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Will not start

Old 11-08-2017, 02:21 PM
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Will not start, fuel flow? vacuum issue? who knows...?

Bike will fire up when using starter fluid, but dies after. Checked petcock and fuel flow no issues. Fresh fuel and carb was rebuilt and cleaned out. Must be issue between the fuel valve and carb intake to cylinder. Or could it be something else. I want to say its not getting fuel to the carb, but when i disconnect the fuel lines from tank, they have fuel in them. Is it at all possible they could be clogged? Thats a pretty big diameter.

And when testing the vacuum to the petcock for fuel flow, I got a proper size hose and connected it to the vacuum port and began to suck and it would initially open up and fuel would start to flow but would eventually stop. Does that suggest the diaphragm needs to be replaced? How exactly is that supposed to work?

Also, how do I drain the fuel lines at the carb when I know the bike will sit for a while? Amy pictures would greatly help identify what it is as well.

Last edited by whatthefnck; 11-08-2017 at 05:57 PM.
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Old 11-08-2017, 05:42 PM
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Originally Posted by whatthefnck View Post
Also, how do I drain the fuel lines at the carb when I know the bike will sit for a while? Amy pictures would greatly help identify what it is as well.
Prop the tank, turn the petcock to the off position, put tank down start the engine and run dry. Or you can drain the carbs with the drain screws on the bowls.
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Old 11-08-2017, 05:48 PM
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Here's the drain screw. You can connect a hose to the nipple to catch the fuel.
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Old 11-08-2017, 05:51 PM
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Wink

Originally Posted by whatthefnck View Post
And when testing the vacuum to the petcock for fuel flow, I got a proper size hose and connected it to the vacuum port and began to suck and it would initially open up and fuel would start to flow but would eventually stop. Does that suggest the diaphragm needs to be replaced? How exactly is that supposed to work?
You need a consistent constant vacuum source, like a mightyvac with a gauge. Connect that to petcock vac and test flow. You may be loosing proper suck to keep it flowing.
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Old 11-08-2017, 05:53 PM
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Originally Posted by whatthefnck View Post
Bike will fire up when using starter fluid, but dies after. Checked petcock and fuel flow no issues. Fresh fuel and carb was rebuilt and cleaned out. Must be issue between the fuel valve and carb intake to cylinder. Or could it be something else.
I'd guess the lines on the petcock have been improperly connected.
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Old 11-08-2017, 06:19 PM
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Originally Posted by Wolverine View Post
You need a consistent constant vacuum source, like a mightyvac with a gauge. Connect that to petcock vac and test flow. You may be loosing proper suck to keep it flowing.
If I'm sucking the tube and continue so, the fuel will continue to flow. If I try to pinch it off it will slow to stop. If I start sucking and then plug with finger tip or my tongue, it'll slow to stop also. So the constant seems to work.

Originally Posted by Wolverine View Post
I'd guess the lines on the petcock have been improperly connected.
I connected exactly the way disconnect, and illustration shows in the graphics of the manual. I'm pretty sure, unless I screwed up, which could be the case. But I don't see how I could screw up refitting the gas lines. OH ****, maybe I'm reconnecting to the tank wrong. I hooked up the hoses to the tank underneath, a breather tube and a drain tube. Reconnected to the rear side of petcock with vacuum line, after mistakenly hooked the vacuum line to the petcock drain.

**Did I incorrectly hook up the hoses under the tank maybe? A breather hose and drain hose to the tank itself? Was I supposed to use one of those for the petcock drain instead? Its been so long since I disconnected I'm not 100% certain how I disconnected them.

Last edited by whatthefnck; 11-08-2017 at 06:27 PM.
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Old 11-08-2017, 07:27 PM
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Originally Posted by whatthefnck View Post

