Hey, im kinda new on this motorbike stuff and im trying to diagnose why my bike is running rich. Its a Honda CBR600 Hurricane 1990.
Plugs are showing signs of running rich, also bike takes couple takes to start and black smoke allways on full throttle.
But im wondering whats the normal fuel pressure on these things because the old owner has put aftermarket fuelpump and fuelfilter on the bike and im thinking its because of it.
Also it starts to run poorly at about 7k rpms, just pops and bangs and when holding throttle it will start to work again on a couple of seconds and rev up where it should.
Im sorry If theres a thread about it allready, couldnt find it. And sorry If english is bad im from Finland and nobody seems to know about these older bikes around here.

 

Pump pressure makes zero difference. Float valves stop flow into carbs when level in bowls reaches proper level.

Most likely someone in bike’s past jacked up fuel-levels in mistake belief that more fuel gives more power. Actual opposite is true. Remember that ‘69s hit-rod saying? You’ll want to restore carbs back to factory OEM settings:

1. Measure all jets and verify they are stock sizes. Don’t look at numbers because many POs drill out factory jets. If they need to be replaced, only get factory OEM jets from authorized Honda dealer. All those “carb kits” come with incorrect sized jets, they often don’t even match each other in same kit.

2. Replace all rubbers: float valves, fuel-rail O-rings, pilot-screw O-rings, float-bowl seals, slide-diaphragm if needed.

3. Set float levels to factory settings

4. Set mixture-screws to factory settings

5. Sync carbs