Bonneville America Forums Forums Technical Forums Exhaust Crossover pipe

FRIAR JOHN - Yes I still have the clip. I emailed it to another member who posted it up for me (big brother). If you want I can send it to you. As with any recording it does not do the exhaust note justice.

I still do not see a problem with removing the crossover pipe as long as you go to a more open muffler. Two 90 deg. bends is not ideal for anything to flow smoothly. You do the math and that is a 180 deg. bend? How will that flow the “pressure wave” better? Anything moving will take the path of least resistance. Any other path option will cause turbulence. You want more air in you create a straight free flowing intake. You want more exhaust out you create a straight free flowing exhaust.

Someone finally did a before and after dyno and proved little or no change. That was not good enough for some members.

For those of you against the mod what power loss are you thinking you will lose without the crossover? I can see how with stock mufflers you may loose some (very little if any) power. You open the muffler at the same time you stay the same or get (a little) more power. Why not do more than through out technical theories on how exhaust works, and prove or disprove your theories.

TheDog33 has proven when the crossover is removed no power has been lost (in fact gained some with free flowing mufflers).

It is up to the members against the mod to do dyno test and prove removing the crossover will cause one to loose power.

If they do loose power I am sure it will be minute at the most. You gain a lot of sound and loose no power (proven) at all from removing the crossover pipe. Open the exhaust and intake up if you want to gain power.

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It is up to the members against the mod to do dyno test and prove removing the crossover will cause one to loose power.

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Nah, no one needs to prove anything one way or the other regarding that x-over pipe I figure. There's been some good thoughts on the subject here, including sound logic and technical prowess. I continue to enjoy each and every opinion on the subject but am still unsure about the mod... that's why I put in a removable plug. I can reverse my decision anytime I want. I do however look forward to firing up the bike (yeah, still too cold) to see (hear) the results of eliminating x-over exhaust.

I did the same thing...I can pull the plug when ever I want...I need to get a sound clip, cause it sounds no different to me...

No need to prove anything because you would have to prove them under all possible variables. I doubt my power gain was due to cross over removal since it was so small. More likely the weather that day. Wendy's showed no gain and no loss. Both bikes have open pipes.Sound difference is small, it just separates the sound of each cyl a little. I would do it again and if I thought it hurt anything I would have replaced the headers.

I added the sound file to the Audio-Video page after converting it to MP3.

http://www.bonnevilleamerica.com/resources/audio-video-files/

Nice sound. Is the idle set a bit slow?

I may have come across a little strong on the point I was trying to make. My point is the argument was all baised on power and how exhaust flowes. Someone steped up and did a test proving (for their two bikes at least) they had little or no power change. If you think it will cause power loss, it is up to you to step up and prove it. I have no idea how you would prove or disprove the exhaust flow. Like I said with stock mufflers I can see power loss. I bought my bike with TORO's on it. I cut off the xover pipe with my TORO's and noticed I got a great note and could feel no power loss or gain. I went to the 32" turnouts and gained a awsome sound and look. I still feel no power loss or gain.

I guess it would be a safe bet to agree, if you cut the crossover pipe open the muffler up.

It is a little hard to set the idle. The tach starts at 1,000rpm. I have it set where I can see it trying to move from the 1,000rpm mark. So it is right in the middle of what the book reads. (900-1100 if I remember correct).

The clip is the first crankup after I put the 32" turnouts on so the motor may be cold and I did not choke it or reset the idle at that time (I wanted to hurry up and hear the sound).


Thanks Friar John for putting that up. Like I said that clip is no justice for the sound it makes in person.

Anyone in the DFW area can contact me if they want to hear it in person. I am planning on going on some trips this summer and will post where I plan on traveling so those of you close can have a TBA meeting or something.

Okay, I got out for a decent snort today and can finally comment on life after plugging the crossover pipe. I like the sound bunches more now that each pipe sings to it's own tune. It may have had an impact on performance, but I don't really know 'cause I played with the carbs somewhat and have some fine tuning to do there. But I'm able to imagine this simple mod will work well with my new Specialty Spares that I'm waiting for!!

Just done my crossover pipe, and like Keith I'm a lot happier with the sound, if I have lost some power this want bother me, I have also found that it is not popping as much????

Just a wee bit of an update on this topic. With the x-over pipe plugged and after a few rides I began to suspect this mod had an ill effect on performance. The other day I removed the plug and oh yeah, it made a difference. The bike woke up BIG TIME!

Bear in mind I'm running TORs are the moment (SSs are coming) so there is a fair amount of exhaust restriction. More open pipes would I'm sure, compliment the plugged x-over pipe mod better.

For sure, with restriction the exhaust needs somewhere to go and the cross over supplies that by allowing some to go out the other pipe.I may have had no change on either of our bikes because I am running totally open exhaust.

I don't have any close neighbors, woods across the street and I own the woods on the other 3 sides.

I am running open exhaust as well but still have the cross over in. Never saw need in changing it. Its nearly too loud now.

I could be wrong here Chad, but I don't think the issue here is that by eliminating the crossover pipe or defeating its purpose with a plug, "makes the exhaust note any louder". I think the point is that each "power-pulse" sound coming out of each of the exhaust tips becomes its own separate exhaust note, and thus might sound a little more like the older vintage Triumphs.

(...or at least that is what is hoped for by the guys who are doin' this, I'm guessin')

Yup, that's what I was hoping for.

removing the cross over does not make the bike louder it just separates the sound as Dwight said. You will never get that old sound with our bikes but it is a little closer. You need the 360º engine to get that old Triumph sound.

And even with the 360's, you'll never quite match the sound of the longer stroke Meriden Triumphs, but you can come close.

I did something similiar with the stock baffels on my BUBS.

You will find that within a monthall your glass is blown out, and your chain is covered with it.

My solution, I used some perforated metal (curtasy of an big old school satalite dish)and enfolded the glass in it. then worked it till i could get the baffel and the new pces into the pipe. I think it worked pretty good,, I had 5 guys come up to me at a rally to compliment the sound.

I agree the idea is to get that old school triumph thump. It is not the exact thump but it is close. You would need a 360 crank to get that.

The 270 without the xover may even become its own classic sound in 40 years. I like it and have never come across anyone who did not like it. Most everyone who does the mod loves the new "Thump".