What's on your bench today?

[spudulike]

What sort of computer stuff. Could be a best of both worlds here....

 

Computer keyboards Rich, 20 years in manufacturing and 10 in Sales/Marketing - it is the roots in manufacturing where the mechanical knowledge partially comes from!

[AlvinD]

The black lines are OK if they are not scores, they appear to be caused by heat and if you can't feel them with your fingertip then the cylinder is OK. You can usually tell if the scores are through the Nikasil as the acid/alkali will fizz along the score if it is through the plating.

 

As long as the bore is smooth, all should be OK - from the pic, it looks like there may possibly be a chip out of the top of the exhaust port???

 

Hi spud, it is the photo that makes it lookalike a chip but its nice and smooth now. That wee black line I couldn't feel with my fingertip but could catch it ever so slightly with the finger nail. Abit more 1200 grit sorted it out and now it's nice and smooth would I be right in saying that transfer can occur above the port as well as below?

[spudulike]

Hi spud, it is the photo that makes it lookalike a chip but its nice and smooth now. That wee black line I couldn't feel with my fingertip but could catch it ever so slightly with the finger nail. Abit more 1200 grit sorted it out and now it's nice and smooth would I be right in saying that transfer can occur above the port as well as below?

 

Yes, on real bad ones it can be on the inlet side as well! If the transfer isn't fully removed, you run the risk of damaging the rings. If the seize has been bad, it is also worth running a diamond file around the exhaust port to make sure the bevel is clear of aluminium as well.

 

I usually use different grades of wet and dry paper to lightly hone the bore.

[agg221]

Don't know an awful lot about the history of this saw but it's vintagey for sure. Had it for a year and the rainy day came today to get stuck in. Removed approx 1/8 of a small tree from inside. Brought back to life with a carb clean and new diaphragms/gaskets, and a fix to the recoil pawl springs, rope and spring. Arm yanking compression but what a powerful saw.

 

The bar is 23ish inches and knackered.

 

It's a Sandvik bar with the following on it:

 

1765-59 1.5mm .058" 3/8" 72 dl

 

If i wanted a new smaller bar and chain how do I go about choosing? What dimensions are carried to the new bar - how can I know if the oil holes will line up ( i held an old thinner bar to it and the oil holes didn't line up with the oiler)

 

Any help apreciated.

 

Thanks folks and happy new year to all

 

It's one of the later Danarm 55s - they were originally yellow and black (all metal), then dark red, then metallic blue and finally yellow plastic, so I would guess early '80s?

 

The information on your bar - it's currently running 0.58" width drive links on the chain, and 3/8" pitch. The 72 dl is drive links, so the length of the chain to order. The rest is the Sandvik part number.

 

I would definitely be looking for a shorter bar - it's not that big a saw so probably 16" max. A replacement bar will say how many drive links you need on it. I wouldn't change the 3/8" pitch as you need this to mate with the sprocket, so unless this is also shot I'd leave well alone. You can change the drive link width if necessary - 3/8" pitch chain is commonly available in 0.53", 0.058" and 0.063".

 

For reference, you can get bars for the Danarm 1-36 at 12", 14" and 16" new from Oregon, so it may be worth establishing if they use the same mounts.

 

Out of interest, what is wrong with your bar?

 

Alec

[Eddy_t]

Can you lower the idle to around 2,700rpm? If you have the L screw on one turn out and the revs won't come down, I would suspect an air leak and if it remains unchecked, the next stop is a fried piston:thumbdown:

 

Have you set the WOT at 14,000rpm? and if so, is the screw on turn out?

 

If you are richening the mix beyond the normal 1+1 turns - go very carefully as you are compensating the air leak by richening the fuel system!

 

To be fair I couldn't be arsed too much with tuning the saw in, it was difficult to tach and get the screwdriver in at the same time, didn't bother with the high revs, just riched it up so it wouldn't lean seize, comp is high at 175psi hot, the saw has been used and abused, brakes knackered, exhaust has a bolt snapped on it, etc. he just wanted it to rev up without bogging, so that's what I did

[AlvinD]

Got the cylinder cleaned and all nice and smooth that was in my previous pic post. Fired it all together and let it run erratically (the carb is banjaxed, I just wanted it to warm up to get a reading) for a good couple of mins. It ran on like there was an air leak.

 

I'm pretty confident that the cylinder and piston end of the saw is decent. A compression reading came up at 135psi forgive me for my lack of experience but I take it there's only the crank gasket and seals left to check?

 

All hoses seem ok though I do have a cracked tank breather that leaks petrol but surely this wouldn't be an issue?

I don't have equipment to do vacuum or leak down test.........YET

[Rich2484]

Get a decent carb first. If the carb is scrap then the saw wont run properly until its a nice carb set up right.

[spudulike]

Got the cylinder cleaned and all nice and smooth that was in my previous pic post. Fired it all together and let it run erratically (the carb is banjaxed, I just wanted it to warm up to get a reading) for a good couple of mins. It ran on like there was an air leak.

 

I'm pretty confident that the cylinder and piston end of the saw is decent. A compression reading came up at 135psi forgive me for my lack of experience but I take it there's only the crank gasket and seals left to check?

 

All hoses seem ok though I do have a cracked tank breather that leaks petrol but surely this wouldn't be an issue?

I don't have equipment to do vacuum or leak down test.........YET

 

The running on is a possible sign that the crankcase is pulling in air when in its vacuum state, the items a vac and pressure check will show up are carb inlet manifold leaks, impulse line leaks, cylinder base gasket leaks, decomp leaks, crankcase gasket leaks and crankshaft seal leaks as well as any cracks etc

 

The carb itself can leak air as well but the leak down test should not include this.

 

You should rule out that the throttle valve isn't snapping shut properly - had issues like that before!

[tuttle]

Hey so i decided to give a spare cylinder i had lying around abit of a clean up for practise. i used caustic soda. Mainly what im asking is... can the cylinder be used? I was cleaning around the exhaust port and it feela smooth but if you look carefully there are a small group of black lines. has this scored through the nikasil?

 

i'm not sure whether or not this is of interest.....Caustic soda is known to completely breakdown aluminum if left to soak, don't know if its an issue.

[AlvinD]

Hi Tuttle the caustic soda was only left for a few mins each time and applied where necessary on the cylinder, worked a treat

 

And it was thoroughly washed with water during and after.

 

@Rich: I plan on getting the carb sent away across eBay they refurb them for 25 sheets, is this worth doing? Or do I have to shell out 80 nooper on a new one?

 

@Spud: Quite a vast range of things it could be , time for some new tools :thumbup:

Could you elaborate on the throttle valve please?

 

I'll start with the carb and work my way from there, thanks guys.

Edited December 29, 2012 by AlvinD