electronic ignition what will interchange??

Okay, at the risk of looking a little stunned I was told that pretty much all the stock electronic ignition components will interchange on the 550 650 750 1000 etc. I put the electronic components from a newer 650 onto my '79-650 sr replacing the points system. When I ran it up I got backfiring and popping while under revs. I don't have a timing light available, pretty sure I got it all together correctly, is the plug gap different? Had a buddy tell me some time ago when he did his it was just swap out the components and away he went? What am I doing wrong? any ideas? The bike has been parked now for the season but am starting to get the itch to do the winter refurbish and this is one of the things I want done before next riding season.Any help now would be great, would like to get the drivetrain end of it done before starting on the cosmetic.

Be more specific. What components did you replace? The coils on a points ignition are 4 Ohm the ons on a electronic ignition system they are 2.2 Ohms. This will give you a very short dwell and a very small spark.

Just like Otakar said, the old points coils are not really meant to work with the electronic ignition. That may be the issue, or it could just be that your old coils were starting to go out. Did it run fine with points?

Many components will swap between the models you mention, but the actual pickup plates won't interchange between the 1000 and the 550/650/750-4 motors. The 900/1000/1100 uses a larger diameter plate.

The igniters will interchange though.

All of this is only for the earlier electronic ignitions using mechanical advancers. The later ones starting around 83 or 83 depending on model, uses different pickups, and electronic advance. Those parts won't interchange.

I think the electronic ignition coils will interchange between the earlier ones and later ones.

Other issues to check are make sure the advancer is working up to spec using a timing light. Another possibility is that maybe the igniter is getting weak.

If you need a new one, you can make one.
home.comcast.net/~loudgpz/GPZweb/Ignition/GPZgmHEImod.html

I had some problems when I did a similar swap as you did, and went back to the points for a while.
I then bought some kz750 coils that are for the electronic set up, and it's worked great the last few years.
The 750 coil's mounts are further apart than the 650's, so some mounting mods are needed. I filed the rear mounting hole further back a little hoping I could do the same to the front (move the hole forward) but could not get nuts onto both mounts.
I ended up using a long zip tie on one end and bolted on the other end.

I've swapped electronic over on my 78 650. Using 550 pickups/plate/advancer cam and 750 igniter. Still have the stock points coils and it's been running smooth for over 30,000 miles...am I looking at having to replace those coils?

Thanks for the info so far,, I did not replace the coils, they are still the stock ones for the points. They seemed to be working fine when the points were still in. The igniter etc that I used were off a newer 650 or 750 around the 80-81 year range I believe.

Kent if your bike has been fine for 30,000 miles, I think you'd know by now if there were any issues.
My swap just didn't work quite right. Could have been the IC Igniter too as I did change it as well.
I also swapped coils as I thought it may have been part of the problem.

The systems until 1982 take 2.2 Ohm coils. The system will work with 3 ohm coils found on 79s but will have a hard time giving you a good spark on the older 4 Ohm coils. A quick way to find out if that is the problem is to close your spark plug gap to .5mm (.020) see if it runs better. If it smooths out than the coils are your problem.

I run the Dyna Gray coils (2.2 Ohm) with mine and have the plug gap open to 1.5mm (.060) It gives better gas millage that way and I have not had any problems with spark blow out with the 11:1 pistons and at 10500revs, on my 1150 motor.