MS 361 build will not start

[429p]

I have assembled an Farmertec MS 361 kit, first time for me.

The engine will not start. I might get a "burp" at first with the choke on, then nothing with the choke on or off. I waited a couple of hours, and then i do not even get a burp after trying to start again.

Spark plug is not wet. I do have a spark at the spark plug. I cranked the engine with spark plug out of the cylinder, and I see a spark.

1. I have tested the fuel tank. The tank holds pressure, and it does not hold a vacuum. I think this means the vent is working.
2. I pressure tested the carb through the input fuel line, and it holds pressure.
3. I blocked off the carb and the muffler port for the pressure test of the case, seals, and cylinder. I pulled a vacuum, and did the pressure test through the impulse line. Vacuum and pressure test shows good. I used the Farmer tec case assembly tool to join the case halves. The seals do not look prolapsed. i did replace the decomp valve with a Stihl decomp valve. Farmer Tec valved leaked.
4. i put a NKG spark plug on the cylinder.

I am going to go back and do another vacuum and pressure test.

I suspect that the impulse line is not pulling a vacuum or pressurizing the carb. Is there anyway to test this?

I could pour some fuel into the top of the cylinder to see if that will get it to start. I have tried this once, but i will try it again.

thanks in advance

 

[429p]

More information, I used the base gasket that came with the kit, and I did not check the "squish."

 

[Stem]

pour a small amount of fuel thru the carb & then try to start it? are the fuel & impulse hoses new oem?

 

[429p]

Stem, i will try the fuel in the carb trick. Fuel and impulse hoses are Farmer Tech that came with the kit. thanks!

 

[cuinrearview]

@afleetcommand has a vid I watched today that mentioned the carbs on those being inconsistent. I think. I was only half paying attention, but that should tell you something about the quality of his vids if they get my attention given the subject matter.

 

[Pincher]

Of the three kits I put together, zero percent of the carbs worked properly out of the box. Two of them I got to function, one has been a struggle.

 

[cuinrearview]

Of the three kits I put together, zero percent of the carbs worked properly out of the box. Two of them I got to function, one has been a struggle.

I'm starting to understand now. They're like buying a junk saw from a shop, only all of the cleanup is done, they're just ready to troubleshoot and fix.

 

[Pincher]

Stem, i will try the fuel in the carb trick. Fuel and impulse hoses are Farmer Tech that came with the kit. thanks!

For initial startup, the supplied farmertec hoses should work. Just check they dont leak and the passage is open when installed. Could possibly be pinched/kinked off. Many times it has been mentioned in other threads that metering springs are sometimes too long, too strong or just wrong for the application. Lever height should also be checked. Im not familiar with this kit, hopefully someone with real world experience chimes in soon.

 

[huskihl]

I'm starting to understand now. They're like buying a junk saw from a shop, only all of the cleanup is done, they're just ready to troubleshoot and fix.

Lol

 

[timberjack90]

When I had set the needle height I bottomed them out to count turns an the tips broke off the needle but I'm not very careful sometimes

 

[429p]

So I put fuel mix into the carburetor body. Still no start. So, this fuel shot into the carburetor should cover all the bases, right? Fuel , air, spark = running engine, or at least a short burst of life. What should I buy next for parts , or should I spend money on a professional diagnosis? Thanks

 

[Pincher]

Flywheel key shear?

 

[429p]

Flywheel key shear?

I have read about flywheel key shear. I would think you would not be able to crank the saw. The flywheel would just spin on the shaft. Can the nut and the tapered shaft hold well enough to turn the engine over with a sheared key?

 

[Pincher]

Can the nut and the tapered shaft hold well enough to turn the engine over with a sheared key?

Yes it can. The keys main purpose is to index the flywheel to crank for proper ignition timing. The taper fit is the main holding force. Does the kit flywheel have a cast in place key like a stihl ms361 or a separate key?

 

[429p]

Yes it can. The keys main purpose is to index the flywheel to crank for proper ignition timing. The taper fit is the main holding force. Does the kit flywheel have a cast in place key like a stihl ms361 or a separate key?

The key is separate. Slot in flywheel, and slot in the shaft.

 

[Ksaws]

Hello all. New here. Been lurking for a while

Had this exact problem on my 361 build and discovered the spacer that goes around the intake boot the carb bolts up against was a whisker too thick and prevented the boot from sealing to the carb properly. Thinned it a bit on a belt sander (I know the implications of mentioning a belt sander around here but don't worry, no cylinders will ever get near it....) and problem went away.

Worth trying. And btw it runs quite well for something with no oem parts. It's my loaner saw so I'm not too fazed if it craps itself.

Oh and the tank vent needed a hole made in it as it was fully sealed..

 

[429p]

Yes it can. The keys main purpose is to index the flywheel to crank for proper ignition timing. The taper fit is the main holding force. Does the kit flywheel have a cast in place key like a stihl ms361 or a separate key?

I will remove the flywheel, and check it out. Thank you.

 

[429p]

Hello all. New here. Been lurking for a while

Had this exact problem on my 361 build and discovered the spacer that goes around the intake boot the carb bolts up against was a whisker too thick and prevented the boot from sealing to the carb properly. Thinned it a bit on a belt sander (I know the implications of mentioning a belt sander around here but don't worry, no cylinders will ever get near it....) and problem went away.

Worth trying. And btw it runs quite well for something with no oem parts. It's my loaner saw so I'm not too fazed if it craps itself.

Oh and the tank vent needed a hole made in it as it was fully sealed..

I pressure/vacuum tested the cylinder, carb, and seals last night with no leaks found. I would have guessed that if the intake boot was not sealing, I would have been able to find a leak- but who knows? I am scrambling to find any solution right now. I will try your suggestion of sanding down the spacer around the intake boot. Thank you.

 

[backhoelover]

When pressure and vac test you need to turn flywheel to make sure seal holding under movement. This will also show impulse on the mity vac tester gauge

 

[MustangMike]

I have not done a 361 kit, but have done several 440 and 660 kits.

The carbs that came with the 440s were such crap that I stopped trying to use them, so that may be a problem.

But based on what you are reporting, I think the spun crank is the most likely problem.

As previously mentioned, the key just indexes the flywheel, friction between the flywheel and crank should hold it in place. But some of them are not machined as they should be and move a bit. You will generally not be able to notice it until you remove the flywheel.

If you have spark, and you do not get a kick when you pour a little fuel down the carb, my guess is the flywheel has moved.

Always make sure both surfaces are very clean before you assemble them (I use brake cleaner on them) or they will spin. They will also occasionally spin even if you do everything right, the fit on these kits is just not as good as OEM.

Good luck with it, and keep us posted … you will get it to work!

Also, you should always check the squish, and make sure the bevels on the cylinder ports are OK.