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V Star 650 Carburetor issue?

16915 Views 43 Replies 13 Participants Last post by Pancake81, 13 d ago

dt.15r

Discussion Starter · Mar 6, 2020

Hello, everyone. I hope everyone is having a good day/night. I just recently bought a V star 650 Classic (01) for $1,500. The person who sold it to me said he was selling it for so cheap because he said he messed up the carburetor trying to do a DIY job. Something to do with either the needle inside the carb. So he says. When I start the bike cold, and turn the choke on, it idles good and everything. But when I open the throttle it dies. On my rebel 250 when I did a cold start on her she would let me open the throttle to get the revs up. But that's not even the main issue. The main issue is on 1st gear, when I wanna take off it feels like its about to die, so I open the throttle more and it does the job. I didn't think it required so much throttle to be open. The other issue arose when I was on the highway. I noticed that I went up through all the gears on the 650 and it didn't want surpass 60 mph. Which was pretty bizarre to me. Because my 250 would go 85mph and reach its max speed. It honestly felt like it wanted to go more but it couldn't. The revs weren't even high. In my introduction I gave an example that went something like this "it felt like it was the weight of a 650 but the power of a 250" maybe even less than the 250 tbh. I only say that because it didn't want to go pass 60mph. I just wanted to know if you guys would recommend switching both carburetors out with new ones? Would that fix the problem im having? Thank you so much for taking the time to read this thread. I hope everyone has a good day/night. Any help would be grateful thanks.

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NorthernRider

· #2 · Mar 6, 2020

If you're sure it's a carb issue (which it sounds like it is) you'd be better off doing a cleaning and rebuild. I'm not a carb expert but there are some members here who know them well and can talk you through it if you have some mechanical abilities. If that's not something you're comfortable doing it would probably be cheaper to pay a shop to do it than to just replace the carbs.

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KCW

· #3 · Mar 6, 2020

if you go to bikebandit.com and put in the year make and model for your bike

then you can follow the OEM parts tree down and find out how much a new carb will cost for your bike

make sure you are sitting down - 1 new carb will cost more than you paid for the bike - for the price of 2 new carbs you could get a really nice ready to ride low miles 1100, 1300, Road Star, Royal Star....

attempting to fix the carb yourself is the lowest cost way, the kit with the replacement jets and seals (o rings) is not expensive, but it will take at least 6 hours of your time to get the carbs off the bike, go over them and adjust them, put them back on the bike, and then do some fine tuning.

that is assuming the carbs have not been ruined by the previous owner

another option is to find a used carb for the one you think is bad, either by shopping around at local bike repair shops to see if someone has one, or looking on ebay or craigslist for someone parting out a wrecked bike

there is still some risk of getting a used carb that needs to be cleaned, but if the history of the bike is known and someone was riding it regularily and something happened to the bike, you have good odds of getting a good used carb

From your other posts it sounds like the bike is running on one piston - it should be easy to see which exhaust pipe quickly gets hot when you start it, and which one is just getting warm. The warm one has the bad carb.

You can down load the yamaha factory service manual free in pdf format - easy to find with google. Read thru the section on removing the bad carb from the bike, see if you think you would be comfortable with that level of work. No special tools are required, you will need a torque wrench to put the bike back together properly without stripping out the bolts that screw into aluminum

Go from there - let us know how you want to proceed. There are people here who can walk you thru the carb rebuild.

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KCW

· #4 · Mar 6, 2020

You will have one disadvantage rebuilding the carb yourself. The previous owner had it apart and screwed it up.

Normally if the carb has never been touched since the bike was new, you can take it apart screw by screw, take photos of everything, make notes of where every part goes, and then clean it as you go and put it back together with the new parts from the carb kit

but the previous owner was in there, and did something wrong - so there may be parts or washers or spacers... in the wrong place, or missing

in other words, if you put it back together the way it was with new parts, it might still be put together wrong

that is where taking the carb to a shop might be better - someone who has rebuilt them before will know where all the parts go, and will know if something on the carb body is damaged.

you can figure it out by yourself from looking at the exploded carb drawings in the manual and at bikebandit.com, but it will be a tedious process

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KCW

· #5 · Mar 6, 2020

noticed in your other thread you are having trouble getting the bike to start

if its only running on one cylinder that is understandable

the normal sequence is to pull the choke all the way out
turn the key to run and wait till the fuel pump stops running
crank the starter with NO throttle twist
the bike should start within 3 to 5 seconds (normally)

as soon as the bike fires you can let go of the starter and then give it just a bit of throttle
and you should be able to push the choke in half way

after about 3 minutes of idleing or riding you should be able to push the choke in all the way

if the bike is running on one cylinder its going to be difficult to start
but you just need to get it running again enough to see which carb is bad

dont ride the bike anymore like it is - if one cylinder is not firing that piston could be getting washed down with un-burnt fuel
or it might not be getting any fuel at all - you can only tell by pulling the spark plug out, see if its soaked with gasoline

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KCW

· #6 · Mar 6, 2020

One more think

this may not apply to you, if the previous owner damaged the carb

but if a bike is running on one cylinder, its also possible the float bowl is stuck and the carb is flooding out the cylinder - too much fuel for it to fire

normally gas would come out the carb overflow tube, down on the right side of the top of the engine case, and drip on the ground. If its doing that while you are riding you might not notice, but you should be smelling gasoline.

