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If I weld a cap on the crossover pipe it would turn my jackpot 2/1/2 with s&s grand national slip on into a full 2 into 1 system? I would notice any gains? Sound and performance wise?
If I weld a cap on the crossover pipe it would turn my jackpot 2/1/2 with s&s grand national slip on into a full 2 into 1 system? I would notice any gains? Sound and performance wise?
On a street driven bike, with just a Stage I (air cleaner/exhaust) mod, or even with a bolt-in cam, I seriously doubt it.....
Exhaust manufacturers go to great lengths designing and building collectors for smooth exhaust flow. That little capped off piece of crossover pipe, I suspect would have to negatively affect the airflow. I seriously doubt it would give a similar flow/performance as a well designed 2-1 head pipe.
If you haven't already, a good dyno tune may give you a better seat of the pants change with your current exhaust system.
Here's my story. A few weeks ago, I was on the freeway, doing the posted speed limit of 65....yet my speedometer was showing 80. I guess I'd better get that checked.
Traffic was busy and I hit and ran over a solid chunk of metal. Hit the front tire and it bounced up, then hit under the bike with a very loud metallic thud. I was worried it hit the engine, oil pan or transmission. Checked the information screen and it showed oil pressure good. Look back for leaking or smoking. Nothing. Got home a few minutes later. Looked at front rim, no damage. Looked under the bike at the engine and didn't see anything. A few days later I was putting air in back tire and looked underneath and what i saw was incredible. I had smashed the underneath cross over nearly flat.
This is the Cobra Pro Chamber. I called and Mike at Cobra was very helpful and said he could send me a replacement pipe. This was on Friday. Would ship out on Tuesday and take several days. In the mean time, I cut out the bad section and used a piece of exhaust flex pipe. It worked. Another buddy had made a cap to block off his stock exhaust on his 2025. He gave it to me to try. With a little modification I was able to get it to fit. The cuts to expand it did allow a very small amount of exhaust to leak out.
using exhaust flex tube
Here is the block off piece After the cross over chamber, blocked off the pipe
Went on another ride. Well, now I notice some difference. With the original setup, there was a stumble off the line up to 2000 rpm. With the pipe blocked off, there is NO stumble. Great acceleration.
Tomorrow I am going to my indy shop and have the bike put on the dyno just for a power run. I had a power run done 18 months ago so I can compare to that data sheet. I have received the new cross over. I will put the new cross over on , and go back for another power run and see the results. I might just leave this as a 2-1 set up.
Went on another ride. Well, now I notice some difference. With the original setup, there was a stumble off the line up to 2000 rpm. With the pipe blocked off, there is NO stumble. Great acceleration.
Tomorrow I am going to my indy shop and have the bike put on the dyno just for a power run. I had a power run done 18 months ago so I can compare to that data sheet. I have received the new cross over. I will put the new cross over on , and go back for another power run and see the results. I might just leave this as a 2-1 set up.
I'll post results.
It would seem your mod combination needed a little more back pressure...
Whoever tuned it before, should have been able to minimize, or get rid of that stumble....
A poor tune, will hold back a good exhaust.
A good tune can make a substandard exhaust do well.
You can't accurately compare different exhaust systems, without also doing a proper tune for each individual exhaust change....
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