What's on your bench today?

[agg221]

Thats brilliant thankyou it has a old oregon 25" bar and chain which came with it when i was talking to the guy i bought it off he said it hadnt been replaced in his ownership so im geussing its pretty old.

Im geussing its a duromatic bar i have also posted another thread asking if any one can reccomend a new bar and chain for it.

 

OK, firstly the bar isn't a Duromatic - this is the Stihl brand of hard nosed bar. This type of bar has no sprocket on the nose, instead the chain simply runs round the nose in a groove. They were relatively common for bigger '70s saws and are particularly temperamental about chain tensioning. If they've been run too tight they can wear the nose rail causing the burr I described, but yours isn't one of these.

 

As Spud says, you also need to check that the nose sprocket is free running.

 

With regard to bars - before replacing I would check that this bar isn't OK. If you clean the rails through, check that there is enough remaining depth and that the chain doesn't wobble from side to side then you could have a fair bit of life left in it yet.

 

If you do need to replace it, check the condition of the clutch sprocket at the same time. If you're not bothered about originality I would be inclined to replace the clutch sprocket with an aftermarket rim sprocket and go over to a 3/8" pitch. You can then get a 3/8" sprocket nosed bar to suit. Whether you stick with .404" or switch to 3/8", I would go for a 24" or 30" bar, probably the latter. It will pull it well and I'd rather have the extra nose weight on a non-chainbraked saw (although personally I'd use a chainbraked saw - this one can be converted).

 

Chainsawbars (Rob D) has a good selection - I think he even has specific links to bars that fit to 051, and offers an Arbtalk discount. If you look elsewhere, any bar advertised to fit an 088 will fit, although check whether the oil hole needs enlarging to line up.

 

Alec

[t5pete]

Thank you alec much apperciated

[GardenKit]

Thinking out loud here a bit...... If I'm short of torque at the top end, what's the cause, or fix..?

It's had new crank seals, piston ring, carb diaphragms & gaskets, new carb mounting gaskets, tank breather, plug & air filter.

Things not replaced: Fuel line & fuel pick up.

Starts perfectly. Idles well. Accelerates nicely. Dies off after a couple of seconds at WOT, so fuel starvation. I haven't had a chance in daylight to have a good go at tuning it, it's more or less on stock settings. I'll replace the fuel hose on the off chance that it's collapsing, and the pick up on the off chance that it's restricted.

Any other thoughts....?

After checking the fuel supply out I would tune the carb, your symptoms could simply be that its a little weak on the H screw.

If you cant tune it out then its possible that the metering arm is a little low.

Try these simple things first. Good luck.

[spudulike]

Thinking out loud here a bit...... If I'm short of torque at the top end, what's the cause, or fix..?

It's had new crank seals, piston ring, carb diaphragms & gaskets, new carb mounting gaskets, tank breather, plug & air filter.

Things not replaced: Fuel line & fuel pick up.

Starts perfectly. Idles well. Accelerates nicely. Dies off after a couple of seconds at WOT, so fuel starvation. I haven't had a chance in daylight to have a good go at tuning it, it's more or less on stock settings. I'll replace the fuel hose on the off chance that it's collapsing, and the pick up on the off chance that it's restricted.

Any other thoughts....?

 

This sounds like fuel starvation to me, few things to check, check the metering arm height, check the impulse line, if it is holed, it will be producing less pump action. It sounds a little like the tank breather despite it being changed, loosen the fuel cap and see if the problem clears.

 

Make sure the fuel line and filter are not holed of blocked and worth pressure checking the carb to make sure it isn't leaking.

 

Worth richening and weakening the H screw and looking at the effect it has on the saw.

[WorcsWuss]

Thanks Steve & Barrie.... metering arm might be worth re-visiting.... I didn't take the needle out the first time I looked into the carb, but when I stripped it down fully this time the needle had been put in upside down by a previous keeper..... Wouldn't have thought this would bend the metering arm but I'll have a look.

No impulse line, takes it straight through the carb mounting plate. Will double check the tank breather, may be that it's not seated properly preventing it from venting sufficiently....

Thanks chaps!

[t5pete]

Update time removed the cover for the bar today and the ammount of crap that was packed in there was unreal so cleaned it all out and then inspected the sprocket to see if it has binded luckly it hadnt and was lovley and free also the teeth were in nice condition on the sprocket so this then left the bar when i removed the bar it was packed full no wounder the cain wouldnt move freely also all the oil holes were blocks so after a good rake out and then blow through with air the chain now turns freely i deff need a new chain tho as i noticed two oif the teeth have been riped off so now on the hunt for a new 25" chain the bar didnt seem too bad the chain fits nicley in it with only thing i had to do was file around the edge as there was a lip.

The exhaust has seen better days but should do me fine for a while also managed to find a production date and was made in 1978 so not bad at all for a 34 year old saw.

 

Once ive got it mechanically sound i would like to spruce it up a little what paint would any one reccomend for the white bits espically around the exhaust housing.

Edited December 4, 2012 by t5pete

[spudulike]

Flipping Husqvarna 40, all sorts of problems but got the thing sorted in the end - stripped the KM100 down as the thing still wasn't running right, the cutter holds pressure and vacuum but seems light on compression at around 90psi.

 

The carb is in the US cleaner and will re-assemble and test once together.

 

Stripping an MS200T down, one of six machines!

[Rich2484]

I had another 200t on the bench tonight. For a little bit of tweaking again. That two done now.

 

Onto an ms026 soon.

 

Sorry the bench is still under restriction so no pics.

 

Should be posting some again next week.

 

Damn I love stihl saws...... Yes I said it what you lot going to do about it. :001_tt2: :lol:

[GardenKit]

I had an MS200T in today as well, chain brake not working and not running at all well.

 

The chain brake was easy, dig out all the compacted sawdust and bio oil and replace the little two post insert. Simples. Replaced the missing centre dowel which locates the cover.

 

On to the running issue. Starts up, revs briefly, stops.

Checked impulse tube, OK

Checked pickup tube by pressurising with carb tester. OK

Remove and inspect inlet boot. OK

Strip clean and re-kit carb, but it was clean anyway, refit and test. No better.

Do the carb again, refit and test. No better.

Whacked on a new (020) carb. PERFECT:biggrin:

 

Now, whilst I would like to find out what was wrong with the original carb, I really can't be bothered, so the new carb is staying on. It will be cheaper for the customer in the long run anyway.

[GardenKit]

I was talking to Spud earlier today about 'leak down testing' on a 4mix engine. This type of testing has not so far been mentioned on this thread, but is a useful follow up to a compression test on a 4 stroke engine.

In fact, on many small engines found on lawnmowers etc, its not possible to do a compression test due to the built in decompressor.

A 'leak down test' applies a measured airflow to the engine at TDC (compression). By measuring the loss in pressure and flow through the engine, and listening to the position of the airloss, it is possible to identify problems such as blown head gaskets, worn rings, burnt valves etc.

This is the Briggs leakdown tester.