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Author Topic: Jet sizes for 591cc CB550  (Read 1058 times)

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Stevien1

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Jet sizes for 591cc CB550
« on: August 04, 2007, 07:23:36 PM »
Just curious what size jets and clip position other people are running with the "605" 591cc big bore kits.  This is with stock 500/550 carbs.

My bike has the "605" pistons, ported cyl head, Web 58A cam/springs, 4-1 Mac megaphone exhaust, Uni pod filters, DynaS, 3ohm coils, D7ES plugs.

I started off running 40 pilot, 120 main, and clip on the 4th notch (one richer than stock).  Started great, part throttle was good- but it had a huge bog around 3/4 throttle.  WOT was fine once it got past the bog, plugs read fine.  I noticed the bog is worse with the choke on 1/4 and clears up as soon as I open the choke back up.  I'm thinking its too rich in this area, so maybe raising the clip back up to the 3rd notch will help....  ???

Looking for input, thanks!
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Offline bwaller

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Re: Jet sizes for 591cc CB550
« Reply #1 on: August 04, 2007, 09:39:16 PM »
My engine also runs the 61mm pistons, Web cam, some head work, 3ohm Dyna coils and ignition. The squish is tighter than stock and compression is bumped to 10:1.  I have a different exhaust and use the stock intake plenum with a single large K&N with PD46 carbs. It likes the needle raised one notch, stock pilots and 105 mains (stock is 90).

 It pulls like a train and gives an unbelievable 55 miles/USg
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Offline clarkjh

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Re: Jet sizes for 591cc CB550
« Reply #2 on: August 05, 2007, 04:24:17 AM »
Well, my "555cc" kit is 4 into two, 022A carbs, stock jets, needle on second clip from the top, stock cam, H'mans ignition.  Pulls like a raped ape.  I get the "bog" at the transition from "pilot" to "needle" circuit, plugs are good, so plan I dropping the needle to the last notch and see what happens.  I'm getting about 37 mpg.
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Stevien1

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Re: Jet sizes for 591cc CB550
« Reply #3 on: August 06, 2007, 08:20:38 PM »
Well I tried moving the needles back to stock (clip on 3rd notch).  The bike did not like it at all!  It lacked power everywhere and it would be really slow to return to idle.

So I changed the needles back to 4th notch (one from the bottom) and upped the main to 130.  It idles ok and midrange is GREAT- however the bog around 3/4 throttle is still there (not as bad).  It's still a little slow to return to idle, maybe the air screws are too lean (1/2 turn leaner than stock).

Wish I had a portable wideband O2 sensor to tune this thing with!   ::)
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