**Did I incorrectly hook up the hoses under the tank maybe? A breather hose and drain hose to the tank itself? Was I supposed to use one of those for the petcock drain instead? Its been so long since I disconnected I'm not 100% certain how I disconnected them.
Search PVLIR
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Old 11-09-2017, 01:28 AM
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The 10mm nipple and hose on the bottom of the tank is the fill overflow drain, the 4mm nipple and hose is the tank vent, both of which vent to the atmosphere. On CA bikes I believe these go to the charcoal canister. The nipple and line from the base of the rear carb goes to the small horizontal nipple on the left side of the petcock. The small nipple coming out of the bottom of the petcock is the diaphragm atmospheric vent.(no hose connected) The small nipple on the base of the front carb (RH) should be plugged.
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Old 11-09-2017, 06:20 AM
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Originally Posted by CaryDG View Post
The 10mm nipple and hose on the bottom of the tank is the fill overflow drain, the 4mm nipple and hose is the tank vent, both of which vent to the atmosphere. On CA bikes I believe these go to the charcoal canister. The nipple and line from the base of the rear carb goes to the small horizontal nipple on the left side of the petcock. The small nipple coming out of the bottom of the petcock is the diaphragm atmospheric vent.(no hose connected) The small nipple on the base of the front carb (RH) should be plugged.
awesome, thx for that. I'm reassured I connected properly. So my problem must be something else.
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Old 11-24-2017, 07:38 AM
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I'm still stumped. The carb has been pulled and cleaned. The fuel lines are clear. The gas valve and petcock is all hooked up properly, and diaphragm is functional. The fuel tank cleaned out and replaced old fuel with spruced up fresh fuel with a bit of octane booster and some stabil. But I still cannot get this thing going on anything other than starter fluid thru the airbox. WTF is wrong. Full battery too. I know someone out there has got to have an answer. I'm dying to go ride, but at this point I'm about ready to burn this ***** and buy a new bike grrrr
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Old 11-24-2017, 07:44 AM
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"16/43" how much difference you think adding 2 teeth to your rear sprocket did? I'm debating on adding 2 in rear or dropping 1 in front..
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Old 11-24-2017, 04:10 PM
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Won't feel any difference if the bike doesn't start...

Fuel, compression, spark.
Pull the supply hoses to the carbs. Use a piece of hose and supply continuous vacuum to the petcock and confirm fuel flows. No guessing...
If it flows, you have a carb issue and need to pull them to inspect float bowl needles. Are they stuck closed?
If it doesn't, you have an issue in the petcock/tank.

It sounds to me like you aren't getting proper vac to start the supply of fuel.
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Old 11-25-2017, 01:47 AM
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Thx wolverine. I'll get back with that, but I've already done the constant vacuum and confirmed the petcock is good. Also pulled the carbs and hd them professionally cleaned. So I'm stumped. Maybe I'll pull em again and bring elsewhere.
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Old 11-26-2017, 05:55 AM
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Originally Posted by whatthefnck View Post
Thx wolverine. I'll get back with that, but I've already done the constant vacuum and confirmed the petcock is good. Also pulled the carbs and hd them professionally cleaned. So I'm stumped. Maybe I'll pull em again and bring elsewhere.
Seems clear it's a fuel delivery problem. Have you disconnected the fuel lines from the tank and put some fuel in them, bypassing the petcock altogether?
Also the quote in red is, to me, a red flag.
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Old 11-26-2017, 06:53 AM
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Originally Posted by xeris View Post
bypassing the petcock altogether?.
Great recommendation. We use one of these Motion Pro bottles at the shop. You'd have to get a Y to connect both lines on the hawk.


As everyone is agreeing, fuel delivery is your issue. It's either petcock or carbs or lines in between.
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Old 11-28-2017, 10:15 AM
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Push tubing onto both carb drain nipples, place in clear container, then open the drains on both carbs one at a time, apply a constant vacuum source, fuel should be flowing really easily and at a good rate from both drains...
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Old 12-02-2017, 09:40 PM
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Originally Posted by Fastguy59 View Post
Push tubing onto both carb drain nipples, place in clear container, then open the drains on both carbs one at a time, apply a constant vacuum source, fuel should be flowing really easily and at a good rate from both drains...
Ahh ok so if i open up the petcock then it should flow consistently out of the carb draining points... as if i opened up a faucet.
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Old 12-03-2017, 07:04 AM
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Originally Posted by whatthefnck View Post
Ahh ok so if i open up the petcock then it should flow consistently out of the carb draining points... as if i opened up a faucet.
Yes, but you need to apply a vacuum to the petcock. When the engine is running, it produces a vacuum inside the intake. This vacuum is used to, in simple terms, to turn the petcock on. So, fuel will not flow unless the engine is running, or a vacuum is applied to the petcock.

Just so it's a little more clear, the petcock has a mechanical On-Off lever, and it also has a vacuum actuated On-Off.

Last edited by CruxGNZ; 12-03-2017 at 07:07 AM.
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