Huztl farmertec p&c kit pics/review/build/etc ms440

[alabama xl]

I finally got the parts I ordered to rebuild the top end on the MS440 my buddy gave me a while back. Since I couldn't find enough info to satisfy my slightly obsessive cravings for knowledge, I needed up ordering a standard 50mm kit, the big bore 52mm kit, the standard 52mm kit for ms 460, and the big bore 54mm kit for the ms 460. I have an oem gilardoni (or is it gillardoni???) jug on this saw with a torn up spark plug thread.

My goal with this thread over the coming days as I have time is to document my experience buying bits and bobs for this saw from China, comparing them as best as I can to the OEM stuff that I have, and then putting the saw back together. I've got most of a machine shop and a pretty decent set of measuring tools, and probably have access to any measuring tools that I don't personally own, through friends at work. I'm hoping between myself and more experienced members of the site, that we can get some numbers on port timing, port width, squish, and whatever else we need to know. And hopefully at the end of it all, I have a running saw for felling and doing light milling work.

If this is of interest to you, please follow along and contribute what you can! Pics and more info to follow, but for now, I need to go work on building a new chicken coop.

 

[Bobby Kirbos]

Build the saw first. THEN, use it to cut lumber for the chicken coop project.

 

[alabama xl]

so after almost 4 weeks of waiting my parts finally arrived. wrapped in a couple layers of bubble wrap with packing tape around them. They were proud enough of their work to put a "made in china" sticker on it all.



Opening it all up, I found the boxes with my 4 piston and cylinder kits.



unfortunately one box didn't make it unscathed, and neither did its contents. I'm gonna have to email the nice folks at huztl and talk about that tomorrow. There are also a few other issued we need to resolve before I pay my credit card bill for this stuff.


we ended up with a bent cooling fin:


and some damage to the base of the cylinder:


It's probably nothing that can't be cleaned up - though I'm not sure about the cooling fin. I have a feeling that will snap if I try to bend it back. At the very least, it is something that shouldn't have happened if things were packed better.

 

[alabama xl]

This is the OEM cylinder with the damaged spark plug hole. As you can see it is a Gilardoni. In working with motorcycles in the past, I've seen that there are often three sizes of cylinder and piston, marked as A, B, & C. I'm not sure if the A in the part number here indicates a particular P&C size combination, but here the part is 1128 A. I don't remember why they have the three sizes. if anyone can add input as to why that is, please speak up.


The Huztl cylinder is not marked with any part numbers whatsoever, and is definitely inferior in terms of the finish quality. I found no major voids in the casting, but around the spark plug hole, they opened it up so big that the fins are no longer connected across the front.


probably not a big deal in terms of use, but it doesn't look as nice as the OEM cylinder



you can also see that they cut the casting sprue off on the OEM cylinder and then cut grooves for the cooling fins, whereas the Huztl cylinder has the gate/sprue cut flush with no further machining. This is a corner that might be successfully cut, but would affect cooling at least a tiny bit.

 

[alabama xl]

The intake and exhaust port on the Gilardoni OEM cylinder have been chamfered nicely all around, and seem more consistent. The ports themselves are somewhat smoother than their aftermarket extra cheapy chinese counterparts

The huztl cylinders are less consistent along the edges of the ports, and show what appear to be a couple of minor chips in the corners. I will be cleaning these up a bit along with trying to smooth the interior of the intake/exhaust, along with the transfer ports before putting this into service.


There are random burrs on all of the cylinders where machining jobs were done, including the spark plug hole, and where the intake boot connect. All of this is easy to correct, but shows a lack of attention to detail, that likely reflects other corner cutting. Even with government subsidies and super cheap labor, and zero to no environmental protection rules, you can't make a first rate P&C kit for $12 and still turn a profit. The question will be whether it runs good enough to make the inferior workmanship and corner cutting a valid trade off.

 

[alabama xl]

I measured the Gilardoni cylinder and it's pretty close to 50MM in diameter. Measured twice, rotating 90° between measurements. Depth is 72mm. I actually measured 72.12, but I'm using a digital caliper as a depth gauge. It's a very nice caliper, but a proper depth micrometer would get us a more accurate reading. The Huztl cylinder measures 50.06-50.07mm in diameter, and 72.35 deep. I'd like to find my telescoping gauge set and measure the cylinder diameters deeper down than 1cm down that can be done with the calipers. I should be able to get a set from a friend on monday or tuesday, if mine don't turn up by then.

