The ol Stihl 046 Magnum has me thinking it needs a new piston and cylinder. The Boss swears he can hear the bearing on the wrist pin going out, I don’t hear it. I do know that the saw has a messed up original cylinder and an aftermarket piston. I also know that the saw is pretty low on compression nowadays. I have somewhere around, and this is pure speculation, 200 hours on the current setup. Could be more, pretty sure it’s not less. So, the old tired cylinder and the new aftermarket piston (Hyway) have gotten along nicely for quite a while, but I’m ready to make a saw that can spank the Stihl 066 the Boss likes to drag around. (I had the matching cylinder to the new piston, but messed it up trying to port it. It’s a nice looking paperweight for my desk now…)
A couple of years ago I burned up the original piston and scratched up the cylinder in the process. I ordered an aftermarket kit and decided to try my hand at porting and polishing. I got a Hyway kit that was the same 52mm bore as the original Stihl cylinder/piston. I spent about 3 hours with a Dremel grinding on the ports, making them how I wanted, only to screw up the cylinder with a file. For your information, you shouldn’t run a file towards the bore (the inside of the cylinder) you can tear up the coating they put on the bore to make the cylinder last. That is a sure way to ruin a cylinder, in other words. I needed a saw for a job, so I stuck the Hyway piston in the Stihl cylinder and went back to work. It’s always been on my list to get the saw patched up, so here we go.
I have always been keen to try a big bore kit, I mean, more CCs in the same package has to be better, right? We’re going to try to find out. The recommendation from the shop I got the kit from is to go with a Meteor kit, even though they are the original size, at a 52mm bore. I should probably listen, but I’m too interested in getting 6 or so free CCs from a big bore kit. They run 2mm over stock bore, at 54mm. I understand the companies have done no work to the timing, but I’m still interested in a big bore kit.
There are a few brands I found offering a big bore kit for the Stihl 046. I did as much research as I could online, and found out the people writing about big bore kits are less than impressed, in general. I have read bad things about the NWP kit that Baileys carries, so I didn’t stop and shop there. The store I have gotten many parts from has a few, so I started there instead. They have an Amazon page too, so that’s nice. Here it is. I have always just gone straight to their site, however. They carry three big bore kits, really two. They carry a Total kit and two Hyway kits. The Hyway kits only differ by the accessories included, the cylinder and piston will be the same on each of those kits. Since I have already tried some of Hyway’s products, I thought I’d give Total a try.
Total Big Bore Kit
The Total kit comes with a cylinder, piston, wrist pin, rings, and cir clips to hold the piston on the wrist pin. It comes in a plastic bag with a bit of newspaper to keep things from bouncing around too much. I decided I should replace the wrist pin bearing, so I ordered one of those too, along with the Caber rings. I have Caber rings in the Husqvarna 55 and they are great rings. The inexpensive rings I got for it lasted around 10-15 hours before I started loosing compression, where I have something like 100-150 hours on the Cabers and they are still going strong! They get my vote!
Upon a brief inspection the Total big bore kit looks great. This thought lasted all the way until I looked at the exhaust port. That thing is a bit crooked. That didn’t bother me too much as I had planned on doing some port work myself. I would straighten it all out! Flipping the cylinder over the intake port looked even worse, but still workable, I thought.
I pulled the piston out of the bore and checked out the rings, wrist pin, and cir clips. Those all looked fine and dandy, so I moved on to the piston. It is shiny! The machine work on it looks good to me, the only exception being a stippled ring around the top. I think this ring is about where the squish band is on the cylinder, so maybe it bounced around a bit in shipping and made that mark. I wasn’t worried about the markings, I don’t feel they would effect performance one way or the other.
Moving on to the inside of the cylinder made me think the kit would make a good paper weight. The chamfering on all the ports is atrocious, to put it mildly. I briefly thought this would not be an issue since I was going to do some porting of my own. I tossed this thought as soon as I measured the spacing between the intake and exhaust ports. There is a definite overlap, this cylinder will freeport, I’m sure. Freeporting is when the exhaust and intake are open at the same time, and the fuel/air mixture goes from the carb straight to the muffler, skipping the whole combustion process. If the porter working on this cylinder had made smaller bevels on the ports this cylinder would have been fine. As it stands, perhaps they should consider finding a new line of work…
There is some cylinder coating in the transfer ports. No biggie, except for the fact that big ol pieces are flaking off, just ready to fall down in my crank case and destroy the bearings down there. This wasn’t a deal breaker, but it would have taken some work to get out and all cleaned up.
