Hindle with everything else stock?

[Traumahawk]

There is a nonsense, as with more restritive mufflers than stock, main jets need to be reduced too....

Here is a thread that I asked about 2 years ago..."Back pressure vs enrichening carbs".

Hope this helps.

http://vmaxforum.net/showthread.php?t=25903&highlight=predator

 

[thor_eyerdhal]

What's more restrictive than stock?

Almost all slip-on mufflers for Vmax..

 

[davesax36]

Not at the header...
The way I understand it, most of the back pressure is created at the beginning of the header. Gases cool and create the need for effective scavenging, and the stock cat/baffle/whatever giant heavy box helps eliminate certain emissions. I can't think of a set of slip-ons that have decreased pipe inlet diameter relative to stock. Nor do any include anything less than a straight path out replacing the baffle section of the stock pipes.

Or I'm totally wrong. That happens, too.

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[thor_eyerdhal]

Look at the inner of the stock central box, it is totally empty and the four primaries stop suddenly in it.
This act as a pressure wave termination box. It help savenging in the primaries (by creating strong backpulses) and it reduce backpressure effect of the rear mufflers.

This is why stock mufflers make more power than almost all aftermarket slip-on ones (none of them have a big empty box)

But my first question was :
-Stock intake and engine with slip-ons mufflers more restrictive than stock=>Common
advice for main jets is keep stock or reducing
Stock intake and engine with 4in1 headers less restritives than stock => advice for main jets is reducing too...

That is not logical.

 

[davesax36]

Maybe it's down 1 jet size for anything (stock or slipons) and 2 sizes for greater flow of bigger headers. I think that's the end of my actual knowledge. Somebody smarter is gonna have to say something.

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[Traumahawk]

Maybe it's down 1 jet size for anything (stock or slipons) and 2 sizes for greater flow of bigger headers. I think that's the end of my actual knowledge. Somebody smarter is gonna have to say something.

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I'm repeating what Sean told me....LOL....I asked him 3 times to make certain that I was right.

It was minus 1....for stock. If you look back at some of the early literature, both front carbs were supposed to have 150 jets, while the rear were 152's.

PLUS minus 1 for slip-ons. So....minus 1 plus minus 1= minus 2.

 

[davesax36]

I'm gonna run 147.5s with the hindle. Should be the same as your kerker. Right, hawk?

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[Traumahawk]

I'm gonna run 147.5s with the hindle. Should be the same as your kerker. Right, hawk?

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To me that makes sense. Did you read my post about "sounds like a good deal?" The motorcycle dyno here is 85 an HR, unlimited amount of runs. So one of these days come on up here, I'll buy some time, and you can run your bike thru if you want.

http://vmaxforum.net/showthread.php?t=32636

 

[davesax36]

We'll definitely do that.

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[Traumahawk]

Plus, I still have slip ons right now (kerker slip on's and stock head pipe) and the 147.5's. When I get back home, I'm planning on doing a dyno run so I can get a baseline HP, (as opposed to the 106 hp in Topeka, with the 152's...same exhaust set up as now) and see if there is an increase, then do a run with the kerker 4-1 and see if there is an increase with the 147.5's.

That should get some good solid controlled numbers.

I know that every dyno is different..but the only other thing I could do is to go back to Topeka.

Here is a PDF of that run, you can see that I'm rich, with the 152.5's.