A couple of things that I don't yet know how to measure properly are the width of the ports, and their top and bottom edges. I could take a piece of thin paper and use it to make a template of sorts, but I'm thinking there is probably a proper tool that I don't yet know about. Someone familiar with porting work can perhaps speak up and tell me how best to do this. It would be nice to be able to more accurately compare between the OEM and aftermarket cylinders. Once I have mapped out this info, I will then compare the big bore kit, and the two ms460 cylinders. I'm especially interested to see how the 52mm MS440 big bore cylinder compares to the 52mm MS460 standard sized cylinder. Transfer port volume/size comparison would be interesting in addition to the obvious comparisons of port timing.

That's all for now. Please let me know if there are measurements that I am missing from this comparison, and if there is anything else that I should be looking for.

 

[pioneerguy600]

Place a sheet of paper into the cylinder, trace out the exhaust port of each cylinder, also you can make a lead pencil etching of all the ports and transfers to measure and compare. Port mapping is easily done this way.

 

[alabama xl]

I've got to get back to working on this chicken coop, but will hopefully have some time tomorrow or monday to do the port mapping using paper and pencil or dirty oily fingers (my usually method for making rubbings on to paper for making gasket templates, etc). I also need to dig out the saw from my shed and compare wrist pins and pistons. I think the oem piston and rings are still ok (I hope!), so will probably re-use them rather than the parts that came with this kit. When it comes time to try out the big bore P&C kits, I'll probably order some nicer rings to minimize risk of rings failing on me.

 

[alabama xl]

so I was looking at the ports on this cylinder today, and noticed a casting defect in the intake port. there was some sort of issue with the mold, and there is more material in one corner that restricts the overall open area. everything else at least looks close to the original. Fortunately relatively easy to get to with a small die grinder or some files. the other cylinders don't seem to have this problem

 

[alabama xl]

Another QC issue that I found was where they drilled and tapped for the exhaust. The on the left hand hole, they drilled to deep. It doesn't go through the cylinder wall, but it's yet another strike against these guys.

 

[pioneerguy600]

Ya, no surprise there, port shapes and flash, ridges etc are very common in these AM kits, worse even is the bevelling around the exhaust ports in almost every cylinder I have seen, either next to none or gone way overboard on bevels.

 

[alabama xl]

on the surface, the piston looks to be OK. on closer inspection, there are a couple of flaws in workmanship and design.



First is the ring retaining pin. it is slightly large diameter than the OEM pin, and it is placed poorly next to the groove. This is supposed to be a press fit, but they made their hole too small for the pin, and placed it slightly too high. This results in a small bulge in the ring groove. Fortunately, they managed to "engineer" the rings to fit, but making the round cut that is supposed to go around the pin bigger than on the OEM rings. so it fits, despite their poor workmanship on the piston. A problem that still exists, is that it feels like the ring might get pinched a bit still because of that bulge, which could cause it not to be able to move as freely as it is supposed to. The rings themselves measure at a consistent 1.17mm, whereas my OEM rings measure 1.15mm. The ring groove on the piston measures 1.22mm, OEM is 1.26mm. The OEM piston and rings are used, so may have worn slightly? neither has undue play, at least to my slightly calibrated eye/hand. If I were to use this piston, I would try to clean up that bulge, just in case it were to pinch the ring somehow.

the other major flaw I see with this piston is the shape of the area where the wrist pin goes through. More specifically where it connects to the body of the piston. On the Huztl, it has a fair number of sharp edges, whereas on the OEM, it is more rounded. Good engineering practices indicates that we should minimize sharp interior corners when possible to reduce opportunities for stress cracks to form. Given the physics of what is happening, and the forces involved, I don't think this is really going to be an issue, but it is indicitative of corner cutting and poor craftsmanship in general.

Here are some pics of OEM piston for comparison showing proper pin placement and ring seating around the pin, along with the better designed area around where the crank pin goes.



As far as the pin and the bore in which it fits, they are machined very nicely. The pin is good and hard, and probably ground and finished smoothly enough for the job. A file will jump over its surface, rather than cut. It is consistent in diameter, and the ends are finished square enough, measuring at most 32.90mm and 32.75mm on the opposite side. It measures 11.98mm consistently along its length on all sides. I have no idea if it is too hard, or if there is such a thing for a piston pin. It is nice to see that at the very least, they are capable of making at least a few of the most simple of parts to a high enough standard that one isn't nervous about them failing. But that isn't saying much. The pin is definitely thicker diameter material and heavier than the OEM pins, as others have noted. Wall thickness is 2.18mm. Since I'm re-using the OEM piston and pin at the moment, rather than moving up to big bore P&C, I haven't removed OEM pin to measure it.

