Rough running at high rpm

[wolfen]

Ok guys and girls, I joined this forum yesterday after looking all over the internet to no avail
I have a Cub Cadet LT1018 with a 18.5 Briggs I JUST got it running right last night after fuel issues, ol issues carb issues and want to flat out choke the moron I bought it off of, I changed the Needle in the Walboro carb ( original Nikki with the backfire valve on the bottom is toast) I installed today and it ran perfect, my grass is almost Knee high in the back, I'm only cutting half deck and not using cruise, i'm going as sow as I can, now, all was good for two passes on about half an acre, now when its warm at half throttle is runs perfect, and full throttle it acts like the choke is half on only without the black smoke, I assure you the choke is NOT on, but its driving me crazy, any help is greatly appreciated
I'm doing my best to completely restore the mower because the cut is better than a brand new murray , which is what I always had when I lived in the city, now I'm in the country and a murray push mower is no longer an option LOL

Update : I just started it up and the governor rod wiggles back and forth at high idle too

[Billy-O]

Maybe you're thinking a bit backwards on this..... Try pulling the choke out a little when your tractor starts running rough at WOT and see what happens. If it runs better, then you're looking at fuel starvation problem.

[ol'George]

Originally Posted by wolfen

Ok guys and girls, I joined this forum yesterday after looking all over the internet to no avail
I have a Cub Cadet LT1018 with a 18.5 Briggs I JUST got it running right last night after fuel issues, ol issues carb issues and want to flat out choke the moron I bought it off of, I changed the Needle in the Walboro carb ( original Nikki with the backfire valve on the bottom is toast) I installed today and it ran perfect, my grass is almost Knee high in the back, I'm only cutting half deck and not using cruise, i'm going as sow as I can, now, all was good for two passes on about half an acre, now when its warm at half throttle is runs perfect, and full throttle it acts like the choke is half on only without the black smoke, I assure you the choke is NOT on, but its driving me crazy, any help is greatly appreciated
I'm doing my best to completely restore the mower because the cut is better than a brand new murray , which is what I always had when I lived in the city, now I'm in the country and a murray push mower is no longer an option LOL

Update : I just started it up and the governor rod wiggles back and forth at high idle too

If we are to assume "wiggles" means the governor linkage is trying maintain a set throttle position, then you might indeed be experiencing a lean condition as Billy o posted.
And if choking improves the performance, you need to clean the fuel system,
starting simple @ the tank and following the flow to the carb.
if no restrictions are found then the carb needs addressed, as to disassembly and cleaning thoroughly.

[wolfen]

Originally Posted by Billy-O

Maybe you're thinking a bit backwards on this..... Try pulling the choke out a little when your tractor starts running rough at WOT and see what happens. If it runs better, then you're looking at fuel starvation problem.

Nope pull the choke lever and it runs the same only with black smoke, pull out more and it runs worse then chokes out and shuts off

Originally Posted by ol'George

If we are to assume "wiggles" means the governor linkage is trying maintain a set throttle position, then you might indeed be experiencing a lean condition as Billy o posted.
And if choking improves the performance, you need to clean the fuel system,
starting simple @ the tank and following the flow to the carb.
if no restrictions are found then the carb needs addressed, as to disassembly and cleaning thoroughly.

The carb is clean I did it before I installed it so unless there's sludge I didn't see in the tank when I cleaned it its still clean, as for lines, all three have been blown out with 100 psi of air pressure. so the only thing is could be is the carb is either too small for the engine or the motor is shot, because the carb ran fine on a 14.5 Briggs on the Murray I replaced with this Fine cutting machine..





Air filter ....new
Fuel pump..New
coil...........checker for proper voltage, Pretty Blue spark in light conditions
Carb.........Walboro originally purchased to replace a Briggs on a 14.5, packaging said 12-18hp engines
Spark plug.Champion , proper numbers condition, new.


Here in a few after I finish my beer, I'm going to replace the innards on a Nikki and install it, if the symptoms are the same, I assume its the engine, if I get different symptoms I will order a brand new carb, I have three possibilities bookmarked

[wolfen]

ok Heres todays update, I removed the valve cover and found that one of the valve tops was missing after installing one I discovered that one of the lock nuts was screwed up and not tightening like it should, so I took a cap for a valve and two nuts off one of the two 14's I have out back after that I readjusted both intake (4) and exhaust (6) I left the engine cover off reinstalled the plug and started it up it runs fine at 1/4 throttle and up to 1/2 throttle, but like before at higher rpm it runs rough and with the cover off I put my hand over the intake and felt the air, when it hits hard like the choke is on you can feel the air coming up through the carb.
I'm at the point I'm about to buy a push mower and junk this thi9ng, because I don't have the money for anything except a internet carb for $17
Please help

[wolfen]

Turned out to be the engine, something having to do with the governor is broken, I haven't taken it apart yet but I did replace it with a 18 HP Ic for now that runs better than the 18.5 did My grass is cut