1979 vs 1980

[Guy&2goldens]

Greeting all,
I had purchased a 1980sg (3U9-001…) which the cylinders needed boring and the pistons were pouched. So I picked up a 1979 (2H7-100…). Guy had it torn down in boxes. Motor was intact though and I do have to pull the the head etc… and check it over. He had also put a 1999 R6 front clip on it. I don’t think I will be using the R6 front clip as it’s like driving down hill all the time lol and I’m more of a numbers matching person. So would there be any advantage over either frame? Guy said it was a 1978 buy going by the vin it shows as a 79. I do want to use the seat, tank etc off the 79.

so just looking for some suggestions on which way to go from those with more experience with the bike. I do see there is a few differences on the two frames but all in all they look pretty much the same to my eye. I will have to use the front clip off the 80 but that’s not a big swap over.

thanks kindly for any input and Happy Holidays.

[Radioguylogs]

If it were me, I would look at the cosmetic parts for each model, and choose the frame that goes with the best set of fenders, side covers, seat, etc....

The engine and the front clip will interchangeable with either frame, although you should keep the Ignition Control Module to match the engine. The ignition coils and ballast resister ('79 only) should stay matched the Ignition Control Module

The seat, grab bar, and side covers are not interchangeable.

The '79 vs '80 engines have different valve sizes, and different spark advance mechanisms- that's why they need the matching Ignition Control Module.

[Guy&2goldens]

Good points. I will inspect the frame tomorrow on the 79 make sure no cracks or anything. Based on what you mentioned Radioguylogs, I’d be going with the 79. It also came with a 4 to 1 Gemini exhaust. Couldn’t find any info on them though. Guy did say he re-jetted the carbs. I will have to go through all that as well.

[Tonyxs11]

first off whats a "front clip" ????
I have a 79 SF with a seat and grabrail off an 80 SG, the seat fits with no problem but i did modify the bottom edge so it followed the slope of the side panel, (using SG side panels would been better) the grab rail fits the top shock mounts as normal but had to drill an extra hole to fix the rear mounts to the frame.

[red bandit]

The 79f triple trees/forks are different than the 80sg triple trees/forks. Keep them paired. The 79 is a better running engine.

[Guy&2goldens]

The 79f triple trees/forks are different than the 80sg triple trees/forks. Keep them paired. The 79 is a better running engine.

It is an F model going by the vin. I took a closer look and do see the difference there in the tubes and the wheel mount. So I may have to use the SG or track down a new front end. *sigh*.

[Guy&2goldens]

first off whats a "front clip" ????
I have a 79 SF with a seat and grabrail off an 80 SG, the seat fits with no problem but i did modify the bottom edge so it followed the slope of the side panel, (using SG side panels would been better) the grab rail fits the top shock mounts as normal but had to drill an extra hole to fix the rear mounts to the frame.

front clip is the triple tree, forks etc. not sure why the call them a “clip” here …

[Tonyxs11]

front clip is the triple tree, forks etc. not sure why the call them a “clip” here …

yeah seems a bit odd !!! but at least I know now

[Guy&2goldens]

So checking this bike over. The vin is 2h7-100274. Which I understand is the 79 xs1100f. The sticker on the neck does show mfg in 1977 however. In. 10/77. Any thoughts? Motor and neck do match for vin.

[red bandit]

Are you sure it's not 10/78?

[Guy&2goldens]

Are you sure it's not 10/78?

Yup, positive

[LAB3]

Any thoughts?

Here's three different ideas that would make sense.

1) Left over bike from 1977 at the factory that got stamped and sold as a 1978

2) Mis-stamped numbers at the factory, I'm assuming that Arabic numerals are not something the a average person deals with on an everyday basis in Japan.

3) Numbers restamped when someone swapped an engine to save from having to get it inspected and retitled as an "assembled" machine.

To me, number three seems most likely! Are there any casting numbers or other symbols on the cases that might point in that direction? Maybe someone more experienced could chime in on that one.

[Tonyxs11]

could it be a pre-production model ? ive seen this with Suzuki's

[Guy&2goldens]

Here's three different ideas that would make sense.

1) Left over bike from 1977 at the factory that got stamped and sold as a 1978

2) Mis-stamped numbers at the factory, I'm assuming that Arabic numerals are not something the a average person deals with on an everyday basis in Japan.

3) Numbers restamped when someone swapped an engine to save from having to get it inspected and retitled as an "assembled" machine.

To me, number three seems most likely! Are there any casting numbers or other symbols on the cases that might point in that direction? Maybe someone more experienced could chime in on that one.

No, it doesn’t look like it’s been restamped. I thought that too. Also, the sticker has the same number listed. 100274. So it’s a three way match in that aspect. I am thinking more of a late frame made in 77, and they had enough frames for the 78 model and used it for a 79 instead going by the vin. I just find it odd is all. It does have the Canadian sticker on the neck too.

[Radioguylogs]

Car model years start earlier than the corresponding calendar year.

For example, production of 1978 model cars would normally start around July of 1977. I think the laws actually allow model year production to start in January for the following calendar year.

Your frame might have been scheduled some months before final assembly.

BTW, I think 1978 was the first model year for the XS1100.

It seems peculiar that your VIN doesn't start 2H7-110xxx instead of 2H7-100xxx :
http://www.xs11.com/faqs/153-serial-...ry-colors.html