HELP Please...it caught fire

[inline300]

Well fellas

Figured Id post what I learned, maybe someone one day can use the info to save theirself 35 bucks. :biggrin:

Earlier I mentioned the plastic shaft that holds the choke butterfly, melted. I got to looking at it, remembered someone give me a couple weedeaters, yeah I know, sounds odd. I remembered the choke and throttle shaft on the weedeaters were fairly long, considering the ports themselves are not big at all.

Long short, if you have the choke butterfly off the lawn mower carb, you can use the brass throttle shaft off the weedeater and the spring off the weedeater choke shaft, combined with a hacksaw, drill bit and about five minutes, to make what will appear to be an OE product. :biggrin:

 

[briggs]

is the mower running now

 

[inline300]

I was hoping someone would sell a replacement gear and not have to buy the entire assembly but apparently, they do not.

My way of saying, no I havent bought the parts yet but soon.

Ill let yall know how it does.

 

[inline300]

Parts still havent arrived...imagine the shop will get them tomorrow.

I was able to get another push mower running.

Someone give me a yardman 6hp I think. It had sat in the rain for years, no air cleaner cover, so it was full of water.

Checked compression, zero. Took the head cover off, noticed the intake valve was seized. After much prying and wigglin and curse words, it came out, I cleaned it, stuck it back in, threw the head cover back on, I didnt even put a new gasket on it, changed the oil. It fired right up. :laughing:

I also got an old self propelled snapper mower, that thing was rotted and seized all over, think it was a 4hp engine, wonder if anyone would buy/need parts off the engine?

 

[inline300]

I have good news and bad news.

Good news:

Governor is in place. Engine fired right up. Everything looks clean and shiny and almost new. No oil shooting out the pvc box. :laughing::thumbsup:

Bad news:

Engine runs at a very very low rpm than youd expect.
If I remove the airfilter/cover (which is brand new), the rpms will increase to what I consider normal but still not quite as powerful as Id expect once the blades are engaged.
The little pvc box or whatever you wanna call it now vents directly to the atmosphere, I disconnected it from the air cleaner.
Sure enough though, if I remove the airfilter/cleaner, the rpms will shoot up, put it back on, they drop down, ya almost think its gonna die but it keeps on running.
Choke operates correctly, as does the throttle blade/linkage.
I adjusted the governor best I know how, by setting the throttle lever to fast, making sure the choke wasnt engaged, loosened the governor arm, turned the governor shaft clockwise as far as it would go, tighten the governor arm to the shaft.

So it would seem to me, that its running rich or perhaps theres another issue??

I checked the deck bearings, blades move freely, belt is routed correctly.

All I know to do at this point, is check the compression psi again.
Clean out the carb one more last time.

With the air filter/cover in place and wide open throttle, I tried to adjust the air screw on the carb, it made no difference whatsoever. Thinking thats a clue and maybe theres junk in the carb or perhaps I missed it before. New fuel filter is in place, lines and tank are clean.


Something makes me think poor compression but I dont wanna jump the gun and have it resleeved or bored, hell, Im not sure what is the standard procedure on these small engines, bored or sleeved?


Any suggestions welcome.

Thanks

 

[jhwentworth]

I have good news and bad news.



Engine runs at a very very low rpm than youd expect.
If I remove the airfilter/cover (which is brand new), the rpms will increase to what I consider normal but still not quite as powerful as Id expect once the blades are engaged.
Sure enough though, if I remove the airfilter/cleaner, the rpms will shoot up, put it back on, they drop down, ya almost think its gonna die but it keeps on running.
Choke operates correctly, as does the throttle blade/linkage.
I adjusted the governor best I know how, by setting the throttle lever to fast, making sure the choke wasnt engaged, loosened the governor arm, turned the governor shaft clockwise as far as it would go, tighten the governor arm to the shaft.

So it would seem to me, that its running rich or perhaps theres another issue??

I checked the deck bearings, blades move freely, belt is routed correctly.

All I know to do at this point, is check the compression psi again.
Clean out the carb one more last time.

With the air filter/cover in place and wide open throttle, I tried to adjust the air screw on the carb, it made no difference whatsoever. Thinking thats a clue and maybe theres junk in the carb or perhaps I missed it before. New fuel filter is in place, lines and tank are clean.


Something makes me think poor compression but I dont wanna jump the gun and have it resleeved or bored, hell, Im not sure what is the standard procedure on these small engines, bored or sleeved?


Any suggestions welcome.

Thanks

Okay, with the air filter off, the engine governor regulates engine RPMs at about 3,000?
Air filter on, the RPMs drop way down?
If both statements are true don't worry about the load on the engine.
The air filter will slightly increase the fuel-air ratio, but not enough to make this difference.

As for as a rebore on the engine; most people replace the engine or junk the mower.

What's the spark plug look like? Sooty and black? What is the compression while starting? Have you checked the key in the magneto? If the spark were seriously retarded you could see the engine not carrying the load (although I don't understand why the air filter would make a difference).
Testing the compression will confirm the valves are working correctly, and a look at the key will verify the timing.

 

[inline300]

Compression cold is between 50 and 55psi

flywheel key is fine, I took the flywheel off and reinstalled during assembly.

put a new spark plug in, ran it a couple minutes, it was definitely darkening.

also noticed fuel spittin out of the carb, intake side as it ran.

she be rich I guess.

I just remembered the timing gear on the crankshaft had came loose, and I just put it back thinking it should be fine, now Im wondering if the timing is off a tooth or not. huh.

 

[inline300]

It was the timing.


Shes running fine now.


Bet the compression psi is a little better too, but I havent checked it, probably wont, it cut the grass fine. I think the dead battery it came with is gonna charge up nice too.


Thanks folks.