Installing XJ headers on 79 SF

[WSL91]

I'm removing the Kerker from my 79 and installing a set of XJ Headers and some aftermarket mufflers. I think this will be a decent looking setup. Anyway I ran into a problem which I'm sure someone else has before. The XJ Exhaust flanges bottom out before the pipes tighten up. There is about 23/32 distance between the pipe end and the flange on the Kerker and 11/16 on the XJ. While just over 1/16th difference its enough that the XJ flanges bottom out.

So I see at least 3 options.
1. Add something between the motor port and gasket
2. Add something behind the flange on the pipe before the cast exhaust flange
3. remove 1/16" off the cast flange.

Option 3 is doable but would be hard to get a real even cut with a hand held grinder. There is a recess cut in that sets on the pipe flange so it doesn't have to be perfect.

Option 2 seems like maybe a wrap of clothes hanger wire under the cast flange might do the trick.

There are hard plastic spacers/gaskets in the exhaust ports now, I have on my desk 4 new Yamaha 4be-14613 gaskets which may be a tad thinner than the hard plastic ones that are in the exh ports now.

Any ideas?
Thanks

[daveyg]

Maybe u could double up the exhaust gaskets? Or remove the cast flanges and send them to me and for a small fee I'll machine down the flange back to the recess...

[WSL91]

These are the mufflers I bought and I have some 1.5" OD stainless cut off at 3.5" length which fits the XJ headers. Should look pretty decent when done and I only have a small fortune in it, not a large fortune. I'm actually in the range of an aftermarket exhaust but one of the headers I bought came with an XJ muffler which I needed for my XJ. I have a spare XJ muffler thats kind of ugly (the one I removed) but couldn't come up with a mate so I went with the Helix Mufflers off Amazon as that was the cheapest I could find them. Note they are 3" dia and 19.875 long, not 4" and 20.8" long as advertised. Looks like I'll still have chrome exhaust on the SF, I like chrome.
John

http://www.amazon.com/gp/product/B00..._ya_os_product

[crazy steve]

It's not the flanges bottoming out but the exhaust nuts; you need to install shorter studs. Yamaha used two different flange lengths on the stock exhausts, with matching short/long studs. Your '79 has the longer studs as the '78-79 OEM exhaust had the longer flanges...

[WSL91]

Steve
I can actually see the cast flange bottom out on the bosses that the exhaust studs are threaded into. I actually would only need to remove material where the bosses are, not the entire flange. I'll fiddle with it again in the morning. I'll throw the new exhaust gaskets in too and see if that makes a difference. I'll look close at the nuts and verify they aren't bottoming out. Perhaps what I'm seeing is an engineered bottom out so that the exhaust washers can't be destroyed by over tightening? With the flanges bottomed out there is still hardly any stud getting past the threaded part of the nuts which are part threaded and part hex head. The Yamaha exhaust gaskets are quite different than what is in it.
Film at 11:00 and hopefully will include the new install I've nicknamed the bike Chewy in honor of its previous mechanic Chewbacca. Every time I fiddle with the bike I find something else "farmerized" as we refer to it in the antique tractor world. I should post a picture of how they attached the engine guards!

[crazy steve]

There's no difference in the head castings where the exhaust attaches, so it's probably the gaskets that are giving you grief.... The XJ exhaust should fit.

[natemoen]

Double up the gasket. Lots do it and it is quick, easy, simple, and safe.

[WSL91]

They are on. Using the Yamaha gaskets worked. Had to make a run to JC Whitney @ Lasalle-Peru IL but that's not too far from here. I wanted the mufflers with the tapered ends but they are 27" long and these are 24". As it is I'll have to drop a muffler to pull the rear axle but I can live with that. The Helix mufflers I bought on Amazon came out of the box somewhat smaller than advertised so they are going back. For the record XJ mufflers are 22" long.

With the Kerker on it ran like crap up to 3k rpm then took off like a rabbit. With these pipes it behaves more the same over the entire rpm range but doesn't quite accelerate like it did. I'll have to pull the carbs and see what Chewy did in there. I'm guessing they were not rejetted but the needles were just raised.

I leaned on my like new XJ seat today resting on my knuckles and heard the UN-mistakable sound of bubble wrap popping........... Chewy told me it was a new old stock seat. I'm betting Yamaha didn't install bubble wrap under the seat covers.

If you look the bike now has an XJ front fender and CB750 handlebars. What you can't see is that I have a working 160 speedo. I installed my old original XJ master cylinder (sloped) as its a better fit for the bars BUT it doesn't quite move enough brake fluid to lock the front rotors. It's bled and working correctly but it nearly bottoms out in order to apply normal front brakes. I may need to pick up another XV920 M/C like I did for the XJ when I de-linked the brakes. I can lock the rotors on my XJ with the XV920 M/C (The 920 Virago had non-linked brakes and dual front calipers)

[WSL91]

Forgot to add here is the XJ header with a short piece of 1.5" OD tubing. In my case I bought Stainless as I didn't know if any would show and this won't rust. As it turns out with the mufflers I ended up with the entire SS piece is covered up. This piece was 3.5" long and was inserted 1" (length of the stock muffler bushing)

[jjz28]

my double saddle seat looked brand new on my 920 virago and i leaned my nuckels on it and it did the same, the thread was all dry rotted. I hated that, it looked brand new. I put my 920 m/c on my xs750, looked a lot better without that big plastic resevoir on it.

[crazy steve]

I leaned on my like new XJ seat today resting on my knuckles and heard the UN-mistakable sound of bubble wrap popping........... Chewy told me it was a new old stock seat. I'm betting Yamaha didn't install bubble wrap under the seat covers...

What you probably heard was the thin plastic liner that Yamaha sewed to the underside of the pattern so it didn't erode the foam. That gets brittle with age and breaks....

[tom clisham]

Looks great!

John: exhausts came out great. Looks very much like stock.

[WSL91]

John: exhausts came out great. Looks very much like stock.

Yes the headers cleaned up better than I expected. 1 had random rust and I used Mothers aluminum polish (paste) on one of those yellow sponge one side/green scouring pad other side scrubbers. The one I used was worn down from kitchen use but the green side and some Mothers really takes rust off chrome. For light rust the yellow sponge worked fine, for heavy rust the green side works but at a cost. You can't rub too hard or you produce small scratches in the chrome. Overall I'm happy but its pretty quiet now. 1 plus is with 4 into 2 I can tell which side the miss is coming from which I've known about but with the Kerker it was a mystery

On a side note the people at JC Whitney were very nice and allowed me to open parts on the counter and inspect. I wasn't sure what to expect but it turned out to be like an Reilly with a 500,000+ sq ft stock room. You have to order parts through them not the regular number if you want to pick them up.

I checked the idle mix adjust and found the 4 to be all over. Set them to 2.5 turns out and ran the same. Changed it to 3 turns out and the bottom end is noticeably better.

[jimbyjimb]

That looks great. I like the sound on the XJ mufflers too. Somebody had installed XJ pipes on my SG before I bought it and I like them a lot. Good rumble, not too loud.

[crazy steve]

Great job on the pipes....