What will it do, no crossover pipe???

[kevxs1100]

I decided to put a set of those megaphone mufflers on my XS1100SF that you can buy from JCWhitney. After I received them I was surprised just how nice they were. My mufflers were totally shot, so I cut them off and put the new ones on. I was surprised again because they look pretty damn good on there! The only thing is I had to cut the headers on each side in front of the crossover tube to install the new aftermarket mufflers. It sounds and look great, but what can it do not having the crossover tube??? I haven't ridden the bike that far yet (I plan to this weekend), but it seems fine. Has anyone ever run without a crossover or install these mufflers??? Are there any problems that can come from not having a crossover pipe???

-Bob in SE PA.

[ratbyk]

Cross over pipe

Bob, just go and ride it! You are gaining far more in appearance and sound pleasure then the little bit of mid range torque that you "MAY" have lost. The new mufflers with a exhaust system with some continuity to it is likely giving you more power than you lost with the ratty mufflers and a cross over pipe.
I remember back in 75 we were running a 427 alloy block Vette in the Trans Am Series. Foltz Engineering provided us with a cross over system to fit our existing header/exhaust system. They claimed we would pickup 17HP. Well, after a great deal of work and fabrication we got it neatly installed. Our lap times never changed even a 10th of a second.
Ken/Sooke
78E Ratbyk
82 FT500 "lilRat"

[Ken Talbot]

We are running a set of slip-ons on SWMBO's 'H As you have described, the cross-over is gone, and I would have to say I can't tell the difference.

[TopCatGr58]

Shouldn't he monitor his spark plug color to ensure that the new pipes aren't breathing so much better that he could run a bit lean? Of course I have to admit that I put a set of 4-1 pipes on mine shortly after I got it, and ran it that way for years without ever rejetting and never burned a valve/piston!!! Enjoy, and how about a picture or two??
T.C.

[kevxs1100]

I will keep an eye on the plugs. That is a great idea. I will post some pics soon (when I figure out how). I have been putting this bike together over the winter and all most have it done. I almost sold it foolishly here recently (I was a little light on cash), but I have come to my senses. I have a 1979 XS1100SF. I just had it painted black (tank, fenders and side covers). It looks like a midnight without the gold (I like the chrome better). I rebuilt the carbs and brakes and just put on the new mufflers. I want to put on some new tires and enjoy it the season! Thanks for the input on the exhaust.

[chevy45412001]

x-over

Doesn't it work like on cars. The cross over helps to scavange the system and helps midrange?.I dont miss it on my xj. Cant tell its gone.( 4-1 kerker on mine. )

[skids]

Re: x-over

In a sense the 4-1 has a collector pipe that acts as a crossover.

Originally posted by chevy45412001
Doesn't it work like on cars. The cross over helps to scavange the system and helps midrange?.I dont miss it on my xj. Cant tell its gone.( 4-1 kerker on mine. )

[Jerry]

Most, not all, 4-into-2 system use a crossover pipe to help exhaust scavaging at lower RPMs. The stock XS/XJ system has it, and the used Jardine system I put on has it. Would you notice if it was gone? I am not a lightweight guy and frequently pull my small trailer on long-distance rides, so any difference in low-end performance is noticeable to me. If you are a lighter rider, keep the bike up in rpms by downshifting for better performance, you are not likely to notice any difference.

[Geezer]

Originally posted by Ken Talbot
We are running a set of slip-ons on SWMBO's 'H As you have described, the cross-over is gone, and I would have to say I can't tell the difference.

I have a pair of Sportster mufflers on the Mongrel sans crossover pipe and I can't tell the difference either.

They also end well before the axle and make tire changes easier.

Geezer

[Renegade]

Re: x-over

Originally posted by chevy45412001
Doesn't it work like on cars. The cross over helps to scavange the system and helps midrange?.I dont miss it on my xj. Cant tell its gone.( 4-1 kerker on mine. )

I think it is more for the sound than for the performance with bikes. Although with extremely restrictive mufflers, the crossover may help by directing some of the exhaust gas to the muffler with the least pressure at the moment.

[skids]

Re: Re: x-over

I put some harley muffs on a 78E and cut the crossover off. There was a noticable loss in performance from about 2700 to 3300 rpms. When I extended the adapter sections of pipe, it did help, but the torque was still a bit soggy feeling in that range. The carb synch showed some loss in vacuum there also. I believe the crossover is for performance, although it might give it a deeper tone as well. Harley pipes do not produce Harley tones on an XS1100.

Originally posted by Renegade


I think it is more for the sound than for the performance with bikes. Although with extremely restrictive mufflers, the crossover may help by directing some of the exhaust gas to the muffler with the least pressure at the moment.

[Renegade]

Re: Re: Re: x-over

Originally posted by skids
I put some harley muffs on a 78E and cut the crossover off. There was a noticable loss in performance from about 2700 to 3300 rpms. When I extended the adapter sections of pipe, it did help, but the torque was still a bit soggy feeling in that range. The carb synch showed some loss in vacuum there also. I believe the crossover is for performance, although it might give it a deeper tone as well. Harley pipes do not produce Harley tones on an XS1100.

You have just discovered one of the drawbacks to exhaust changes with CV carbs. CV's are very sensitive to changes in either the exhaust flow or the amount of airbox restriction. Simply changing the head pipe length by a few inches will affect CV carbs. I have been through this game with three different bikes that my brother has owned, and there are variables that I couldn't even start to explain that come into play. The 350 worked best with 1.75" pipe that was about 2 feet longer than stock with no muffler, while the 650 worked better with shorter and smaller diameter pipe and a more restrictive muffler.
There is a magic range where everything is happy, anything outside of that range becomes a tuning headache.

As for the tone, you can deepen the tone by going to larger diameter pipes. But you trade gas velocity and low end performance for the deeper sound.

[webbcraft2150]

I have had a set of the JCW "extra long" mufflers on my 80g hardbagger for 3 years now and have had no problems with running rich/lean. The sound gets a little deeper as the "wear" in. So far, have been pleased with looks and performance of this $100 setup. Plus, they weigh alot less than the stockers.