motor rev

No. It shouldn't sputter/hesitate.

Sounds like John needs a synch/adjust/clean maybe. Where are you John, possibly one of us can help.

Have you checked your hex bar for tightness? This is the first check to be done because it is the easiest. I had the same problem with my first 550 Spyder. I had no idea that the bar (that connects one carb to the other) was loose until a friend immediately found the problem. We checked the carbs for sync, tightened the bar, and voila!...no more sputtering at lower speeds.

I've found that high performance air cooled engines, with dual carbs, don't like to be lugged at low rpm.

If you're driving around town at 2000 to 2300 rpm your engine won't like it.

Cruise around town between 2800 and 3000 and see if your engine runs smoother.

I'm in lompoc one hour north of Santa Barbara . The car runs much better when adequately warm. Probably could be cleaned and sync check. A friend has gauge just need to get it.

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True the car wants to be pushed and does run great opened up. Thanks

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If it is stumbling it is likely the pump jet. Could be clogged, need adjustment, or the wrong size. I have the same type problem with high altitude. Trying to find the compromise between 8000 ft. and sea level. Still have not been able to dial it in.