[Kristian08]

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.

 

[swifty2014]

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?

 

[Kristian08]

New filter screens for the float valves.
Plugs are brand new.
Didn't see any cracks or splits on the rubber diaphragms.

 

[swifty2014]

Is the throttle cable pulling all the way at the carbs when you twist the grip full throttle?

 

[Kristian08]

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

 

[Kristian08]

Oh yeah jets are new, pilot jets are new, float valve new, and float seat and screen new and mixture screws new

 

[Magickiwi]

It almost sounds like a vacuum issue to me, like one of the hoses is cracked or slipped and isn't giving enough suck.

 

[CSRoad]

I would guess:
1. carb boots leaking big time.
2. Slide Diaphragms with a hole, crack or a tear.
3. Cheap Chinese rebuild kit off eBay or Amazon.

 

[Kristian08]

K
I'll check the hoses again.
The t coming off the carb is open not connected to anything.
Could that be it and if so where would that go.
Maybe the hose fell off.

 

[Kristian08]

Carbs are new. They were cracked.
It's a dynojet kit and everything else is oem

 

[Magickiwi]

K
I'll check the hoses again.
The t coming off the carb is open not connected to anything.
Could that be it and if so where would that go.
Maybe the hose fell off.

Try blocking it with a bolt and tape the bolt in place. Then do your run and see if it moves better. Dangling vacuum hoses are a good place to start.

 

[Kristian08]

Thanks I'll try that in a few

 

[Kristian08]

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.

 

[Magickiwi]

I don't know much at all about balancing jets so hopefully someone that does replies. I think the vacuum line needed to be plugged, assuming it's a vacuum line and not a vent.

 

[KC_97Shadow1100C]

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.

 

[Kristian08]

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

 

[Kristian08]

Just pulled the plugs after running it. Rich.

Need to lean it up.

 

[Kristian08]

Plug was brand new 2 hrs ago

 

[CSRoad]

K
I'll check the hoses again.
The t coming off the carb is open not connected to anything.
Could that be it and if so where would that go.
Maybe the hose fell off.

The T-ffitting is the bowl vents from the carbs and the discconnected hose is meant to be that way and just hangs down.

 

["Captain D"]

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