oneadam12
ArboristSite Guru
Lakeside said I would benefit more from a tach that read chain speed rather than inductive pickup for my Husky 570, does anyone have any expierence with this type? http://tinyurl.com/wltlp
non-contact tach
- Thread starter oneadam12
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stihlatit
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oneadam12 said:
I bought one similar to that and found I could not use it. You have to apply some reflective tape to the chain and it would measure the revolutions of the chain on the bar. I guess that is what Lakeside means by chainspeed. I was not sure how the chainspeed would equate to the true RPM of the crankshaft so I bought the inductive tach that Bailey's sells....it seems to work fine.
I guess if I had to I could figure a formula to equate the chain speed from the true RPM of the crank which is what the book specs give you but that was more thinking that I wanted to do at the time.
Could put the tape on the sprocket but then you would not have the load of the chain and bar on the engine. If you did it that way and max the RPM to spec, you would have a nice safety margin upon installing the bar.
Bailey's tach is called a Sendec hand held. Url below.
http://store.baileys-online.com/cgi..._id=qeXvYSeb&mv_more_ip=1&mv_nextpage=results
Lakeside53
Stihl Wrenching
I don't remember what I said, but measuring "chainspeed"??
To measure crankshaft speed without a normal inductive tach you just measure the flywheel or clutch drum speed. Chain speed can be calculated if you know the engine speed.
Why won't a "normal" tach work? What is the the original context of your question ot my response?
To measure crankshaft speed without a normal inductive tach you just measure the flywheel or clutch drum speed. Chain speed can be calculated if you know the engine speed.
Why won't a "normal" tach work? What is the the original context of your question ot my response?
oneadam12
ArboristSite Guru
sorry, those were probably the wrong words. My 570 has the rev limiter on it, and you advised that a normal tach is a pita since the rev limiter kicks in. Sorry about the misquote.:blush:
Lakeside53
Stihl Wrenching
On the OLD (circa 1990) Stihl 064/066 with rev limiting igntion, the method was to tune slowly up (lean out) to 11k, then add 1/2 turn more... I don't like that at ALL!!! but that's the stihl factory method. It assumes too much about the carb and saws condition.. etc.
oneadam12
ArboristSite Guru
So...sneaking up on it is the accepted way to tune this type of ignition? I have not used a tach to tune before, but since being here I am convinced there is a benifit to using one. Just trying to make sure I get it right when I buy one.
paladin
ArboristSite Operative
I have had a tech tach 20k for about a year now and have had very good luck with it and it is very easy to use and works well. It measures engine rpm off of the spark dont know if this is what you are looking for but it is a nice unit.
Lakeside53
Stihl Wrenching
oneadam12 said:
The only problem is determining the point where the reading is invalid, and then knowing how much more to turn the H screw in... I don't know what that would be for a 570.
Canyon Angler
Addicted to ArboristSite
For what it's worth, I saw a vibration-type tach in the Foley-Belsaw Small Engine Parts catalog...you can order the catalog free here:
http://www.foley-belsaw.com/Catalogs.html
I think the tach was maybe $20
http://www.foley-belsaw.com/Catalogs.html
I think the tach was maybe $20
GPH85
ArboristSite Operative
A vibration tach measures, well harmonics or vibrations and is for tuning most mower engines. It's a simple wire harmonics measuring device. Basically you turn the wire out to the length it needs to be then adjust the governor on the engine until this wire starts vibrating or moving back and forth like crazy. Doubt you could use it on a chainsaw without knowing what the wire length needed to be for the chainsaw you are working on... Plus there's the fact that the chain gives off harmonics and could possibly interfere a little.
GPH85
ArboristSite Operative
I tried the Baileys site and didn't get anything, but searched and found. Here it is...
http://store.baileys-online.com/cgi-bin/baileys/1112?mv_session_id=ewpB5WW8&product_sku=17122
http://store.baileys-online.com/cgi-bin/baileys/1112?mv_session_id=ewpB5WW8&product_sku=17122
Chainsaw Master
ArboristSite Operative
oneadam12 said:
Seems to me that sprocket size would have more to do with chain speed than bar length, a 8 tooth sprocket drives a chain @ X speed no matter what length the chain was. Chain speed and chain RPMs are two different things.
oneadam12
ArboristSite Guru
yeah. :bang: I think I was brain dead when I typed the first post. this is what I meant to type "..because you can still make it too lean and burn it up... PITA to adjust correctly as the tach will read wrong as it skips sparks and the ear won't pick the right point, so be conservative... To adjust a limiting coil, really need a tach that looks at the flywheel (or clutch drum) speed, not sparks." Quote from Lakeside in regards to a rev limiting question by me. (Don't know how to make the Quote button work on a different post)
oneadam12
ArboristSite Guru
Alright, how about this, what if I make a bracket to replace the chain gaurd that will hold the bar a chain on safely, but have an opening to see the clutch drum and reflective tape?
Lakeside53
Stihl Wrenching
Ombesb said:
NO...
Lakeside53
Stihl Wrenching
oneadam12 said:
Just remove your top cover. If you can see the flywheel rotate, you can measure it. personally, I wouldn't bother. Just leave it slightly rich and forget it.
