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Discussion Starter #1
Sometime last summer, my 2002 V Star 650 started cutting out at anything but light acceleration as well as anything over 50 mph.
Just pulled the plugs and they are carbon fouled.
Never winterized it last winter. Started it up every month. Ran some seafood through it.
Planning on pulling the sides of the carbs off and cleanings jets. Also will replace fuel filter.
Am I looking in the right direction?
 

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usually when the carbs are gunked up it runs lean and burns the plugs.

If the plugs are black, your choke could be sticking on, or your float bowls might be hanging open and flooding the engine. That would usually pour gas out the overflow tube on the right side, between the cylinders, right on top of the engine case.

A really dirty air filter will make the engine run rich, could also be oil blow by from worn rings. If your air filter is not white like paper then replace it.

How many miles are on the engine?

Does it use any oil between 4000 mile oil changes?

the only other maintenance thing I can think of is, when was the last time the valves were checked/adjusted?
 

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Discussion Starter #3
Air filter is clean. Doesn't use any oil. 26,000 km on engine (16,000 miles). I'll check for gas overflow (I haven't smelled any). How would I dislodge a float? Gonna pull the tank and at least change the fuel filter. I'll be able to have a better look with the tank off, too.

I don't believe the valves were ever adjusted. The only Yamaha bike shop here in town don't even know how to adjust the valves! How do you like that?
 

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Sometime last summer, my 2002 V Star 650 started cutting out at anything but light acceleration as well as anything over 50 mph.
Just pulled the plugs and they are carbon fouled.
Never winterized it last winter. Started it up every month. Ran some SEAFOOD through it.
Planning on pulling the sides of the carbs off and cleanings jets. Also will replace fuel filter.
Am I looking in the right direction?
WELL, I’d start looking first at what you’re FEEDING your bike. Never tried “SEAFOOD” before. Are you using shellfish or certain varieties of crustaceans??
??
 

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Discussion Starter #5
WELL, I’d start looking first at what you’re FEEDING your bike. Never tried “SEAFOOD” before. Are you using shellfish or certain varieties of crustaceans??
??
Haha!!! I never saw that. Crazy spell correct. That was intended to be Seafoam.
 

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If you know the valves have never been checked or adjusted that is something to look into. Its all simple wrench and screwdriver work but you have to pull the carbs off the intake manifold (tubes) to get the cylinder head plastic covers off, to get the covers off the tappets to check them. Its about a 2 to 3 hour job if you have never done it before.

Checking them is easy - you turn the engine over with a socket wrench on the crankshaft (little quarter size cover on the left side) till each piston is at top dead center, then you push feeler gauges between the tappet and the end of the valve, and see which one fits. If the valves are too tight or too loose, you back off the locking nut and adjust the screw till its correct, then carefully tighten the locking nut down again.

The service manual is available on line in a pdf format for free for the 650. It has the procedure for the valve check. There are probably youtube videos too.

Having said all that, I dont think a tight valve would make the engine run rich.. but you should still check them at some point. If they are too tight the valve cannot close all the way and the sealing surface starts to burn away.

with only 16k miles on the bike there is no way your rings are worn out and blowing oil into the combustion chamber.

I forgot to ask the obvious: has the bike been modified? Aftermarket exhaust or intake filter pods? Has the bike been re-jetted or adjusted on the PMscrews to run 'better' ?
 

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Discussion Starter #7
As far as the valves, if anything, they need tightening up. There is a clatter. Maybe that's normal.
No mods that I'm aware of (I got it 2nd hand with 18,000 km on it).
Got the tank off. Found what was rattling away inside. One of the bolts had come loose from the gas cap (gold bolt) and fallen down in. Got that out with a magnet.
I should probably consider pulling the carbs since I have the tank off. This vid demonstrates how to do some cleaning by just pulling off the covers of the carbs. He does stress not to upset the floats as they are difficult to adjust.
My fuel filter seems quite clean. I replaced it anyways.
I didn't see any sign off fuel coming out the overfill tube at all. So, I suppose all I can do is pull those jets shown in the vid and blow them out.
 

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You said you pulled the plugs and they were fouled out with carbon. Did you replace them and see if the bike runs any better?

Something running rich (like the choke stuck on) would make the plugs carbon up.

Once the plugs get fouled to a certain point the bike will not run well, like you said - stalling out under power.

I know a lot of people tear into their carbs and clean them, but if the bike is properly stored over the winter that should never be necessary.

I assume you put 4 ounces of seafoam in the gas and ran that thru the bike, or is it not running well enough to drive off 4 gallons of gas? If the bike wont run well enough to ride it, then yes you need to clean your carbs, there is no other way to do it if the gas wont flow thru them.
 

