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2002 Yamaha Vstar 650 Custom
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Discussion Starter #1
Hey guys!

recently picked up a sweet looking 650 custom from a friend. He had it sitting for a bit since 2014... it turns over and somewhat starts but dies right after starting for about 1-2 seconds. It can hold a better start if I spray some carb cleaner in the air vent.
I have already taken the carb housings off and removed the jets and cleaned them with carb cleaner, but still won’t hold a start. I’ve already put new gas in it as well. Replaced the spark plugs too...

I’m stuck as to what it might be..
Let me know what you guys think? 👍🏼
 

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Check the rubber manifolds, they crack and loose seal to the heads over time.
not expensive to replace and rather easy.
 

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the jets do not engage until you are past 1/2 throttle twist

did you clean the PMscrews, the choke passage, and the float assembly?

a bike that sat 5 years with fuel in the tank will be full of jello and gum - requiring a very thorough cleaning (not just a spray with cleaner)

if it sat with no gas in the tank the tank is full of rust, which ends up mostly in the fuel filter, plugging it completely

your bike needs what they call on Craigslist: TLC

Pull the plugs just to make sure the are not fouled, but most likely the engine is not getting enough fuel

also take the air filter out and make sure the intake is not full of bees or ants

And BTW, you are using the choke with no throttle twist when you start it, yes?
 

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Welcome to the forum Joe. You've got some good advice already. Like KCW said, any bike sitting that long will need a good carb cleaning, even if it was stored with stabilizer. It extends gas life, but not indefinitely. There are some good carb people here who can help with any questions you have.
 

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welcome from NY and another 650 owner. If the advice above doesnt help, try pulling the fuel line off after the shutoff valve and see if it is pumping into a collection bottle to make sure the pump is working and lines are clear. Try putting some sea foam in the gas if you get in running to help clear the carbs. The others are surely correct that a good carb cleaning is in order.
 

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2002 Yamaha Vstar 650 Custom
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Discussion Starter #8
Hey!!
UPDATE!

Alright so I Went ahead and removed the carbs and completely rebuilt them with a kit I purchased from Amazon. Jets, washers and all. Added a little bit of sea foam to the tank again with new fuel (91). I also made sure to flush the lines from old fuel that might have still been in there. I repacked the fuel filter as well! I removed the spark plugs and made sure they were gapped correctly. Both were at .032.
So finally got it started and running! Made sure to pull the choke out and let it warm up for about 3-5 minutes and slowly push the choke back in. Once it feels completely warm, I can’t help but notice the idle is a little jumpy - not completely uniform I guess. Lol
Could this still be the sea foam in it? Should I leave it running until the gas is all up and put more fresh gas in it?
I feel accomplished to get it running, but I want it running smooth with no hiccups. 👍🏼👍🏼
 

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WTF - That's a good looking bike. Aside from the burn mark on the exhaust corresponding to the front cylinder she looks amazing. By the look of the bottom pipe looks like the front cylinder is running lean, the rear cylinder seems fine. You might want to check the adjustment on the Idle Mixture Screws. For a 650, at least for my 2001 650 Classic, the initial recommended adjustment is 2 1/2 turns out.

Seamfoam is not going to make the bike idle jumpy, however if the front cylinder is running leaner than the rear one that will make your idle unstable.

Also, if the bike was mine I would replace the spark plugs with new ones.

NGK DPR7EA-9
 

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What RPM is the idle set at. The Vstar 650 bikes are designed to idle at 1150 - 1250 RPM. It might seem a little high but at that RPM the oil pump is properly circulating oil.

92705
 

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Hey guys!

recently picked up a sweet looking 650 custom from a friend. He had it sitting for a bit since 2014... it turns over and somewhat starts but dies right after starting for about 1-2 seconds. It can hold a better start if I spray some carb cleaner in the air vent.
I have already taken the carb housings off and removed the jets and cleaned them with carb cleaner, but still won’t hold a start. I’ve already put new gas in it as well. Replaced the spark plugs too...

I’m stuck as to what it might be..
Let me know what you guys think? 👍🏼
Completely take the carbs apart and do a complete clean on both , every jet every screw , I went through almost 4 cans of carb cleaner when I did mine.
 

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Don't spray carb cleaner on any rubber parts, it will deteriorate them.
 

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Of course I should have added I bought full rebuild kits for both carbs. New floats , seats , needles and jets I took every piece if plastic and rubber off and shot carb cleaner in every little stinking hole I could find to get any debris out.
 

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2002 Yamaha Vstar 650 Custom
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Discussion Starter #17
WTF - That's a good looking bike. Aside from the burn mark on the exhaust corresponding to the front cylinder she looks amazing. By the look of the bottom pipe looks like the front cylinder is running lean, the rear cylinder seems fine. You might want to check the adjustment on the Idle Mixture Screws. For a 650, at least for my 2001 650 Classic, the initial recommended adjustment is 2 1/2 turns out.

Seamfoam is not going to make the bike idle jumpy, however if the front cylinder is running leaner than the rear one that will make your idle unstable.

Also, if the bike was mine I would replace the spark plugs with new ones.

NGK DPR7EA-9
Would this be the same as carb syncing? Or is this the idle knob that’s visible?
 

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Nice job getting it running

first thing: the 650 is tuned to run on regular fuel. Obvious from the photo it has aftermarket exhaust, so it may have been jetted to run on hi octane, but I dont know why someone would do that because its not a hi compression engine and premium comes at a $$$ premium.

If the bike was tuned (jetted) to run on regular then it will run lean on premium. Regular has more energy per ounce than premium.

The idle screw increase the RPM of both carbs together by opening the sliders a little more.

To sync the carbs you need to put a vacuum gauge on both intakes, with the bike warmed up, and adjust the sync setting so both carbs are pulling the same vacuum at idle. There are threads with more detail on this and some videos on youtube.

DO NOT let the bike sit and idle just to burn fuel thru it. Take it for a ride. The carbs only flow thru the PMscrew idle trickle and it wont do much good to run all your gas thru at idle. With the seafoam in the tank you want it washing thru all the parts of the carbs, which means on the highway throttle wide open in 4th gear up to 55mph (HP peak) and wide open im 5th gear up to 75mph (HP peak in 5th). Every chance you get going up a hill open it up and let that seafoam & fuel flush thru.

If its running lean you will notice popping and maybe backfiring on compression braking ( shutting the throttle closed while you slow down in gear).

If you get a lot of that, then look at your plugs, see if its showing signs of running lean, and the consider putting the premium gas in your car (that can compensate with its fuel injection sensors), or backing out the PMscrews 1/4 turn at a time until you like the way its running.

I assume when you did the carbs you had the PMscrews out, and you set them both a certain number of turns out from the stop. That is the starting point for tuning it, depending on how it runs you need to tweek them in or out.

I would do all that first, make sure the carb is running as well as possible with maybe 50 to 100 miles on it, then if you think the idle is still jumpy then sync the carbs.
 
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