Where is the Fuel/Air Mixture Screw? - Honda Rebel Forum
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post #1 of 7 Unread 12-02-2019, 09:33 PM Thread Starter
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Where is the Fuel/Air Mixture Screw?

There may be a simple answer to this question, but I’ve searched everywhere. I just bought my ‘86 Rebel 250 and it was running extremely poorly. It idled decently, but wouldn’t go above 55 on a good day. The throttle got really boggy at higher RPMs and wouldn’t allow me to keep up with traffic.
I pulled out the carb, took everything apart, and cleaned the entire thing (the injectors and all). It runs much better now, allowing me to get up to 70 easily. I adjusted the idle stop screw (the one with the black plastic head on the right side of the carb next to the throttle cables).
Problem is I’m still having a bit of issues at higher speeds/RPMs (still better than before). After reading some forums, I found out my bike is probably running rich, so I should adjust my air/fuel mix?
I’ve searched for days and can’t find out where the darn air/fuel screw is. I read that it’s on the left side/underneath, and is a flathead screw? I’ve also seen that it’s got a tab over it so that you can’t easily adjust it (due to EPA standards).

Please help! I’ve got a big trip ahead of me and I’m really needing to get this adjusted.
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post #2 of 7 Unread 12-03-2019, 10:50 AM
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probably not your issue, but...
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post #3 of 7 Unread 12-03-2019, 10:52 AM
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my guess is a clogged main jet
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1985 CMX250 ... 1986 CMX450 ... 2005 Ruckus 50
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post #4 of 7 Unread 12-03-2019, 04:27 PM
 
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Your 86 may look like mine if the brass plug sealing the AF screw in hasn't been removed
if you find a plug drill a small hole tap in a small screw and pull plug out
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96 VS800 Intruder (sold 2018 ), 87 CMX250C Rebel,
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post #5 of 7 Unread 12-03-2019, 05:25 PM
 
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renfro - I'd like to hear how this worked out, or how it is working out. The idle mixture screw should really only make a difference at idle (and just off idle). I think if you read just a little way into the 'Rebel AFR' thread, to the point where I post graphs, you'll understand how your bike's AFR vary from the factory. And if you keep that in your mind when messing with your bike, you'll probably have one great running bike.

If your bike is an '86 and can hit 70 mph, it's not far off. Mine maxes out at 72 mph (flat, level, no wind, sitting upright) and mine is a 2016. The speedometer reads 75ish, but GPS verifies that's 72 mph.

2016 Honda Rebel 250 - The "Piglet."
AFR sensor equipped and downsized to a 0.105" main jet.
The only changes so far.
Bought on 6/29/19 with 44 miles.
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post #6 of 7 Unread 12-04-2019, 02:26 PM Thread Starter
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Quote:
Originally Posted by 01-7700 View Post
probably not your issue, but...
Mine definitely doesn’t have that! Thanks for the input!
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post #7 of 7 Unread 12-04-2019, 02:27 PM Thread Starter
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Quote:
Originally Posted by SoakedKarma View Post
Your 86 may look like mine if the brass plug sealing the AF screw in hasn't been removed
if you find a plug drill a small hole tap in a small screw and pull plug out
That’s exactly what mine looks like. Thanks for the help!
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