Date: 29-03-20  Time: 18:42 PM

Author Topic: Carb problems or is it something more?? Fazer 600  (Read 684 times)

Dman2019

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Carb problems or is it something more?? Fazer 600
« on: 15 January 2020, 12:50:30 PM »
Hope you guys can give me some ideas how to fix my bike Fazer 600, mark 1, 2000 reg


Last year I cleaned my bike with the engine running (due to previous issues with electrics on other bikes) and the fuel was lower that I thought.  Two days later I went to take the bike to get a rear tyre and the bike struggled to start and barley ride able.  Managed to get back from the tyre shop and clean the carbs up enough to get it working enough to go on my trip to Germany, Ok at motorway speeds but struggled on the lower speeds.


When I got back I gave the carbs to my mate who took them apart.  Said the Sliders/needles were a bit loose and could do with new ones.  Official replacements from Yamaha are worth half the cost of the bike and unable to find any kits that contain the jets etc but found a decent set of replacement carbs on ebay.  My mate has taken bits from both set of carbs and make the best we could into one set this has been sonic cleaned before reassembly.


Fitted the carbs but the pilots were not set to factory setting, balanced the carbs and the bike sounded back to normal.  While test driving it showed there was a problem.  Around 4.5 to 5000 rpm the bike struggles with acceleration and seems to stutter.  When you eventually get over the 5000rpm marker the bike takes off again.  This only happens when the bike warms up and you slowly accelerate.


If the bike is cold or you accelerate hard from a standing still there is no issue.  Talked to a few people and they advised just to ride the bike for around 500miles for the carb bits to bed in.  This made sense to me but I know the pilots were out.  Compared to what it was when I first had the problem is was certainly worth putting up with for the time being.


Finally had 5 mins to myself last weekend and the pilots had been playing on my mind, took the carbs off as I have no adjuster tool and reset the pilots to 2 turns out.  Put an inline fuel filter on as well as a back up to the original fuel filer and I can see if there is any issues with the fuel.  Balanced the carbs, all sounded good rev'd through the ranges etc.


Took it out last night.  Again when cold its like it was like before, accelerates through the previous problem of the stutter, fast and slow.... then the bike warms up and the issue is still there, plus a new one. 
When stopped at traffic the revs have started sticking at 2000 rpm,  I play with the rev adjuster on the carbs and it settles down again but this kept happening a few times.


Lastly when on tick over the rev counter pusles and bobs up and down a little.  Idle rev's sett to the manual.  This never happened before


Any ideas what to do next?


As the issue seems to be when the engine warms up is it now something with the engine as the carbs seem fine when its cold and when being rev'd in the garage.


A further note, the book says to set the carbs between 230 to 250mm but when I have balanced them and my mate has balanced them they only go to 125mm.  I can't see how to get them any where close the service manual's recommendation.


Penny for your thoughts, Ive looked at several forum notes and not sure what to do next.


Cheers

Darren
« Last Edit: 15 January 2020, 12:51:30 PM by Dman2019 »

bazza

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Re: Carb problems or is it something more?? Fazer 600
« Reply #1 on: 15 January 2020, 02:55:34 PM »
sounds to me like u still have some small issues to iron out with the carbs but your main problem is quite likely to be ht caps, if u still have the originals then get some ngk ones and snip 5-10mm off the leads. another thing to check is the fuel lines, make sure the 2 breather hoses are not trapped under tank

Dman2019

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Re: Carb problems or is it something more?? Fazer 600
« Reply #2 on: 15 January 2020, 04:19:48 PM »
Cheers, I have been thinking of getting a sonic cleaner to redo the carbs myself so I know they are done. As far as i am aware the breather pipes are ok, will look into the other ht caps as well.

darrsi

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Re: Carb problems or is it something more?? Fazer 600
« Reply #3 on: 16 January 2020, 07:03:35 AM »
You never mentioned the TPS at all in all of that (Throttle Position Sensor).
A bad TPS can cause difficulty starting, poor/rough running at low speeds and generally makes the bike feel like shit.


Located on the right side of the carbs, with the covered wire that plugs into it. It should be checked before and after a carb balance.




The TPS outer case unplugs, it's a bit fiddly, i normally gently use a flat key to unhook it.
With key in ignition switch it on (don't start engine).
Unplug the TPS
The rev counter needle should go to 3000rpm.
Then plug it back in and the needle, if positioned correctly, should land on the 5000rpm mark.
If it goes to 0rpm or 10,000rpm it needs adjusting back to 5000rpm.
If it goes back to 3000rpm it's totally knackered.
To adjust it, the 2 screws need slackening with a security torx allen key, then rotate the TPS unit until it lands on the 5000rpm spot.


Be aware, these units can slowly break down rather than just stop working so can misbehave for a while until you realize it needs replacing.



There are more detailed explanations on here so have a good look about as i'm about to head off to work now.


Note: DO NOT BUY A USED ONE if it is faulty. You have been warned!

https://www.ebay.co.uk/itm/YAMAHA-FZS-600-FAZER-1998-2003-THROTTLE-POSITION-SENSOR-TPS-NEW-MIKUNI-PART/174012130639?epid=17017134017&hash=item2883ee654f:g:jBcAAOSwRytb6JaY
« Last Edit: 16 January 2020, 07:05:38 AM by darrsi »
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Jamieg285

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Re: Carb problems or is it something more?? Fazer 600
« Reply #4 on: 16 January 2020, 12:27:36 PM »
Are the carb rubbers in good condition? 

His Dudeness

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Re: Carb problems or is it something more?? Fazer 600
« Reply #5 on: 16 January 2020, 06:53:01 PM »
If the revs are staying high since you took out the carbs I'd be thinking the carbs might not be seated fully and there might be a vacuum leak. You could spray some wd40 around the intake area and listen for a change in revs. I'd also check that the throttle cable is routed correctly, that it's not adjusted too tight and that it snaps back properly when you release the grip. Also check that the choke plungers are all returning properly.

I'd agree with bazza the ht caps are a possible problem. They're a common failure and can cause a misfire. You could try spraying some water around the caps while the bike is running and listen if the engine stumbles. You can also run the bike in the dark and look for arcing. Another trick is put water on the exhaust headers and see if one header dries slower than the rest, that can show a cylinder that's not running properly. The ngks caps are very cheap so worth replacing anyway.

If the bike has been running badly for a good while I'd take out the spark plugs and inspect them, clean them off and see if that helps. If they're very bad I'd replace them. I haven't had TPS problems so I'm not sure what symptoms from that are but I know darrsi has had trouble with his so it's worth checking if he says so. Another possibility, Red98 had serious problems trying to solve a stutter, he rebuilt half the bike trying to find fix it and it turned out to be a bad reg/rec so that could be worth checking.
I'd start by ruling out those problems one at a time because they're the easiest. If you're confident all those things are good then look at the carbs. As a quick test on the carbs you could try leaving the choke on a bit and ride the bike. If the symptoms improve then it would point to the problem being a lack of fuel from the carbs.

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Re: Carb problems or is it something more?? Fazer 600
« Reply #6 on: 16 January 2020, 07:33:55 PM »
If the revs are staying high since you took out the carbs I'd be thinking the carbs might not be seated fully and there might be a vacuum leak. You could spray some wd40 around the intake area and listen for a change in revs. I'd also check that the throttle cable is routed correctly, that it's not adjusted too tight and that it snaps back properly when you release the grip. Also check that the choke plungers are all returning properly.

I'd agree with bazza the ht caps are a possible problem. They're a common failure and can cause a misfire. You could try spraying some water around the caps while the bike is running and listen if the engine stumbles. You can also run the bike in the dark and look for arcing. Another trick is put water on the exhaust headers and see if one header dries slower than the rest, that can show a cylinder that's not running properly. The ngks caps are very cheap so worth replacing anyway.

If the bike has been running badly for a good while I'd take out the spark plugs and inspect them, clean them off and see if that helps. If they're very bad I'd replace them. I haven't had TPS problems so I'm not sure what symptoms from that are but I know darrsi has had trouble with his so it's worth checking if he says so. Another possibility, Red98 had serious problems trying to solve a stutter, he rebuilt half the bike trying to find fix it and it turned out to be a bad reg/rec so that could be worth checking.
I'd start by ruling out those problems one at a time because they're the easiest. If you're confident all those things are good then look at the carbs. As a quick test on the carbs you could try leaving the choke on a bit and ride the bike. If the symptoms improve then it would point to the problem being a lack of fuel from the carbs.










 :agree        well said DUDE, some great advice there    :thumbup
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His Dudeness

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Re: Carb problems or is it something more?? Fazer 600
« Reply #7 on: 16 January 2020, 07:54:24 PM »
If the revs are staying high since you took out the carbs I'd be thinking the carbs might not be seated fully and there might be a vacuum leak. You could spray some wd40 around the intake area and listen for a change in revs. I'd also check that the throttle cable is routed correctly, that it's not adjusted too tight and that it snaps back properly when you release the grip. Also check that the choke plungers are all returning properly.

I'd agree with bazza the ht caps are a possible problem. They're a common failure and can cause a misfire. You could try spraying some water around the caps while the bike is running and listen if the engine stumbles. You can also run the bike in the dark and look for arcing. Another trick is put water on the exhaust headers and see if one header dries slower than the rest, that can show a cylinder that's not running properly. The ngks caps are very cheap so worth replacing anyway.

If the bike has been running badly for a good while I'd take out the spark plugs and inspect them, clean them off and see if that helps. If they're very bad I'd replace them. I haven't had TPS problems so I'm not sure what symptoms from that are but I know darrsi has had trouble with his so it's worth checking if he says so. Another possibility, Red98 had serious problems trying to solve a stutter, he rebuilt half the bike trying to find fix it and it turned out to be a bad reg/rec so that could be worth checking.
I'd start by ruling out those problems one at a time because they're the easiest. If you're confident all those things are good then look at the carbs. As a quick test on the carbs you could try leaving the choke on a bit and ride the bike. If the symptoms improve then it would point to the problem being a lack of fuel from the carbs.










 :agree        well said DUDE, some great advice there    :thumbup
I put my guessing hat on and that's what I pulled out :lol Could be totally wrong but that adds to the excitement of diy mechanics (bodging)  :lol

darrsi

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Re: Carb problems or is it something more?? Fazer 600
« Reply #8 on: 16 January 2020, 08:49:47 PM »
Just to add to my usual TPS input, if you balance the carbs with a faulty/on the way out TPS then they are not actually balanced at all, so the bike will run rough as hell.
Been there, done that.... :'(
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Re: Carb problems or is it something more?? Fazer 600
« Reply #9 on: 19 January 2020, 04:25:56 PM »
If the bike is running well when cold and at high RPM it wont be leads, plugs, coils, needles or vacuum loss.  The carbs on these bikes have an enricher circuit, what Yam call the choke.  But it's not really a choke in the normal sense in that when operated in doesn't physically increase the idle speed by closing the throttle butterfly and acting on the throttle linkage.  All it does in close off the air bleed on the pilot circuit slightly enriching the fuel mixture i.e. a choke effect.


This is controlled by small plungers which sit at the front of the carb, below the crab top just as it joins the induction rubber, as you operate the choke lever, the plungers are pulled out.  These stick and you only need one not to return fully and you will get exactly the symptoms you're describing.             
« Last Edit: 21 January 2020, 06:15:37 PM by Gnasher »
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Dman2019

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Re: Carb problems or is it something more?? Fazer 600
« Reply #10 on: 21 January 2020, 12:25:12 PM »
Cheers for all the advice.


I've previously checked the TPS and it seems ok, well within the ranges, may need a little adjustment to make it exact.  Think its just over the 5000 rpm mark.


Think I've made some head way.


A mate said to try a compression test on the cylinders.  All cylinders are coming in very low, about 2/3rds down on compression around 4kg/cm2 instead of 12 to 15kg/cm2


To me this is corresponding to the carbs when i tried balanced them and they were also coming in at a lower range to the books.


If this is the valves/piston rings has anyone else had these done recently?  I will check out all the other suggestions as well first, but looking at how much a garage will charge to fix this?


Would like to do it myself to save the labor charges but the girlfriend won't be happy with me being in the garage for a week or two.


Wondering if its worth fixing or moving on to something else.  Cheers

His Dudeness

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Re: Carb problems or is it something more?? Fazer 600
« Reply #11 on: 21 January 2020, 05:22:08 PM »
Are you sure you did the compression check correctly? Did you warm the engine before you did the test? Did you fully open the throttle? Are you sure the air filter is in good condition? Were you cranking the engine with a strong battery? Did you repeat the test with some oil in the cylinders? And what were the results after you added the oil?

I have a bike with low compression from worn rings/cylinders. The symptoms it's showing are it's hard to start when cold, it's down on power and top speed and it has a lot of blow-by into the crankcase. It's hard to start when cold however if you put a little oil in the cylinders it start instantly because the oil is sealing the cylinders and bringing the compression up. After it starts it runs well, it has no hesitation or spluttering anywhere. I think in your case it seems more likely that you had a spark issue after cleaning the engine, then later down the road you had a carb issue and you did some carb work and either it didn't fix the problem or it made the problem worse.

Just so we're all clear what exactly are your current symptoms?

Dman2019

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Re: Carb problems or is it something more?? Fazer 600
« Reply #12 on: 22 January 2020, 06:37:05 AM »



Did you warm the engine before you did the test?  Yes
Did you fully open the throttle? Yes
Are you sure the air filter is in good condition? [/size]Yes
Were you cranking the engine with a strong battery? [/size]Yes
Did you repeat the test with some oil in the cylinders? [/size]Yes but my oil can is rubbish so not sure how much oil when in, similar results
And what were the results after you added the oil? Not sure due to the above


Just so we're all clear what exactly are your current symptoms?

At the moment when the bike warms up I get a delay in acceleration/juddering when gently accelerating.  This happens around 4000 to 5000 rpm, maybe as low as 3500rpm, this happens in different gears, ie when you down shift etc

Accelerating hard is fine, it goes through 3500 to 5000rpm fine.

In idle the rev counter is surging a bit and not staying in one place.

New issue when warm and you stop the rev's get stuck and I need to fiddle with the adjuster to bring them back down.  This didn't happen until I readjusted the pilots back to factory setting to 2 turns out.

Carbs have been balanced and come in around 150mm but I think the book says it should be 250mm.  The bike seems fine to ride, I just have to be mindful of the rev's issue, I know its old but should things be as out as that?

Will check out all the other suggestions to try and eliminate the electrics etc

Cheers


darrsi

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Re: Carb problems or is it something more?? Fazer 600
« Reply #13 on: 22 January 2020, 06:50:57 AM »
Did you warm the engine before you did the test?  Yes
Did you fully open the throttle? Yes
Are you sure the air filter is in good condition? Yes
Were you cranking the engine with a strong battery? Yes
Did you repeat the test with some oil in the cylinders? Yes but my oil can is rubbish so not sure how much oil when in, similar results
And what were the results after you added the oil? Not sure due to the above
Just so we're all clear what exactly are your current symptoms? At the moment when the bike warms up I get a delay in acceleration/juddering when gently accelerating.  This happens around 4000 to 5000 rpm, maybe as low as 3500rpm, this happens in different gears, ie when you down shift etc Accelerating hard is fine, it goes through 3500 to 5000rpm fine. In idle the rev counter is surging a bit and not staying in one place.
New issue when warm and you stop the rev's get stuck and I need to fiddle with the adjuster to bring them back down.  This didn't happen until I readjusted the pilots back to factory setting to 2 turns out. Carbs have been balanced and come in around 150mm but I think the book says it should be 250mm. 
The bike seems fine to ride, I just have to be mindful of the rev's issue, I know its old but should things be as out as that?
Will check out all the other suggestions to try and eliminate the electrics etc
Cheers
« Last Edit: 22 January 2020, 06:54:57 AM by darrsi »
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darrsi

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Re: Carb problems or is it something more?? Fazer 600
« Reply #14 on: 22 January 2020, 06:56:42 AM »
Cheers for all the advice.


I've previously checked the TPS and it seems ok, well within the ranges, may need a little adjustment to make it exact.  Think its just over the 5000 rpm mark.


Think I've made some head way.


A mate said to try a compression test on the cylinders.  All cylinders are coming in very low, about 2/3rds down on compression around 4kg/cm2 instead of 12 to 15kg/cm2


To me this is corresponding to the carbs when i tried balanced them and they were also coming in at a lower range to the books.


If this is the valves/piston rings has anyone else had these done recently?  I will check out all the other suggestions as well first, but looking at how much a garage will charge to fix this?


Would like to do it myself to save the labor charges but the girlfriend won't be happy with me being in the garage for a week or two.


Wondering if its worth fixing or moving on to something else.  Cheers


Previously checked the TPS?
When?
Because you're describing everything that happens when they start to fail.
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Dman2019

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Re: Carb problems or is it something more?? Fazer 600
« Reply #15 on: 22 January 2020, 12:06:42 PM »
Hi, Yes checked the TPS the other day, I have the old one of the other carbs, I can try that one

Dman2019

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Re: Carb problems or is it something more?? Fazer 600
« Reply #16 on: 22 January 2020, 12:16:04 PM »
Are the carb rubbers in good condition?



Yes they seem all ok, I've double checked all the screw clips holding all the rubbers to the carbs on both sides, all tight

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Re: Carb problems or is it something more?? Fazer 600
« Reply #17 on: 22 January 2020, 05:24:55 PM »
If the engine is only pulling 150Hg there's something very wrong with the pilot circuit probably the screw setting.  Unless you can get the intake vacuum between 230 - 250mmHg you're never going to set the carbs up correctly and the bike will run like a dog.


I suggest you recheck each carb and what you've or I think you said mate put in and how.     
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His Dudeness

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Re: Carb problems or is it something more?? Fazer 600
« Reply #18 on: 22 January 2020, 06:53:43 PM »
If the engine is only pulling 150Hg there's something very wrong with the pilot circuit probably the screw setting.  Unless you can get the intake vacuum between 230 - 250mmHg you're never going to set the carbs up correctly and the bike will run like a dog.


