365/372 kit builders thread

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Hi everybody.
Countless threads and info on this subject already, nevertheless I would like to invite you to post your experiences here.

As we all know the 365/372 is out of production, there is still and will be for 30 years to come this saw in it's original state available in the "used" market.
We all agree that to refurbish a Swedish made original Husky would be the best thing to do, however - this thread is not about that.

This thread is about the joy and frustration of puzzling together crude Chinese copied parts in to something that might work.
And about the problems that may appear both in the build and after some time running, and how to solve them.

Please feel free to post your comments, questions, experiences, links or videos.

 

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Though I hope this thread will not be about "my" build, I will start out with what parts I have ordered in addition to a 365 kit.

To have an alternative to the kit parts I have ordered these parts from Hyway:
- The carburettor rubber manifoil. (because the kit part is reported to have a poor fit)
- A complete chain adjuster. (I wanted this OEM but it was above the budget)
- AV buffers. (because they where not too expensive)
- Crank oil seals. (to have in case I need it)
- 52mm pop-up piston kit.

And I have ordered these OEM parts:
- Rubber O-ring on the crank clutch side. (because it is reported to be missing from the kit)
- The carburettor rubber manifoil clamp. (because it was not too expensive)
- Oilpump adjuster spring. (because I have seen some comments about that, not sure what it's about though)
- The bar mount studs.

In retrospect I would recommend to wait and see what comes in the kit before buying any additional alternative parts.

 

[lostone]

O-ring on clutch side.
Coil since Afleet warned about them.
Had to shim oil pump.
OEM intake boot and clamp.
Raised oil path to line up with bar/bar plate.
All OEM on brake since it was junk.
Put Echo fuel tank vent since mine pulled a vacuum.
OEM muffler since kit isn't legal for USFS.
Echo fuel line.
OEM choke lever since mine wouldn't stay clipped in.
That's for starters, yes a lot of stuff but the build allowed me to learn a lot about two stroke engines.

 

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Yes that o-ring is on the clutch side I guess.
I'm looking forwards to see how the Hyway intake boot looks/fits compared to the Chinese, it's still aftermarked but atleast a different animal.
About the brake (brake band, spring and linkage) I ordered a different one from Aliexpress, but it might be junk too. The brake on my 038/381 kit was ok.
I'm looking forwards to investigate the fuel tank vent when/if I get that far with it, I need to see it and how it works or; not works.
I'm also looking forwards to check out the oil pump, on my 038/381 kit I rebuildt it somehow both to deliver and not to leak.
Fuel line on my 038/381 kit has held up well, I will give it some time to get the first hand experience.
About the coil I have actually not seen anyone complain about it, so I guess I'll get the first hand experience with that too.

I ordered a different muffler from Aliexpress with a screen, looks like this and is said to fit;

Husqvarna 385 385XP 390 390XP 372XP 372 371 365 365XP 362 ​

It dont look as cool but if it actually fits I will certainly try it out. Hyway makes one like this also.

I think what the 038/381 kit taught me (except anger management) is that a 2 stroke engine is pretty simple stuff, not rocket science at all.

 

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Well it's sertainly an A1+ on delivery.

I have not looked through all the parts yet, and I wont be able to start my own build for some time.
But my initial thoughts is that;
- I have seen some complaining about the plastic parts, well they seem pretty solid to me. I really cant see what that is about.
- There is no dirt in the crank bearings, they roll smooth and nice. This was not the case with my 038 kit though it's a couple of years ago.
It do need some cleaning inside before the crankcase can be assembled though, I would expect nothing else.
- The chainbrake linkage seems good, there is a standard fuel vent and the o-ring that everyone complains is missing - is there.

- The chain tensioner looks pretty decent to me, not anything like the one I got in my 038 kit back then. There is even a NGK spark plug.
I will of course try to stay with the kit parts and perhaps my ordering of extra parts was a waste, but I just like to have some alternatives when I'm at it.

It definitely seems like a slimmer and more dynamic entity than my much loved 038/381.
36mm piston stroke compared to 34mm at the 038 should provide some additional torque as well.

