'79 loses power (farts...?)

[jthiessen]

I am having this issue where my bike will loose power no matter how much I throttle, it wont go past 2-3k RPM.
It happens intermittently, sometimes when I am starting the bike, sometimes when I am cruising 50 km/hr, sometimes when I'm climbing a hill.
The bike will drop down to 2-3K RPM. It starts to sound farty and bubbling and I loose my speed. Sometimes it will pick back up and be good for a bit, sometimes it stalls...

Any ideas?
TIA

 

[SoulMan]

I am no expert. Havent even ridden my bike yet or worked on one until just a month ago. I wonder though if this could be a timing issue... I am curious to hear what others say. I wonder what the condition of your spark plugs and spark plug wires are like if they have been replaced yet or if they are older and maybe also need attention.

 

[xschris]

Sounds like bad compression or a bad valve/rings. I had a 2-stroke dirt bike do that years ago just before it snapped a piston ring. It may just be dirty carbs.

 

[jthiessen]

I am no expert. Havent even ridden my bike yet or worked on one until just a month ago. I wonder though if this could be a timing issue... I am curious to hear what others say. I wonder what the condition of your spark plugs and spark plug wires are like if they have been replaced yet or if they are older and maybe also need attention.

The spark plugs are in decent shape, and wires and coils are only a couple years old...
My points may need some attention?

Sounds like bad compression or a bad valve/rings. I had a 2-stroke dirt bike do that years ago just before it snapped a piston ring. It may just be dirty carbs.

This problem originally happened 2 years ago. Since then I've had the cylinders honed and have new piston rings put it. Unfortunately that didn't fix the problem. I've had the carbs apart and cleaned thoroughly, so I feel it shouldn't be that...

 

[NewHavenMike]

I bet its a clogged petcock lol. Or your tank is sealing and causing bad flow

Whats your compression like? Theres a multitude of maintenance related things to take care of before you can get to the source. You should do all of it and verify that its all in spec and up to date.

The joy of owning an old bike is the maintenance routines.. The joy of owning a modern bike is the lack of maintenance routines, or atleast intervals that are much larger.