Seat mount question (1979 special)

[OldGreyBeast]

Is this stud welded on the topside of the seat pan or is it threaded in? I tried to turn it with a pair of vice grips and it didn't want to move. I have no idea how the previous owner of this seat managed to break that flipping stud off but they did.

[DEEBS11]

"I have no idea how the previous owner of this seat managed to break that flipping stud off but they did."


They probably grabbed it with a set of Vise Grips.

[DiverRay]

I think they are welded on the other side of the pan. It's been a few years since I've had the seat apart, so I'm not 100% sure.

[cajun31]

It is part of the pan and it is very easy to break them. DAMHIK.

[DEEBS11]

To repair that you would have to cut off what's left of the stud with a Dremel. Grind it flat. Center punch and drill a new hole. Then re-tap (it looks like M6 or M8) carefully (not a lot of meat there on the pan). Cut a piece of threaded stock the correct length and install it with Lock Tite red. When installing the nut to secure the seat, it just needs to be snug, not Godzilla torqued.

When installing or removing a stud, install two nuts on the stud that are tightened against each other and remove by turning the nuts. Only use Vice Grips to adjust your carb pilot screws.

[OldGreyBeast]

It is part of the pan and it is very easy to break them. DAMHIK.

Thanks cajun. I ordered some of these - https://www.amazon.com/gp/product/B09W61R31H/ I'll see if that works to supplement the stud and also act as the collar for the rubber damper. If it doesn't look like this will work I guess I'll try my hand at welding another bit of M6 thread on there. Getting it lined up right will be a bear, but I don't want to take the whole seat apart.

[OldGreyBeast]

To repair that you would have to cut off what's left of the stud with a Dremel. Grind it flat. Center punch and drill a new hole. Then re-tap (it looks like M6 or M8) carefully (not a lot of meat there on the pan). Cut a piece of threaded stock the correct length and install it with Lock Tite red. When installing the nut to secure the seat, it just needs to be snug, not Godzilla torqued.

When installing or removing a stud, install two nuts on the stud that are tightened against each other and remove by turning the nuts. Only use Vice Grips to adjust your carb pilot screws.

If the stud's broken off anyway I generally just vice grip it out. I don't think there's enough meat on the seat pan to drill and tap it, it's pretty dang thin.

[DEEBS11]

Another possibility is a Nut-Sert or tack weld a nut on the pan (carefully).

[cajun31]

The question is what shape is the rest of the seat in? Might be better to start with another seat unless everything else is still there. Here is a listing from Ebay 1979 YAMAHA XS1100 SADDLE SEAT | eBay. This is the seat from your model/year. If you look at the pictures in this listing you can see the rest of the hardware needed to mount the seat to the bike. The bolt you have broke off is needed to mount the actual system Yamaha came up with to mount the seat to the bike and most of that hardware is unobtanium. The listing I posted from Ebay is actually not that bad on the price for all you are getting. The cover is either original or at least original in style for your year/model. I have used nut-serts for other projects and they are very good. You would have to run the replacement bolt from the bottom up and get it locked in place in order to mount the rest of the mounting hardware you need to mount the seat. I have bought several used seats off of Ebay just for the seat pan and hardware with no regard for the actual condition of the rest of the seat. I just recovered the seat with a replacement cover. On the 79 special there was also a Yamaha emblem on the back of the seat. Do you still have that emblem? I am a purist when it comes to restoring these bikes so I like everything as it was originally. That may not be a factor for you. The reason I mention that is because the special seats on the specials were basically the same as far as putting the seat on the bike was concerned. The covers changed a bit and on the Midnights they used a stepped up version of the seat. My point is they all will mount.

[OldGreyBeast]

I do have all the mounting hardware, the seat I have is in pretty good shape overall. One tear on the passenger seat (which I fixed with a vinyl repair kit). The metal grab rod and the plastic "Yamaha" branded cover are intact but a little scuffed.

[Ranger_xs1100]

Looks like you have a seat from a 79 standard that you want to mount on your 79 special. I think it may mount ok, but you may have some odd looking gaps between the seat and the side covers. You can read about the seat differences here: Interchange Guide: Seats, Grab Rails, Sidecovers, Taillights - XS11.club Forums

[OldGreyBeast]

Dang. It was listed on ebay as being for a 79 special

[DiverRay]

The sides on the '79 Special drop about 1" from the front of the seat to the back, not strait as your seat is. I modified an '80 Special seat to fit my '79, but it took some welding to get it usable. Check the parts for sale on this site, and maybe put in a "want to buy" and see if the one year only '79 Special seat is available.

[DEEBS11]

79 SF seat

https://xs11.club/forum/buy-sell-tra...eas#post880776

[OldGreyBeast]

79 SF seat

https://xs11.club/forum/buy-sell-tra...eas#post880776

PM sent. I've bought some stuff from him before. Thanks for the link Deebs!

These XS1100 are a lot harder to buy parts for than the Honda CBs I'm used to working on lol.