 

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Yeah this is not going to be a "stock" build, I really wanted to - I'm happy with the kit alright, I think probably by reading old threads and waching old videos the parts in this kit have changed because I don't recognise the complaints. The plastic rear handle with tank an all feels super sturdy - by force and by weight.
No doubt it's good to go as it is, however - when you build from scratch the power of choices is yours. That's the beauty of it.
I'm just cuddling with this in between other stuff and I have started removing the coating in the crank department with some paint remover.
It's not necessary to do it and I have never seen anyone else do it, but now you have.
Nothing wrong with the crank bearings - it's proper solid and tight bearings, but I have some SKF bearings on the way along with a Turkish made crankshaft.
It's all candy you know... a little bit of this and a little bit of that.

If you however deside to pop out the seals and bearings, there might be some metal fragments coming out as well.
On my 038 I used pressurised air as well as pressurised water to clean them out, this time I wanted to be 100% sure.
Even though I had vashed the crankcase parts and the bearings was running smooth and free, I was surprised how much metal spon had accumulated at my work surface after I had carefully knocked out those bearings and seals. It was probably not all from behind the bearings and seals but some was for sure.


At this point I'm not looking at building a chainsaw, my project is to put together this crankcase and I have all the time in the world to do it.
I think doing a kit in a hurry is just a shame if you are impatient to get it done it's better to just get something ready made.

 

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GETTING STARTED

At this time I'm watching videos on youtube at the subject; crankcase, crankshaft, crank bearings and seals.

I wanted to list some of the videos I found the most useful, but what occurs to me is that;
They all do it a little different; some tidy and gentle, some a little more crude, some right to the point, some steering around the porridge, some successful at first take, and some with a little problems along the way.

The fact is that I have difficult selecting any one from the other, because they all teach me something valuable.
Most of all that there is a lot of different ways and preferences going about this, but allso useful hints and info about all sorts of things.
I think they all contributes to give me a clearer picture and a better foundation of how I would want to do these things based on my own preferences.

 

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I thought I'd show a couple of the things you should be prepared for with a aftermarked kit such as this.

Here you can see I have drilled out the impulse tube nipple, there are two reasons for this;
- First I want to install a piece of brass tube instead and I will bend it just slightly perhaps 10 degrees to the right for it to get a better angle for the impulse tube in the direction where it needs to go, and also a slightly better clearence towards the carb.booth. This is not strictly neccessary, I just want to do it. I will use a 4mm brass tube and mount it with JB weld hi-temp epoxy (its the "pro" long cure version, 300 Celsius).
- Then there is the bulge in the metal at the cylinder seat, you can see from the pictures that the nipple has been slammed in there and the tool has hit the edge of the cylinder seat surface and the metal bulges upwards. This needs to be adressed.

I will use a glass or aluminum plate with 400 grit wet sanding paper glued on to it and carefully remove the bulge.
You could of course also use a dremel and a carbide millbit and remove just the bulge without removing the nipple, there is plenty of gasket surface.

Then there is the cylinder seat surface itself, it differs about 0,10mm in height on the two halves at the front, and about 0,05mm at the rear.

The base gasket might take care of that, but I might try my glass or aluminum plate to carefully even the odds slightly here too.

Here you can see the same thing as with the impulse tube nipple, the bar studs slammed in there have bulged and even fractured the metal a little.

I'm not saying this as critisism to Farmertec in any way, I'm just saying this is - or might be; what you get.

The pistons are really nice with a near perfect tolerance in the cylinders, the cylinders are quite coarse honed and no doubt need the extra oil to run in.


The 50mm cylinder that came with this 365 kit is chrome i think, you can (or at least I can) see the white silvery cylinder coating/plating.


The 52mm big bore is actually Nikasil as far as I can see, it has a slightly gold like color at the cylinder coating - quite different from chrome.

 

[Ronie]

Yes that o-ring is on the clutch side I guess. I see at the oil pump kits on Aliexpress they use a thin wide washer in it's place it seems.

I think that @lostone is talking about this o ring, you can use grease or a sealant in it's place but if it were mine I'd use the o ring even though they seem to disintegrate over time. Don't be surprised if you have an idle problem with the aftermarket carb, some do and some don't.

Edit: I should have said tuning the low problem, not idle problem.

 

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I think that @lostone is talking about this o ring, you can use grease or a sealant in it's place but if it were mine I'd use the o ring even though they seem to disintegrate over time. Don't be surprised if you have an idle problem with the aftermarket carb, some do and some don't.

Edit: I should have said tuning the low problem, not idle problem.

