Running on rear cylinder only
- Thread starter rfranz1952
- Start date
Has he tried the old stock ignition coil, wires and trigger plate to see if he has a compatibility initital timing setup problem? I remember there are so many different aftermarket combinations, that it is hard to match them all up. Just my 2 cents. :newsmile04:
Spade5
Active Member
I seem to recall that a coil can produce a nice spark on a plug in open air but will not be strong enough under compression. Maybe it can only fully discharge randomly. I know that all coils are not the same but have no clue which one you would need. I may be wrong but one with seemingly better numbers might not be as good as stock specs.
rfranz1952
Member
Problem resolved!
A case of several issues, both unlikely, masking each other.
Problem # 1: I removed the coil and had it tested. While the technician said that the resistance tested within parameters, it was very marginal. In short, it wasn’t officially bad, but it was very close to it. Given that the testing is done under very different conditions than typical riding conditions, and the erratic spark quality I observed, I chose to replace it.
Re-assemble the bike to the point where I could start it. It starts! Both cylinders fire, reasonabley regularly.
BUT:
It smokes like a (EDITED). And fuel is still standing off outside the carb! Pig Rich. Hmm.
I find the old CV-40 carb, and slap it on to see how it runs. The bike fires right up, runs much better (considering the carb isn't even tuned to this build), no smoke. Must be a problem with the Mikuni, eh?
I pull the bowl off the mikuni, check for dirt, check the float, pull the jets—just looking for something unusual. Nothing.
Pull the top off the carb, look inside, work the throttle. Whats that? A black screw, lying sideways, jammed up against the needle. The needle is about an inch higher than it should be as a result, and jammed in that position. As a result, fuel has just been pouring into the engine, at the equivalent of about 75% throttle—at idle.
Inside the Mikuni, there is a screw that anchors a pivoting assembly designed to hold the needle down. Apparently this screw came completely unscrewed, and jammed up against the needle, which prevented the needle from moving up and down with the slide. We eventually did manage to remove the jammed parts—with some difficulty. The needle was also seriously bent. We got everything replaced—with the screw tightened with blue lock-tite. Hopefully this will prevent a repeat.
After restoring all of the original parts, the bike once again runs smoothly.
I would like to thank all of those who helped with suggestions.
[notes]
A Friendly Reminder - Harley Davidson Community
[/notes]
A case of several issues, both unlikely, masking each other.
Problem # 1: I removed the coil and had it tested. While the technician said that the resistance tested within parameters, it was very marginal. In short, it wasn’t officially bad, but it was very close to it. Given that the testing is done under very different conditions than typical riding conditions, and the erratic spark quality I observed, I chose to replace it.
Re-assemble the bike to the point where I could start it. It starts! Both cylinders fire, reasonabley regularly.
BUT:
It smokes like a (EDITED). And fuel is still standing off outside the carb! Pig Rich. Hmm.
I find the old CV-40 carb, and slap it on to see how it runs. The bike fires right up, runs much better (considering the carb isn't even tuned to this build), no smoke. Must be a problem with the Mikuni, eh?
I pull the bowl off the mikuni, check for dirt, check the float, pull the jets—just looking for something unusual. Nothing.
Pull the top off the carb, look inside, work the throttle. Whats that? A black screw, lying sideways, jammed up against the needle. The needle is about an inch higher than it should be as a result, and jammed in that position. As a result, fuel has just been pouring into the engine, at the equivalent of about 75% throttle—at idle.
Inside the Mikuni, there is a screw that anchors a pivoting assembly designed to hold the needle down. Apparently this screw came completely unscrewed, and jammed up against the needle, which prevented the needle from moving up and down with the slide. We eventually did manage to remove the jammed parts—with some difficulty. The needle was also seriously bent. We got everything replaced—with the screw tightened with blue lock-tite. Hopefully this will prevent a repeat.
After restoring all of the original parts, the bike once again runs smoothly.
I would like to thank all of those who helped with suggestions.
[notes]
A Friendly Reminder - Harley Davidson Community
[/notes]
Last edited by a moderator:
Ken S.
Active Member
Problem resolved!
A case of several issues, both unlikely, masking each other.
Problem # 1: I removed the coil and had it tested. While the technician said that the resistance tested within parameters, it was very marginal. In short, it wasn’t officially bad, but it was very close to it. Given that the testing is done under very different conditions than typical riding conditions, and the erratic spark quality I observed, I chose to replace it.
Re-assemble the bike to the point where I could start it. It starts! Both cylinders fire, reasonabley regularly.
BUT:
It smokes like a (EDITED). And fuel is still standing off outside the carb! Pig Rich. Hmm.
I find the old CV-40 carb, and slap it on to see how it runs. The bike fires right up, runs much better (considering the carb isn't even tuned to this build), no smoke. Must be a problem with the Mikuni, eh?
I pull the bowl off the mikuni, check for dirt, check the float, pull the jets—just looking for something unusual. Nothing.
Pull the top off the carb, look inside, work the throttle. Whats that? A black screw, lying sideways, jammed up against the needle. The needle is about an inch higher than it should be as a result, and jammed in that position. As a result, fuel has just been pouring into the engine, at the equivalent of about 75% throttle—at idle.
Inside the Mikuni, there is a screw that anchors a pivoting assembly designed to hold the needle down. Apparently this screw came completely unscrewed, and jammed up against the needle, which prevented the needle from moving up and down with the slide. We eventually did manage to remove the jammed parts—with some difficulty. The needle was also seriously bent. We got everything replaced—with the screw tightened with blue lock-tite. Hopefully this will prevent a repeat.
After restoring all of the original parts, the bike once again runs smoothly.
I would like to thank all of those who helped with suggestions.
[notes]
A Friendly Reminder - Harley Davidson Community
[/notes]
As I said and thought from the git go, too much gas.
Ken
didnt understand this reply as 2000 sportster is a fairly simple beast when you twist the grip the carb buterfly opens when the piston goes down it sucks air in causing a depression behind the slide as there is a drilling from that side of the slide into the area above the diaphram it sucks the slide up letting more air/fuel through the carband into the cylinder that is sucking
anyway as to your not firing cylinder problem you need to start doing some fault finding start by trying a known good spark plug
then new plug lead
do a compression test on the cylinder and check for intake leek where the manifold bolts to the cylinder
had a guy appear in my shed last week with coil and plug leads in hand saying he had no spark
pulled the plug leads off and both were corroded where they went into the
coil and had been a loose fit cleaned them up and adgusted their fit so they were nice and tight havent heard from him since
so look at the simple stuff first take it 1 step at a time and if all else fails bring it round to my shed
Brian