Big bore and stroked Husky 395 build.

[srcarr52]

I thought of this project in May of 2014 when building a lot of 394's. I had bought an NWP 395BB top end to go on a 395 builder carcass and thought why not make it a stroker too. So I bought a 2100 crankshaft and started to look at what machining needed to be done.

Flywheel side of crank needs machined to fit 395 flywheel.


Cases needs some clearancing.


Then life got busy and the project went to rot in a box. Said box was moved from the garage of my old house into the basement of the new house were it rotted in climate control for 2 years... until a few weeks ago.

 

[srcarr52]

I started with machining the crankshaft. I was worried I'd have to grind them but they cut pretty easy with a good carbide insert.

I dialed in the taper with a junk 395 crank. I was lazy and used a die to cut the threads instead of single pointing them with the lathe.

I also built a quick and dirty way of holding the crankcases on the mill to enlarge the OD seen in the foreground of pic #2. I made 2 cranks... just in case.

 

[Frank bierce]

This is gonna be awesome!!

 

[mgr1]

Looking forward to this build.
Are you gonna surface hardening the cranks again after there date with the lathe?

 

[Marshy]

Sweet!
What's the difference in stroke? What will the final displacement be?

 

[srcarr52]

Next up was clearancing the cases, a cnc mill makes short work of this.



Short video of cutting the case until I had to set everything down to increase the feed speed and hold the tank side to keep the part from ringing. Also I'm trying to use the vacuum to keep the mag chips off my mill but it's failing due to a plugged hose. I gave me a little jump when it started to ring.

 

[srcarr52]

Looking forward to this build.
Are you gonna surface hardening the cranks again after there date with the lathe?

They were surfaced hardened but not very thick, probably more for the bearing surface than the flywheel taper. So I wont be hardening them.

Sweet!
What's the difference in stroke? What will the final displacement be?

Oh yeah... I should probably give some background.

395 stock is 56mm bore, 38mm stroke for 93.6cc.

2100 crank is 40mm, +2mm. 395BB is 58mm, +2mm. For a total of 105.7cc. +12.1cc!

 

[srcarr52]

I needed to make a spacer to raise the cylinder for the increased stroke. I quickly made a CNC program to cut them. The simple conversational programming of my Milltronics mill makes it pretty easy, pocket here, pocket there, there, there and there... mill a few lines for the outside and poof you have a spacer. I milled the two opposite sides with curves to keep the part stable, and then cut it free with the straight cuts.



Total machine run time was around 7 minutes. I sped up the video so it wasn't so boring.

Again... I made 2.

 

[srcarr52]

Some port pictures... big transfers!

 

[srcarr52]

The castings on these BB cylinders suck, the fins are almost blocked off with casting flash and misalignment of the forms. I took 13g just off the outside of the cylinder. It got a lot lighter after that from porting... but I forgot to weigh it finished.

 

[srcarr52]

Mufflers... how do you make 106cc breath? LOL, a big muffler outlet.

Started with a 4-1/2" angle grinder and a cut wheel.


Then used a sheet metal seam ripper in an air hammer to get rid of the rest of the original outlet. Again... doubling up on work for the next build.


I didn't get a good picture of the deflector, but you can sort of see it here fully assembled... waiting on carb doctoring. It's also giant, but has a screen.

 

[EvilRoySlade]

Did you calculate shim thickness just to fit the piston then plan to cut your jug to fine tune the timing and squish?

 

[srcarr52]

Did you calculate shim thickness just to fit the piston then plan to cut your jug to fine tune the timing and squish?

Yes, I wanted to skim cut the cylinder base to make sure it was flat, so I aimed the spacer slightly loose. After cutting the squish my desired amount I had to knock 0.012" off the base to make the squish clearance perfect.

 

[Marshy]

This thing going to be running today?

 

[srcarr52]

I'm out of pictures so we'll just cut to the video of it running. It was a rough day trying to get to testing. I ran 3 different coils before I found a suitable one. I still think this one may be loosing sparks at high RPM but it wasn't as noticeable as others with the timing light. I have a known good coil that I can pull off my other 395 some other day. With the timing light on the saw I also noticed the china 394/395 coils are much different timing than an OEM, not a good deal.

 

[EvilRoySlade]

So you didn’t cut with exhaust timing as a target? Or you must’ve run your program and that’s how you got your target squish removal. It’s been a while since I played with it.

 

[srcarr52]

So you didn’t cut with exhaust timing as a target? Or you must’ve run your program and that’s how you got your target squish removal. It’s been a while since I played with it.

I used my Excel sheet and split the difference with the intake and exhaust so I'd have room to clean up both. In the end I should have dropped the jug a little farther so I could aim the transfer ports a little more. The AM cast transfer actually aim down in the bore and I didn't catch that till I started grinding on the transfers, right now I suspect they are too flat. More run time and piston wash may tell the truth.

 

[rocco490]

I like the idea of this a lot with just the stock 395 piston and cylinder and the 2100 crank. awesome build!!!!

 

[drf256]

Amazing work as usual Shawn.

 

[Time's Standing Stihl]

Buuurp