20hp Briggs "stumbles" on aceleration ?

[BigBlockMan]

Hey Dave,(smallblock450SL)
Do you have the advance key in yours?

[smallblock450sl]

Originally Posted by BigBlockMan

Hey Dave,(smallblock450SL)
Do you have the advance key in yours?

Tom, yes I do. Do you have an idea? My last 23hp with an advanced timing key didn't "stumble" ,It just "poped" on deceleration. Any help would be great. Thanks to all that replied. Dave

[shawn.m]

I have the advance key also in mine. My exhaust is pretty black and the plugs are black so I am running rich. I have to do some more troubleshooting to figure out if I am rich at idle, mid or full.

[smallblock450sl]

Tom, where are you? It ran really bad out of the shop today, so I pulled the plugs (had previously changed out to NGK-BKR5E's..was told that that was the cross referance from the originals) very strange...the plug was black, not wet or fouled, but the electrode tip was very clean and "blond" color (like lean). More fuel for the fire. Any suggestions? Thanks Dave

[BigBlockMan]

Dave
not sure on the plugs, BCPR6ES was stock. We run BCPR5ES as it is a little hotter, do to not running WOT all the time. Could even go to a BCPR4ES

The 2 barrel normally has a small lag at low end due to the fact motor loses vacume for a second when both barrels slam open at once. Even happens in cars, Accelerator pump cures it just dont have one on 2 barrel. Alot also depends on exhaust back pressure. What are you running for exhaust and muffler.

[shawn.m]

hmm I am running the briggs gold plug. it was good for a while and then started fouling out. replaced them and it still came back fouled in about 3 weeks.
I am running the CPP header with no muffler.

[smallblock450sl]

Originally Posted by BigBlockMan

Dave
not sure on the plugs, BCPR6ES was stock. We run BCPR5ES as it is a little hotter, do to not running WOT all the time. Could even go to a BCPR4ES

The 2 barrel normally has a small lag at low end due to the fact motor loses vacume for a second when both barrels slam open at once. Even happens in cars, Accelerator pump cures it just dont have one on 2 barrel. Alot also depends on exhaust back pressure. What are you running for exhaust and muffler.

Thanks for all your help Tom. I installed the new plugs and same affect. I am running your header pipe with a "supertrap" muffler. Not reall pretty job, but sounds great. Could it be a fuel issue? There is gas in the fuel filter, but what is this about a "high performance" fuel pump? I can install any Yamaha fuel pump I want , just don't know witch one to use. Thanks Dave

[shawn.m]

i have Toms High Volume fuel pump. It is the pump from the 31-35hp motor so it pumps a bit more volume fuel than the stock 18-23hp one

Hey Tom
the NGK.com web site says the plug for our 14-23hp motor is the BKR5ES with the V-power BKR5E
A BPR6EY V-Power shows the same as BPR6ES BCPR6ES
the main difference looks to be the 5/8 shell or 13/16 shell.
Picked up a couple of BPR6EY tonight and will try them and see how they work

[BigBlockMan]

Shawn
Not sure if you know but with NGK the higher the number the colder the plug is. I would expect your cart with no muffler to have a little lag but no muffler should lean it slightly. You should not be having a fouling issue, Have you just serviced you K&N? I have seen them run rich if you over oil the filter

[shawn.m]

I have a post from a day or so ago where I show how dirty my K&N gets. basically caked with a layer of dirt. Need to do a real good cleaning and buy the filter sock from Alpha Carts.