed for lol

 

[qurotro]

From my observation, revving the saw without B an C, engine have different running characteristics. I migh be wrong.

 

[NPKenny]

From my observation, revving the saw without B an C, engine have different running characteristics. I migh be wrong.

Exactly! Like immediate throttle response!

After building or repairing a saw, I will often get the first tune with only the Powerhead so I know it will start and idle. After that, all meaningful tuning happens with a bar and chain, preferably while cutting.

 

[~WBF]

About '93 I had an external clutch that pulled apart on my ported 266. I/3 of the clutch brushed my hair as it flew by. I had it revved up about 1,4000 RPM. When someone does that around me then I'm looking for something to hide behind.

I would see my mechanic buddy set a lot of the 365/372 with the onboard clutch that way on initial start up. You can tell if the saw is going to set up or not or if he needs to try a different clutch of carb. You can set up your low jet and be a little conservative with your high if you know what you are doing.
He would drag the drum or sprocket to simulate the chain been on. So when you put the chain on the idle would be close.



There is a big difference in what he is doing because he is trying to put a product on the bench that may have been built from scratch then move on to somthing else.
If there is a possibility that you may have to go backwards then he doesn't want to go forward any further than he has to.

 

[huskyboy]

After I threw the clutch off a 394 200ft across the yard I decided not to rev them without a b/c anymore . Lol

 

[Al Smith]

Only once and that was on a gear drive McCulloch .Spun the clutch off as the RPM's were dropping .Found everything intact and undamaged about 200 feet down my drive way .Never again .That was at around 9,500 RPM certainly not 14,000 .Won't run that fast .
I spun the string head from a weed wacker too once .The last time I saw it was over 500 feet away heading north .It might have made it to Canada by this time if it could figure out how to get over Lake Erie .

 

[Marshy]

The clutch bearing is designed to control the clutch drum at idle as soon as you give the saw a rev the clutch shoes engage and the bearing is locked and no longer spinning.
Reving a saw WOT with no bar and chain and then letting off the trigger and shutting the saw off you will still hear the clutch drum spinning at about 20k for a min or two not really what that little bearing was designed for lol

20k? Saws dont even turn that fast. I believe it wont hurt that bearing one bit.

 

[NSEric]

I tried this once to check the oiler on my saw after switching to a different clutch drum/rim sprocket, the new clutch flew out the garage door, I couldn't find all the parts and had to buy a new one but the oiler worked lol.

Every time I see someone doing this on youtube I expect to see the clutch go flying.

 

[CR888]

You can do it only if wearing a singlet (truckie/wife beater type), shorts & flip-flops after a few beers when its getting dark & your neighbours have just sat down 4 dinner.

 

[rogue60]

20k? Saws dont even turn that fast. I believe it wont hurt that bearing one bit.

Was exaggerating trying to help make a point
thought that was clear will know better next time no exaggerating! Lol

 

[RIDE-RED 350r]

After I reassemble a saw I've rebuilt, I'll do a brief test run without B&C. But it's just to set the idle and try a few very mild blips of the throttle. Piss-revving with no B&C (no load whatsoever) can be particularly bad for a saw with no rev limiter. I still wouldn't do it with a rev limited coil either.

 

[drf256]

I try to put a B&C on it, but a few blips at WOT won’t hurt a saw without the B/C. You can’t tune the H that way, and really not the LA or L to any degree of certainty.

I no longer do it without a clutch cover attached at minimum.

I launched a NOS 262XP clutch across my lawn and into the woods one time.

After many hours with magnets and a prayer to St. Anthony (at my wife’s suggestion) I luckily found the 3rd shoe.

 

[Outback]

I did that 6 years ago on a 262 rebuild. "Lucky" me it was in my shop so when they stopped flying around I could find all 3 shoes and get a new spring. Outside would have been a MF. I wrench the clutch on pretty good now when I tighten the flywheel and I put a BC on first before the test'n tune.

 

[Spladle160]

With no B&C I bet there are some saws (modified) that would get pretty close to if not past 20k. I've blipped them up to 6k or so with no B&C. I consider that living on the edge.

 

[Nutball]

The clutch bearing is designed to control the clutch drum at idle as soon as you give the saw a rev the clutch shoes engage and the bearing is locked and no longer spinning.
Reving a saw WOT with no bar and chain and then letting off the trigger and shutting the saw off you will still hear the clutch drum spinning at about 20k for a min or two not really what that little bearing was designed for lol

I wondered about that too, so I tested it on my 303t a week or 2 ago and I saw that the engine had to slow back down to near idle speed before the clutch would disengage, then the drum is left spinning at around more like 2krpm

 

[Michael Rupley]

I think if you rev it up to about 8k and throw the chain brake on it will tighten the clutch.

 

[Al Smith]

I think where you run into trouble is if and when a screw on type of clutch has been removed for whatever reasons and reinstalled .It's just the inertia from reving up and then letting it back off unscrews the clutch .Types with a tapered crank shaft with a nut most likely would not unscrew .
Some of those damned things like Stihl you can't hardly get them unscrewed .The nut thing on the clutch spider is so thin you have to use a belt sander to grind the chamfer from a box end wrench or deep well socket to gain purchase then use a three foot cheater bar .Trying not to break the anti vib mounts .What were they thinking ?

 

[Al Smith]

The neat thing about Stihl is you can change the drum,rim,whatever in a flash .Then you have outboard clutches with a screw on and every body had a different idea .They all had special spanners or pin end end clutch tools that are next to impossible to find .Then you either make one or try to knock it loose with a drift punch and a brass hammer .Old saws can be a pain in the buttocks with issues like this .Some times you just have to walk away and cool your jets .An 8 pound hammer will only break something .