Husqvarna 55 question

[PES+]

Just another couple of thoughts

You say the plug seems to be getting fuel..if it is soaked with fuel it may be flooding....if it is then the needle is stuck open or the tip is suspect.....also I have seen people forget to re-install the arm spring.

Was there fuel mix in the case of the saw when you pulled the cylinder to check the base gasket?

If so....it is carb trouble most likely the needle.

I thought of another way to check for a torn out seal.....if the cylinder is off just fill the case with premix and see if it leaks out either side of the case.

If the cylinder is one you can do the same by putting the piston at BDC.

If that is in fact the problem it will leak out fairly obviously.

Some farmers use saws for cutting hay bails and with an outboard clutch they rip out the clutch side seals because of the strands of hay and twine getting in behind the clutch.

 

[mifirewoodguy]

OK! here goes nothing! I've since replaced the whole carb off a running 55, also changed the coil off the same saw, this saw still ceases to run, it gets good fire and almost starts but still no go! I have yet to pull the flywheel off to check the woodruff key but this saw seems to new to have something like that wrong with it. Im told it only has about 15-20 hrs on it. Its a homeowners saw so Im thinking it probobly hasent seen much abuse. For the life of me this one stumps me. Lets review, new piston and rings,honed the cylinder and everything looks nice, replaced the base gasket and carb gasket, new spark plug and carb rebuild. totally replaced the carb with a carb from a working 55 and also the ignition unit. Compression checks in at approx 148 lbs after 3 pulls. It will fire several times but wont start, PLEASE HELP ME FIGURE THIS OUT......Lee

 

[echoman8]

OK! here goes nothing! I've since replaced the whole carb off a running 55, also changed the coil off the same saw, this saw still ceases to run, it gets good fire and almost starts but still no go! I have yet to pull the flywheel off to check the woodruff key but this saw seems to new to have something like that wrong with it. Im told it only has about 15-20 hrs on it. Its a homeowners saw so Im thinking it probobly hasent seen much abuse. For the life of me this one stumps me. Lets review, new piston and rings,honed the cylinder and everything looks nice, replaced the base gasket and carb gasket, new spark plug and carb rebuild. totally replaced the carb with a carb from a working 55 and also the ignition unit. Compression checks in at approx 148 lbs after 3 pulls. It will fire several times but wont start, PLEASE HELP ME FIGURE THIS OUT......Lee

Hi,

When I had my shop, I would have 8 mechanics working in the summer and about 3 in the winter. Of all the mechanics that worked for me each of them lost at least a whole day working on a chainsaw with the identical symptoms you are quoting. I have lost a few days myself.

It is amazing how little clearance it take for some compression to get past the rings and fill the vacuum in the crankcase which prevents the intake of fuel.

In your first entry, you posted that the exhaust had metal transfered from the piston to the cylinder and you honed the cylinder. Although it may not be visible, I feel there is some wear somewhere that allows the least bit of compression past the rings into the crankcase.

A compression test is of no use whatever to diagnose this problem. This could still occur with 200 psi on the top end. It is the bottom of the cylinder that is responsible for the crankcase vacuum that sucks the fuel/air mix into the motor.

Best luck,
echoman

 

[PES+]

Check the key....then report back

If the saw kicked back it is possible that the flywheel spun when the chain brake tripped.

It happens on the cast in keys more than the separate key flywheels as the taper does not seat accurately with the cast in keys.

 

[rupedoggy]

I think the 55 has two different cylinders. One has open transfers and the other closed. The piston must be the correct one to work. Check the new piston with the original to be sure the skirts are the same. Mike

 

[SawTroll]

I think the 55 has two different cylinders. One has open transfers and the other closed. The piston must be the correct one to work. Check the new piston with the original to be sure the skirts are the same. Mike

More than two, as some early EPA ones were only 51cc.......

 

[andrethegiant70]

I think the 55 has two different cylinders. One has open transfers and the other closed. The piston must be the correct one to work. Check the new piston with the original to be sure the skirts are the same. Mike

Ooo! Good call!! While you're in there it might not be a bad idea to get some calipers around the lower portion of the piston. I have to say that it really sounds like you're not pumping fuel. I've heard the suggestion to check your flywheel key.. you really have to do that also. You're driving yourself needlessly buggy if that's the problem.

 

[Ole Farmerbuck]

I've heard of spark plugs firing good until under compression. Any truth to that? Never know.

 

[mifirewoodguy]

Good Ideas guys and I'm all ears and thankful your here for me! Abotu the piston being the right one, I'm quite sure it was a 45mm or 51cc and not the 46mm/55cc because the first piston I ordered without taking the old one out and micing it with calipers, but since then I have thrown the old piston out so theres no way to verify the type or if their the same skirts. Is there any way to check the cylinder at the bottom end to see if there is some out of round issue going on? with out a dial indicator or precise tool? would it show if I took the cylinder off again and looked at it? Echo brought up fule and Im thinking the same thing myself because everything else seems to check out good top end compression,good spark. I will take the flywheel off just to see if the key is still intact and where it should be. And believe me Im taking all the suggestions I can get even if they sound silly because I know it might be that one silly little thing that fixes this saw.... Thanks again and Ill keep everyone posted on my progress....Lee

 

[mifirewoodguy]

If anyone has any pic's of the 2 different pistons so I can compare I'd love to see em or if anyone knows of a site where I can visually see them I'd apprieciate it... I ordered them from partstree.com and I figured I got the right one but maybe not....Thanks Lee

 

[HiOctane]

If anyone has any pic's of the 2 different pistons so I can compare I'd love to see em or if anyone knows of a site where I can visually see them I'd apprieciate it... I ordered them from partstree.com and I figured I got the right one but maybe not....Thanks Lee

If you got an open port cylinder,the piston then should be a "full skirt".If you have closed port port cyl,the you must have a piston with"open window" each side.

