MS440 Build w/ thick 17mm crank balanced to 56% HD Spring, HD Pin. HD Pin? Whats that?

MS440 - 50mm bore x 38mm stroke
Thick 17mm crank (normal thickness is 15.5mm) balanced to 56%
HD Spring
HD Pin
(blaming @ImpulseRocket for this one)I did this on the 49mm 72cc "100notcc" due to this being the cheapest engine only listing. Around the same price range are 66cc in REALLY bad shape, such as thick black paint everywhere. I was able to adjust the timing on the 49mm cylinder, modified the stock head and sold it. I only needed the case and the other goodies, even though I have boxes of parts, it was either pay $76 for an engine only listing, or pay around $40 on a case only from CDH. There is a $25-$30 listing for just the case, it even says "8mm" however everyone receives 6mm cases.

Decking the case was the longest process by far. I put the piston at TDC and had roughly 2.5mm of the skirt in the intake port. I then took the piston to BDC and about 2.5mm was open from the top of the piston crown to the top of the intake port (cross talk) I decked the case to 2.2mm and filled the M8 crank case stud holes with aluminum 6061 hex bolts, cut the excess off so it is flush with the case, then put JB weld in (must use aluminum and no other metal) It made zero sense to add JB Weld first then to deck the case. It would be a complete waste on top of JB weld absolutely RUINS sandpaper. I took marker and drew strokes over the deck opening. The purpose of this is so when you sand it, you can see if you have high spots or low spots. If you're sanding it and there is a section where the marker is being removed but the rest of the deck is covered in marker, then you know that section is a high spot.

I bought the cheapest 1.5mm solder to measure squish. Using Fel-Pro 3025 (1.6mm) and the squish was so high that the piston crown wasn't biting the solder. I then made a base gasket out of Fel-Pro 3046 (0.8mm) and my squish was around 0.85mm which is perfect.

I need to make a very important note. When you drill the case to make new tapped holes to mount the saw cylinder, you MUST stick with whatever you're going to use as a base gasket. I made a gasket out of Fel-Pro 3025 (1.6mm) and it was so thick that each case halve couldn't "lock" into each other. I went down to 3046 (0.8mm) and it was perfect. I drilled my holes and tapped them. If six months from now, I decide I want to use gasket maker, I will run into issues because that would bring the case halves closer into each other, and as a result where my holes are won't align with the cylinder. I must stick with 1/16 aka 0.8mm thick gasket material for life.

HD Spring is this one here which is rated for 474lbs. Keep in mind, once you bore out the spring, shave material off etc, you do lower the max load. Stock spring is 275lbs or so, and the HD BBR one is 375 I think. I had a machinist bore it out as the "cups" on each end are 20mm OD. Do not shorten it, whatever you do. The OD was slightly larger than what the case was meant for and rubbed slightly. As opposed to shaving off material inside (the clutch bearings rely on the taper to be seated) so I took an M14 x 1.00 nut, put it on the shaft and spun my drill on the lowest setting. It shaved off the material where it was rubbing, so I went back in the case and shaved only where the rubbing was and where it needed to be shaved, instead of just shaving everything.

Now, @ImpulseRocket brought up a good point that I didn't consider. All these HD spring upgrades, but people forget that the parts on the shaft (the pin which is honestly the heartbeat of the shaft) isn't designed for that strong of a spring. I bought some super strong steel rod, and cut it down to 4mm x 20mm and made an HD pin. The pin in the stock clutch assembly is 3.7mm and literally would fall out of the threaded cup. This is a recipe for that pin to bend slowly overtime until it looks like a broken arm.

Lastly, I went with studs instead of the typical socket cap screws. I did not feel comfortable especially during the "testing phase" loosening and tightening black oxide steel hardware in super cheap chineseium. I did read it is ideal to actually drill and helicoil the hole so that your hardware is tightened against steel (stainless) as opposed aluminum. I red threadlocked the studs and bought M5 coupling nuts as it is easier to thread those on as opposed standard hex nuts.

Any questions?

1.65" CNC Mount was needed. I wasn't able to fit my exhaust in there. I was really shocked at the result, I now have more than enough room
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Just flexing having a thick 17mm crank. I had a 17mm - ZL-40mm and it was my best preforming china doll, most likely due to increased compression.

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Thick cranks Runwell thin.png

Transfers 1.jpg


This is the HD Pin I was referring to
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I widened the face of the port and not the port itself as I didn't want to affect timing. If I didn't remove material from the face of the port, then the port would block my intake manifold.

intake.jpg

440 front.jpg

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Jesus dude, use context clues. Nobody is blaming you for anything.
Try using an "LOL" when joking, like I do...Rocket is a much more serious dude than I am and may not have known that, that was a contextual joking type of referrence...lol.

