Issue developed during Inzane trip.

[John Schmidt]

Backstory is...I didn't make it to IZ but that has nothing to do with the issue.

The trike runs great at speed, however during the trip it developed what can best described as a "flutter" at low RPM. It seems to come from the left side, you can blip the throttle and it goes away. Running down the road at most any speed above idle, it runs fine and smooth. But pull into a parking lot and while downshifting, causing the RPM to drop, it will start the flutter. The carbs were overhauled a couple years ago for that reason and have worked great since, now it's back. It didn't seem to affect the gas mileage so I'm kinda flying blind here. Any suggestions? One person suggested it could simply be a vacuum leak but my thoughts are that would affect the entire range of RPM. I don't plan to pull the carbs until I'm ready to swap the motor for the reverse capable Wing motor I have...probably a project for later this year. I don't want to miss the riding season here in Wisconsin, those three days are precious indeed. 

Just had a thought, often a dangerous event in my garage! Although being desmogged, I do have two vacuum lines used for the cruise control reservoir, one to each side of the engine. I don't use vacuum for the petcock since I have a Pingle. However, the cruise vacuum lines do have small one-way valves in them, positioned between the vacuum port on the back of the intake and the reservoir. I'm going to ride over to my daughter's place today to wash off the results of hundreds of miles riding in rain, and before I go I'll block off those cruise vacuum lines as an experiment. Stay tuned! 

[Jess from VA]

Check the vacuum caps on the back of the intakes.  Or replace them.  They can be cracked where you can't see them.

Also, please explain flutter better.

[John Schmidt]

Jess, I can't think of a good description. Maybe rolling/fluttering your tongue as you blow out. It almost sounds like an "air thing" when it happens. That's what made me think of the one-way valves used in the vacuum lines to the reservoir. If bad internally, at low RPM there may not be enough suction to overcome a slight leak but at higher RPM it does.

Just a guess which I plan to test.
Gee, I'm a poet and didn't know it.
But my feet show it...
They're Longfellows.  

UPDATE:  Seems the on-way valves may have been the problem. I pulled them off the vacuum ports and capped the ports off with some Red Eye caps I have. After sitting for a while, the trike always starts and runs a bit like its owner first thing in the morning...use your imagination here, you won't be far off. Once warmed up, runs fine(not like its owner). I'll replace the valves but last time I went looking they were hard to find, apparently emission systems are now engineered to operate a bit different. In the mean time, I'm leaving them off to further test the results but it ran good yesterday...again, unlike its owner. 

[Pappy!]

Just a guess which I plan to test.
Gee, I'm a poet and didn't know it.
But my feet show it...
They're Longfellows.  

But they smell like Dickens.......Sorry couldn't resist.

 "and runs a bit like its owner first thing in the morning..."

You mean constant backfiring??

  

[Jims99]

One way valves? Is that for a cruise control?

[John Schmidt]

One way valves? Is that for a cruise control?

Hey Jim...first line of my second paragraph. Yes, for the CC.

Casey...no backfiring, at least not constant. Just creaks, groans, hard starting and harder to keep going.  Some mornings these 84 yr. old joints sound like I just poured milk over a bowl of Rice Krispies.