Help unlocking an MS170

[Haywire Haywood]

I'm playing with an MS170 that belongs to a friend of mine. We wanted to mod the muffler and solve it's hard starting nature with a fully adjustable carb. We ordered the one that Brad said he used but we can't keep it running. It's got a new carb kit. The only thing fit-wise that's different is that the stock carb was the intellicarb and the new one isn't. I assume that we have to plug the spot in the air box where the other carb's snorkel went to avoid an air leak, but the hole there is tiny. I figured it would run at least halfway decent without plugging it.

Brad, what carb settings did you end up with before you modded the muffler? This time I did the smart thing and didn't mod the muffler till we got it running right on the new carb.

thanks,
Ian

 

[blsnelling]

Not blocking the Intellicarb port won't give you an "air leak" per say, but it will allow unfiltered air into the saw. Yes, you should block it off, but it won't affect the starting and running of the saw at all.

I'd set the screws at 1 turn out. I'm trying to remember the impulse passage on the saw and carb. Does the impulse come through the intake boot against the mounting flange of the carb, or is it a seperate hose fitting on the carb?

 

[blsnelling]

I just went back and did some reading in my old thread. You've got to modify the impulse passages. LINK

 

[Haywire Haywood]

It comes through the flange.

Ian

 

[blsnelling]

It comes through the flange.

Ian

Did you use a WT215? The impulse passage is not in the correct location. You have to modify the carb. The pilot hole is already there, I think blocked with a brass plug. You'll also need to block the original port. You're not getting any impulse signal to the carb, and therefore, no fuel.

 

[blsnelling]

I found all of the below farther back in that same thread.

1. Remove the brass plug from the impulse passage on the rear face of the WT215.
2. Plug the original passage with JBWeld or something similiar.
3. Install the carb. Do not use the Intellicarb cover from the original carb.
4. Block the hole in the filter housing where the Intellicarb port inserted.
5. Drill holes in the plasic for access to the screws.
6. Install a small screw behind the throttle linkage, blocking the slot, so that linkage will have enough travel to go WOT. Do not bend the linkage or the carb may not fully return to idle.

Pull the brass plug circled in red and block off the hole circled in yellow. Without pulling that plug you have no impulse signal. Make sure you block that Intellicarb port in the housing though. It actually enters the clean side of the filter through that little slit. If you don't, you'll end up with garbage in your engine.

 

[Haywire Haywood]

I just went back and did some reading in my old thread. You've got to modify the impulse passages. LINK

Ok, I see what we did wrong last time. (this has been under the bench for a couple months)

I popped the brass plug out but didn't plug the old port. I squirted some permatex in the hole now. When it sets up I'll try it again.

thanks,
Ian

 

[Haywire Haywood]

How much muffler mod did you give the little tyke?

Ian

 

[blsnelling]

Muffler Mod

 

[Haywire Haywood]

Ok, plugging that hole seemed to make the situation better. It runs now, badly, and only at like 1/2 turn out on the low speed. Any more open than that and it dies. wadda ya think?

Ian

 

[Haywire Haywood]

Figured it out. I took the carb off to check the metering valve to see that it was set right and to see if the gasket/diaphragm was in the correct order and discovered it was stuck... open. When I put the new needle in, I had the pivot pin all the way over against the right side under the screw. It wasn't sitting completely on the opposite support shelf and had the lever in a bind. I loosened the screw and slid the rod all the way over to the left, tightened the screw and all was good.

Ian

 

[blsnelling]

Glad you got it figured out Ian. Isn't stuff like that a pain in the butt?!!

 

[Haywire Haywood]

Especially when you KNOW it should work and it just doesn't want to cooperate.

Ian

 

[pgg]

On a small chainsaw, a fixed jet carb is way better than a twin jet adjustable setup. The fixed jet carb gives better throttle response and more power. Changing from a fixed jet carb to a twin jet adjustable is a down-grade in performance. The 'fixed' main jet has a better more efficient fuel delivery. They're a better carb for a small hi-strung motor. The extra response and power is very noticeable. The 'fixed' jet is fully replaceable to whatever size best suits. The low (idle) circuit is also steadier and more reliable.

 

[Haywire Haywood]

Horse patties.

 

[pgg]

Fixed jet carbs whip twin jet carbs for response and power, swap em' round a few saws and see for yourselves

 

[blsnelling]

On a small chainsaw, a fixed jet carb is way better than a twin jet adjustable setup. The fixed jet carb gives better throttle response and more power. Changing from a fixed jet carb to a twin jet adjustable is a down-grade in performance. The 'fixed' main jet has a better more efficient fuel delivery. They're a better carb for a small hi-strung motor. The extra response and power is very noticeable. The 'fixed' jet is fully replaceable to whatever size best suits. The low (idle) circuit is also steadier and more reliable.

How did you come up with that?

 

[MotorSeven]

uhmm Ian....it's "horse apples" or "cow patties" unless the horse has had too much bran.
I had a 170 in my hands at the pawn shop the other day. It's marked $70. I took it out and ran it, but something didn't sound right and it was leaking oil all over the place. The little voice said, "walk away"


RD

 

[blsnelling]

The little voice said, "walk away"


RD

Was that your wife, or your better judgement

 

[MotorSeven]

No, it was judgement.....I swear.....
It had to be, I was given my tea bags for the pawn shop trip.
Had to return them upon arrival at home.......:chatter: