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Losing my mind - Carb/Starting issue V-star 650

43K views 30 replies 11 participants last post by  compjan 
#1 · (Edited)
Hey fellow riders! Well, I am a new guy here on the forum, but I thought I would take a shot at asking my question, with the hopes of getting my issue resolved. I will try to get ALL the details in, so this might be a LONG post. Sorry in advance, but I am trying to be thorough!

Here goes:

Basic stuff:
-2001 Yamaha V-star 650 Classic
- The bike is stored OUTDOORS under a heavy duty cover, between my cars.
-Miles; 3,600KM (Canadian model)
-Owners; I am the third owner. First owner modded it a bit for his wife, second owner never rode it for 2 years, and I bought it from him.
-Owners manual has been read, yes. Sadly, they don’t have any tuning info in there!
-The following mods are on the bike: Aftermarket slip on exhaust (cobra-style slash cut). Changes I have made; 92.5 main jets (90 is factory), 22.5 pilot jet (factory 20’s), 0.020” shim X 1 per needle.
-Searching topic: I have scoured this forum, and tons of other forums – close to my problem, but never a solution that works for my situation

Now for the nitty gritty, and the past history/problems I have had, what has been resolved, and what persists.

I will do it in point form, for easier following:

- Purchased bike from a local guy, when i went to look at the bike, it would fire up right away on Choke (high RPM as it should have), then warm up, and idle nice and steady with the choke pushed in. THE ONLY issue it had, was the rear cylinder would flood a bit and spit fuel. it burned, but poorly, and spit quite a bit of gas (yet it did burn some off). The owner told me that he was trying to clean the carb and broke the little wire arm on the Needle Valve, so he made one out of guitar string. (This was later revealed to be true, and I will get into it in the next point). The bike came equipped with aftermarket slip on slash cut pipes. They are Loud as hell, and they DO have baffles. They technically should not require a rejetting, but I did a minimal uppage in the jets (more later).

-Brought bike home via friend's truck. Step one: Let's get that carb out, cleaned and repaired. Went to bike shop, got a "replacement" needle valve. Turned out to be too short, kept flooding the rear cylinder even worse (thank you tech guy at the shop *rolls eyes*). I ordered a factory needle valve assembly (Yamaha genuine part # 8, with o-ring, mesh screen, etc). Installed it. All jets were cleaned, etc. OK bike was cleaned out, 100% stock and factory spec now. I went to crank it... Nada. Sputter sputter, die. Occasional startup, die. NOTE: here is something weird: The bike has a better chance of being started leaning to the RIGHT (brake lever side).

-OK This is ridiculous, let's work on it more. I replaced the main jets with 92.5 (factory is 90) to help a little with the slightly increased flow from the slip ons. I also used a little seafoam in the gas, to try and help de-gum anything that might have got sticky. *At this point the inside of the carb is 100% fine, no issues from the stock parts*

I was able to get it started by leaning to the right, and took it for a short ride down my street... Coughing, and sneezing back through the carb - all symptoms of being lean.

- I noticed one day, when working on it, that if I take off the airbox, and stick a cloth in the air intake, covering 2/3rds of the air flow, it would start up and run fine, enough that I could ride it.

hmmm got me thinking: It must be running too lean!

- Next changes were 22.5 pilot jets (20 is stock, so not a huge jump, if any jump at all), and the PMS screw caps drilled out, and turned out to 2.75 (2.5 is stock) from seated position.

Went to start it. Hmmm interesting: It will, upon the first crank with the choke pulled out, start RIGHT AWAY, keep HIGH RPM and die after 5 seconds or less. Then it will not respond to cranking, BUT WILL grab and start sometimes with the choke PUSHED IN.

In fact, with the last mods, after only 6 or 7 tries, I was able to get the bike to start, but only with the choke pushed in (aka ZERO choke).

At this point I was able to take the bike for a ride down my street, shift gears, and ride it normally. Only thing I noticed was a bit of sluggishness at 0-25% throttle, aka during pilot jet duties/etc.

SO THE MAIN PROBLEM AS IT STANDS: It won't start easily, choke does nothing really (I know the choke works, as mentioned, on the first crank most days it has been sitting, it will catch and keep high revs for a few seconds, then dies), and is still kind of sluggish at low RPM/0-25% throttle.

Still, no more coughing/sneezing at this point, but starting it is torture.

Any ideas guys?

PS I am aware someone will say I jumped too far with the jets and whatnot, but I feel the changes in the jets are SOOO minute, that it should not affect the bike too badly.

In fact, the new pilot jets seem to have helped the bike a bit!

My thoughts on what I think it could be: Pilot jet pathways are clogged? (I am sure I cleaned them!) or maybe fuel isn't getting to the carb somehow.

NOTE ON SPARK PLUGS: I put in a new set of plugs yesterday, haven't had a chance to try starting yet (Canada = COLD in November).

RANDOM THOUGHT: Is there any chance that, because it is stored outdoors and it is cold lately, that my carb is simply too cold to start? As in, my settings are just fine, but because the temperature hovers around 40-45F, that my carb is cold? (I hard the v-star 650 has carb heater coils, no?)

ANY HELP WILL BE APPRECIATED!

UPDATE UPDATE UPDATE: I made you guys a video to show you how I can get it running by shoving a cloth into the air intake. Clearly an issue with being too lean at start up!

 
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#2 ·
Have you checked properly for leaks in the inlet manifolds. If it runs when you choke the air intake, maybe air is leaking into a manifold?
 
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#4 · (Edited)
To reply to the last two:

Cruza: I thought the same, but I have taken the air intake apart numerous times, and even fixed any places that may have leaks, made sure all clamps are down tight, inspected for cracks and breaks etc. I suspected the same thing as you, but I cannot seem to find a place where it would leak in.

nick57: Well that's what boggles me too. The airbox IS stock/factory. So why is it leaning out NOW all of a sudden? It must be my fault somehow, as the bike started up no problem on factory settings at the guy's place, before I bought it - it merely ran too rich/flooded on one cylinder, but that was resolved with a Float needle valve assembly (new one, with all new pieces).

The ONLY piece that was replaced at the start of these problems, was the float needle valve/and it's housing. At that point it ran like a sick turtle, whenever it did start. Now with the larger jets/shimmed needles, at the least it runs properly when accelerating. (I DID NOTICE when I bought it/picked it up and rode it over to the truck to haul home, that it also coughed and wheezed. So it was lean then too, but at least it started).

Spark plugs (I put new ones in a few days ago, but the old ones are beside me here on my desk) are .... well I can't tell, because of all the tinkering as of late. The rear cylinder one is dark, with the tip being a lighter beige. The front spark plug is dark, which would make me think too rich... but when it was leaned out a bit, it ran like crap, so I don't want to go back to that :(

I am stumped guys!
 
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#5 ·
Yes the 2001 XVS650 has carburetor heaters. Some (just on this forum alone) state they are needed and some say they are not needed. You might belong to the former. Good luck!

ps.
I understand you are a lumberjack and you're okay
:D
Apparently that's the rumour going around ;)

As for the heaters... I am going to test that theory, by applying a low-setting on my heat gun and gently warming the carbs up then trying to start it. If that at all helps, I will know two things; 1) it is temperature related and 2) its time to move to Florida and hang out with my uncle!
 
#8 · (Edited)
You know, I was thinking that, but admittedly.... I have no idea how to measure/check that :confused:

Could you help me out? Its definitely something I want to look into, as it may be a HUGE possibility (the floats were removed at one point to install those needle valves, so it is the ONLY thing that was really touched after the cleaning, and it seems plausible the problem lays there)

EDIT: Would this be accurate? --> http://650ccnd.com/floatbowl.htm
 
#10 ·
Oh, maybe I wrote that wrong? After replacing the float valve/assembly, I tried starting it on fully stock jets etc. No reaction.

It runs pretty swell now, once you get it running (like I did with the cloth). I had it running today, took it down some back roads, and with the cloth covering half the intake, it was pulling hard and strong.
 
#11 ·
Careful the cloth doesn't get sucked through the carb and into the inlet, can do some damage. Float levels are critical.....it's worth finding the procedure and setting yours. The fact that it can run when leaning over.....sounds as if level may be an issue! How about your air/fuel mixture?
 
#13 ·
That's the right procedure, what you need from a manual or the internet is the exact measurement for your model's float height. Although a bike will run with the height wrong it will only run properly when the float height is spot on.

You really need to know at what height the fuel in the tube should come up to when measured against the side of the float bowl.

On some carbs you can measure the float height by taking off the float bowl, turning the carb upside down and measuring from the flange to the top of the float but I don't think you can do this with the Yamaha.
 
#14 ·
Alright, I measured the fuel in the bowls with the help of an "assistant" (my father... oh man, is that man ever fun to work with..).

I made the mark (using the bottom of the curve on the fuel level in the tube) - 4.5 to 5mm below the fuel line mark on the bowl cover.

Technically it is supposed to be 7.5-8.5mm

But that makes no sense, my bike is too lean on start up, so it would need the extra fuel...

I am starting to suspect my CHOKE. The actual choke assembly on the carb. The cable may be moving, and the little arm moves, but the internal mechanisms may not be working as they should be.
 
#15 ·
You should check your chokes for sure but I would correct that float height too. I know you say your problem is running too lean but running too rich can also give you starting issues.

Maybe by leaning the bike to the right you are allowing the float height to drop and be nearer what you need. Just a thought.
 
#16 ·
Re: leaning the bike - that was my dad's thought. he said that it was probably a sign of float level/gasoline in the bowls.

So Today I am going to check out the choke assembly, and then probably tweak those floats a little bit if that doesn't do it.

One thing at a time, right guys?
 
#18 ·
Sigh, well good news is it runs once it is (with great stubbornness and difficulty) started up. With a lot of voodoo magic and weird angles, I can get it putt putting, and then warmed up. Once it IS warmed up, it will run no problem with the factory airbox on, etc

Bad news is that I still can't get it to start up cold/easily. I took out the carb Friday, and have worked on it over the weekend (cleaning accelerator pump, choke/enrichment passageways). Also, using a multimeter, noticed the TPS was a little out of whack (Should read 650-750Ohms resistance, but was at 851, so I brought it down to 709-722ohms)...

but then, like an HUGE IDIOT, I didn't just enjoy riding it yesterday, the last possible day to ride in our wonderful city/area (sunny, over 52F, no wind during the day), but rather toyed with that stupid carb.

Knowing my luck, I accomplished nothing, it still won't start, and now it is raining today (another 50F+ day), and tomorrow, and then Tuesday it will be sunny and like 32F. (I am using Fahrenheit for our American friends, since it's predominantly US guys on here :) )

SO the basic update is: I should have ridden it, since it does run, rather than trying to perfect it for the startup issues.

Conclusion: AS OF 10:00Am today, still not running, BUT I AM YET to re-install the carb after cleaning and adjust.

Hoping that the choke work I did, the TPS adjust, and the double checking of pilot/accelerator pump/PMS/etc passageways has done the trick.

Even if I did fix it, I can't ride it anymore. I am LEGIT considering moving in with my uncle down in Florida. I am sick of cold weather. :D
 
#19 ·
Spring is here in Canada (almost).... The bike comes out of storage in the next couple of weeks, and I think either the battle begins again (with the carb), or the smarter move: I will see if any of the mechanics around are free and reasonably priced, and have someone else deal with it this year...

So that's my update for now!
 
#20 ·
I have a 2005 xvs 650 custom w/13,800 mi. bone stock. Installed cobra slip ons now it won't start with the choke pulled. I drilled out the welsh plugs and re-set the pms screws, factory setting is supposed to be 2.5 turns out, the rear carb was at 2.5 and the front was at 1.5 ( the front cylinder had a little bit of backfiring on decel) so I backed the front pms out to 2.5 to match the rear and the backfiring was gone. I disabled the AIS, still hard to start cold but runs great when it warms up, while I had the tank off I noticed the intake boots/manifolds have a crack in them right next to the vacuum ports, I found out this is a common problem due to the heat between the cylinders and the age of the bike. I have some on order, will let ya'll know.
 
#21 ·
if you have a vacuum leak it will run lean all the time - do the propane / WD40 spray test around the intake boots, and make sure your vacuum gauge ports are sealed

if the compression is low (tight valve) you will fiddle with the carbs forever and it will never run right - when was the last time the valves were adjusted?

if your fuel pump is failing the bike will run intermittently and be hard to start - check your fuel pump output flow

Its also possible you are not using the choke right. To start the bike:

turn the key on and if you hear the fuel pump running wait till its stops (its filling the float bowls if you can hear it Bp Bp bpbpbpbpbpb b p b ppp...)

turn the fuel petcock on and pull the choke all the way out

do not touch the throttle, push the starter button

as soon as if fires push the choke in half way (till the engine idles normally) if you leave it all the way out the engine will quit in a few seconds

ride the bike for the first 1/2 mile with the choke half way out, then push it in all the way.

If you dont follow all of these steps, the bike WILL be difficult to start
 
#22 ·
Ok, got the new intake boots on and no difference, the old boots did have cracks in them but they were just surface cracks i.e. no vacuum leaks. So I got my self a beer and lit a cigarette then sat and just looked at the bike going thru everything I had done to it in my mind. I didn't start having any issues until I put on those cobra slip-on's. More research...come to find out the new pipes don't provide any back pressure at all, even though they are baffled they are nothing more than straight thru 'drag pipes'. So with no back pressure the mix is rich, so when you pull the choke to start it, it won't start, it floods. So I don't use the choke, once it does start and warms up ( I keep the throttle cracked a little til it smooths out) it runs fine all day long. More research...I found a fix, DK customs has Thunder Torque Inserts which should give it the back pressure it needs, not only that but it should lean out the mix like the factory exhaust did which will bring up the power at low and mid range. When I get 'em installed I'll let ya'll know.
 
#24 ·
Well, I got those thunder torque inserts in.. after I removed the baffles and got 'em installed they did give the bike more power due to increased internal scavenging and more back pressure but I felt they were too small, 1 5/8" in a 2 7/8" pipe. So I went to my local Ace hardware and got enough bolts and washers to make a 2" set, these gave the bike even more power across the full rpm range. Also gave it a more 'throaty' sound (just flat obnoxious) with a deeper tone. I also did a cold start as KCW had suggested, with the choke pulled all the way out it still didn't start so I pushed it all the way back in and pulled it out to the 2nd click and it started right up and went to a higher idle as before with the stock pipes. So my next thing to do is to synchronize the carbs. I'll let ya'll know.
 
#25 ·
just noticed I posted:

turn the key on and if you hear the fuel pump running wait till its stops (its filling the float bowls if you can hear it Bp Bp bpbpbpbpbpb b p b ppp...)

turn the fuel petcock on and pull the choke all the way out
obviously you have to turn the petcock on before you turn the key on to run the fuel pump

I can no longer edit my original post to get the sequence right
 
#26 ·
I finally found out what was wrong, the pilot jets were clogged up again. I pulled them out again and no daylight thru them, so I sprayed 'em out re-installed them and she fired right up with the choke pulled out all the way. I let it run for a few seconds (at high idle btw) then pushed the choke in to the halfway point and let her run for a few more seconds (about 30 sec) then pushed the choke in all the way. She idles great and runs even better. With all of this ethanol gasoline it'd be best to run some kind of fuel system cleaner in the tank and /or a fuel stabilizer every once in a while or better yet spend a few extra cents and buy non-ethanol fuel especially if your bike is gonna sit for awhile like in winter.
 
#27 ·
nice work on getting it running

if you ride your bike all the time the e10 fuel is not a problem

the issues come up if you ride the bike twice a month and top off the tank.

If you fill the bike in May and put two gallons in it in June, half the gas in the tank is a month old

if you put 2 gallons in it in july, 1 gallon of gas is still two months old

if you go away in august and then take it out again in september, a gallon of gas in your tank has turned into jello...

People who only ride intermittently, and never know when they will ride again, would do well to keep some Seafoam in the tank all the time

thats what I do with the 2 gallon can of gas for my lawn mower and snow blower - its always 1 ounce of seafoam per gallon of gas, because it can sit half empty in the garage for months.
 
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