Gas cap-how to tell if it is venting??

[zenBD]

So far blew through the cap and it is venting... Later today I'll try the Sven test...

 

[zenBD]

So... tried the Sven test, and flow looks good... video link attached... So, now I have no idea what the hell is going on... what the popping noise was about, or why the bike runs like garbage. So much for quick & easy. :bang:




Fuel FLow - YouTube

 

[francoblay1]

Dirt in the Carburetor? Clogged or almost clogged jets?

 

[zenBD]

Dirt in the Carburetor? Clogged or almost clogged jets?

Nope... pulled the float bowl and it is clean as a whistle... int. and main jets clear and tight. I'm wondering if the cap stops venting when hot?? Also, I was tipped off that the fuel line from the petcock to the carb could be getting too hot because it rests against the cylinders without protection... causes gas to vaporize?? I put a sleeve on it just in case. Now I'm waiting on a carb rebuild kit for the diaphragm before I can try the bike again... some of mine stuck to the top of the carb when I pulled it. I feel like I only have the issue when the bike is pretty hot...

 

[Diesel Dan]

1. Top off gas tank. Why? Less air gap.
2. Remove fuel line at tank.
3. Install a line from tank to gas can.
4. Turn on petcock or turn ignition key on to cycle the fuel pump [if applies].
5. Watch the flow stop or keep flowing into container.

If:
It flows, then no change as in no gas cap clogging if petcock style.
It trickles and almost stops and this is the fuel pump style, then yes, a problem.
It flows out real quick when you pop the gas cap = It's the gas cap.

How do I clean a gas cap?:

Buy bulk vinegar like at costco for 3 bucks a gallon. For a day or more, dip the gas cap in a plastic cup full of vinny so you can throw it away later. Pour the vinny in the sink and clean that too when you wash out the gas cap with hot water. Then air dry it or blow dry it out.

Rubber will swell ever so slight so remove any rubber. Do not worry about internal rubber, as long as it has a sealing effect it won't pop out like a jack in the box when swollen, meaning.

Install gas cap, top off tank, repeat the flow test.

This is a cool test to do:up:......Great tip about the Vinegar!!!!!!! Thanks Sven!!

 

[Dragonslave]

Have you made sure that your petcock screen is not clogged? I had this happen only to notice the lining was flaking out of my tank. It wouldnt happen all the time. Just when a big piece of liner would get wrapped around the petcock screen.

Also have you checked to see if you may have bad gas? Put some into a mason jar and see if it separates after a few hours.

 

[zenBD]

Have you made sure that your petcock screen is not clogged? I had this happen only to notice the lining was flaking out of my tank. It wouldnt happen all the time. Just when a big piece of liner would get wrapped around the petcock screen.

Also have you checked to see if you may have bad gas? Put some into a mason jar and see if it separates after a few hours.

I did check the petcock & it was clear... At least it was clear when I checked it... Can't say I know for sure if there is a piece of liner bumping up on it intermittently. Nothing fell out of the tank either though. I've also run a bunch if gas through... It's been happening over the course of more then one tank.

 

[bigdogtech01]

Cutting out while going down road might be electrical rather than fuel. Check the ignition key switch. If you slowly turn key from full ON position towards the direction of OFF (counterclockwise) and it seems to turn off right away, only a few degrees of movement, most likely this is the cause of problems. That and if the key seems to be very loose inside the tumblers while ON. And especially if you can take key out with the ignition ON.

 

[zenBD]

Thanks Andrew... I'll check that also. I guess I have been focused on fuel because of the sound I described above... like something had been released from being "sucked in" when I shut the bike off. There was another time when I had been riding, shut the bike down, then shut off the petcock. I heard a "moan" like sound that I thought came from the carb, then later found a drop of gas on the cam cover. I was thinking that all things considered it was sounding like a venting issue. However, when I get the carb back together I'll look into electrical and the ignition switch like you mentioned. My father was thinking maybe compression releases could be involved... not fully closing intermittently from one ride to the next... does that sound like a possibility?

 

[bigdogtech01]

Thanks Andrew... I'll check that also. I guess I have been focused on fuel because of the sound I described above... like something had been released from being "sucked in" when I shut the bike off. There was another time when I had been riding, shut the bike down, then shut off the petcock. I heard a "moan" like sound that I thought came from the carb, then later found a drop of gas on the cam cover. I was thinking that all things considered it was sounding like a venting issue. However, when I get the carb back together I'll look into electrical and the ignition switch like you mentioned. My father was thinking maybe compression releases could be involved... not fully closing intermittently from one ride to the next... does that sound like a possibility?

