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Discussion Starter #1
Here the story and whats been done to my 2003 V-Star 650:
  • Aquired Bike from friend who left it sitting for 5+ Years!
  • Cleaned and rebuilt carbs
  • Replaced Fuel & air filters, Petcock
  • New Battery
It starts right up no problem without choke, if it pull out the choke it dies, if i give it gas it dies. However if i let it idle as is for a while it will then pick up on the rpms and i can get on the throttle. I took it for a test ride and it doesnt not pick up speed and i got all the way to 5th gear but cant go any faster than 45mph yet felt like i was at the end of the gears each gear change. Going up hill in first (driveway lol) it dies unless i give it alot of gas while feathering the clutch.

Could it be the Fuel pump? Fuel pump doesnt prime everytime but IDK if it should if their is gas in the bowls? It does turn on but could it be weak and gummed up with the bad gas that sat for so long causing it to die while idling and lack of power on the road?
 

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you can check the fuel pump by pulling the line to the carbs off, point it in a bottle, and turn the ignition on and off a few times - with no restriction from a close float it should keep pumping fuel out (as if its attempting to fill the float bowls).

You did not say you drained the old gas out, or rinsed the tank with a carb cleaner.

If the bike sat with the gas tank full it would be full of gunk from the broken down 10% ethanol gas.

If the bike sat with the gas tank empty it could be full of rust, and putting new gas in it just flushed rust into your new fuel filter.

You also did not mention the condition of the spark plugs.

your description of it only being able to hit 45mph sounds like its running on 1 cylinder. Start the bike up cold and while its idling touch the exhaust pipes front and rear, right where they come out of the heads - if its running on one cylinder then one will quickly get hot enough to burn your finger, the other will only get warm (from the compression stroke heating up the air and then pumping it out).

Let us know what you find with the plugs, what the inside of the gas tank looks like with a flashlight, and whether both cyinder exhaust connection points are getting hot.
 

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BTW, normally after cleaning the carbs and petcock and putting new gas in the bike you still need to put some carb cleaner in with the new gas - but something is presently very wrong on the bike - its top speed in 5th gear is about 105mph.

another thing you did not mention: was everything inside the air filter box clear? sometimes bees or wasps get in there and make a nest...

If none of the things I mentioned lead anywhere you will want to check the compression on the engine, to make sure you dont have a valve stuck open or broken rings on one piston.

Sometimes when a bike sits for years, it was broken when it was parked.
 

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Discussion Starter #4
KCW thanks for the quick reply! I did flush the tank out and rinsed it. I did replace the plugs though. Tomorrow i will check if the pipes do differ in heat. If thats the case couldnt i also pull a plug wire off one at a time to see if its not firing?

Okay so i just did that fuel pump test today... What happened was it clicks and pumps the fuel for a second or two after i cycle the key on and off but the clicks get weaker and weaker. I dont hear the sound of the pump working like i do on my R6 or in a car only clicks. could the pressure be weak?
 

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Discussion Starter #5
The bike was parked because the rider was scared to ride, she only rode it a few times after purchasing it used from a well known dealer. It was running perfect before it sat, seen it for myself. Yes i made sure and cleaned the air box. there was a few twigs on the dirty side of the air filter but none made its way through.

Never done a compression test but i can rent the tool and figure it out. Would you happen to know off hand what the compression should be? (if not i can research it)

Edit* Yes i also did put some cleaner in the gas after cleaning as well.
 

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KCW has given some great things to check. Sounds like a fuel restriction either prior to carbs or jets themselves. Did you blow air threw all jets? The pilot jets have small holes in the sides, where they clean? Did floats move freely? The fuel pump is only an assist pump. The bike will run without the pump working at all. But since the carbs are higher than bottom of gas tank you need several gallons of fuel in tank. If you do find one cylinder not firing and plug looks good, make sure plug wire is pushed all the way into boot. It's easy to slightly pull out and cylinder will not fire. We had someone here fight a miss and that was the cause. Keep us informed.
 

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Discussion Starter #7
Thanks Lesblank, Imma hit Oreillys tomorrow to rent the compression tester ill let you guys know my numbers. I did blow are and thoroughly cleaned the jets and pilot holes. I use welding tip cleaners to clean my jets and pilot jets and whatnot, that tools makes it easy. However just this morning i suspected maybe i didnt put a plug wire on correctly so i took them off and put them back on so i dont think thats the issue. Maybe ill rent a spark plug tester while im at it.