 

[mifirewoodguy]

if the cylinder is cut out on the sides about half way up is that a ported cylinder?

 

[mattinky]

if the cylinder is cut out on the sides about half way up is that a ported cylinder?

That would be an "open" port cylinder, if it were "closed " port you would still have the transfer passages but they would be enclosed, or covered so to speak

 

[andrethegiant70]

Open vs. Closed Ports

Hopefully, this clears things up a bit. The first pic is a CLOSED PORT setup from a 55. Notice that the piston is solid, with no holes other than for the wrist pin. Looking at the cylinder, note that the ports open directly to the piston. The piston serves as the "wall" of the bore as it moves, if you will. This style of piston for the 55 is only used with the style of cylinder shown.

Now look at the second picture. This is a good example of a closed port top end. Its not from a 55, but it will suffice for demonstrative porposes. Notice the "windows" in the piston. Also note the ports in the cylinder are only open at the ends (the bottom and the top). They are actually closed "channels" cast into the cylinder walls. In the case of the 55, this "windowed" piston is only used with the closed port cylinder.

Since there are several styles of top end for the 55, you can't just order a piston, you've got to specify exactly which one. It should be obvious by now that the wrong piston, whereas it may fit into the bore, will not produce a running saw. I will say that I've seen far more open port setups on the 55 than the closed ports.

I don't think any of us are saying this is really your problem, but hopefully this information will help you make sure one way or the other.

 

[mifirewoodguy]

OK I tore into it again last night and I do have a closed port, (ports on each side of the cylinder are open all the way to the bottom edge of the cylinder) and a solid piston. But I also have 2 -350's Im currently working on and both of them have the open port cylinders ( theres 3 holes in each side of the cylinder one large hole about 1/4 of the way up from the bottom and 2 smaller holes about 1/3 the way up the side of the cylinder) and both of them had solid pistons removed from them just like the one in the top pic of the 55 with closed port cylinder. But I think I get it now! Anyways I removed the flywheel and the key is molded into the flywheel itself and was intact, I re-honed the cylinder slightly just to be sure its nice and clean and it looked nice, even inspected it again with a bright light to be sure I wasnt missing any debris. I put it all back together and still it acts like it wants to run especially with the compression release pushed in but wont run. In my opinion its acting almost like a flooded saw that wont clear itself. I do have a spare cylinder off an older 55 laying around wondering if I could swap em out and see if it makes a difference? guess I'm at the point of throwing parts at it now till I get it to run. This has been a real learning experience for me , I have never had a saw that was intact and in good shape that I just couldnt figure out why it wouldn't run. Now I'm on a mission to get this sucker to run for my own piece of mind. Thanks again for all you guys are doing to help. I hope some day I can repay with my own knowledge from what Im learning. Lee

 

[andrethegiant70]

Hi, Misterfirewoodguy! I may be reading your post incorrectly, but you might want to read my post again and look closer at the pictures. You indicate that the port in your cylinder is "open all the way to the bottom" and is therefore a closed port system. It is exactly the opposite. The top picture of the 55 setup is of an OPEN PORT system. You also state that your piston is "windowed." If you have a windowed piston running in a cylinder with the "ports open all the way to the bottom," you've got the wrong piston. Again, could be that I'm reading it wrong.

 

[mifirewoodguy]

Andreathegiant!
Well I figured it was the oppisite and didnt want to say something i knew nothing about, but I was right in saying I do have an open port cylinder and Im using a full skirt piston. Surfice it to say we both were a little mixed up if you care to go back and re read both our posts. The closed port cylinders I was speaking of were off 2- 350's Im currently working on and both had full skirt pistons removed from them. So I think were both on the same page and I thank you for the info....Lee

 

[ironray]

If it's a Zama carb check this out:
http://www.zamacarb.com/pdfs/TechGuide_2007.pdf

If I read your posts right it starts but dies quickly. If so, did you check the vent for the gas tank? Also, check the fuel line where it goes under the filter assy. I put mine together once where it was pinched.

 

[sawdoctor]

I would confidently put a months wages on it being a bad cylinder. Seen it before (funny enough on 55's and 51's among others) after cleaning up the cylinders and fitting new pistons and rings

I now will not even waste my time attempting to clean anything more than a few minor marks out of a cylinder.

Good luck

SD

 

[buck futter]

Read this and take it as gospel.....


If a 55 has a decomp on it, the saw is closed ported and you need a skirted piston which is tough to get even from husky.



I would be willing to trade an open port cylinder that would work with the piston you have if your cylinder is ok. Or I would also trade you a 46 mm jug if you wanted.



Pm me if interested.