Huztl MS 440 Initial Impressions, and Build

[Bedford T]

Dswensen I posted right after your post and it's clear I was addressing your written doubt. But if you need a red line I will draw it for you.

Been many posts about people having trouble with various things that were not obivious and resulted in low compression readings. So your conclusion was puzzling and I asked. Further your throttle not being operational is unfortunate

 

[EB Saw]

Okay so, I have about 10 to 15 min of tuning in the garage and it's runnig okay, I am having issues with the carb, the idle adjust really doesnt help at all, the adjusting screw is to small so even when you bottom the idle screw out it still isn't enough, and it takes half the stroke to even touch the throttle lever. It is obviously a tolerance and quality issue. I did however get it to run and idle okay, I can't get it to settle anymore than 3200, but throttle response is good. I let it idle for a while and got it warmed up, I have it extra rich for the initial runs just to get all the beargs lubricated, i didn't want to tune the high speed just yet but I did get it to 15400 for a secound. That is just with the 1 turn out on adjusters, she creamed and really smoothed out, the vibrations on this saw compared to my 441 is insane, probably something I will get used to. Obviously I will fatten up the high speed when I start it next but wow it pulls.
As for the carb issue I think I am just going to find a used oem, and rebuild it, something like a carb you really need things to be precise and from what I have gathered the ones from china are not.
Everything else is working good though, really impressed with it!

Off topic a little but, on the clutch side, what seals the shaft off so crank case pressure can't just escape. I know there is a seal there and the little seal bushing piece, there is no seal on the bushing, air I would think would just travel through the bushing, no? I really don't know it seams the ms 440 and 460 are this way and I was wondering how it seals.

 

[Bedford T]

Eb Did you pressure test your case?

 

[tbohn]

Ni

Nice! Mine came with tapered bar studs. The non-tapered ones require a little more fussing when installing and tightening the bar. Also, the bolt head that holds on the silver bar guide looks like it is too large diameter. It will probably interfere with the slot in the bar. Watch for this. It could prevent solid tightening of the bar. They do have a smaller bolt but most of the kits that I have received have the large one. You can replace it or grind it down some.

The photo shows the bolt head sticks out past a straight line between the bar studs. I did stick a bar on and it did NOT create an issue. I had a few of my 660 kits where the bar did not fit past the bolt head and I couldn't snug up the bar.

 

[blsnelling]

The photo shows the bolt head sticks out past a straight line between the bar studs. I did stick a bar on and it did NOT create an issue. I had a few of my 660 kits where the bar did not fit past the bolt head and I couldn't snug up the bar.

The correct bolt has a much smaller diameter head.

 

[EB Saw]

Eb Did you pressure test your case?

Yes, and there was a slight air leak at the bushing the seal was fine, I decided to leave it because I saw no other seal in the IPA and there was nothing else I could have done, so I just built it, anyone know how it seals.

 

[tbohn]

Anyone ever use a Forester platinum bar? I think it's going on the 440 when my 52mm cylinder and throttle linkage arrives.

 

[EB Saw]

No but I purchased there 5 rivet bar and it should be here tomorrow!

 

[tbohn]

And here is a photo of the tapered bar studs.

 

[Bedford T]

i would not run it again. look at the ipl. well how does it seal..cant wait till i get mine so i can figure that out

 

[blsnelling]

There is only one seal. 19 supersedes 18.

 

[EB Saw]

There is only one seal. 19 supersedes 18.

I got that but what seals the little collar from air going between it and the crank shaft.

 

[Ozhoo]

Yes, and there was a slight air leak at the bushing the seal was fine, I decided to leave it because I saw no other seal in the IPA and there was nothing else I could have done, so I just built it, anyone know how it seals.

I use a little loctite 515 on the inside of that sleeve. Never had one to leak that way.

 

[EB Saw]

I use a little loctite 515 on the inside of that sleeve. Never had one to leak that way.

View attachment 551751

Yes that is what i mean, part 11, thank you!!, but it is spinning how does the Loctite seal? Hey if it works it works, i might have to give that a try, do you think motoseal could work as well.

 

[Ozhoo]

Yes that is what i mean, part 11, thank you!!, but it is spinning how does the Loctite seal? Hey if it works it works, i might have to give that a try, do you think motoseal could work as well.

Use what you have. You should grease the outside of the spacer as well.

 

[EB Saw]

Thank you Ozhoo, i will give that a try. I purchased another cheap Chinese carb for 12 bucks delivered in two days so i can see if its all of them or i just got a dud, we will find out. I will seal up that crankshaft and pressure test it again and with the new carb it should work, the air leak could have been destroying my tuning and hopefully the new carb fixes it. If not i will buy an OEM then i have no excuse to get this thing running perfect.

 

[blsnelling]

Did you have the clutch installed when pressure testing? If not, the bushing will not seal. I would also put a thick grease between the crank and seal just for good measure.

 

[EB Saw]

Okay, so i got the case ready to test. Held 8 psi fine and 8 whatever vacuum is measured in.
I took the little collar/spacer out and cleaned it then added moto seal to the shaft and slick honey to the seal surface. Let it set up for 15 minutes then tested, while testing i turned the crank 3 full revolutions no loss of air, good to go, thanks guys for the help. I hope that was my problem but on Thursday when my new carb arrives we will see.

 

[blsnelling]

You're going to have fun if you ever have to remove that seal! Tightening the clutch against it should seal it. If not, a little grease would.

 

[tbohn]

I THINK that because the squish band is so narrow on these cylinders, excessive squish velocity is not really an issue.

At 30 mils squish, 13,500 RPM, and assuming the squish band is basically parallel to top of the piston, the squish velocity is <15m/s. At 20 mils its less than 20 m/s.
(I just received my internet PhD on squish velocity this afternoon!)

I refined the squish velocity calculation. Here is a screen shot of the calculations. The max squish velocity occurs at 338 degrees AFTER TDC (22 degress BTDC). This calculation is just using math on the given geometry. There are several assumptions like the treating the squish band geometry as a simple ring that make these approximations. That said, it does indicate that squish measurements above 20 mils should not create an issue with squish velocity. Most of my internet research suggested that you want to keep squish velocity less than 30 meters per second.
You do want high enough velocity to get good mixing but not too high that it impacts the combustion process. You also do not want pre-combustion due to high pressure. I am not smart enough or interested enough to learn more about these topics.
My point is don't worry about it!