I'm the one thats the class clown around here...lol...Rocket is the more cerebral, serious one...lol.
 
Try using an "LOL" when joking, like I do...Rocket is a much more serious dude than I am and may not have known that, that was a contextual joking type of referrence...lol.

I'm the one thats the class clown around here...lol...Rocket is the more cerebral, serious one...lol.
I will use lol and play nice with others
 
Update.

It runs very well. I was able to crack 30mph at half throttle, but to be honest, I built it for more low-end power. I'm able to scale steep hills no problem. There are steep hills my 49mm would be on the brink of stalling out on, that it can just go up 25mph no problem. I did have some nasty problems at first.

MS440/460 and/or MS660 exhaust leak like crazy. They're a box, and then a cover that goes over it. I went to an MS361 exhaust which is a sealed unit and doesn't leak.


I absolutely love this. I haven't had the balls to go WOT, but just being able to scale super steep hills is good enough for me.
 

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That would probably scream with a tuned pipe

I am open minded to it when it gets warmer out. The YZ85 appears to pair well with the 440. I don't want to just throw a random pipe on to say I have a pipe, I want something that will work in harmony with the exhaust and transfer durations

I needs a saw carb.
For a china doll (40mm intake) I do have something nice for you.

This adapter states "47mm to 40mm" however it is inaccurate. It is 48mm to 40mm, and I own two of them for when I used to run a PZ20.

The Stihl 090 carb is a 46mm mount. Making the 48mm side more oblong would allow you to mount it, and then of course having to drill a pulse line. I have considered running a saw carb, but I'm still not fully understanding how instead of a main jet like in float bowl carbs, just a turn of a screw fixes it. It sounds to me you only have two screws (idle and upper throttle) which makes me wonder "what about in between" how you would have a needle to tune that.


Then this adapter is for Walbro carbs. BBR sells it for $40! haha

I am uncertain of the dimensions (aside from the 40mm mounting points) however this allows you to run a piston port setup.

 
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Try using an "LOL" when joking, like I do...Rocket is a much more serious dude than I am and may not have known that, that was a contextual joking type of referrence...lol.

I'm the one thats the class clown around here...lol...Rocket is the more cerebral, serious one...lol.
Jesus dude, use context clues. Nobody is blaming you for anything. If I made something on a suggestion you made, and something went terribly wrong. Okay, maybe someone is really blaming someone.
Can confirm. It's not that I am more serious. I am just far more literal and direct than most.

My brain is wired different from "normal" people, so much like people with dyslexia can't read without difficulty, I often struggle to pick up on some levels of innuendo or other types of humor. Not that I don't love a good dose of sarcasm mind you, but in my life I have found it easiest just to stick with direct honesty when I am unsure of what I am dealing with.

No need to take things to 11 when a person is simply asking an honest question. Replies like "Jesus, dude, use context clues" aren't very called for, especially when you never answered prior to that point after my initial post. Following it up with "Sad this has to be explained" is also completely out of line, and rude. Your response was more like that of a person who got annoyed by somebody repeating the same thing over and over after you answer, but you never answered. Try escalating things more gradually than 1 queston and first answer and a subsequent post BOTH before I even had a chance to respond, are demeaning and insulting.

Uncalled for.
 
Can confirm. It's not that I am more serious. I am just far more literal and direct than most.

My brain is wired different from "normal" people, so much like people with dyslexia can't read without difficulty, I often struggle to pick up on some levels of innuendo or other types of humor. Not that I don't love a good dose of sarcasm mind you, but in my life I have found it easiest just to stick with direct honesty when I am unsure of what I am dealing with.

No need to take things to 11 when a person is simply asking an honest question. Replies like "Jesus, dude, use context clues" aren't very called for, especially when you never answered prior to that point after my initial post. Following it up with "Sad this has to be explained" is also completely out of line, and rude. Your response was more like that of a person who got annoyed by somebody repeating the same thing over and over after you answer, but you never answered. Try escalating things more gradually than 1 queston and first answer and a subsequent post BOTH before I even had a chance to respond, are demeaning and insulting.

Uncalled for.
My bad for being unnecessarily harsh
 
My bad for being unnecessarily harsh
It's all good! I grew up around some very harsh people in an industry that doesn't treat people with kids gloves. I have a thick hide, so I can let most stuff just bounce off and not affect me personally. Still, I appreciate the apology. Thank you.
 
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