Huztl MS 440 Initial Impressions, and Build

[EB Saw]

sounds good, Monday afternoon the piston retainers should be in and i can put her togeather, ill post the out come.

 

[weimedog]

Can you elaborate on the cylinder timing a bit, I don't fool to much with that yet and am still trying to understand, did delaying it make it run worse? Thanks any info is helpful. I know there are other threads but just a few words is all I need at this point. Thanks

Some PURE speculation, sort of a generic vs. saw specific thought process.....but here goes:
Three things happen. Exhaust opening is delayed by a couple of degrees.. that can help the power down a little lower in the operating RPM range. Typically not something big displacement saws would need, but a common approach for the little saws. The intake has more duration. This can help get a little more gas / air mix into the bottom end, can be a plus; on some saws that actually can be a minus as the duration stock is pretty aggressive. Of course too much duration and the thing will start being lethargic to throttle input. The transfer ports are also lowered. If the piston at BDC was at the floor of the transfer stock, and you cut .060, now the floor of the transfer is .060 below the top of the piston at BDC... Effectively reducing the working x-sectional area of those ports along with altering the timing. Most builders see this as a necessary evil.. but also the same builders like to raise the top of the transfers... I'll let you think about that a bit... And yes there will be a change in performance, and my guess is going from .087" squish to .033" will more than make up for any potential losses due to the transfers and actually both a little more "delay" in the exhaust opening along with increased secondary compression because of the squish modification MIGHT make for a stronger saw all through the lower part of the working RPM range. You may have taken a little from the top because of the exhaust and transfers, but I doubt you would notice it unless you had a dynamometer. Of all the things changed, the only one that worries me relative to the performance of that build is the effect on the transfer ports. Now if you could raise the transfers some, at least to the stock timing numbers....and get that exhaust back to stock...you might start seeing some real interesting characteristics with the blend of changes you have made ..

 

[EB Saw]

Thank you so much, at least for this cylinder I am going to leave it, for the next one I will need to figure out a degree wheel and figure out port timing numbers. Does anyone know stock ms 440 numbers or numbers that are a good runnig saw.

 

[Bedford T]

Cross has designed a well thought-out performance cylinder that is on par with the Huztl quailty. But are wanting to improve it.

Mastermind design

 

[dswensen]

Working on my 044 build - about 1/3 done.

So far, the throttle rod is missing, the chain tensioner is not serviceable (quality of materials is too poor - pot metal), and the tension spring for the chain brake is unusable. All needed parts I have ordered from alternate sources and on the way. I also found the piston pin circlips to be made out of non-spring steel wire - will be replacing those for sure.

Although the other problems listed I had heard from others, the tension spring for the chain brake was a problem I had not heard of yet. The larger "anchoring hook" was fashioned incorrectly, which made installation impossible. Also, the too-large diameter of the spring meant that the cover that protects the chain brake assembly could not be installed. Perhaps the tension spring was for another model? I don't know, but a new on is on the way.

The parts problems are annoying, sure. But the big-boy jigsaw puzzle sure is fun!

 

[EB Saw]

I had the same issue with the chain brake spring, I threw it out, and I was able to get the chain tensioner working good enough. The oil pump is real poor quality, I am gonna try and make it work though.

 

[Bedford T]

How about a photo of the spring next to a ruler. Maybe some can verify the problem against another if we see it

 

[EB Saw]

Definitely, tomorrow i can upload some pictures. I thinking of just getting an oem spring.

 

[EB Saw]

Since i dropped the piston .060 do you think advancing the timing on the flywheel would help to compensate for the retarded spark?? If i understand it right, now the fuel-air mixture is ignited later in the compression stroke right?

 

[tbohn]

Since i dropped the piston .060 do you think advancing the timing on the flywheel would help to compensate for the retarded spark?? If i understand it right, now the fuel-air mixture is ignited later in the compression stroke right?

The port timing is not related to the ignition timing.

 

[drf255]

Stock timing is all over the place, even with OEM jugs.

Not sure why you didn't have the machinist take a bit more off the base to get squish near 20-25.

How thick did your base wind up?

Until you put a degree wheel on it, you really have no clue where your ports are at.

Torqusoft has a pretty good program that converts measurements to degrees. It's fairly accurate also.

Good numbers for your saw are around 102 exhaust roof opening, 120-122 transfer roof opening and 76 intake floor opening. You can modify the intake opening by relieving the piston skirt if need be.

Besides not being true perpendicularly and bad squish/chamfering, AM jugs are notorious for exhaust roofs that are too flat and wacky timing numbers.

The one thing I would add to your build is a Meteor piston with the pins and clips. They're under $50 and are darn good pistons that come with caber rings. That's the one area I see that I just wouldn't skimp on. You've come this far.

 

[dswensen]

I will see what picture I can get.

The problem with my spring was two-fold.

One: the diameter of the coils was too large to fit in the recess and allow the plastic protective cover plate to be put on - and that was without the rubber sleeve being put on the coils.

