[Ram Jet]

Originally Posted by ///M

Hey guys, couple issues I've had over the past few weeks of riding (or well, 3 full days of riding as I've been on vacation as of late).

If I'm cruising through town (30mph) or really anywhere below 6-7k rpm (mind you I am just cruising, not accelerating or decelerating) it will begin "bucking" or seem like there may be a misfire (or something of the sorts). Also it idles fantastic when cold (and does not require any choke no matter the ambient air temperature). When hot it'll idle for roughly 5 seconds and drop RPM until it stalls. If I am on the throttle and accelerating through the midrange RPMs it does not have a single issue. It only arises when maintaining low speeds.

Would this be an issues with the carbs? And if it is, would it be an adjustment or would it be dirty idle circuits? Another thought was a possible vacuum leak (going to replace all lines when I get home from my trip, along with fuel lines just for safe measure).

The issues vanished completely after I opened it up getting on the interstate (WOT all the way to redline through 3rd gear) and then returned the next day (and has not gone away since then, no matter how hard or easily I run it).

Gas is fresh (tried with 87 and 93). I'd also like to add that it starts a lot quicker when cold than hot. Cold it'll start with no choke after a couple seconds and idle at 1700rpm. Hot it will take a solid 5-7 seconds of cranking and slight bits of throttle added to get it to go (and then require throttle to keep it idling).

Also would like to add that after 3 tanks of fuel it averaged 55 mpg all tanks of mostly 50mph-ish twisty roads.
Would my float adjustment possibly have it too rich?

Sorry for the long post. Mixture of thinking out loud and questions :P

I would check the pilot air screws. If you haven't already, pull the EPA plugs, unscrew the pilot screws and examine the "O" rings. If they have deteriorated replace them and adjust the screws out from their seat 2.5 turns. It's worth a check to be sure. This will entail carburetor removal if you haven't removed the EPA plugs previously.

Bill