I am stumped

[BA80]

So the issue with the miss is back. It's not carbs, it's not coils, it's not the TCI box, the plugs or plug caps. I have switched out all those components with know good ones from my hop up bike.
So.... do I start thinking about defective pickups? Do I replace the pick ups with the ones on my hop up bike or is there something else I should be looking at before I do that.
The miss is not as bad as it was last year. is affecting # 1 and #4 and is present across all throttle settings.
Perhaps it's just an OLD WEAK ignition system?

It's that alien mother ship that passed over.

If it's 1 & 4 it has to be a coil or a pick up coil.

Have you ohmed out the pickup coils?

I had a set that drove me crazy on an SG a couple years ago. They ohmed out at slightly lower readings than the spec range. This bike WOULDN'T start (no spark) if the temperature was below 40º F. If I heated the timing cover it would eventually start and run on 2 cylinders until the engine warmed up a bit then the other 2 would kick in. Swapped out the pickups and it works fine to this day. Go figure.

[79XS11F]

It's that alien mother ship that passed over.

If it's 1 & 4 it has to be a coil or a pick up coil.

Have you ohmed out the pickup coils?

I had a set that drove me crazy on an SG a couple years ago. They ohmed out at slightly lower readings than the spec range. This bike WOULDN'T start (no spark) if the temperature was below 40º F. If I heated the timing cover it would eventually start and run on 2 cylinders until the engine warmed up a bit then the other 2 would kick in. Swapped out the pickups and it works fine to this day. Go figure.

So they can be defective or become defective over time. how do I test them? Is the process in the manual?

Rob

[BA80]

The testing procedure and specs is HERE

[bikerphil]

You can try checking voltage at the red/wht wire at the solenoid positive solder joint. The TCI gets it's power from this wire. If it is much lower than the voltage reading taken at the fuse panel, you have a weak/corroded/poor connection supplying needed voltage at the TCI. It's an easy check that only takes a minute. GL

[DiverRay]

If it is much lower than the voltage reading taken at the fuse panel, you have a weak/corroded/poor connection supplying needed voltage at the TCI.

Don't forget, you need AT LEAST 10.5 Volts to fire, and 11.5 Volts for a good spark. Check you connection at the ignition switch as well! A drop of over 0.2 Volts is a problem.

[BA80]

Good points however, the stated problem is with just 2 cylinders though. 1 & 4.

[79XS11F]

The engine fires right. It's just got an occasional miss on 1 and 4 across the board.
Rob

[BA80]

If this is your "modified" bike then it's just a guess but you probably have a pick up coil shorting internally or a pick up coil wire that is shorting or fixin' to break.

[79XS11F]

If this is your "modified" bike then it's just a guess but you probably have a pick up coil shorting internally or a pick up coil wire that is shorting or fixin' to break.

No it's not the modified bike. I checked the pick up wires they were good. but I will check them again before I pull the entire timing unit out of her.
The Accel coils are 3 Ohm type so if I try them on again I guess I am suppose to remove the ballast resister which I didn't do on ether bike.
Rob

[BA80]

No it's not the modified bike. I checked the pick up wires they were good. but I will check them again before I pull the entire timing unit out of her.
The Accel coils are 3 Ohm type so if I try them on again I guess I am suppose to remove the ballast resister which I didn't do on ether bike. Rob

So, it IS modified.........

[79XS11F]

So, it IS modified.........

No it's not? I have the access coils on my bench but could install them pretty fast.

[BA80]

Looks like by your signature you have a lot of other XS's. Borrow some STOCK coils and see if that makes a difference.

Go from there.

[79XS11F]

Looks like by your signature you have a lot of other XS's. Borrow some STOCK coils and see if that makes a difference.

Go from there.

I have already switched out the coil for 1 and 4 with others I have here with no luck. This is why I am thinking pickups is the problem but I don't really want to switch out the entire timing unit with the one on my modified bike if I can avoid doing that. I don't really want my modified bike becoming a "parts bike" LOL

Rob

[BA80]

Best test though. If they come off they can go back on.

[79XS11F]

Best test though. If they come off they can go back on.

I'm going to go at it tomorrow I guess.