Little Chainsaw Engine

[HitmanV]

I'm trying my hardest to get this little motor running.

I have checked i have a spark, its pretty small and doesnt make a crack noise when it sparks. Maybe its a little weak?

I have made my own fuel tank where i can prime the engine by blowing into the tank through a black pipe, and fuel runs into the carb as i think it should.

I have tried to start with the choke open and closed, using a drill with a bit that kinda fits on the place where the normal pull starter would bite.

I do notice some fuel spitting out form the crank case where i opened it. Maybe it wont run if its not sealed 100%.

I am getting some good compression, it pops back if i try turn it with my fingers.

Please help, any ideas?

EDIT: sorry the photos are all sideways - ill take a video to make up for it.

 

[landuse]

Pics fixed. Are you sure that enough fuel is getting to the carb, or maybe too much and it is flooding. Have you tried putting a teaspoon of fuel in the plug hole, putting the plug back in and trying to start it. If it seems like it wants to start, then you have enough spark, and maybe fuel delivery is your problem.

Where is the fuel leaking out of the crankcase. That doesn't sound right

 

[HitmanV]

Where is the fuel leaking out of the crankcase. That doesn't sound right

i opened the bottom of the motor (i think its the crank case cover) it had a rubber paste seal that i cleaned off. So i suspect its not sealed properly. On the down stroke, new air is pushed into the combustion chamber, it could be escaping in the gap, pushing a little fuel/oil mix out with it.

Ill try your suggestion and put a couple drops of fuel in the chamber.

Thank you

 

[landuse]

If air is getting in through the crankcase, that might be causing the engine not to start

 

[Lucky7]

I literally just fixed one of those small chainsaw motors. It was a McCullough Power mac 35cc. I think I had the same problem as you that the fuel was leaking out the crankcase. I scraped it all off. Put some yamabond(gasket maker) on. Modded a spare key way (woodruff key) to fit. Put it all back together and it started in a 2 minutes. The broken woodruff key could make the spark plug timing all wrong. Maybe try a new spark plug. And I don't know if this is could make a difference but are you spinning the engine the same way it would normally turn if you pulled the pull start?

 

[HitmanV]

Maybe try a new spark plug. And I don't know if this is could make a difference but are you spinning the engine the same way it would normally turn if you pulled the pull start?

I'll try a new spark, and seal up the crankcase. And yes, i am spinning it in the right direction. At one point i didnt but, thats a risk you take when trying to start with a drill.

Thanks for the reply

 

[Lucky7]

Yes I have heard if there is a weak spark outside the chamber that it under the pressure inside the head could not spark at all. What do you plan on doing with this motor?

 

[HitmanV]

I'm torn between building a chopper for a 5yr old. or a RC airplane.

 

[HitmanV]

wierd, i found some gasket sealant in my garage. I don't remember buying it.

so i applied it and im buying new sparkplug today.

ive never started a engine before that isnt already mounted on something.

one other note: were would i find a belt that fits on that clutch

 

[landuse]

I have no clue where you would get a belt. I would start by looking at what it used to have. You can then maybe track down where you can get them. What was the clutch from?

 

[HitmanV]

It used to have a chainsaw belt, but thats not going to be safe to use. The clutch is the same that came out of the chainsaw.

 

[HitmanV]

Modded a spare key way (woodruff key) to fit.

I didnt know these engines had a woodruff key or what it even does. Where do i find it, and what should i check for?

EDIT: Oh i see it keeps the magneto fly wheel from getting out of sync with the piston position.
Luckily for me, the axel has a big groove in it that the flywheel sit on and it cant be changed. So im sure its still in time.

 

[landuse]

I didnt know these engines had a woodruff key or what it even does. Where do i find it, and what should i check for?

I think he is talking about the flywheel key. I think...

 

[Lucky7]

Yes I am, flywheel key, key way, woodruff key, etc.

 

[HitmanV]

i broke my starter, so i wont upload the video, its embarrasing,

building a new starter

 

[HitmanV]

Built a new starter, its working.

I used my angle grinder and a large bolt to shape a key that fits the starter teeth on the flywheel and used my drill again to start it. I first blow some air in my fuel tank, pushing fuel into the carb and then a quick burst from the starter and its going. It idles great.

Now i want to tune it so its running nicely.
I see a H and L screw ( i assume its for the fuel mix )
and another screw for the throttle min (idle throttle position)

what speed should it run at, and how can i easily measure it?

 

[landuse]

Built a new starter, its working.

I used my angle grinder and a large bolt to shape a key that fits the starter teeth on the flywheel and used my drill again to start it. I first blow some air in my fuel tank, pushing fuel into the carb and then a quick burst from the starter and its going. It idles great.

Now i want to tune it so its running nicely.
I see a H and L screw ( i assume its for the fuel mix )
and another screw for the throttle min (idle throttle position)

what speed should it run at, and how can i easily measure it?

I have some pdf manuals for those carbs if you would like me to mail them to you. They are for Walbro carbs. I think yours is the same. If not, the principles of carb tuning will be similar