Finally!

[Nubian]

Just found a 1979 Special parts bike, no title, complete except for exhaust, 13000 miles. Finally got an 1100 engine with a kickstarter! Engine, tranny, rear drive are interchangeable, right? Was wondering if with so little miles there would not be the dreaded 2nd gear issue, if not would I be better off swapping engines?

[crazy steve]

...Engine, tranny, rear drive are interchangeable, right?

Yes, mostly....

If your '81 still has the original ignition on it (4R0 TCI), you'll need to swap some ignition components. The '79 has a mechanical advance behind the pick-up coil plate, your '81 doesn't, that's done electronically. So you need to either install the '81 bits on the '79 motor, or swap to the '78-80 ignition box. The latter may not be a bad idea, as those are much easier to find compared to the one-year-only '81 box...

[Rasputin]

Steve the XS parts finder shows a 4RO on the 80SG. Am I misunderstanding and should the 80SG be a 2H7 TCI?

[crazy steve]

Steve the XS parts finder shows a 4RO on the 80SG. Am I misunderstanding and should the 80SG be a 2H7 TCI?

Yeah, I've noticed that too; all I can say is the one I had used the 2H7 box. I had two SG motors, both had the mechanical advance...

[Rasputin]

Mostly wondering as I picked up a 80SG parts bike. The po had electrical issues and the bike would not run right. I have a spare 4R0 and thought that may be the fix. I have not yet torn it apart in any way so I do not know if it has the mechanical advance or not. We now return you to your regularily scheduled thread

[Nubian]

Yes, mostly....

If your '81 still has the original ignition on it (4R0 TCI), you'll need to swap some ignition components. The '79 has a mechanical advance behind the pick-up coil plate, your '81 doesn't, that's done electronically. So you need to either install the '81 bits on the '79 motor, or swap to the '78-80 ignition box. The latter may not be a bad idea, as those are much easier to find compared to the one-year-only '81 box...

Great! I heeded your previous advice and stocked up on those TCI boxes I have two in reserve, travel with one and the other stays at home. Now I can I have the option of swapping these components if need be for whatever reason in the future Now how about that second gear thing, at what mileage (average) does it usually start showing up. I figure different riding styles would definitely affect that.

[bikerphil]

I had one go out at 7K and another at 13K, 2nd gear that is. If it goes out on you, just fix it and do the washer swap and you'll be good for another 50K+ miles.

[Nubian]

I had one go out at 7K and another at 13K, 2nd gear that is. If it goes out on you, just fix it and do the washer swap and you'll be good for another 50K+ miles.

Just fix it, you are funny, no problem for you I bet. Not fun for me, seems challenging

[cywelchjr]

Great! I heeded your previous advice and stocked up on those TCI boxes I have two in reserve, travel with one and the other stays at home. Now I can I have the option of swapping these components if need be for whatever reason in the future Now how about that second gear thing, at what mileage (average) does it usually start showing up. I figure different riding styles would definitely affect that.

It all depends and sometimes it never shows. As for the timing components, you can simply tie the weights down so they can't move without removing them if you don't feel like actually swapping the parts. It's just as effective and that's really the only difference. As for the bike Rasputin is having trouble with, it could be that the weights are stuck and it not GETTING any mechanical advance.

[BA80]

I believe that you should run the ignition that came with the engine. The internals of the SF engine are different, cams, compression ratio, ect., and may not play well with the different timing curve on the H.

I would also consider running the SF carbs if they came with. They are much easier to adjust and tune in my experience.

[bikerphil]

Just fix it, you are funny, no problem for you I bet. Not fun for me, seems challenging

If it needs to be done, there is plenty of help here and maybe another member close by to lend a hand. You might be one of the few lucky ones who never experience 2nd gear failure.

[crazy steve]

...Now how about that second gear thing, at what mileage (average) does it usually start showing up. I figure different riding styles would definitely affect that.

I've never had that problem, so I can't say. While the motor is out, flip it upside down and pull the pan; get in there with a flashlight, and as you shift through the gears, look at the dogs/slots on the gears. If any are shiny metal or rounded at all, it needs the 'fix'...

Yes, I think riding style can have a lot to do with it.

[jetmechmarty]

Yes, I think riding style can have a lot to do with it.

It's shifting style. This one needs very deliberate shifting. Steve, you obviously have it down. Many others of us, not so much.

Marty (in New York)

[crazy steve]

Yeah, these bikes don't tolerate sloppy shifting well at all. If you ever have the bike pop out of gear (any gear) once in a while, you're not shifting firmly enough...

[Rooster]

shift

Lack of a firm shift, or at 23K the second gear could be toast. Sometimes I wish it were more cut and dry with an old bike, but my guess is with these as well built as they are the other bikes out there must have some real issues