Mcculloch 4hp no start

[john8504]

#73952

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.

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[retiredoz]

#73955

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]

#73997

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.

[jcrigan]

#74008

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

[david-bartlett]

#74009

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

[Mumbles]

#74016

I have a good running example of one of these motors sitting in the garage and I can always pop the cover off to compare it to yours. I might see something you’ve missed. It doesn’t have points in it though as it came with a Nova II module already installed.

[john8504]

#74021

It sounds clear and strong when I pull cord. The points are right as I look at them. I’ll take a pic tomorrow and post here.
Yes cam is metal and is fixed. It operates appropriately.

[john8504]

#74073

Here’s pics of ingnition. How about do I check exhaust for it being clogged?

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[Mumbles]

#74075

I’d be more concerned about the condition of the ignition components than the exhaust.

The points should be removed and cleaned of any dirt or scale and polished until they are shiny. The electrical connections look corroded to and the condenser has probably seen better days. This mag might fire a plug without a load on it but once the plug is reinstalled and under compression, it may not have enough oomph to do the job.

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[john8504]

#74077

I’ll take them off again and rewire the connections and see what happens. I did take he points off once and used some steel wool to clean them up because they were corroded pretty bad

[john8504]

#74078

Where might I find a new condenser?

[Mumbles]

#74079

You want them smooth and shiny with no scratches on them for best results. Using progressively finer grits of wet n dry paper will give good results. Usually I start with 4-600 depending on the condition and finish up with 1500 but 800 will give good results to. A used piece of paper with the sharp tooth on it worn down works good to.

[Mumbles]

#74080

quote John8504:

Where might I find a new condenser?

That’s a Phelon mag with cap P/N PG or FG-7270? I’d try a Google search first or place a want ad in the Free Classified section here or if you can find the uF rating for it, replace it with a Vishay cap with the same or close uF rating.

Quality replacement Vishay capacitors can be found here at Digi-Key with ratings of 0.10, 0.15, and 0.22 uF to cover most outboard magnetos. Click in the upper right to change your country/location.

https://www.digikey.ca/products/en?x=23 … =bc2607-nd

https://www.digikey.ca/products/en/capa … =bc2608-nd

https://www.digikey.com/products/en?ven … =bc2609-nd

[john8504]

#74102

I did pull points off again and there was a burn mark. Also upon inspection, they do not seat flat with each other. I guess I need to start with another set of points and condensor

[Mumbles]

#74107

Burned points are a sign of a bad cap. Try cleaning and polishing the points first and then source a new cap.

I found the original Phelon cap listed and it is P/N FG-7270 and is rated at 0.16 – 0.18 uF. (Microfarads)