I doubt compression releases are a problem. They are either good or bad, no in between.
Some noise can come from the one way valve (like a PCV valve) that is inline from rear cylinder head to air cleaner backing plate. Good idea to remove valve and push the rubber out of it, then install back inline.

 

[Sven]

I doubt compression releases are a problem. They are either good or bad, no in between.

I agree with tach01. Compression will cause a no to poor idle of say one cylinder is hung up. During a ride, this would hiss at every compression stroke as the piston pushes the air out of that release mechanism.

1. Poor miss while riding = Not compression
2. Poor miss while riding = Not fuel flow
3. Poor miss while riding = Possible spark.

Why?
A. Comp = Bike starts and idles is my assumption.
B. Fuel = Bike starts and idles is my assumption that the fuel jets are clean or no idle if either jet was clogged and/or partially clogged.
C. Spark = Bike has a miss while riding, yes?
D. Variable = It's either a plug wire, a spark plug, a lose battery cable, or if cutting out electrically, then this key fob business of a key switch.

Why spark? Because it starts and runs. Because you say the carb is clean, so it ran fine before, correct? No jetting to solve if it was running good then, but now this new miss. So, back to spark someplace is the guess, we eliminate the other 2 variables out of the way.

Make sense?

 

[zenBD]

Thanks Andrew... I'll check that also. I guess I have been focused on fuel because of the sound I described above... like something had been released from being "sucked in" when I shut the bike off. There was another time when I had been riding, shut the bike down, then shut off the petcock. I heard a "moan" like sound that I thought came from the carb, then later found a drop of gas on the cam cover. I was thinking that all things considered it was sounding like a venting issue. However, when I get the carb back together I'll look into electrical and the ignition switch like you mentioned. My father was thinking maybe compression releases could be involved... not fully closing intermittently from one ride to the next... does that sound like a possibility?

Here's a video of the key... doesn't seem to be the issue... what do you think?

https://www.youtube.com/watch?v=PqhclDqCg3c

 

[zenBD]

I agree with tach01. Compression will cause a no to poor idle of say one cylinder is hung up. During a ride, this would hiss at every compression stroke as the piston pushes the air out of that release mechanism.

1. Poor miss while riding = Not compression
2. Poor miss while riding = Not fuel flow
3. Poor miss while riding = Possible spark.

Why?
A. Comp = Bike starts and idles is my assumption.
B. Fuel = Bike starts and idles is my assumption that the fuel jets are clean or no idle if either jet was clogged and/or partially clogged.
C. Spark = Bike has a miss while riding, yes?
D. Variable = It's either a plug wire, a spark plug, a lose battery cable, or if cutting out electrically, then this key fob business of a key switch.

Why spark? Because it starts and runs. Because you say the carb is clean, so it ran fine before, correct? No jetting to solve if it was running good then, but now this new miss. So, back to spark someplace is the guess, we eliminate the other 2 variables out of the way.

Make sense?

This does make sense, Sven... thanks for this. I missed this post before my last reply. I don't think the bike was missing actually... sort of "running rough" and unresponsive when I blip the throttle. I realize this is a crappy description, but I don't know how to describe it any better. I think I may be having two problems here.

The bike is pretty new to me, and I haven't had a lot of time riding it without problems, so I do not have a good baseline. I have been wrestling with a clutch slippage problem for quite some time... Andrew posted about my attempts... ( he's been helping me with a lot of advice and infromation) He posted about a forum guy who spent loads of cash and got screwed by bad mechanics...that was my sorry ass.

