TheSamba.com :: View topic - intermittent engine problem runs rough stumbles etc

Mon Apr 01, 2019 8:29 pm

ive been putzing with acvws about 40 years and have always had good luck but this problem my trike is having is a real head scratcher, and i have been fixing things the last owner did to it.

its a 1600, dp, dual advance dizzy with electronic ignition, pict 34 3, buggy dual exhaust,
electric fuel pump with holley regulator and 2 fuel filters one before one after the pump.

it would run great then i would let it sit a few weeks and it would run raggedy, rought try to or just stall, then clear up and run good again, it would be running bad i would go to put it away and it would run good again, i would fire ut off for a cruise and it would seem like plugs were fowled but after a bit it would clear and run great.

so things got worse about a week ago, the fuel pump would go out then kick back on so i decided to change the filters since i had to pull the pump to fix the wires it works great now but the engine would run good until it came off choke, then stumble run rough if i got on it it would run okay but coming off throttle sometimes would sputter, buck run like crap then clear up,

the valves are correct, no vacuum leaks, carb was adjust when it was running well as was the timing, plugs looked good,

thinking it might be carb i rebuilt the carb and at first it seemed to have fixed the issue it was running sweet then out of no where runs like crap, i tested and tried 3 different coils, no help.

keep it mind it didnt always do this and at times ran good it would come and go but now seems not to go away,

i noticed something tonight that might be a clue to those more savvy than myself, it was idling about 1000 rough when i move the throttle arm by hand to goode it it might move 1/8 to 3/16 " and it seemed to have no effect until after the arm moved about 1/4 " then it would rev.

i cant afford to buy parts just to see if they will or wont help,

any guesses?

Tue Apr 02, 2019 1:44 am

Points? Condenser? When you say that it runs rough after sitting, is it sitting outside where water can get into the carbs?

Tue Apr 02, 2019 11:05 am

Quote: its a 1600, dp, dual advance dizzy with electronic ignition, pict 34 3, buggy dual exhaust,
electric fuel pump with holley regulator and 2 fuel filters one before one after the pump.

no, it sits in a garage, i might have confused it the sitting part, it ran crappy last night today itmight run good then get bad again orstart out bad and clear up

Tue Apr 02, 2019 8:56 pm

didnt get to mess with it long today but double checked the valves...good.

when hunting my feeler gauge i found a set of bosch platnum plugs and installed them it had autolites in it, it started up nice came off choke and i didnt get to test drive it much but it did great, ran very smooth and doesnt make as much exhaust sound,

more testing will be needed.

i am running the borg warner coil but im gonna make a coil post as they can be confusing.

Fri Oct 18, 2019 1:04 pm

Possibly the centrifugal advance is sticking? You can verify by watching with a timing light. Raise rpm to 3K and watch the advance. It should shift smoothly until it hits max advance at 28 to 32 degrees btdc if it jerks or stops the distributor needs rebuilt.

Fri Oct 18, 2019 8:37 pm

After a lot of testing and retesting, in between life calls and health, I'm very OCD and I had to know what it was, It turned out to be 100% carburetor, I had done a quick rebuilt and then bought a new coil, the problem returned, that ruled out coil so after really studying the pict 34 3 i did a much better tear down and rebuilt, Its been running really great, these carbs are fairly sophisticated halfass rebuilds wont wash.