'97 Lacks power

[username23]

Hi all,

My '97 Valk with 43k miles started lacking power. I've changed the air filter and spark plugs, but to no avail. (Started noticing bike lacks power most obvious at highway speeds, almost as if it's starved for fuel.) Any suggestions?

Thanks.

[RTaz]

maybe rebuild the fuel petcock...and replace the screen in the tank

[SANDMAN5]

Check the simple stuff first. Vac lines been replaced? Had the gas tank
off and pinched the vent line? Did it start all at once or come on gradually?

[username23]

Definitely started suddenly. I hadn't had the tank off before it started acting up. Will check for pinched lines and I think I'll pull the petcock and clean that fuel screen, too, even if it ends up being something else that's causing my "performance anxiety".

[fudgie]

If its a black one then this is to be expected.

[Willow]

Check your vacuum line to the petcock first.

Reach around behind the carb runner and feel the vacuum line.  See if the line feels cracked or deformed.

[Rio Wil]

Might try a few other things also, when it is exhibiting the lack of power on the highway, turn off the petcock and see how long it takes to significantly reduce power.  At 60 mph in 5th gear, it takes 67 seconds for mine to run out of gas.  If yours is significantly less time, then you have a fuel flow issue.  Also, pull the vac line on the petcock, replace with a line you can pull a moderate vacuum by mouth. There should be  NO vac bleed off, if so the diaphragm is broken and needs to be replaced. If you don't have any leak off, pull the gas line on the output of the petcock, add a line going to a bleed container on the floor and apply the vac again.  The petcock should flow about 100 ounces per minute. Significantly less than that and there is a fuel restriction somewhere, ie, the diaphram is not being retracted fully to allow flow, the filter screen is dirty......

[Dave Weaver]

Another thing to try is the venting of the fuel tank via the fuel lid.  Place a spare key in the fuel lid and when the bike seems starving for fuel, reach down, turn the key to open the lid and see if performance improves.  If it does, your problem is in the venting of the fuel tank.

[Ricky-D]

Try changing you source for gasoline!

Different gasoline!

***

[Kaiser]

If its a black one then this is to be expected.

LMAO! 

[username23]

Has anyone had experience with a cover set from K&L? Is it worth using, or is it better to go with OEM?

[Wago]

Hi all,

My '97 Valk with 43k miles started lacking power. I've changed the air filter and spark plugs, but to no avail. (Started noticing bike lacks power most obvious at highway speeds, almost as if it's starved for fuel.) Any suggestions?

Thanks.

Almost surely your petcock is not holding vacuum. Symptoms are identical to yours. See if you can pull and hold a vacuum using the vac line. If vac bleeds off quickly, repair or replace the petcock.