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Discussion Starter · #1 ·
Here is a graph of a pipe comarison where we tried all three of these pipes on a gas cheetah pv 472cc motor with the power valves. We did 3 back to back runs on all three pipes and I took the 2nd run for each pipe and put it on the graph. These were all inframe pipes. timing was at +8. Stock ign, on an automotive dyno so no eddie current to fool here.

blue = Shearer sb
green = rdz sb
red = Shearer bb

It looks like the bb pipes fell on their face at the higher rpm. Any thoughts or feedback on this pipe comparison. I know some people love bb and some love sb. Lets here your opinions. Let em rip!

 

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Was any jetting changed. My bb. Shearer inframes made 11 more hp jetted down 3 jet sizes over where I had it jetted with my my SB inframes.
 

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That's what I'm thinking also. The jetting needs to be tweaked in order to show accurate results.
 

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Discussion Starter · #6 ·
Good Feedback. Keep it coming. The pv's closing a little was a very good suggestion. That may be the case.

The jetting was kept constant to compare the pipes at 142 mains. These were in 35 pwk's on gas. We first spent a lot of time on jetting getting max hp. The 142 mains gave the best results but were right on the edge of lean. I wouldn't dare go any leaner than that. I ran the bike with 145's to be safe off of the dyno.

I know most of you guys are using no pv's (cubs) or block off plates. This may be the important difference.

Has anyone found that the sb is also better than the bb pipes on a big motor less than 500 cc's???

Mailman
 

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Yes, Mailman and I have the same motor and the debate rages as to which pipe I should buy. I have the same 472 powervalve cheetah. I need an inframe pipe. Can anybody give us a nice long opinion as to what pipe they like for this combo and why. Chris will run the OOF and I will run INFRAMES so all answers will be helpfull. I need to buy soon so I need to know BB or SB? CPI or SHEARER? I DUNE/DRAG. He DUNE/HILLSHOOTS. THANKS.
 

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Nate Mccoy had me run BB pipes on my 421 due to the SB pipes falling off pretty far in hp after say 2 or 3 long passes like we dune racers do.
He is however a fan of high timing and ports even his 397 cubs for BB pipes.
I'd say if you richened the BB jetting up couple sizes and bumped the timing to 9 or 10 they might shine and not fall off as much when ran back to back. Just a thought.
 

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Discussion Starter · #9 ·
This gas motor will only tolerate an honest +7 with back to back runs. I can get +8 to work on the dyno but it rattles plugs loose at the hill. I think most will agree that +7 is a pretty sweet spot for a lot of built banshee motors on gas. IMO.
 

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Discussion Starter · #11 ·
We don't use an a/f sniffer so there are no readings. We read the graph and check plugs. I know this drives Nate crazy but my local dyno guy has a pretty lengthy explanation why he doesn't use them.
It would be a great topic for another post.
 
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