Two Questions on header pipes

[fbenach]

Hello everyone!! Hope you are good out there!!

OK, after a couple of years of work, I finally feel satisfied with the engine performance, little by little, I managed to have this machine on its point. (79 R65 European, double front discs)

Its time to concentrate on paint and mufflers. My header pipes are quite rusty, specially the right unit.

I´ve been thinking of replacing those and found a nice unit (35mm OD) that has two crossovers, and my original pipes have only the front crossover.

My doubt is: is one the original set up or is it two? Is is possible my headers are not OEM?
What should I expect of adding the second rear crossover with these pipes?

On the other hand, I see some bikes don't have those crossover at all... is it a good thing to eliminate the crossovers with a set of customized units with no crossover?

I would love to know what the guru´s opinion is on the matter.

Thanks again in advance, your experience has always been so helpful on my choosing a way to go!!

Cheers from Costa Rica!!

Fernando

[montmil]

You may note that earlier Airheads had zero X-over pipes on the exhaust headers. Then, as on your R65, BMW Motorrad added a single crossover near the front and later on, a second pipe near the junction of the header/muffler connection. Lots of chat on the reasoning: including a quieter exhaust as, in effect, two mufflers were available for each single exhaust cycle.

With my 1983 R65, which had rusty but solid headers, I removed the x-over pipes, cut and ground away the header pipe stubs, used the now junk x-over tubes to shape blanking plates for the headers and welded them in place.
   One-inch wide, tan-colored fiberglas heat wrap from Jeggs hot rod supply and stainless steel ties completed the job. Norton Dunstall-style mufflers completed the exhaust system's overhaul.

No worries regarding your choice of header replacements.

[thrang]

My original R65 had a single cross over and the restoration doner bike came with a double pipe set up, so I think none, one or two will work equally well so long as you set the carbs up correctly.  

Got to say though I do like the look of the Dunstall style silencers on Monte's ride. Although I am loath to chop up a good airhead if I ever decide to get round to building an R100 cafe I'd probably go that route.

[Barry]

Fernando,
Your 79 would originally have had the single balance pipe. 2 balance pipes came in 81.

You might want to check the 2nd balance pipe doesn't foul the stand which was different on the later bikes.

[fbenach]

Thanks fellas... I actually like Mont´s work on the pipes, didint think of the thermal tape!!!

and Barry, thanks for the tip... I didint think of the centerstand either!!! My friend down here has a R65LS with two crossovers and uses the same centerstand (I think), will check on that!!

Will show pictures of it!!!

Cheers!!

[Red_Hen]

I also like Monte's setup with the exhaust tape and cool pipes - Monte, where did you buy yours?  I see some on Ebay but not quite as cool as yours.

[montmil]

The '83 R65 pictured has EMGO -off shore mfg- Dunstall repops. They are chromed. Inlet ports on the ones I received required the use of the included brass adaptors. My '81 R65 has the same Dunstall-look in stainless steel from EPCO and have 35mm inlets. Not sure if EPCO is still in business.

The tan fiberglas heat tape is 1-inch wide from Jeggs. For best results and visual good looks, you must overlap each preceding turn by a factor of one-half. Otherwise, you will end up with a lumpy looking wrap job. Install requires soaking the 'glas tape in water to rinse away most of the short, loose glass fibers. Also prevents these unfriendly bits from being drawn into your lungs. Same safety precautions here as when working with glass cloth and resins. Both ends are secured with stainless steel tie-wraps avail at most Big Box home improvement stores for far less money than Jeggs requires.

http://www.jegs.com/

[Red_Hen]

Thank You, Monte!

[Tony Smith]

One cross over or two?

No idea if there is a performance difference and doubt that it is significant if there is.
 
What I can tell you is that twin cross over headers take twice as long to fit and are a pain in the behind to take off.

A single cross over header system slips on and off with only mild loosening involved, the twin cross over (unless you have an off-sider helping who will hold the bike upright with both stands retracted requires the disassembled headers to be laid more or less in the right position next to the bike. Then with the first and second hands you line up the cross overs whilst steadying everything with your third and fourth hands. And of course the eyes in the back of you head help with lining everything up.

Not a fan of tin cross over systems.

[montmil]

Another removal option for the twin x-over headers that can be done single-handed:

With the bike on the centerstand and mufflers removed, allow the complete header system to lay on the floor below the bike.

Next, stand beside the bike and tilt the machine up on one leg of the centerstand. Then, using your foot, nudge one of the pipes to the outside. Step to the other side of the bike and repeat. Complete header assembly is now clear of the bike.

Reverse the procedure for refit.