If the float is stuck and flooding the carb it may have flooded gas into the crankcase, seriously diluting the oil. That is not good - dilution with gasoline will damage the bearings and destroy the engine.

If there is evidence the carb was overflowing, change the oil before you run the bike again

usually you can take the oil filler cap off and see if the crankcase smells like gasoline

again this may not apply to you, but it would for future thread readers with a bike running on one cylinder

This is another reason to not ride your bike if its not running right, esp running on one cylinder.

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dt.15r

Discussion Starter · #7 · Mar 6, 2020

KCW said:
if you go to bikebandit.com and put in the year make and model for your bike

then you can follow the OEM parts tree down and find out how much a new carb will cost for your bike

make sure you are sitting down - 1 new carb will cost more than you paid for the bike - for the price of 2 new carbs you could get a really nice ready to ride low miles 1100, 1300, Road Star, Royal Star....

attempting to fix the carb yourself is the lowest cost way, the kit with the replacement jets and seals (o rings) is not expensive, but it will take at least 6 hours of your time to get the carbs off the bike, go over them and adjust them, put them back on the bike, and then do some fine tuning.

that is assuming the carbs have not been ruined by the previous owner

another option is to find a used carb for the one you think is bad, either by shopping around at local bike repair shops to see if someone has one, or looking on ebay or craigslist for someone parting out a wrecked bike

there is still some risk of getting a used carb that needs to be cleaned, but if the history of the bike is known and someone was riding it regularily and something happened to the bike, you have good odds of getting a good used carb

From your other posts it sounds like the bike is running on one piston - it should be easy to see which exhaust pipe quickly gets hot when you start it, and which one is just getting warm. The warm one has the bad carb.

You can down load the yamaha factory service manual free in pdf format - easy to find with google. Read thru the section on removing the bad carb from the bike, see if you think you would be comfortable with that level of work. No special tools are required, you will need a tourrque wrench to put the bike back together properly without stripping out the bolts that screw into aluminum

Go from there - let us know how you want to proceed. There are people here who can walk you thru the carb rebuild.

Thank you so much for the wise help. Ive been on bike bandit a lot very good site ill be sure to check out the Yama section. Yes, it does feel like Im running on 1 cylinder. The good thing is that it drives. I don't mind taking the time out to rebuilding a carb. I have something fun to do now! Hahaha. How does one tune the bike? Is it through the valves? Im fairly new to wrench work but not afraid to learn.

dt.15r

Discussion Starter · #8 · Mar 6, 2020

For

KCW said:
One more think

this may not apply to you, if the previous owner damaged the carb

but if a bike is running on one cylinder, its also possible the float bowl is stuck and the carb is flooding out the cylinder - too much fuel for it to fire

normally gas would come out the carb overflow tube, down on the right side of the top of the engine case, and drip on the ground. If its doing that while you are riding you might not notice, but you should be smelling gasoline.

If the float is stuck and flooding the carb it may have flooded gas into the crankcase, seriously diluting the oil. That is not good - dilution with gasoline will damage the bearings and destroy the engine.

If there is evidence the carb was overflowing, change the oil before you run the bike again

usually you can take the oil filler cap off and see if the crankcase smells like gasoline

again this may not apply to you, but it would for future thread readers with a bike running on one cylinder

This is another reason to not ride your bike if its not running right, esp running on one cylinder.

fortunately this does not apply to me, but I would like to know more about what you are talking about.

KCW

· #9 · Mar 6, 2020

when you clean a carb there are two things that will need to be tuned.. maybe three

you will take the Pilot Main screws (PM screws or PMS) out and put them back in. The manual tells you to gently screw them in until they seat, and then back them out a specific number of turns (2... 2 1/2... its in the manual)

that is the starting point - you will ride the bike and see how it runs, and then if necessary nudge them in or out to get it perfect

also if you take the carbs apart you will probably need to re-synch them - this gets them both equally open when the engine is idling, so that one piston is not producing more power than the other

the 3rd thing - you might need to adjust the idle speed

if you have the bike torn down to where the carbs are off, that is also a good time to check the valve clearance and adjust them if needed - you can only get to the tappets when the carbs are off the bike (which is a 2 hour process to get the carbs off and put them back on)

so while you are in there, its only about 20 minutes more to check them. If you do get new o rings for the tappet covers.

