When I accelerate from a stop the rpms go up but the bike gets stuck at 20 mph. It started happening suddenly too. First time I was stopped at a light turning left at an intersection, accelerating through and got caught at 20 mph as I completed the turn I shifted up and still stuck at 20, Shifted back down and still stuck. Eventually my bike jerked and accelerated properly. This pretty much happened every time I stopped and started.
At one point after starting from a stop it got stuck at 20 and my bike completely died.

I've been riding around for the past couple of days without problem. And it started today around the last 5 minutes of a 45 minute ride.

Stuck at 20mph? Meaning when you get to 20mph, and you continue rolling all the way on the throttle (slowly), it continues going 20mph and doesn't accelerate?

Quote from: smokestack on May 30, 2016, 04:14:28 PM
Stuck at 20mph? Meaning when you get to 20mph, and you continue rolling all the way on the throttle (slowly), it continues going 20mph and doesn't accelerate?

Exactly. I took it back out after making this thread and rode it hard trying to replicate what happened but it wouldn't. I still wanna figure out what caused it to get stuck at 20 and made it shut off.

When you disengage the clutch, does the engine only go up to a certain RPM? Then I'd guess the throttle butterfly in the carbs is getting stuck in a certain position, but I don't know whether or not the throttle cable would still let you pull all the way.

If the clutch were slipping, you'd still have full RPM range when it's disengaged and the power would only be partially delivered to the drive, not just spinning at a constant rate regardless of RPM. You have freeplay in the clutch lever?

Quote from: smokestack on May 30, 2016, 05:48:06 PM
When you disengage the clutch, does the engine only go up to a certain RPM? Then I'd guess the throttle butterfly in the carbs is getting stuck in a certain position, but I don't know whether or not the throttle cable would still let you pull all the way.

If the clutch were slipping, you'd still have full RPM range when it's disengaged and the power would only be partially delivered to the drive, not just spinning at a constant rate regardless of RPM. You have freeplay in the clutch lever?

Say i'm in neutral and the clutch is disengaged. The bike sits at 1.5 rpm and if I rev it I have full range with no issues. Tomorrow i'll have to try again and see if I can replicate it and pay more attention. I do have freeplay in the clutch lever. I can always look over those things aswell.

So my carbs are half off my bike and I was able to check: you would not be able to roll the throttle all the way if the butterflies were stuck.

I'd think you'd feel the clutch slip in first before it got to 20mph.

Check float levels when it starts happening again? Maybe they're both at a height that feeds the pilots but not the mid-mains. Then you could start diagnosing upstream the bowls (fuel lines, petcock, low pressure in tank). You could try switching to prime immediately after it happens, wait a minute and see if it goes away.

And that would be consistent with the way it's behaving. Bowls aren't filling up fast enough, fuel level sinks below the mains, you drop to 20 (and you wouldn't be able to rev any higher either with the clutch disengaged), then then pilot drains them even further and it dies. The petcocks are famous for failing on the vacuum feeds, so PRI should fix if the petcock is bad.

Slipping clutch?......its a simple test.

Check the oil level is ok.
Get it up to operating temp
Position the front wheel up against a solid wall (or something else that's not going to move.)
Give it some revs,
Let the clutch out.

Bike will either stall or spin the rear wheel, either way it will prove the clutch is ok. If it doesn't then yeah.....something in there needs attention.

Don't do it for too long though......otherwise you WILL burn the clutch out 

Are you sure the rpms went up or did the engine just get louder?

When I had an issue with my fuel delivery I would open the throttle and the engine would get louder but wouldn't accelerate.

Quote from: sledge on May 30, 2016, 10:59:07 PM
Slipping clutch?......its a simple test.

Check the oil level is ok.
Get it up to operating temp
Position the front wheel up against a solid wall (or something else that's not going to move.)
Give it some revs,
Let the clutch out.

Bike will either stall or spin the rear wheel, either way it will prove the clutch is ok. If it doesn't then yeah.....something in there needs attention.

Don't do it for too long though......otherwise you WILL burn the clutch out 

I tired this and it shut off like it should. Is it possible that something went through the tubes?

I can check the oil levels again when I get a chance.

Quote from: lucas on May 31, 2016, 07:56:30 AM
Are you sure the rpms went up or did the engine just get louder?

When I had an issue with my fuel delivery I would open the throttle and the engine would get louder but wouldn't accelerate.

This is also a possibility. After reading these replies i'm starting to doubt whether it went up or not, but I think i'm positive the rpms went up.

OK. I'm now positive on my original post. The RPMS rise and it's like my bike sticks at 20mph. It rises slowly but the rpms rise normally. Like it's struggling to get up and go. There was also popping coming from under the tank. Everytime I stopped trying to keep the rpms up the bike would roll and die.

Then I think you have to have 2 problems. 
If the revs rise but the speed doesn't then the clutch is slipping. It's either worn, or misaligned (you said in an earlier post there was free play, do a 3 point adjustment), or it's getting hung up for some reason.
But, nothing with the clutch slipping would cause the bike to die.

Quote from: Slack on June 05, 2016, 12:57:10 PM
Then I think you have to have 2 problems. 
If the revs rise but the speed doesn't then the clutch is slipping. It's either worn, or misaligned (you said in an earlier post there was free play, do a 3 point adjustment), or it's getting hung up for some reason.
But, nothing with the clutch slipping would cause the bike to die.

Yeah. That's what I was thinking the work I have to do on this bike is increasing day by day. I feel like I should just sell it and move on to another bike. But I also find peace in working on it. Double edged sword.