Chain saw woes

[Peter.N.]

I have a Stihl MS170 12" which has served me very well for years, I recently decided to fit a 14" bar and chain as some of the wood I was cutting was to thick for the 12". The bar I bought was a JAK max and the chain an Archer.

I have used archer chains before with no problems but have never heard of this bar, with it the chain keeps coming off if you don't keep the saw dead square to what you are cutting, so I have taken it off and refitted the original Stihl bar for which I will get a new chain.

My question is are genuine Stihl parts much better than pattern parts, I can get two Archer chains for the price of one Stihl and as I say I have used them before until they are worn out with no problem, and is this problem with the bar?

The oiler is working fine.

Your opinion would be appreciated.

Peter

 

[Burnerman]

There's something odd about this one, Peter......this is a new chain you are using with a new JAK bar and of course the pitches match? Can you pull the chain around the bar easily enough by hand?
Did you notice if the drive sprocket teeth were showing much wear, when you swapped them over? A notched sprocket can chew a new chain drive up in a short time.
To me it sounds as if the slot on the bar is too wide for the chain.....personally I use Oregon bars and chains as they are very popular up here - certainly these are as good as the Stihl original. Do check out the bar slot width as well as you can.
I'm a little surprised that the 170 can handle a bigger bar though......doesn't it tend to stall?
John

 

[Peter.N.]

Hi John

Why am I not surprised you appeared, I'm sure you run this forum single handed It all looked OK when I put it together but every time the chain has come off its sustained some damage and gone quite rigid, I have had to work it to unstick the sections, this last time one of the sprocket teeth on the chain broke off. The sprocket itself looks fine. It must have come off at least a dozen times, mainly when cutting through thin branches. There is no slop in the chain and it appears to be running round the bar quite easily - once I straighten it out again.

The saw is designed as a 12" or 14" both chains and bars are offered for the same model. I think I will go back to a 12", never had a problem then and its done some work over the years, I must have been through at least half a dozen chains.

Peter

 

[Burnerman]

Bizarre.....certainly you don't need the chain slinging off but I'm not surprised the chain has some damage when it does so.
Personally I've only had similar problems when the chain pitch and drive teeth depth hasn't matched the drive sprocket and the sprocket on the end of the bar, but this tends to be obvious once the parts are assembled.....any spot tightness there is a bad sign.
For sure, if the chain is flying off with small branches, something is well out!
Do the numbers on the old and new chains tally?
John

 

[Peter.N.]

I didn't check that John, I ordered them for the saw and they appeared to fit OK. I have just ordered a genuine Bosch chain and will see how that goes. I will refit the original stihl bar, it still looks OK in spite of its high mileage.

Peter