Cant keep this thing running!?

Ok sweet! Ya, it was smoking white pretty good when i got her runnin decent. Hopefully that subsides eventually. Like i said, i dont think this thing has ran in years.

 

Ok, update. So i double checked and made sure all of my boots are crack free etc and REPLACED the throttle shaft seals and....no change at all. When i first got her started up and reved it a bit it almost acted normal. Then after about 10-15 seconds of idling she took off to about redline. This is blowing my mind. No vacuum leak at all, its getting fuel, its getting air, and spark...by all means it should be running. Now every time i start it, it shoots up almost immediately. The throttle cable is good and not the cause. Also, still have white smoke after running for a bit. It doesnt seem like much but fills my garage with smoke fairly quickly. :-/

 

Also, after taking my boots off i looked into the engine and see this crap. Im sure this motor has got to be shot.

 

This is where she stands. Once i can actually get her to idle, she goes nuts if i touch the throttle (dont mind the ziptie, i just threw that on before i recorded the video so i can bleed brakes). I have new Carb boots and gaskets coming, so if that doesnt fix it then im at a loss.

 

That's just carbon buildup. They all will have that to some degree. If the engine was shot she wouldn't be able to have a racing idle.

The big question is why the hanging idle is still there.

Remove the throttle cable from the carbs. Will it still behave the same when you control the throttle plates directly from the linkage?

If it does, try slightly loosening the nut that holds the throttle cable linkage to the #3 carb. It is possible to get it too tight, and then it will act to keep the throttle plates from snapping fully shut.

 

Ok, ya it acts the same without the throttle cable connected. And yup, same problem with loosening that up as well.

 

Dang

Are there any signs of cracks in the vacuum caps?

Is there any change when you press down on the enrichment plunger linkage?

 

No cracks in the vacuum caps. And by enrichment plunger linkage u mean the bar thats connecred to the choke? Nothing really. If i go full choke during idle it will just sputter off and die like it should. Im guessing that my carb boots or boot gaskets are more shot than im thinking. That is the only thing i can think of that i havent changed already. Because its obviously getting more air correct? Its forcefully getting more air? This its gotta be a big vacuum leak somewhere.

 

The vacuum leak doesn't have to be very big for there to be a hanging idle, which is part of why they can be so difficult to find. The fact that yours will idle normally on startup indicaes that the vacuum leak is relatively small.

It could very well be a leak at a boot gasket. They can sometimes act like reed valves, and not even start leaking until the airflow increases, such as what happens when you open the throttle.

Things like this can be frustrating. Keep at it, but don't hesitate to walk away for a few days; sometimes fresh eyes see better.

 

Another thing, and maybe not likely since you are inferring that it happens by itself . . . Are the carbs synched? Out of synch carbs can create a high idle - but usually it occurs after you turn the throttle and open the butterflies.

 

I bench synced them but nothing more than thay for now u til i can get it running right. Then ill fine tune her.

 

Ya, im basically at a stand still until i get my new gaskets and boots in anyways.

 

From the last videos you posted, I am guessing all cylinders aren't contributing equally. It should be a lot smoother when revving. I also second a vacuum leak that allows it to run away like that. Def get the carbs rebuilt and valves adjusted. You should be in a much better position then. If it still races, you can track down the vacuum leak w/ a propane torch (unlit of course).

 

Ya my carbs are super clean, ive rebuilt the hell out of em! Lol

 

Ok, so update....

Replaces the carb boots and gaskets, still doing the EXACT same thing. Not really aure what could possibly be causing this to happen anymore. I've literally replaced everything that could possibly be wrong. Intake, carbs, carb rebuild, throttle shaft seals, carb boots, gaskets....idk how its getting air into the engine still. The butterfly valves are closed yet when i rev it more than 1/4 throttle it takes off, comes down slightly, and stays high until i kill it. :-/

 

You need to do a running synch. Ideally, colortune, running synch - rinse, lather repeat.
Bench synch will get you close, running synch dials it in. Out of synch carbs can do what you are describing.

 

How though? It doesnt make sense. If ALL of the butterfly valves are closed when it happens, wouldnt that mean the leak would be happening after the butterfly valves right?

 

when the butterflies close they cover the idle circuit port in the carb throat, so their all not closed all the way.
before you do the running sync that you have to do, put some teflon tape on the bolts for the yics passage.
did you put those shaft seals in the right way?

 

Do what Polock says, cause I don't know YICS.

I do know that if you don't have a properly synched set of carbs, and as you said, twist the throttle (opening butterflies) that the idle can run away from you. . . . We can go back and forth with this, or you can actually DO IT , or better still strap that puppy to a trailer and drive east to north central Wisconsin. Leave it near the barn, I will get to it.

Just scanned back through this thread . . . couple things.
1) where did you get your carb rebuild kit from?
2) are carbs verified wet set?
3) are your valve clearances in spec?
If you have not checked your valve clearances you need to. Because if there is a required shim change then a running synch has to be done all over again.

 

Also I forgot to mention that any amount of choke kills my bike, even when cold. I cant even cold start it using the choke.

 

Did you inspect the fuel jets? It's possible that a PO drilled them out.

 

Sorry, which ones are those again?

 

They are the jets that are in the float bowl. You would have removed them when you cleaned the carbs.

 

Fixed! Ok, so if anyone else ever has this issue again we will know where to send them for sure! All I did was back out the fuel air mixture screws 1/2 turn and it ran like a dream. Not really sure how this wouldve caused the throttle to run like that and it did it before i swapped out the mixture screws so im not sure. When i replaced them I backed them out 2.5 turns, apparently I shouldve gone 3 turns out. Maybe my higher altitude has something to do with it!? Well anyways, now to fine tune the carbs and check valve clearances and it should be back on the road after sitting for probably a decade.

 

Watch you plug color for a while, and listen for popping out of the exhaust under deceleration.
Elevation may be an issue for you, but richening the fuel mixture is the opposite of what's needed at higher altitudes.


The solution that you came to makes me think that a PO may have installed leaner jets at some point. I don't recall any of us asking what size jets you found when you openend the carbs up.

 

Ya, im not sure what jet sizes were in there. I couldnt even read them at all they were so corroded and old. But i bet somehow with my altitude and me running pods it somehow came to like it a tiny bit richer i guess.

 

That should have been mentioned at the start.
You're not cleared to ride carefree just yet.
Bumping the idle mixture up is definitely masking a lean condition, but it won't make up for being lean anywhere else but at idle.
You may be fine considering that you're working with a lower air density to begin with (compensating somewhat for the leanness caused by the pods).
Pull the plugs after a 20 mile ride and look for shiny silver flecks. If you have any on the plugs the fuel mixture is dangerously lean.

 

I did mention it back on the first page on my 3rd post in. But ya I'll check it out and see what they look like. Ill probably color tune it first though, just to get it right.

 

My apologies for missing that.

Here's the issue though. With a significant increase in altitude, the fuel to air ratio becomes richer than at sea level.
You have pods, so that leans things out by 2 jet sizes (approximately), which should not have been so much that you would need to increase the richness of the idle circuit.
The wiggle-factor here is that the stock jets are on the lean side anyway, so typically there isn't any need to rejet when moving up to your altitude.
So it's odd to me that you needed to set the idle mixure scews on the rich side to get her to idle corectly.

I just want to make sure that you're not running on the edge of being so lean that you put a hole in a piston. The idle circuit can be spot-on, but if the mains aren't...