I will do the temperature test first.
 

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on the fuel pump, did you pull the output line to the carbs off?

normally when the bike has sat overnight, when you turn on the ignition and turn off the kill-switch, the fuel pump will run for a second or two, makes a low hum, like you asked an old man a profound question and he has no answer HhMmmmmm......

that because when you park the bike hot and turn the petcock off the float bowls evaporate out, and have to be filled the next morning

if they are full when you turn the key on, you will hear nothing - thats why you have to pull the fuel line off the carbs and see how much flows out.

This might be a good time for the good news: the factory service manual for your bike is on the internet, if you search for yamaha factory service manual Vstar 650 it should be easy to find as a free download. There should be a fuel pump test description in it better than I can type out from memory.

The only drawback for the pdf free manuals is the table of contents links dont always work, so if you find the page in the index, you have to scroll thru it page by page to get to the right section.

from what you said the fuel pump sounds like its a bit off - one shortcut (if it is bad) you can put the line from the fuel filter right to the carbs, and the bike will run correctly if the tank is full. The fuel pump is there because the bottom of the tank is below the float bowls, so when you get below half a tank the bowls wont fill without the fuel pump.

Im not sure, but I think a faulty fuel pump will block the fuel line, even when the tank is full - so thats something you can try with a full tank of gas to debug it, bypass the fuel pump.
 

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Discussion Starter #9
KCW, I will try that! Its not at full its at about half.

I did pull the output line to the carbs off. It would dump fuel however i get ZERO hummmmm only clicks, i even put my ear right to the pump and only clicks.

Did not know the PDF was free online, i will be Downloading that now. Thanks for all the info!
 

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best way to tell if both cylinders are firing is to start the bike cold, and touch those head to exhaust connection points - they will get hot together if both are firing

you can be fooled by putting your hand over the muffler tips, because the exhaust stroke pushes out air even if the spark did not ignite the fuel, and the dead cylinder will still be pumping out warm air at the other end of the muffler.

there is a really inexpensive spark tester you can get that goes between the wire and the plug, check the spark before you check the compression

if the bike was running when it was parked, then a stuck valve or broken ring is unlikely.
 

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Les, I think we are only not suppose to post links to other forum discussion websites

so that one website does not try to lure members away
and
to prevent arguments between members on different forums
 

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I'd also check for possible intake leaks, fuel level in the bowls and sync the carbs. Pulling and inspecting spark plugs might be helpful as well. My wife's old 650 had similar issue, turned out to be a bad intake leak thru one of the rubber boots and carbs were out of sync (front cylinder was running very rich while the rear one was lean). I rebuilt the carbs, installed new fuel filter, new intake boots, adjusted fuel level in the bowls and synced the carbs with DIY sync gauge. Problem was solved.
 

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Discussion Starter #16
KCW you were correct, the Front cylinder is not running but the Rear is.
Compression:
Front 150
Rear 145
Both spark plugs are firing and both had fuel on them.

Pulled plug on front cylinder and bike ran the same. Their is in fact fuel in both bowls.

Spark plugs I’m using are NGK DPR7ea-9
 

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Discussion Starter #18 (Edited)
Okay so I took the new boot off and put the old one back on and there is still a leak from the same exact spot. It’s where it seats on the block towards the front of the bike. So not today because I have to leave, what should I do? Sand the block to be sure it’s 1000% clean??? I’m stuck on how to seal it correctly since both are working and I did it the same as the rear and it’s fine.

Any tips or tricks?

Maybe apply some gasket maker to the oring to help?
 

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Are you talking about oring with arrow pointing to it. Possibly the oring got misaligned on installation. That would leak air causing your issues. I suggest to inspect closely and replace if needed. Another possibility, old oring material still on engine face. If so, clean surface to remove. Good luck and keep us informed.

 

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Discussion Starter #20
lesblank, That EXACTLY whats leaking, the arrow is even pointing near the exact spot. I bought them off ebay, maybe thats why they arent sealing good? The oring came preinstalled on the boot and doesnt look misaligned. I didnt clean the surface up much because to the eye its looks very clean, i just got some carb cleaner and wiped it with a rag. I will look to see if i can get the oring dimensions and see about getting a replacement from McMastercarr or somewhere.
 
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