As it stands, this kit is going back to the dealer. He has sent me another kit as a replacement… Let’s see what he chooses for me!
Total “Stihl 046 Magnum” big bore kit photo gallery
Hyway Big Bore Kit
He went with a Hyway kit to replace the Total one. I am happy, I was kind of afraid I would get another Total kit and be disappointed some more. Good job, Weedeaterman!
Looking at the box is like judging a book by its cover, but packaging matters! They are both in bags inside boxes, but the Hyway kit comes in a bag in a box in a box. No, that’s not a typing error. The Hyway kit has much better packaging. By far. Total used old newspaper to hold the piston in the cylinder, Hyway uses a foam plug. You decide…
Inside the first box is an invoice, decompression plug, and a base gasket. Good so far. Taking out the second box lets you see a shiny black/grey box with their name all over it. Opening this box gives you access to the kit! The first thing I notice is the box that holds the rings. It appears to be the exact same box as the Caber one, and is just as hard to open. The rings do not have the Caber logo on them, nor does the box, so I can only assume they are not Cabers. They look fine and dandy though, so I’ll be giving them a spin! I still have the Caber rings, so if I run into any issues with the Hyway ones I can drop them right in.
Opening the plastic bag gave me a view of the foam plug. I thought that was a really nice touch! It’s almost as if Hyway cares if the kit arrives in one piece. 🙂 The casting on the outside looks good, no flaws or mystery holes, at least nothing worth discussing. The ports look just fine from the outside, no one has gone Dremel happy as far as I can tell. There are some casting bits that I will smooth some day, but I’m going to run it “stock” before I decide on going all crazy with my own Dremel. The threaded holes on top look great, no junk in the threads, like the Total has.
Pulling the foam plug lets the piston out. In it are two sets of wrist pin cir clips and the wrist pin. The piston looks very nice. There are some bits to clean up on the inside of it, but nothing to get excited about. One thing I noticed was that the top does not have any funny stippling, just the machine marks and the direction arrow. The Total and Hyway pistons look similar enough that I wonder if they came from the same factory… Makes me wonder if the cylinders shared a home too. Looking at them side by side I would say…. Yes. The inside of the Hyway cylinder better pop, or I’m gonna be sad again.
Looking at the inside has made me relieved. The coating on the bore (Nicosil) is very nice looking, I think it helps that Hyway used a regular hone instead of a ball hone. It looks so much better than the pitted chrome on the Total. You can even see the hatch marks the hone left.
The chamfering on the ports is not perfect, but far superior to the Total job. There is a spot or two that looks like the guy wasn’t paying attention, but I think it should work fine. The intake port comes to a point on one side, much like the Total one, but it isn’t as severe. I don’t think this one will catch a ring. I’m gonna find out! If I get around to grinding on the ports this is an issue I will address as best as I can. Checking for port overlap, it would appear that this cylinder has none. It looks to be about a 1.5mm gap between the exhaust floor and intake roof. I can find no marring on the bore either, that makes me happy.
Using my Vernier Caliper’s depth gauge all the ports appear the same opening and closing as stock. This tells me that the timing is the same as the saw came with. The shortened piston skirt changes things up a bit though. The Hyway and Total pistons are both about 2mm shorter in the skirts than the OEM piston.
Looks good to me. I’m going to plant this kit on top of the tired ol Stihl 046 Magnum, and get back with ya on how well it works, or doesn’t…
Hyway “Stihl 046 Magnum” big bore kit photo gallery
Well, this was a long one. My new phone takes much better pictures than the old one, now I need to learn how to use it and I’ll be all set! I would have to say that the Hyway kit appears to be the better value of the two. You receive more bits, and the packaging is better, all for the same price. I do think either kit you get should be checked out thoroughly before sticking it on your saw. The Hyway finish is a bit better, but looking at that intake port has me wondering about their quality control. Aftermarket parts can be a great value compared to OEM, but the quality is generally not at the same level. I spent around a hundred on this kit, a factory piston and cylinder would probably run around $400.00, and you would probably have to go thru a Stihl dealer to get it. I don’t have that kind of cash, personally. I probably shouldn’t have gotten the kit that I did…
Thanks for reading along with me! As always any questions or comments, shoot me a line, and I’ll get back with ya as soon as possible! Also, if you have any experiences with aftermarket pistons and cylinders feel free to share in the comments below! Be sure to swing by the Weedeaterman site and their Amazon Store for lots of deals on chainsaw parts and pieces and other stuff! (I might get some $$$ if you purchase thru the Amazon link!)
Stay safe, Cass “Cronkito”
Interested in this saw, read the review here!
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