Husqvarna 55 build: Anyone done a timing advance or have any port timing #'s?

[thefarmboy21]

Started tearing down my open port Husky 55 today. Bought it as a parts saw, because it was bell to be blown up, turns out the spark plug threads were stripped. So I figured I'd pull the jug and fix it and while I'm at it, do some port work and few other misc mods. Has anyone done a timing advance on a 50-51-55? I know STIHL's like about 5 degrees or so, but there's mixed feedback on huskies. Also does anyone have any pictures of port work or port timing numbers to give me an idea of what to shoot for? I don't intend on running it often. Just occasionally to cut firewood etc.....mainly just doing it for the learning experience. I put a 46mm Hutzle kit on a model 50 back in the spring and did some mild porting, but other than that didn't really do any serious mods. I'm just looking to improve my knowledge on ignition timing for 2-strokes, port timing and porting the jug in general. I also may try my hand at hydroforming expansion pipes just for fun. Any and all input is appreciated. I just like fooling around with engines.....my dad is the one who does all the timbering. Thanks.

 

[cus_deluxe]

Im willing to bet u could get good gains from just opening and squaring up intake and exhaust. That and a muff mod, slight timing advance and should make a big difference.

 

[cus_deluxe]

Did a fairly modest muff mod on a 51 i had and just that was very noticeable

 

[thefarmboy21]

Im willing to bet u could get good gains from just opening and squaring up intake and exhaust. That and a muff mod, slight timing advance and should make a big difference.

I didn't think you wanted the ports square? Thought you wanted to keep the same contour, just widen the ports?

 

[thefarmboy21]

I would imagine it would benefit from a timing mod, but I'm not sure how much AND I'm 95% sure that it has an integrated key in the flywheel instead of a regular woodruff key you can remove. So, I don't want to start filing until I know how much to remove.

 

[cus_deluxe]

I didn't think you wanted the ports square? Thought you wanted to keep the same contour, just widen the ports?

Just meant the sides, you are right u want the roof and floor to be a little rounded to avoid catching a ring. You want sides as square as possible, you should be able to remove a lot of material in the corners and sides without changing timing.

 

[cus_deluxe]

And when you do the timing mod keep in mind that the key is only to locate the flywheel, the taper is what holds it on. So even if u take too much off the key, u can still spin it back to stock and run the nut on and it will stay put

 

[chipper1]

There is a lot of info on this family of saws on the opeforum, but I wasn't the one who said that .

 

[muddstopper]

I would imagine it would benefit from a timing mod, but I'm not sure how much AND I'm 95% sure that it has an integrated key in the flywheel instead of a regular woodruff key you can remove. So, I don't want to start filing until I know how much to remove.

A 55 husky has a standard key, its not intregal with the crankshaft. Pic is of a 2005 husky 55 crank.
ETA, the husky flywheel does have a intregal key. So advanceing the timing would require grinding the keyway in the flywheel.

 

[muddstopper]

I am subscribing to this thread as I just asked a similar question about mod'ing a 55 saw I just picked up. I posted my question in my thread about the 365 to 372 bigbore, but the saw turned out to be a 51 and not a 365. Trying to make lemonaid out of a lemon and have the parts for building a 55. My question also had to do with milling the base to increase compression and porting the int/exh ports. I have seen plenty of info about how to do the porting, but nothing about what kind of timing numbers to shoot for on a 55 ports. I am also thinking about doing some ignition timing, but again, I havent seen where anybody has done it or how much they advanced or retarded the flywheel.

 

[thefarmboy21]

I am subscribing to this thread as I just asked a similar question about mod'ing a 55 saw I just picked up. I posted my question in my thread about the 365 to 372 bigbore, but the saw turned out to be a 51 and not a 365. Trying to make lemonaid out of a lemon and have the parts for building a 55. My question also had to do with milling the base to increase compression and porting the int/exh ports. I have seen plenty of info about how to do the porting, but nothing about what kind of timing numbers to shoot for on a 55 ports. I am also thinking about doing some ignition timing, but again, I havent seen where anybody has done it or how much they advanced or retarded the flywheel.

Yea, when I put a 46mm Hutzl top end kit on a model 50 last year, I couldn't find/get much info then either. So this time I'm just gonna experiment if I have to. Machinist at work had already agreed to mill the base if I decide to go that route. Last time I just didn't use a base gasket and it had about .020 squish.

 

[muddstopper]

Yea, when I put a 46mm Hutzl top end kit on a model 50 last year, I couldn't find/get much info then either. So this time I'm just gonna experiment if I have to. Machinist at work had already agreed to mill the base if I decide to go that route. Last time I just didn't use a base gasket and it had about .020 squish.

I have used a couple of those china 55 saw kits. Never had one that worked better than or as good a oem. Of course I only have gut feel to go by, but thats the way I feel.

I have been doing a little research on porting 2cycles. Cutting the base of the cyl will raise compression, This also retards the exhaust port timing and shortens the duration the port is open. This is something I had already expected. My thoughts where if I cut the base by xxx number, then I would have to raise the ports a similar amount just to retain stock timing. Further reading suggests that instead of raising the ports, wideing might be a better solution. Anyways. I am not done studying this project and am hopeing some of those experienced porting gurus might share a little info. If this will post here is a little info I have found, and link to ignition timing http://www.innovatemotorsports.com/resources/myths.php

 

[thefarmboy21]

I have used a couple of those china 55 saw kits. Never had one that worked better than or as good a oem. Of course I only have gut feel to go by, but thats the way I feel.

