Sputtering at high RPM Harley Evo Sportster Discuss Sputtering at high RPM in the Harley Sportster & Buell forums; Since I put V & H shorties on my '06 1200C, when I near the top of the RPM range it sputters (stops accelerating) until I either back off or ...

Since I put V & H shorties on my '06 1200C, when I near the top of the RPM range it sputters (stops accelerating) until I either back off or shift up. Any tips?

[Wrightturn]

Hey Gater,

What rpm does it start ? Sounds like you are hitting the rev limiter or going lean on top end. May need fuel controller to richen things up.

[frisco-rigid]

Hi Gator

I'd bet a dime to a do-nut that it's waaay lean now beause of the exhaust change..
Are these pipes muffled or baffled.? If not they should be cuz you'll get more power..
Is it carb or EFI.?
If carb you will easily be able to re-jet..

I suggest a high RPM plug test near the RPM that the condition occurs..

On the highway get near the RPM that the sputtering occurs.. Keep it constant for about 10 miles.. Try to NOT flucuate RPM's.. When ready, spot a safe place to pull over, (off-ramp, wide spot off road etc) and pull in clutch lever (dis-engage clutch) and switch off ignition in one motion.. DO NOT re-engage clutch or down-shift or anything,, just coast to road-side..
Gloves on and remove plugs.. I bet the porcelain and electrodes are snow white/clean.. If yes, you'll need to re-jet richer..
You know,, we got a couple guys that are prob familiar with the jets that are prob in your carb.. Of course all this time I'm supposing that you are carbed not EFI..

Thanks for the input. Some more info - it is carbed, has stock baffles that come with the shorties & has a stage 1 kit. I'm not sure what RPM it starts at, no tach, but you gotta be gettin' on it "like you stole it." I just cleaned the air filter, changed oil and plugs(stock plugs). Still did it.

[Wrightturn]

Hey Gater,

My head said EFI. Forget fuel controller and rejet the carb. Need to find out what jets are in the carb and go up on the hih speed. I would reccomend a different needle. Have had good results from a 27094-88 to richen thing up acros the entire range. Less than $10.00

[street bob]

Sounds like your maxing out the rpm's..
You gotta be haul'n a## on that bike. My wife has a 1200 custom and I love to take it out every now and again, and I've never gott'n to the point of it breaking up. Its just flying, too fast for me.
I started out on an ol' iron head 72' xlch. I still wish I had that bike. It was my first Harley and I still like sportsters because of it, what a blast I had on that thing!!

Thanks Wrightturn, I'll give it a try. And street bob, yep, you better be hangin' on.

[street bob]

I hope you get to the bottom of the problem, nothing worse than being dissappointed with your scoot!!