compression tester comparison

[spudulike]

Hi

 

Is it possible that the gauge lost its calibration during transit? As I understand a simple pressure gauge is a bourdon tube in a spiral that tries to straighten when pressure is applied thus moving the needle, thats right isnt it Spud?

 

So if you could calibrate it against some known pressure - scratch head for something at or around 150 or 200psi - then you should be able to re-adjust accordingly.

 

N

 

Yup, sort of brass sealed circular tube with a lever type machanism, the pressure unwinds the spiral a little and the lever mechanism accentuates it:thumbup:

 

Bit like a hollow toothpaste tube bent in to a circle - get some pressure in it and it trys to open up......understand?

[GardenKit]

Bit like those things that get blown at parties.

You know, the ones that start off short and curly then shoot out straight when blown.

Usually with a little noise.

[BILLSMOWERS]

Just found a pic of the Stihl one. It does not have a hose, just a solid tube which I guess is of small bore so not adding much to the unswept volume.

 

Reckon you have just got a faulty gauge then Bill.

 

I use a couple of Draper ones now, they seem to outlast all the others.

 

Top tip though. Remove all fuel before testing compression. I did one last year with a brand new Gunson gauge on its second use. The engine flooded and compressed petrol into the gauge which killed it instantly.

lucky the gauge is not mine it's my friends i bought the echo gauge which works fine

[GardenKit]

lucky the gauge is not mine it's my friends i bought the echo gauge which works fine

Another example of Echo being superior to Stihl:biggrin:

[BILLSMOWERS]

Another example of Echo being superior to Stihl:biggrin:

 

got to agree there is it true stihl have started to assemble in china ? if so this could be the kiss of death for stihl:thumbdown:

[Eddy_t]

Stihl, like other manufacturers do not suggest compression testing as being accurate on two strokes

 

 

I'm sorry Barry, I have to disagree there, the husky/partner cut-off saw workshop manual categorically states compression readings, specifically for the k650, 700, 950 and 1250.

[GardenKit]

I'm sorry Barry, I have to disagree there, the husky/partner cut-off saw workshop manual categorically states compression readings, specifically for the k650, 700, 950 and 1250.

Quite so Eddy, and well researched.

 

I had meant to say "like most other manufactures" as I knew some bright spark would set to work on google.

 

Stihl do not issue pressure readings or procedure in their manuals for 2 stroke equipment, but they do for 4 mix. This could be why Bill had seen that the gauge was only for the 4180 powerhead.

 

Like I said, I think compression tests are a valuable aid in the diagnosis of an engine problem, but those tests must be done properly and used in conjunction with other diagnostic methods. If you cannot get a published figure to compare then whatever reading you do get is only a guide.

[adw]

I'm sorry Barry, I have to disagree there, the husky/partner cut-off saw workshop manual categorically states compression readings, specifically for the k650, 700, 950 and 1250.

Hell fire Eddy, you need to move on with the models, K760,K970,k1260, but you are quite right the shop manuals give compression readings.

[Eddy_t]

Hell fire Eddy, you need to move on with the models, K760,K970,k1260, but you are quite right the shop manuals give compression readings.

 

 

Irrelevant if they're able to prove my point, plus my stepdad has one, which I invariably have to rebuild after stale fuel or neat petrol has been through it, gets annoying after the 4th time...

 

Didn't google it Barrie, I already had a pdf!

[spudulike]

Who needs someone to tell you what compression a saw should make or a manual: -

 

200+ tuned

170+ very good

150+ normal well run in

130 pretty shagged

100 buggered

75 well buggered

 

One of the first checks to do on any machine in for service IMO!