Mcculloch 4hp no start

[retiredoz]

The older style Tecumseh with two adjustment needles is pretty close. The pre-'60 3.6 Scotts used a Tillotsen, and I never could figure why they stopped. MD12A for a while, MD35A, there may be others that might work.
If you have an old yard equipment repair shop within reach, they may still have Walbro LMGs, I'm pretty sure they had widespread application..

[John8504]

So I ended up finding a carb for a 70 3.5 mcculloch on eBay and I'm just waiting for it to arrive and see what happens with that. I hope it works.

[retiredoz]

Some Ebayers know not what they have. McCulloch officially spit the bit in '69, and to my knowledge never produced a 3.5. But whatever it is may be close enough..

[John8504]

I looked at it and they might have the year wrong but it looks identical to the once that should be on mine. It'll be here Friday, so we shall see

[John8504]

This is the one I purchased.

[John8504]

So I put carb on and adjusted needles. Still no start. I took crank cover off to check the reeds and the reed stops. They seems to be in good shape. Made new gaskets and out back together. Still same results.

At a loss right now.

[retiredoz]

Are you sure you have fuel flow ? that little eco-unfriendly little button on the bowl is a drain, push it and see if it leaks. If it does, you're OK. Get yourself a can of spray starter fluid, and give it a short burst in the carb throat, and crank. If still nada, I'd check compression.
You could also just try cranking with the choke closed ?

[John8504]

Yeah I've done everything I know how. I rebuild the mcculloch chainsaws as a hobby and I have 4. So I know that the engine is a modified chainsaw. I have that going for me. The carb is a glorified lawn mower carb. When I got the carb in, I took it all apart to see about cleaning and it was perfectly clean. The drain on bottom does its job and I have fuel coming out. (Waiting on a carb kit for it since the drain gasket is bad and causing a leak.). I have tried every throttle position, spraying fuel past the reeds,spraying fuel into cylinder and reinstalling spark plug. My points gap is a .20 and the key is not sheared. My compression is 92. I'm just baffled to what could be going on.

[John C]

Does the magneto have a cam to operate the points? It could have been installed upside down.

[david bartlett]

Is the exhaust clear? I had a two-cycle pump that would not fire one time. Wasps had plugged the exhaust with mud.