Loss of power going uphill

[twmiller]

I have a 1980 XS1100 Special and I recently reinstalled the factory air box. The bike has been running great but the last two times I rode the bike three different times when I was going up a hill it would loose power then it would clear its self out and run fine again. I would greatly appreciate any input on this problem.

Thank You
Todd Miller

[BA80]

It's possible the two have nothing to do with each other. You haven't posted what all your running on your SG.

It kinda sounds like an octy going bad. Do you still have that on there?

I have been through your town many times on my XS on my way to KC.

[twmiller]

Temp Loose of Power

Im not sure what your talking about when you say OCTY going bad? I have also noticed that when I ride the bike for about an hour then turn the bike off for about 15 minutes its hard to start like its not getting fuel. A couple of tanks ago I put some Lucas Fuel Treatment in the bike the type with lube in it. Thats about the time i started having problems.

Thanks Todd

[petejw]

pull the plugs out and see what they look like?
sounds like it could be running rich, bogging down
then taking off, does it happen at a certain rpm
or throttle position?

[twmiller]

Loosing Power Uphill

Thats a good idea I havent checked the spark plugs yet. It doesnt happen at high rpm more like mid to low rpm. I cant figure out if its starving for fuel or getting to much. The bike doesnt stop running I guess it is more like its drowing in fuel. The other thing is its not drinking fuel its gettting good gas mileage.

Thanks Todd

[petejw]

todd, just take note of the throttle position
when it starts playing up, also try it
in different gears and see if it plays up
around the same throttle position then
take note of where that position is, that
will help identify what circuit in the carbs are
playing up.

if its running lean the accelleration will be smooth
but flat,
if its running rich it will feel wet and soggy, usually
bogging down before taking off.

[twmiller]

Loosing Power

It seams to be acting up in lower to mid gears 2nd or 3rd at rpm from 2000 to 4000 and when its under a load like going uphill. It just drops off some what like bogging I can give it gas for a few seconds and it wont do anything then it clears itself out and runs fine. I was also wondering if it could be the ignition box / black box?

Thanks Todd

[BA80]

Todd, The octy is a vacuum controlled fuel valve that sits on top of the carbs in between #1 and #2. It has a diaphragm that will eventually go bad, particularly if the bike has been sitting. If it has a leaky diaphragm it may be letting the fuel valve close at open throttle under a load.

This however may not even be a fuel problem. Another weak spot is the pickup coil wires under the left engine cover. This bike has a vacuum advance on it just like a car, at least until 1981 when it was eliminated, and can cause a similar problem under a load when the vacuum drops.

Do you have a manual? Your gonna need one.

[LoHo]

Sort of like a sticky float? The bike sucks down the gas on that cylinder, losing power, until it gets low enough for the float to move, then kicks back in? Just saying'...

[twmiller]

Loosing Power

That’s what I’m thinking but I’m not 100% sure. I have read that the Lucas Fuel Treatment will loosen up junk in the fuel system and engine but won’t burn in up it tends to float around and get lodged in areas of the engine and fuel system. I don’t know if that’s true but I guess it’s possible.

Thank Todd

[skids]

What we want now is that you fix the problem and tell us what did to fix it!

[twmiller]

Loosing Power

Skids

Im not sure I have the problem fixed because I havent had the chance to go out and ride the bike yet.

Thanks Todd