Carl's Speed Shop supposedly re-jetted the bike for the 2-2 big radius (previous owner didn't re-jet from stock), but I don't know if they did anything at all... it was popping a lot on decel and what not, but it ran strong when I test road it at purchase time in Ohio (Im in Fl now). Carl's couldn't seem to get the clutch to not slip, and after many other issues with them I brought it to another guy. All this time, I'd only ride it for short runs testing the clutch... it never stayed without slipping for long... 20-40 mile stints. The new guy (Chopper Design) sent my clutch and trans to baker. After a rebuilt trans and and a rebuilt clutch, I thought that was all behind me. I had one good day on it where it was running quite well, but I really didn't whack the throttle the whole time. Then, after having a beer at a local bar, I came out to start the bike and the clutch was totally slack (this after 100 miles of it working flawlessly). There were no signs even toward the end of my ride that the clutch was failing. I brought the bike out to the guy who I worked with last... we found that the clutch hub nut had backed off. He supposedly cleaned the main shaft, red loctited it and torqued it to 150 ft lbs. Needless to say... I'm starting to feel like getting more involved with the bike personally... not only to save A LOT of money, but also I want to get a more visceral understanding of this bike.... cause I love the shit out of it (even though it has been a bitch), and I want to know how it works and for it to run correctly.

When I road the bike out from Chopper Design after the hub nut issue, I noticed a lot of vibration... more then usual... especially at speeds above 83 or so. I also noticed that it seems to run rough at around 300 rpm or 70 miles per hourish. I haven't been able to ride it all day since then... only to and from work really (20 minute ride on back roads), due to schedule and weather. I've probably done around 100-130 miles in short trips. I thought something might have been done improperly with the clutch at first, but the clutch seems to be working perfectly... no slip, no creep, and I can find neutral easily. Then, I started thinking I was having a venting issue because I heard that popping sound once, another time I shut the petcock off and heard a moan from the carb...also found a drop of what I thought was gas on the cam cover (now I'm wondering if it was from condensation on the carb body).
ALso, it would die immediately if I didn't have the petcock on when I started it a couple of times... instead of a sputter, then dyeing like usual.

The very weird thing is that so far the issue seems intermittent...just when I think the problem is sticking around, the next time I ride it, the vibration level seems normal, and there really isn't any of this "rough running". I am thinking that my lack of responsiveness might be remedied with some accelerator pump adjustment, and maybe the "rough running" is actually more of a mental issue :loony: ...

maybe the lack of responsiveness combined with the excess vibration was convincing me that the two symptoms were one problem. Like I said... the weird thing is that it doesn't always happen. I just road it today, and although ti doesn't seem particularly responsive, the vibration felt normal at 70 mph and below... I didn't have an opportunity to get up to 90 though.

 

[zenBD]

So... I road it today and it ran really well. No "rough running" and the vibration level was waay down... Just like it used to be! Now I'm thinking... Could this be the tank liner issue? Would it vibrate more as it's trying to run if the petcock is clogging intermittently? I imagine it would act pretty much the same as if the cap wasn't venting. I pulled the petcock once before & the screen was clean. However, I only pulled it out a couple of inches because I didn't think it was necessary to pull the tank and expose the whole thing. I wonder if there could be pieces of tank liner slapping up against the filter at times, then being "washed away" at other times. Sometimes it seems like my intermittent problem might be happening between fill ups... Maybe the gas being poured into the tank moves said pieces around.




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[francoblay1]

I would start making sure my Tank & Carb are real clean... do you have an inline filter too? If so, make sure it is also clean. get this out of the way and you wont have to keep guessing.

 

[zenBD]

Yeah

 

[zenBD]

Carb is clean... Checked it.... No in-line. I'll pull the tank and petcock and really try to look up in there

 

[zenBD]

Isn't the tank liner issue usually marked by a green tint to the gas, though?

 

[Sven]

Flow chart:

1. Gas cap clogged.
2. Petcock flows poorly.
3. Fuel line has collapsed/kinked.
4. Float stuck and is pouring gas out the vent tube.

Now a sealed tank with debris floating from the sealer.

1. Cap = No
2. Petcock = Yes ~ Starves carb but does not.
3. Fuel line = Yes ~ Flows poor but is not.
4. Float stuck = Yes ~ Any little debris is going to clog/open more fuel to overflow, the float needle cannot be sent home.

Do I have bowl settlement?

Pop off bowl.

1. Petcock on = Note flow out the needle and seat.
2. Lift float to stop flow = Either it stops or debris is in between the needle and seat.
3. Clean float bowl at the bottom = I just goose chased taking apart things because I did not believe my troubleshooting guide's flow chart actions.

 

[zenBD]

Just for the sake of anyone interested, I think I discovered the issue (knock in wood). When changing out my scratched motor mount/coil cover I noticed and area on one of the plugs that had been melted away from contact with the cylinder. It must have been making contact intermittently due to vibration. I also noticed at one point that I was able to push it down more on the coil... It had backed off a bit.