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Finally tore into carbs

Old 10-04-2013, 07:08 PM
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Finally tore into carbs

Finally started tearing into the carbs tonight and found out that my TPS was not connected, and I assume has not been connected for some time. But I figured if I had come this far I might as well see what I have jetting wise. Also are the foam air filters that go around the breather tubes in the air box a big deal? I do not have them. Ill continue this as I go. The root of this was putting on jardines from having staintunes and running rich on the low end.
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Old 10-04-2013, 07:38 PM
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I have some sort of a jet kit as I have a needle I assume a FP kit (the needle has 5 slots). For the rear its clipped on the 3rd from the top (middle) with a shim under it, a 178 Main and a 50 Pilot. The front is the same with needle position, a main that says "Factory 172k" and a 50 pilot. I am planning on dropping the pilots to 48. Does that sound right? I am running a paper HiFlo filter and stock stacks. Should I also move the front main up to 175 as OEM?

Last edited by KCCO; 10-04-2013 at 11:12 PM.
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Old 10-05-2013, 01:11 PM
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I can confirm FP needles have 5 slots and DJ needles have 6. FP Also supply 50 pilots and the 172 main in their kit. So yes it sounds like a FP kit to me.

Don't use the 50's they wil be too large for standard headers and aftermarket end cans. 48s or 45s!!! 48s I would have thought depending on what needle height you end up with. With standard filter I would also put the mains as standard 178 rear 175 front. For comparison with my FP kit running BMC street filter I use 178 front and 180 rear on the mains. Needle height you will have to experiment with which will then determine which pilot size to use. I suspect 3rd or forth clip from the bottom (pointy end).

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Old 10-05-2013, 03:19 PM
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Thank you, I went back to stock jetting, 48's plugged one hole on the front slide, set the front needle on the 3rd clip, and the rear on the 2nd from the bottom. Have not road yet, but did sync and it purrrrrrrsssssss. Feels and sounds so much better than before. Now I just have to wait to ride it till tomorrow....
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Old 10-06-2013, 01:00 PM
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Bike runs great! One question though, under 3.5-4k it doesn't really do much but once I hit 4k it takes off. Is this normal or should I start looking at what to adjust?
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Old 10-07-2013, 05:22 AM
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That is right at the point of where the needle starts coming into play. Below this is where the pilot jet is at work.

Sorry "doesn't really do much" does not tell me anything. if you mean a little flat then this could be overly rich making it bog down. Maybe try the 45's to see if this improves idle and below 4k. I also find blocking the lift hole softens and flattens things a bit but overall a lot smoother. So you may loose a little take off power.

Are you adjusting the Fuel mixture screws at all. The D things you have on your carbs over there. These will need tweaking if changing pilot jets. The pilot is the course adjustment and the fuel mixture screw is the fine adjustment. They both work together.

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Old 10-07-2013, 09:07 AM
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The idle is fine, its once it gets into the needle range that it starts being flat and less power than I think there should be. I do not have the air screw tool, and one of the heads on mine is eaten up.... took a hemostat to turn it on the bench. I am shimming the needles up one F and R because adding choke helps the issue completely. I pull this info off of https://www.superhawkforum.com/forum...-carb-q-30114/ post 12-20+
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Old 10-07-2013, 11:22 AM
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Final verdict/set up.

OEM air box, HiFlo paper filter, MCCT, Stock engine (best of my knowledge), OEM slid springs, OEM headers, Jardine Hi mounts.

Front: Main:175, Needle: FP 3rd clip (from top) with one shim, Pilot: 48, Slide: plugged one hole, A/F screw: 2.25 out
Rear: Main: 178, Needle: FP 4th clip (from top) with one shim, Pilot: 48, Slide: stock, A/F screw: 2.5 out.

Synced at 1800rpm, reset idle to 1300 for riding. Pulls great from 2k to red line, no dead spots. I am one very happy person right now
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Old 10-07-2013, 11:52 AM
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Sounds good to me. very similar to mine accept I have the needles on the same clip position and add a shim to raise rear 10 though more (sorry can't remember the metric equivalent) than the front as in hawks carb set up.

If it's running nice then I suggest you ride around for a while and see how it goes. You do realise now you have started tinkering with the carbs that you wont stop and get finicky, then make slight adjustments here and there until it's perfection.

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Old 10-07-2013, 12:07 PM
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The sickness has alreay set in. Now I want to go get a dyno run done for the A/F results and see what my baby actually can produce. But at $85 for the test that's a little more than Inwant to pop right now just to cause myself more work. I know $85 is a decent price for the run out here in SF Bay Area though.
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Old 10-07-2013, 12:39 PM
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I was going to say a dyno will tell you exactly how well you have done and then you could fine tune from there. But yeh dyno prices can be a bit scary. Get it all as dam close as you can by the seat of your pants, ride it around for a while, maybe a tweak of the Fuel screws and/or a shim here or there. After a a few weeks of riding and things still run well, then get a single dyno run to get the chart and have a look at the A/F and curves.

When you do eventually get to the dyno, let the dynotechs know that you tune you own carbs and know what your doing and what does what insde the carbs etc. Tell them you not concerned about max BHP but want to see what your A/F air fuel ratio is doing. Otherwise some dynotechs will tweak the equipment to give you better BHP than what it actually is which could affect the A/F result.

The majority of their customers just go there for bragging rights crap so if a customer goes away with good max BHP they are happy and have something to boast to thier mates about LOL Keeps their customers happy. You don't want them tweaking tha machine and want realistic results.

(:-})

Last edited by cybercarl; 10-07-2013 at 12:41 PM.
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Old 10-07-2013, 12:49 PM
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What is the idea A/F ration I am looking for once I get the results? I have read that 13:1 is best, is that true with the hawk too?

Last edited by KCCO; 10-07-2013 at 01:43 PM.
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Old 10-07-2013, 02:10 PM
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It's not quite as straight forward as that as things fluctuate.

Optimum performance = 14:1 Optimum longevity for engine life = 13:1 These bikes prefer to be on the rich side of things. Richer being the lower number.

You most likely wont get a solid straight line with the A/F being the same right through the rev range. Personally I like to start a little lean and getting richer towards the top end. So I go for better performance low down leading torwards better engine longevity at higher speeds.

Chemically ideal mixture is 14.7:1 at sea level at 68*f with 4% humidity.
Called Stoichiometric. The best mixture at any given time is dependant on RPM, intake speed, air density, temperature and engine load.
Stoichiometry - Wikipedia, the free encyclopedia

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