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dt.15r

Discussion Starter · #10 · Mar 6, 2020

KCW said:
noticed in your other thread you are having trouble getting the bike to start

if its only running on one cylinder that is understandable

the normal sequence is to pull the choke all the way out
turn the key to run and wait till the fuel pump stops running
crank the starter with NO throttle twist
the bike should start within 3 to 5 seconds (normally)

as soon as the bike fires you can let go of the starter and then give it just a bit of throttle
and you should be able to push the choke in half way

after about 3 minutes of idleing or riding you should be able to push the choke in all the way

if the bike is running on one cylinder its going to be difficult to start
but you just need to get it running again enough to see which carb is bad

dont ride the bike anymore like it is - if one cylinder is not firing that piston could be getting washed down with un-burnt fuel
or it might not be getting any fuel at all - you can only tell by pulling the spark plug out, see if its soaked with gasoline

My sequence is this please correct me if im doing something wrong. 1) turn key on 2) cut off switch on 3) push to start 4) open choke. After that I try and opening the throttle with the choke on and it turns off. When I try and take off on a cold start (after turning the choke off and letting it warm) the bike seems to stutter almost seem to die not sure if its taking long time to warm up. Is there anywhere I can post a video to show exactly what im talking about?

KCW

· #11 · Mar 6, 2020

the stuck float

in the carb there is a float that opens a valve that allows gasoline to fill the carb float bowl.

when the bowl is full the float pushes the valve shut

if the float or valve gets sticky or gummy, it might stick open or closed

if its stuck closed that carb will get zero fuel

if its stuck open that carb will overflow, with fuel going out the overflow tube and into the piston

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dt.15r

Discussion Starter · #12 · Mar 6, 2020

KCW said:
when you clean a carb there are two things that will need to be tuned.. maybe three

you will take the Pilot Main screws (PM screws or PMS) out and put them back in. The manual tells you to gently screw them in until they seat, and then back them out a specific number of turns (2... 2 1/2... its in the manual)

that is the starting point - you will ride the bike and see how it runs, and then if necessary nudge them in or out to get it perfect

also if you take the carbs apart you will probably need to re-synch them - this gets them both equally open when the engine is idling, so that one piston is not producing more power than the other

the 3rd thing - you might need to adjust the idle speed

if you have the bike torn down to where the carbs are off, that is also a good time to check the valve clearance and adjust them if needed - you can only get to the tappets when the carbs are off the bike (which is a 2 hour process to get the carbs off and put them back on)

so while you are in there, its only about 20 minutes more to check them. If you do get new o rings for the tappet covers.

Perfect, thank you so much for the advice. Im gonna start ordering the parts and be posting them on here to make sure im grabbing the right kits if that's okay. I hope I can come here to ask for help when im at a learning curve. This should be fun guys! Wish me luck.

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KCW

· #13 · Mar 6, 2020

you dont need to post a video

if you are following the choke sequence (sounds like you are) the bike is just hard to start because one of the carbs is screwed up

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KCW

· #14 · Mar 6, 2020

OK, I know all the lead up to cleaning a carb, but Ive never had to do one myself

Seafoam has kept my carbs clean so far (which is good, Ursa has 4!)

there are several other people here who have done many carbs, and they are always happy to help

there are also several threads on carb cleaning and rebuilding for the 650

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dt.15r

Discussion Starter · #15 · Mar 6, 2020

KCW said:
OK, I know all the lead up to cleaning a carb, but Ive never had to do one myself

Seafoam has kept my carbs clean so far (which is good, Ursa has 4!)

there are several other people here who have done many carbs, and they are always happy to help

there are also several threads on carb cleaning and rebuilding for the 650

Thank you, I really appreciate the help.

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robbyk

· #16 · Mar 6, 2020

You are in good hands with KCW, he's one of the experts on the 650.

Plus one on all the above, I would just like to recommend pulling the sparks plugs to see what they look like. If you are not sure how to read them, take a pic of each and post on this thread for us to see. They tell you if the bike is running too lean or too rich.

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dt.15r

Discussion Starter · #17 · Mar 8, 2020

Recap: I opened up both carbs and cleaned the first one. The second carb got a screw snapped off. Not sure if this was how it was but once I put like a 6mm socket on it and began to loosen the bolt it came off like if it was there but barely.

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dt.15r

Discussion Starter · #18 · Mar 8, 2020

how the carb looked before I took anything off on it. Question : would I have to re thread the tap?

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lesblank

· #19 · Mar 8, 2020

2

Don't panic, should be an easy fix. That screw is brass with a hollow body.

They get seized and break easily. Get some WD-40 and soak that area. With a fine thread screw extractor you should be able to carefully get it out and cause no damage to threads. You need to be slow and careful. Don't use a course thread extractor, you won't be able to get a good bite. Keep us informed on your progress.

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dt.15r

Discussion Starter · #20 · Mar 9, 2020

lesblank said:
Don't panic, should be an easy fix. That screw is brass with a hollow body.
View attachment 92202

They get seized and break easily. Get some WD-40 and soak that area. With a fine thread screw extractor you should be able to carefully get it out and cause no damage to threads. You need to be slow and careful. Don't use a course thread extractor, you won't be able to get a good bite. Keep us informed on your progress.

View attachment 92203

Thank, you. Im waiting on my rebuild kit to come in the mail. While I wait ill be getting that screw out.

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