Two: the large anchor hook that mounts to the stud at the aft end of the spring - the attachment point needs to co-centric to the axis of the spring coils along the center axis of the coils of the spring (like the OEM springs). Mine was offset to the outside (outboard?) of the outside edge of the spring coils. This made the attachment stud too short.

How about a photo of the spring next to a ruler. Maybe some can verify the problem against another if we see it

 

[Bedford T]

Definitely, tomorrow i can upload some pictures. I thinking of just getting an oem spring.

Understanding what you are seeing is part of the journey if you can stand it follow through. We all benefit.

 

[EB Saw]

Stock timing is all over the place, even with OEM jugs.

Not sure why you didn't have the machinist take a bit more off the base to get squish near 20-25.

How thick did your base wind up?

Until you put a degree wheel on it, you really have no clue where your ports are at.

Torqusoft has a pretty good program that converts measurements to degrees. It's fairly accurate also.

Good numbers for your saw are around 102 exhaust roof opening, 120-122 transfer roof opening and 76 intake floor opening. You can modify the intake opening by relieving the piston skirt if need be.

Besides not being true perpendicularly and bad squish/chamfering, AM jugs are notorious for exhaust roofs that are too flat and wacky timing numbers.

The one thing I would add to your build is a Meteor piston with the pins and clips. They're under $50 and are darn good pistons that come with caber rings. That's the one area I see that I just wouldn't skimp on. You've come this far.

Thank you, that is what I was looking for. Your right about getting the squish to .020 now, I might as well, I can swing by and have the machinist take a little more off. As for the meteor piston, right now I am holding off, the whole point of this build is to keep it all China and see what happens, once I get it running and work out the problems then I am planning on modified the saw. I will get an oem piston and rings, mild porting, squish to .020, slight advance on the timing. Once I get a good understanding of how the China parts work then I will start the modifying process, thanks for the help guys, I hope I'm not bothering people with all these questions.

 

[EB Saw]

I will see what picture I can get.

The problem with my spring was two-fold.

One: the diameter of the coils was to large to fit in the recess and allow the plastic protective cover plate to be put on - and that was without the rubber sleeve being put on the coils.

Two: the large anchor hook that mounts to the stud at the aft end of the spring - the attachment point needs to co-centric to the axis of the spring coils along the center axis of the coils of the spring (like the OEM springs). Mine was offset to the outside (outboard?) of the outside edge of the spring coils. This made the attachment stud too short.

I had the exact same problems, the hooks were not bent right and the coil was to large! I am ordering oem today and will take some pics of the old one.

 

[tbohn]

My brake spring did not have any issues. The brake works very smooth.

I did measure the 50mm cylinder from the kit vs. an OEM on the other 440 thread. Both of the cylinders had different lengths front to back when measuring the base to the squish band. I have it written down at home. I think the kit cylinder was 0.072 inches longer on the exhaust side and OEM was about half of that. Just shows you need to measure squish in multiple locations.

How do we get the two huztl 440 threads combined?

 

[Bedford T]

I reached out and got no answer on joining the threads. Maybe some with a good relationship with Brad might ask him if knows. he has been around and might know who to ask. My problem other than an email I don't know either of the owners

 

[EB Saw]

It was my fault, I have only been on this site, heck any forum site for the past 2-3 weeks, still figuring it out! I am all for getting them combined I just have no clue how, hopefully someone does. Sorry guys.

 

[tbohn]

My brake spring did not have any issues. The brake works very smooth.

I did measure the 50mm cylinder from the kit vs. an OEM on the other 440 thread. Both of the cylinders had different lengths front to back when measuring the base to the squish band. I have it written down at home. I think the kit cylinder was 0.072 inches longer on the exhaust side and OEM was about half of that. Just shows you need to measure squish in multiple locations.

How do we get the two huztl 440 threads combined?

After thinking about it some more, there's no way the cylinder walls from base to squish band are 0.072 inches different front side the back side. I will post the real numbers when I get home.

I guess I forgot how bad my memory is.

 

[EB Saw]

The numbers are in!!
Port timing, I have never done this before but feel fairly confident I got it right, if any numbers are way off I probably did something wrong, but I did read a lot about it and followed a step by step guide form the site.

With .059 off the base of the cylinder and the base gasket installed with a consistent squish of .031 here are the numbers.
ATDC exhaust 101 with 158 duaration
ATDC transfer ports 117 with 126 duration
ABDC intake 105 with 150 duration

Now using these numbers I can get close to what is was before I did anything to the cylinder.

With nothing off the base of the cylinder and the base gasket installed with a squish of .089 here are the numbers, again this is close I never actually recorded any numbers with this set up simply getting close with the numbers I came up with.

ATDC exhaust 96
ATDC transfer port 112
ABDC intake 110
Again I figured dropping he cylinder .059 is about 5 degrees on the wheel. Let me know what you think.