What causes: intermittent high revving

[DieselTech]

Ok everyone, rode the Sparesbrook fairly hard today. But what causes or where to look for problem on a intermittent high revving condition, other than a air leak? It's only happened twice, once bout 6months ago, & once today. I shut bike off or kill it with clutch & start bike back up & it never happens again & runs perfectly fine. It's not a consistent enough for me to really worry bout. But it bugs me, I'm thinking some kinda air leak, but I cannot get it to act up as soon as I shut bike off & restart symptom is gone & wont act back up for 6months or so.

 

[DieselTech]

Only thing I can think of with causes, would be a intermittent crank seal issue.

 

[DAMIEN1307]

Only thing I can think of with causes, would be a intermittent crank seal issue.

It almost sounds to me like something getting sucked up to the internal gas tank filter, or at least that opening in case you removed that filter and then releasing after it is no longer trying to draw gas through the gas line...This would result in a leaner air/gas ratio mix very temporarily, until the next time that "floater" gets sucked up to that point again...Something like a fleck of paint, etc....It wouldn't be blocking all gas flow, just enough though to lean it out resulting in that surge.

 

[DieselTech]

It almost sounds to me like something getting sucked up to the internal gas tank filter, or at least that opening in case you removed that filter and then releasing after it is no longer trying to draw gas through the gas line...This would result in a leaner air/gas ratio mix very temporarily, until the next time that "floater" gets sucked up to that point again...Something like a fleck of paint, etc....It wouldn't be blocking all gas flow, just enough though to lean it out resulting in that surge.

Never really thought about the gas tank issue like you mentioned, but since I'm running a saw carb, maybe something made it past filters & temporarily lodged in carb, resulting in a lean condition.

 

[Mossy]

Never really thought about the gas tank issue like you mentioned, but since I'm running a saw carb, maybe something made it past filters & temporarily lodged in carb, resulting in a lean condition.

I've had filters that came with some debris in them from manufacturing... Little bits of plastic...

 

[Chainlube]

Take the carb off and pop the fuel intake side off, rinse the whole thing down with some carb clean. Put in a nice white bowl first and see what you rinse out. Check the screen while your in there. Some sludge can be holding up the needle causing it to rev.

Once started, the fuel sloshes around and frees it up and it will be good for some time, then all of a sudden some will collect on the needle again.

 

[DieselTech]

Take the carb off and pop the fuel intake side off, rinse the whole thing down with some carb clean. Put in a nice white bowl first and see what you rinse out. Check the screen while your in there. Some sludge can be holding up the needle causing it to rev.

Once started, the fuel sloshes around and frees it up and it will be good for some time, then all of a sudden some will collect on the needle again.

Did you eat too many of them perch? Chainlube I'm running a saw carb will that still effect it. It's a tillotson Hl-324a carb.

 

[Chainlube]

Did you eat too many of them perch? Chainlube I'm running a saw carb will that still effect it. It's a tillotson Hl-324a carb.

The needle is the one under the diaphragm, pay close attention to the gaskets when you take it off. On the back of some of the diaphragms is a clip that hooks on to the needle arm, not sure if yours is like that though, but make sure the diaphragm goes back on it if it is. The little arm will have a U in the end, if no U, then no worries.

 

[Chainlube]

Did you eat too many of them perch? Chainlube I'm running a saw carb will that still effect it. It's a tillotson Hl-324a carb.

Looks like a float needle, just no float.

 

[DieselTech]

The needle is the one under the diaphragm, pay close attention to the gaskets when you take it off. On the back of some of the diaphragms is a clip that hooks on to the needle arm, not sure if yours is like that though, but make sure the diaphragm goes back on it if it is. The little arm will have a U in the end, if no U, then no worries.

Ok mine has the u deal that hooks, I'll check that out. See if anything is in there. Thanks.