Harley Davidson Community - View Single Post - Rear Cylinder not running unless Carb Intake 90% covered

cansel kansu · 06-24-2008, 10:48 AM

Spraying water will do the same. if there is a leak, water will be sucked in and idle will also increase. this is very common way of finding intake leaks at most of the engine repair workshops.
I had pretty much the same problem till yesterday.
I first changed the places and then replaced the spark plugs with new ones, no help!
First changed the places of spark plug wires connection points on the induction coil end and then replaced with new ones, no help!
I got my compression ratio measured, 9 bars both cylinders, no prob...
Tried to tune the ignition angle by rotating the igniton module, no help. (I was the first one unscrewing the fixing screws of the ignition module plate, there was no screw tightening mark on any other place before I started to tune) then did the static tuning before closing the cower.
I was just hopeless about finding a solution and started to check ebay for buying a single fire igniton kit or a complete upgraded carburator yesterday then I wanted to give a try for tuning the carburator. I took the carb out and set the idle mixture adjustment screw only 1 turn off from the max in position. now I can hear that both cylinders are firing. the new problem is, idle rpm increases as the engine warms up, up to 15-20 minutes. when I adjust the idle after 20 mins, then cold running will be too low. this is not annoying me as much as loosing the back cylinder so I consider my back cylinder problem solved.
any suggestions for the idle fluctuation issue is wellcomed.

06-24-2008, 10:48 AM	#9 (permalink)
cansel kansu Start The Engine Join Date: 2008, Jun 21 Posts: 27 My Mood:	Re: Rear Cylinder not running unless Carb Intake 90% covered Spraying water will do the same. if there is a leak, water will be sucked in and idle will also increase. this is very common way of finding intake leaks at most of the engine repair workshops. I had pretty much the same problem till yesterday. I first changed the places and then replaced the spark plugs with new ones, no help! First changed the places of spark plug wires connection points on the induction coil end and then replaced with new ones, no help! I got my compression ratio measured, 9 bars both cylinders, no prob... Tried to tune the ignition angle by rotating the igniton module, no help. (I was the first one unscrewing the fixing screws of the ignition module plate, there was no screw tightening mark on any other place before I started to tune) then did the static tuning before closing the cower. I was just hopeless about finding a solution and started to check ebay for buying a single fire igniton kit or a complete upgraded carburator yesterday then I wanted to give a try for tuning the carburator. I took the carb out and set the idle mixture adjustment screw only 1 turn off from the max in position. now I can hear that both cylinders are firing. the new problem is, idle rpm increases as the engine warms up, up to 15-20 minutes. when I adjust the idle after 20 mins, then cold running will be too low. this is not annoying me as much as loosing the back cylinder so I consider my back cylinder problem solved. any suggestions for the idle fluctuation issue is wellcomed.