About the O-ring yes I think so too, and it is supplied with the kit, even though I already ordered an OEM one since it was reported missing.
I have two carbs for my 038 and they both performs perfectly, but for this one I have a new original Tillotson HE-18A carb on the way too so I actually have an alternative to the aftermarket one that came with the kit.
The Tillotson carb is actually quite affordable, they are still made and you can buy them directly or through a dealer. The inner venturi is 16,5mm and that is the same as the aftermarket kit carb. I'm not saying its any easier to adjust but if you have problems with the one that came with the kit it might be worth checking out.
https://tillotson.ie/shop/he18a-carburetor/

 

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The big bore cylinder compared to the Hyway big bore / pop-up looks like this;


The intake port pictures got a little blurry but they are basically a similar size, the Hyway on the right slightly more rectangular.


The exhaust ports, the Hyway on the right is notably bigger stretching sideways.


Here comes the biggest difference, Hyway on the right - those transfer ports are huge!


The cylinder honing is smoother on the Hyway, even the combustion chamber is smooth and clean. The port edges is also bevelled.


The Hyway piston rings have a slightly bevelled edge.

 

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My thoughts on the cylinders is that of course you get a more performance ready cylinder with the Hyway, with the smooth honing you dont need the massive 25/1 fuel/oil mixture to run-in those first 10-20 hours perhaps. But if you consider getting in to some porting you could improve the Farmertec and after run-in it would probably have much the same performance. I do think those slightly bevelled edged piston rings is a good idea though, for safety perhaps and run-in.
Anyway, both the 50mm and the 52mm Farmertec cylinders have the same porting and though I have never seen an original Husqvarna I would guess they are atleast similar to the original one, so with that in mind the juiced up 52mm at 76,5ccm should give some satisfiable power as it is.

 

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I thought I'd show what I did to improve the cylinder seat surface.
This varies so you might get a crankcase that already fits perfectly or perhaps you consider this to be less important, but its not that difficult to do something about it if you want to. I have used a glass plate meant for a welding mask, I had to shorten it a little and I did that with a diamond disk on my minidrill.


Then I have used a marker to color the surface so that I have control of where and how I am sanding, I have used 400 grit paper dry.

You can see from the right photo how important it is to see what you are doing, you don't want to make grooves.

To get the surface level I carefully use pressure at the right places, and I constantly varies directions and patterns to avoid making grooves.

I repeat the whole operation until I'm happy with it.
Finally I color the surface again, this time I use as little pressure as possible and just carefully remove the color.

Then I have repeated the operation with 800 grit, then with 1200 grit without the color.
And finally with just the glass plate and metal polish.

When I'm done with it I have rubbed it just a little with a cloth.

I might use a little gasket sealer at this surface when I mount the cylinder, so with that in mind you could stop after 400 grit perhaps.
In fact I believe a little surface retention is an advantage if using a gasket sealer, something for the sealer to sink in to and hold on to.

 

[link]

Well its not overly popular this thread, I dont exactly have to stand in line to make a post but I guess that's a good thing...

Anyway I thought I'd post something about what I have done to my cylinder.
I don't do "porting", I consider that to be about changing the timing of the ports and I think you really need to know what you are doing, exactly what you want to achieve with it and I also think to be successful you need some experience as well.

But I do what I can do, and that is to make some better dynamics in whats already there if possible, and I think it is.
You get a unique opportunity to look at this while you still have your crankcase parts separate, because you can see whats happening from the inside.


Here I have adjusted the cylinder skirt a little to make the transaction from crankcase to cylinder slightly better.


I like to bevel the edges multiple times before I make a curve, it makes it easier to "construct" a smooth curve and to have the result repeatable.


I'm looking to make a sort of aerofoil leading edge shape rather than to make knife sharp edges.


Here I have smoothen it with a diamond drillbit, you dont need to do that unless you have your tuxedo on and wants to post your pictures at the internet.


And this is my favourite toolbits.

I will clean up the intake and exhaust channel a little too, that's really easy to do.

It might not make a noticeably improvement to how the saw runs, but whats important to me is that I did my best to do what I could.

 

[Ronie]

One thing a lot of the aftermarket cylinders suffer from is a large squish and low compression, I would get my crank in and measure the squish in both of those cylinders before I spent time grinding on them.

