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Join Date: Jul 2010
Location: Grass Lake, Mi, USA
I didnít reread the whole thread so this might be a repeat:
1) You can adjust the needle position less than 1 groove by using small thin washers.
2) These carbs can leak internally and if they are leaking internally you will never be able to get the tune right. If you havenít already, replace the gasket between the needle/ seat block and the main body. Also replace the gasket between the main jet holder and the carb body.
3) If the issue is at 4000 rpm remove the filter lid, start the bike, raise the rpm to 4000 and hold a few times. If the vacuum slides are not rising together, or if they are dancing around when held at a steady rpm, then that may be the problem. Remember, the needles are attached to the vacuum slides. If the slides donít hold steady then the needles will be fluctuating with them. This probably contributes to the needle and emulsion tube wear in that rpm range. If they donít stay synchronized, check the diaphragms, slides move freely, replace the o rings under the caps, verify the caps are flat/ sealing, verify the breather tubes flow freely in both directions.
'96 Ducati SS900CR, '07 S4RS, '06 Busa, '77 Bonny,
'00 Superglide, '85 Sportster, '78 SR500