Where the pin mounts in the piston measures a consistent 12.03mm. I don't have adequate tools at the moment to measure the width of the retaining ring grooves, but can come up with a way to do that if anyone is interested. I don't have a simple way to measure how squarely the hole was bored to the rest of the piston, but could probably rig something up to check that if anyone is interested as well.

With the one of the huztl rings placed in the cylinder, I'm getting 0.31mm (0.013") end gap. Same ring in OEM cylinder is giving 0.15mm (0.07") end gap, which seems to fall in the range of acceptability. End gap on the both rings is same.

 

[pioneerguy600]

What do the circlips look like and do they feel soft/not springy enough?

 

[alabama xl]

The circlip which hold the pin in place is 1mm thick, and fits nicely in the groove. Yet another QC issue with the piston, is that the notch (on both sides of the piston) for removing the circlip is not cut deep enough to get a tool in there to remove it. The Huztl clips have an ear on them, which allows you to grab with a pair of pliers, so this is not an issue, but it would have to be fixed if you were to use OEM clips with this particular piston.

I also noted while comparing the two, that the OEM wrist pin has a tapered bore towards the center on both ends to reduce weight, while still retaining its strength. It's these little things that make for great parts, compared with mediocre ones.

 

[alabama xl]

Ya, no surprise there, port shapes and flash, ridges etc are very common in these AM kits, worse even is the bevelling around the exhaust ports in almost every cylinder I have seen, either next to none or gone way overboard on bevels.

The beveling is there, but inconsistent and rough. looks like an afterthought at best.

 

[pioneerguy600]

That ear on the circlip is a dangerous piece, dangerous in that they can and do break off under high RPM`s and do contribute to causing the whole clip to bounce right out of its groove, usually ending up jammed between the piston and cylinder wall. Common occurrence from what I have read and seen.

 

[alabama xl]

What do the circlips look like and do they feel soft/not springy enough?

The clips look OK. They are stiff, but springy, and go back to their original shape when I compress them by hand the amount required to put them in the groove. Since I have three more of these kits to look over and document, I will make a point of checking the others too. 8 clips out of who knows how many thousands made isn't much of a sample size, but it's something, I guess.

 

[alabama xl]

It would be interesting to compare these P&C kits to other aftermarket ones. The actual casting and machining of these is relatively inexpensive, regardless of who is making them, but cleaning up flashing around ports, and making sure things are bored consistently and with sharp tools costs money. Putting proper bevels around the ports costs money if done by hand after the fact. If done as part of the casting process, it costs time and money to run QC on the molds and finished parts to make sure that the patterns are not falling apart and will produce consistent pieces. Not sure if there is a way to actually cut costs from OEM, and still get the same level of consistency and quality. I'm not sure if these aluminum pieces are investment cast or if there is a way to die cast them, but either way, making top quality parts requires more skill than you can buy for $12. It's all a matter of whether you pay someone else to clean up the flashing and flaws, or whether you do that yourself. Given that I wanted some inexpensive parts to use to try my hand at porting, these cylinders seemed like a good price point for that. If I'm going to be mucking with the ports, I might as well be the guy who cleans up the flashing too.

Possible longevity/reliability issues aside, The lesson here is that you can't just buy these parts and expect to install them without any extra time and effort on your part. Perhaps the Hyway brand P&C kits from Taiwan are something you could do that with? They cost 4-5 times these Huztl kits, but I have no idea if they are actually better quality. If I've got some extra money to burn at some point, maybe I get one of them and see how it fares in comparison.

 

[alabama xl]

That ear on the circlip is a dangerous piece, dangerous in that they can and do break off under high RPM`s and do contribute to causing the whole clip to bounce right out of its groove, usually ending up jammed between the piston and cylinder wall. Common occurrence from what I have read and seen.

That is probably why the OEM design does not use them... There's definitely a reason why stihl decided to engineer their piston with the little hole for removal, and no ear on the clip, and it's not because that is the less expensive way to do it.

 

[blsnelling]

so I was looking at the ports on this cylinder today, and noticed a casting defect in the intake port. there was some sort of issue with the mold, and there is more material in one corner that restricts the overall open area. everything else at least looks close to the original. Fortunately relatively easy to get to with a small die grinder or some files. the other cylinders don't seem to have this problem

That is disgusting!