I have been doing a little research on porting 2cycles. Cutting the base of the cyl will raise compression, This also retards the exhaust port timing and shortens the duration the port is open. This is something I had already expected. My thoughts where if I cut the base by xxx number, then I would have to raise the ports a similar amount just to retain stock timing. Further reading suggests that instead of raising the ports, wideing might be a better solution. Anyways. I am not done studying this project and am hopeing some of those experienced porting gurus might share a little info. If this will post here is a little info I have found, and link to ignition timing http://www.innovatemotorsports.com/resources/myths.php

Well I just went went the Hutzl kit, because my grandpa really had no intention on trying to fix it. I told him I could try a cheap $30 Chinese kit....we both agreed that it was worth $30 just for the experience even if it only lasted another firewood season.

I'll have to dig in to some threads about porting and cutting the cylinder. I don't plan on cutting it much....just enough to get my squish down to about .020 but still allow the use of a gasket. If it wasn't for the fact that I can get it done for free and very easily, I would just delete the gasket.

 

[muddstopper]

The saw I will be working on is just another saw I really dont have a use for. I have the new parts to build it back as a stock saw, but figure I will have a little fun with it. Since the saw currently isnt running, the only thing I can compare it to, once built, will be the three other stock 55's I have setting around not being used. I plan on checking the stock numbers of the saw before I do anything such as grinding or milling. That should give me a base line as to what I am starting with and where it ends up. It might take me a while, but I'll post those stock numbers up when I get them. I have a old 55 oem p/c and a new old stock, numbers should be the same, but I will check both. If I havent thrown it away, I also have one of hyway's kits that I burn up in less than 15 min. my fault, not the product. I might compare those numbers just out of curiousity. I am in no way a chainsaw expert, so this is going to be a learning experience for me.

 

[thefarmboy21]

The saw I will be working on is just another saw I really dont have a use for. I have the new parts to build it back as a stock saw, but figure I will have a little fun with it. Since the saw currently isnt running, the only thing I can compare it to, once built, will be the three other stock 55's I have setting around not being used. I plan on checking the stock numbers of the saw before I do anything such as grinding or milling. That should give me a base line as to what I am starting with and where it ends up. It might take me a while, but I'll post those stock numbers up when I get them. I have a old 55 oem p/c and a new old stock, numbers should be the same, but I will check both. If I havent thrown it away, I also have one of hyway's kits that I burn up in less than 15 min. my fault, not the product. I might compare those numbers just out of curiousity. I am in no way a chainsaw expert, so this is going to be a learning experience for me.[/QUOTE

Basically the same here.

 

[muddstopper]

Well, I picked up another complete 55 today. 2004 model way down on compression. This will make me 5 of these little saws. A rebuild will use up the remaining oem p/c kits I have so I think I am going to stop looking for any more of these saws. Still havent found any info about modifying and timing after milling the heads. Nothing on the opeforums for these little saws.

 

[thefarmboy21]

Well, I picked up another complete 55 today. 2004 model way down on compression. This will make me 5 of these little saws. A rebuild will use up the remaining oem p/c kits I have so I think I am going to stop looking for any more of these saws. Still havent found any info about modifying and timing after milling the heads. Nothing on the opeforums for these little saws.

Yea I tried looking up saws with the same stroke yesterday and still couldn't really come up with any numbers.

 

[muddstopper]

I figure on keeping the saw I picked up yesterday stock , its a pretty clean saw , and just sell it. I'll use the opportunity to measure everything when I tear it down. Dont know whats wrong with it yet. I need to order new crank bearings and seal kit first. I also found a 372 yesterday, but I cant get him to put a price on it. Its blown up and been rebuilt once and blown again. I suspect someone threw on a top end and didnt check vacuum. I'm going to keep badgering him until he sells it to me.

 

[thefarmboy21]

So finally today I got some free time at work and setup the degree wheel and took some measurements before I took the jug off to fix the spark plug threads. Here are the factory numbers:

Exhaust-104 degrees
Transfers-120 degrees
Intake-70 degrees
Squish with gasket- .030
Gasket thickness- .010

From what I've read, ideally I'd have the intake closer to 80 degrees right?!?! So if I delete the gasket and get my squish down to about .020 then where and how much do I grind to get my intake numbers more ideal. What should I shoot for on this saw? And does this particular model likely benefit from a timing advance mod? Thanks

 

[David Young]

pull the gasket, lower the intake 1mm widen 1mm on each side. make the port look like a D laying down with the flat on the upper side near the spark plug. Don't hog out the whole intake track and make sure the edge is very smooth.

You would be fine like this but you can also widen the exhaust a little bit like 1 mm on each side Make it look like an oval. square ports are for race saws...there is more to making them a lasting option than just make them square. the shapes I have described are much mor forgiving and will suit you well

two things


Symmetry
chamfer chamfer chamfer.


you can bump you ignition a little if you want.

Hope this helps

David