 

[Maintenance supervisor]

My cylinder definitely benefited from the BGD.
I put A 52mm ft on my G372XP and took about 2 small hand fulls of aluminum out of it , it runs great.
I took the 50mm cylinder from that and put it on the g372 with a pop up piston and some transfer work.

 

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One thing a lot of the aftermarket cylinders suffer from is a large squish and low compression, I would get my crank in and measure the squish in both of those cylinders before I spent time grinding on them.

The Hyway cylinder on my 038 was lifted from the base by the piston when I tried the cylinder on without the base gasket, but I would love to do a base gasket delete if applicable - I already spent some work on the crankcase base surface for it to be ready for it as you can see. But the Farmertec cylinders might have been improved in the squish departement lately for all I know.

 

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So I tried to measure the squish difference between the Farmertec and the Hyway by measuring the distance from the base to the top.

Its very difficult to get an accurate and consistent measure having the caliper all the way down there, but I measured many times in 4 corners on each cylinder.
They are very similar, I concluded an average 0.2mm larger squish in the Farmertec, that is about 0.008" so a very small difference.
If that is good news for the Farmertec or bad news for the Hyway is not known to me at this point in time, but as mentioned on my 038 the Hyway was pretty good.

The Hyway also have a small rim at the top perhap 2mm (1/12") where the cylinder has a sligtly larger diameter than the plating, my guess is that this have some sort of technical reason like preventing damage from sot accumulation or similar. But due to this and considering both cylinders are properly run-in which will take a bit longer for the Farmertec to achive, my guess is that the compression in these two cylinders will eventually be pretty much the same and that the Farmertec will probably not be any lower on compression at least.
Further I have measured the transfer ports and its a little mis-guiding that the transfer ports on the Hyway is bigger than the Farmertec, they are - but they opens at approx the same time and as the piston have a 36mm stroke they will never open fully, so the transfer ports will effectively be the same size.

I will make ready the Farmertec cylinder as well now that I can compare it to the Hyway regarding ports and such, its nice to have a spare cylinder and I have a separate pop-up piston for it aswell. Perhaps I simply need to make two saws eventually to make good use of all my parts

 

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So I have looked at videos on porting now to understand a little more on these cylinders, and I have studied the two different cylinders I have.
And I have decided to use my Farmertec cylinder in favour of the obviously higher quality Hyway and there are primarely two reasons for this.

First the porting on Hyway is somewhat of a Hyway signed thing, the transfers opens at the same time as the Farmertec but the intake and exhaust are both lowered about 2mm in the cylinder. This was exactly the same on my 038 build, I had 4 cylinders in all to choose from and the Hyway had lowered the exhaust and intake on that one too. I guess this is to achieve some higher torque perhaps and a slightly longer intake opening duration or atleast thats how I understand it.
I think probably the Farmertec cylinder is more of a direct copy of the original, because that is all they do over there.

On a second note the Hyway transfer channels is partly a copy of the original channels which is curved a lot outwards like a banana from the base and then guided in to the cylinder in a curved dynamic fasion, but on the inside wall towards the cylinder they are not following this banana shape. They have taken a shortcut here just using a constant cylinder wall thickness and that make the channels expand in to a huge cavity area inside the transfer channels before it then narrows in to the transfer cylinder opening, this is everything but dynamic as far as I know about flow and Reynolds numbers atleast.
Here again the Farmertec is just a copy of the original and both the outer and inner inside walls of the channels follows that banana pattern, making the area of the channels first large against the base - and then gradually narrows the inside area untill it exits in to the cylinder. This is how it should be.

Obviously the Hyway works well and its a much nicer cast on the outside and a lot smoother honing on the inside, thats what I use on my 038 and I love it.
But for this build, I think I prefer the rough copy rather than the enhanced one.

 

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I was googling some and at this point I just wants to understand a little more about 2 stroke engines, I know the basics alright - but exactly why does people do what they do to their cylinders in their quest to make them run "better" than what the educated designers and engeneers who originally made them have concluded with.

I am not going to change any timing or do changes to my cylinder other than making the transitions and channels smooth. I am not going to remove material that would make the air/gas flow at a reduced velocity, or that might reduce the vacuum and compression below the piston because of a larger volume as a result.
I just like to be on the safe side of things, doing modest changes that cannot be negative in any way.

But I am still qurious obviously, so I found this thread using google and I think it was really interesting.
https://www.arboristsite.com/threads/the-myth-of-high-compression-in-2-strokes.320432/