Poor gas mileage and loss of power

[waliszek]

Guys,

I finally got my bike working. I couldn't get it started so I tore the bike apart, but everything tested fine so I put it back together and vrrrooooom, it started. Must have been a loose connection. So now onto phase 2 of getting the bike working....

When I start it cold it starts right up and idles nice. I drive for a mile or two and it is real peppy - like an 1100 cc engine should. After that mile, I can feel power drop and I have to 'give it some gas' to maintain speed. When I come to a stop it will idle down low so that it quits. When I accelerate it slowly moves me along to the speed limit.

At the last two times at the pump I have averaged about 18 mpg. I just pulled the carbs and the floats seem OK and everything moves smoothly. I didn't want to touch the jets, so I left them alone. It still runs the same after I put it back together.

What gives??

Matt

[Ken Talbot]

Pick-up coil wires?
Kinked fuel lines?
Blocked vent hole in gas cap?
Plugged air filter?
Cracked petcock or octopus vacuum line(s)

The "must have been a loose connection" comment points me towards the first item on the list.

[waliszek]

The bad connection was solved- ignition unit connection was loose. I'm getting good spark at all plugs and just put new ones in. The air filter was just cleaned- though I'm planning on getting a new one.

My thoughts are that it could be a bad vacuum line somewhere, but I don't know where to start.

It could be a carb sync issue.

Any more thoughts?

[mro]

Are all cylinders firing?
Have any cool headers in relation to the others?
Have you sync'ed the carbs, adjusted the pilots?
Have you pulled the plugs to check there color?

Vac leak?
When suspected...
I use wd-40 with the straw attached. The spray temporarily fills the leak spot, gets sucked in and burns with the fuel causing rpm to increase slightly.

Engine idleing, spray around the carb boot where it mounts to the head. The carb boots, even with visable cracks generally do not leak themselvs but have seen them leak where attached to head.

Vac sync port caps can look good but can leak.
Check condition of vac hose from the vac advance (the one that goes from engine left side cover to the port on #2 carb body)

On standards check the two petcock vac lines.
On specials inspect the vac line going to the octopus.
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mro

[thewiz]

Just thinkin' a little outa' the box here ...

so to speak ... but .... is it possible that you might have a slipping clutz? Check the adjustment under the cover where the cable goes in .... Loosen the lock nut, then turn in the screw until it contacts something solid and back off a quarter turn, tighten the lock nut ... then readjust the thumb wheel.