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Discussion Starter · #1 ·
Hey guys, I am stumped here. I have a 2002 shadow 750 that won't go over 50 mph regardless of gear. Starts bogging down acting like it's starving fuel.
Replaced fuel filter, cleaned tank filter, cleaned tank, new sparkplugs, has k&n filter and open pipes, jets are correct for my setup. Cleaned carbs twice, balanced carbs, set fuel mixture screw. No when I put the bike on a lift and lift rear tire off of ground the bike will perform beautifully no bogging down. But when I put it on the street it will not exceed 50 mph. I am stumped here. Any help would be greatly appreciated. Clutch is good too.
 

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1983 Honda vt750 Shadow
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You might start it up cold and shut it off and loosen the drain scres on the carbs to see if 1 or 2 ounces of fuel runs out as a starting point.
Then run it hard and when it falters, stop and do the same thing to see if the same amount of fuel is available in the bowls. There are fine screens in the carbs above the float valves that may be restricted.
What color are the plugs?

Were the rubber slide diaphrams perfect?
 
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1983 Honda vt750 Shadow
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Is the throttle cable pulling all the way at the carbs when you twist the grip full throttle?
 
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Discussion Starter · #5 ·
Yessir. It's weird.
Like I said it works perfect when the rear tire is off the ground but when I take it out to ride it won't go past 50 and starts acting like it starving for fuel.
Will rev all the way in first and second then I third and higher can only get as far 50 mph. Once it gets to 50 it acts like it's starving.
It's odd.
I just finished rebuilding a 1982 gpz 550 which runs great. So I do know a little bit in case you are wondering
 

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Discussion Starter · #13 ·
Allright so i capped off the open vacuum line all was good for about 5 minutes then buke just fell on its face. Won't start back up unless I give it full throttle.
I had raised the needles. I think I need to go back in and readjust the needles.
Also once it's running the minute I give it choke it dies. It's also 87 degrees where I am at and at sea level.

I checked to see what jets I used.
115 in the front and 120 for rear.
 

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'97 Spirit 1100 - Chandler, AZ
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Carbs are new. They were cracked.
It's a dynojet kit and everything else is oem
Have you cleaned that K&N air filter?
The fabric may have absorbed crankcase vapors/oils to the point it's choking-off airflow.
You could always try running the bike without it, just to see if it resolves or improves the issue.
 

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Discussion Starter · #16 ·
Well the tube is suppose to be open to atmosphere.
Once I removed cap bike starting idling and running again.
Filter has been cleaned and lightly recoated.
Put it all back to the it was before trying the cap and all runs perfect on the lift. When rear tire is lifted all the ground runs perfect through all the gears but when back on street it bogs at 50mph

Frustrating
 

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1998 750 ACE
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You might look at those diaphargms again???
Did you check `em with a light shining through inside so you could see cracks of light shining through???
Sounds It acts the way mine did when mine were cracked...

Just a thought,
Dennis

Some have repaired them with silicone
 
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