Castle Garden 12.5/102

Evening gents

This thread will contain photos/repairs of my grass cutting Castle Garden 12.5/102 lawn tractor. Drive train consists of a 1999 Briggs & Stratton 12.5 I/C Quiet, and a Peerless 700 (yes, I said that right)





The current problem I have is fuel starvation (at least that's what it appears to be). You can start it up fine but once you start to cut grass it bogs down and dies. I've been through the carb and fuel system countless times and still the same thing happening. It isn't the coil I checked for spark right after it died and there was a strong spark. Any ideas?

Further plans are to re-wire (bypass the safety switches) and maybe 15" front tyres (has 13's on it now)

Changing the tires on the front might affect the mowing deck.  You may need to adjust accordingly.  My in-laws had a mower that would eventually starve out theirs was the fuel filter and clogged high speed jet.  First couple things I would check are the fuel filter and the gas cap vent.  Both can easily starve the engine.

Cool mower! Does it have a live axle then? Also is it overheating? There's a small chance that's why it bogs down once it's under load.

AllisKidD21 wrote:

Cool mower! Does it have a live axle then? Also is it overheating? There's a small chance that's why it bogs down once it's under load.

I thought maybe loss of compression

CraftsmanQuad19 wrote:

I thought maybe loss of compression

I was thinking that too.

You did mention you went through the fuel system.
Other than bogs and dies, does it throw smoke when it does that? Also, just off the wall, when was the last time the spark plug was changed?

mightyraze wrote:

Changing the tires on the front might affect the mowing deck.  You may need to adjust accordingly.  My in-laws had a mower that would eventually starve out theirs was the fuel filter and clogged high speed jet.  First couple things I would check are the fuel filter and the gas cap vent.  Both can easily starve the engine.

I've replaced the fuel line and filter. I haven't checked the gas cap, that could be a possible cause.

AllisKidD21 wrote:

Cool mower! Does it have a live axle then? Also is it overheating? There's a small chance that's why it bogs down once it's under load.

Thanks! I can't see a diff on the axle so I think it does have a live axle. It's not over heating, runs pretty cool.

CraftsmanQuad19 wrote:

AllisKidD21 wrote:

Cool mower! Does it have a live axle then? Also is it overheating? There's a small chance that's why it bogs down once it's under load.

I thought maybe loss of compression

Do you mean once it warms up it loses compression? It starts and runs fine until you put it under load. 

mightyraze wrote:

CraftsmanQuad19 wrote:

I thought maybe loss of compression

I was thinking that too.

You did mention you went through the fuel system.  
Other than bogs and dies, does it throw smoke when it does that?  Also, just off the wall, when was the last time the spark plug was changed?

No smoke. I've tried various spark plugs in it, the current one is brand new.

Hmm.. Gas cap vent would be the simplest thing to check like mightyraze said.

valve lash may need adjusted...

I didn't know you could adjust the valve lash on a Briggs flathead?

AllisKidD21 wrote:

I didn't know you could adjust the valve lash on a Briggs flathead?

you can, by filing the valve stems and or lapping the valves... that said, I didn't realize that was a flathead... the red cover made me think overhead valve... all of my briggs IC engines have the black and silver shroud

Oh ok. I thought you meant they had adjustable lifters like the old Kohler K Series engines. Those things are handy haha!

AllisKidD21 wrote:

Oh ok. I thought you meant they had adjustable lifters like the old Kohler K Series engines. Those things are handy haha!

Briggs ohv engines have adjustable lifters... I had a 17.5 hp single that would do what the OP mentioned when the valves needed adjusting

The Fuel cap isn't the problem. Gonna replace the coil next.

In the chat last night, @Lawren Wimberly suggested that the flywheel key might be sheared. Tore it apart today and the key is intact. Also replaced the coil with one that I know works and the problem still persists. So now I know it isn't a spark issue. This weekend I will go through the carb and fuel system again. I was also thinking that the valves could be sticking but that's unlikely.

Might look into a compression tester.

Is there a lot of carbon built up in the combustion chamber? That would cause a lack of power.

mightyraze wrote:

Might look into a compression tester.  

When turning the engine over by hand, there seems to be enough compression. More than most of my flathead Briggs'

AllisKidD21 wrote:

Is there a lot of carbon built up in the combustion chamber? That would cause a lack of power.

I'm almost convinced it is a fuel problem, but it wouldn't harm to check. I have an 8hp flatty sitting doing nothing so I'm going to rob the carburettor off it just to see if it is a carb problem.

So it runs fine until you kick in the mower?  You mentioned Load.  Is that just mower or also drive?  If just mower, does all the mower blades turn OK and easily.  Is there an idler that could be frozen?

Does it do it just driving around?  Any pulleys there that could be going out?

Just throwing some other stuff out there.

I agree with mighty, check the deck stuff to make sure it's not putting the engine under load too much. If the hubs for the blades are greaseable I'd give them a shot of grease.

The first time I discovered the problem was when the deck was engaged, but it the same thing happens when driving and also if it's allowed to sit at full throttle without anything engaged. It's definitely an engine problem.

Could be something with the governor. Try disconnecting it and see if the problem still persists

Took the head off and blew out all the carbon, took the carb apart and cleaned it out again and it ran a lot better than before. I got half my lawn done when it started surging (if you put the choke slightly on it will run fine, the prob i had before was different, it wouldn't run with or without the choke.) I assume it's still some dirt in the carb, gonna buy some carb cleaner this week and see if I can get her going again.

Was there a lot of carbon in there? If so I bet that would've been a big cause, carbon insulates heat which would probably cause it to start overheating after a while.

surging? Hmm.... bad intake gasket?