Jetting question when changing cams, 88" motor

Started by Shooter1, July 23, 2021, 06:53:09 AM

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Shooter1

I have a '00 FXDX. The bike is basically stock with the exception of an SE K&N air filter, (open back plate), and the solid center baffle plates removed from the stock mufflers. The stock carb is at; 45 pj, 190 mj, N8EA needle shimmed .040, 2 turns out on the air screw and I'm at 1000 ft elev. The bike runs fine with good throttle response everywhere.
I had the SE hydraulic cam plate installed back around 2012 and would like to install either the Andrews 21 or 26 cam set.
My logic says as long as i'm not altering the intake or exhaust, I should not need to modify the jetting. Am I correct in this assumption?
Also, does changing cams result in any different characteristics in terms of vibration, more/less/etc?
Thanks.

turboprop

Quote from: Shooter1 on July 23, 2021, 06:53:09 AM
I have a '00 FXDX. The bike is basically stock with the exception of an SE K&N air filter, (open back plate), and the solid center baffle plates removed from the stock mufflers. The stock carb is at; 45 pj, 190 mj, N8EA needle shimmed .040, 2 turns out on the air screw and I'm at 1000 ft elev. The bike runs fine with good throttle response everywhere.
I had the SE hydraulic cam plate installed back around 2012 and would like to install either the Andrews 21 or 26 cam set.
My logic says as long as i'm not altering the intake or exhaust, I should not need to modify the jetting. Q1 -Am I correct in this assumption?
Also, Q2 -does changing cams result in any different characteristics in terms of vibration, more/less/etc?
Thanks.

1. Yes
2. No, and yes. The rotational mass has not changed so neither will the vibration. But, the new cam will probably shift the operating RPM range which might exhibit a change in the vibrations felt by the rider.
'We' like this' - Said by the one man operation.

kd

Quote from: turboprop on July 23, 2021, 08:17:22 AM
Quote from: Shooter1 on July 23, 2021, 06:53:09 AM
I have a '00 FXDX. The bike is basically stock with the exception of an SE K&N air filter, (open back plate), and the solid center baffle plates removed from the stock mufflers. The stock carb is at; 45 pj, 190 mj, N8EA needle shimmed .040, 2 turns out on the air screw and I'm at 1000 ft elev. The bike runs fine with good throttle response everywhere.
I had the SE hydraulic cam plate installed back around 2012 and would like to install either the Andrews 21 or 26 cam set.
My logic says as long as i'm not altering the intake or exhaust, I should not need to modify the jetting. Q1 -Am I correct in this assumption?
Also, Q2 -does changing cams result in any different characteristics in terms of vibration, more/less/etc?
Thanks.

1. Yes
2. No, and yes. The rotational mass has not changed so neither will the vibration. But, the new cam will probably shift the operating RPM range which might exhibit a change in the vibrations felt by the rider.

FWIW I don't agree with the response to question 1.  You may not have noticed this but when I read the full post, the OP says he is changing the cams (Andrews 21 or 26) and that will change the intake characteristics.  That in turn can effect the exhaust performance.
IMO there are huge implications on intake with cam changes and expecting the setting with stock cams to work is not reasonable.
KD

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