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Discussion Starter #9
I didn’t yet replace the plugs. The electrodes appear clean. It’s just sooty black around the rim and insulator. The bike actually runs fine at light throttle. I took it out in the open and couldn’t get past 50 mph without sputtering. Just cruising below 50 is fine. I’ve gone through 4-5 tanks with it running like this. Strangely, the first time I remember it cutting out was when I got caught in the rain. I figured water might have gotten into the wires coming out of that box mounted on the frame near the horn in the front. Maybe that’s a hint to something other than the carbs?
 

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Pictures help when describing things. Such as how "carbon fouled" your plugs are and the "wires coming out of that box mounted on the frame near the horn in the front." By the way, that does not sound good.
 

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Discussion Starter #11 (Edited)
Well. I got a good update but not what I expected. I should have taken KCW's advice right away. I did remove the carb covers, cleaned both jets out with carb cleaner and compressed air. There was a small bit of sludge inside each cover at the bottom. Put it all back together, put some gas in. Still sputtered when getting on the throttle. Sure enough, after taking off the air filter, she had all the power she wanted. A visual inspection didn't seem to point to a dirty air filter but sure enough....

Anyways, I'm glad I cleaned up the carbs a bit and found the loose bolt in the tank. Also changed the fuel filter.

Now I have to put up with a rainy rest of the week. Bummer.
 

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I ran my 650 up to about 24000 miles doing what the owners manual says for the air filter:

take it out and blow it off with compressed air...

after the 2nd time I did that I realized nothing was blowing off it, so I bought a new one.

thats when I was surprised to see they are suppose to be WHITE like WHITE WHITE. My old one looked like a old grey tee shirt that had been washed with black socks.

That was the only thing I changed, took it on the highway and Wholly Krap at 55mph in 4th gear the air intake box was growling with glee at full throttle, and it did it again at 70mph in 5th gear, still accelerating like nobody's business. (BTW, that is the max HP shift point on a 650, hit 5th gear at 55mph).

Its good you found the gunk in the carbs. Water will pool in the float bowls and then mix with whatever else comes in and make a real goopy mess.
 

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Discussion Starter #14 (Edited)
Come to realize that there's an aftermarket filter assembly on the bike (ha! I said "no mods" earlier). Im presently soaking it in a bucket of soapy hot water. Some aftermarket filters are washable. If it doesn't work, I'll have to purchase a new assembly (Yamaha OEM?). I believe the original owner never kept the OEM assembly.

Just found the aftermarket kit he bought. I notice it comes with new carb jets. I wonder if he installed them.

https://www.pacificcoaststar.com/pcs/v_star_650_baron_bak.htm
 

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thats interesting. Does the bike still have the stock exhaust?

usually people change the exhaust and the intake at the same time, and put in bigger jets to match. If the PO only changed the intake filter but put bigger jets in, that could be why your plugs are a bit carboned up.

BTW, carbon on the white center insulation is a problem, it shorts the center electrode to the outer metal, bypassing the spark gap.

Is the air filter a sponge like material? That is used on dirt bikes, you can clean it with laundry soap, let it dry out, then squeeze a bit of 10W30 motor oil into it, so its damp with oil, which catches the dust in the airlflow.

If you know what kind of air filter it is you should be able to find the instructions for cleaning, oiling, or replacing the element.

Id put the bike all back together with the new spark plugs and see how it runs. Then pull one of your plugs in a about 500 miles and see how the new plugs are doing. If they are getting black again, then you should look into what jets should be in the carb based on the air filter and exhaust you have.
 

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Discussion Starter #16
Good advice.
I soaked the filter, sprayed it with degreaser and scrubbed. Also cleaned the rain jacket that came with it. I can now see through it. It was dirtier than the filter. I’ll run it with it off now. The filter looks better and took the cleaning well. No swelling. It’s in a fin mesh screen. Actually, the bike did come with aftermarket exhaust. It was rather loud. I do like the stock exhaust. Much easier on the ears. I suppose I could get stock jets. But maybe it’s easier just to keep my eyes on the plugs. I think they’ll run much cleaner with the air intake cleaned up. New plugs tomorrow. Thanks so much.
 

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yeah, keep that in mind - he probably put in jets for the louder exhaust.

there are tables you can look up with several intake and exhaust combinations and it will tell you which size jets to use and where to initially set the PMscrews.
 

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Guidelines for 650 jetting.

 

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Discussion Starter #19
Come to find out, the filter I have is by K&N. I shouldn't have used degreaser. There are recharger kits made for these filters, including a cleaning solution to dissolve the oil and dirt and then a pump bottle of oil to recharge the filter. There's a chance I may have damaged some of the fibers in the cotton filter. Looks like our Napa Auto Parts may have the Recharger Kit. I'll check tomorrow and start over.
 

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Unless you are riding on gravel roads you dont have to be too fussy about the air filter

there needs to be something in there, and it needs to let the air thru. As long as it does not collapse and get sucked into the engine its probably ok.
 
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