I suggest you recheck each carb and what you've or I think you said mate put in and how.   
Gnasher I know at idle its the pilot circuit and mixture screws that have the biggest effect at idle but if the butterfly valves where open more than they should be from an incorrect carb balance could that be another reason for lower mmHg readings?

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Re: Carb problems or is it something more?? Fazer 600
« Reply #19 on: 23 January 2020, 07:14:42 PM »
The butterfly's being open more will increase the Hg reading, these should only be open when the throttle is twisted.  With the throttle fully home the Hg reading is set via the pilot circuit only, each must be between 230- 250mmHg at between 1150 - 1250rpm, if the reading is too high the butterfly isn't in it's rest position.  This could be due to a number of factors, bad assembly, worn/broken part/s or incorrect previous carb balancing.


I my experience most owners and many stealers don't know how to balance crabs, they go straight for the butterfly screws when it's the pilot circuit that's the issue.  As I stated unless they're all pulling min/max of 230- 250mmHg with the butterfly's at rest you're wasting your time.   The other real big mistake onwers/stealers make is moving the TPS, this is set at the factory and it doesn't move (unless it's faulty) in operation it's a datum.  They test it, it's reading over/under and they move it, that's it the datum is moved, the reason it's out (and it only works on the one carb No4) is because the butterfly/linkage has moved/worn, so no longer aligning with the datum.  It's the butterfly/linkage that needs bring back to the datum, by resetting them, i.e. level of Hg, then balance all the others, 4-3 then 1-2 then 1-2 & 3- 4.   Just about every TPS has been moved and in my experience just about every bike I've worked on the carbs are out of balance!               
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His Dudeness

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Re: Carb problems or is it something more?? Fazer 600
« Reply #20 on: 23 January 2020, 08:24:57 PM »
The butterfly's being open more will increase the Hg reading, these should only be open when the throttle is twisted.  With the throttle fully home the Hg reading is set via the pilot circuit only, each must be between 230- 250mmHg at between 1150 - 1250rpm, if the reading is too high the butterfly isn't in it's rest position.  This could be due to a number of factors, bad assembly, worn/broken part/s or incorrect previous carb balancing.


I my experience most owners and many stealers don't know how to balance crabs, they go straight for the butterfly screws when it's the pilot circuit that's the issue.  As I stated unless they're all pulling min/max of 230- 250mmHg with the butterfly's at rest you're wasting your time.   The other real big mistake onwers/stealers make is moving the TPS, this is set at the factory and it doesn't move (unless it's faulty) in operation it's a datum.  They test it, it's reading over/under and they move it, that's it the datum is moved, the reason it's out (and it only works on the one carb No4) is because the butterfly/linkage has moved/worn, so no longer aligning with the datum.  It's the butterfly/linkage that needs bring back to the datum, by resetting them, i.e. level of Hg, then balance all the others, 4-3 then 1-2 then 1-2 & 3- 4.   Just about every TPS has been moved and in my experience just about every bike I've worked on the carbs are out of balance!               
Great info thanks! I thought the vacuum in the intake manifolds would be strongest when the butterfly valves were closed that's why I said his butterfly valves might have been slightly open. Guess I had it backwards :lol One more question when you're doing carbs do you set the mixture screws first using the reading on the vacuum gauge, then balance the carbs using the balance screws?

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Re: Carb problems or is it something more?? Fazer 600
« Reply #21 on: 23 January 2020, 08:45:40 PM »
The butterfly's being open more will increase the Hg reading, these should only be open when the throttle is twisted.  With the throttle fully home the Hg reading is set via the pilot circuit only, each must be between 230- 250mmHg at between 1150 - 1250rpm, if the reading is too high the butterfly isn't in it's rest position.  This could be due to a number of factors, bad assembly, worn/broken part/s or incorrect previous carb balancing.


I my experience most owners and many stealers don't know how to balance crabs, they go straight for the butterfly screws when it's the pilot circuit that's the issue.  As I stated unless they're all pulling min/max of 230- 250mmHg with the butterfly's at rest you're wasting your time.   The other real big mistake onwers/stealers make is moving the TPS, this is set at the factory and it doesn't move (unless it's faulty) in operation it's a datum.  They test it, it's reading over/under and they move it, that's it the datum is moved, the reason it's out (and it only works on the one carb No4) is because the butterfly/linkage has moved/worn, so no longer aligning with the datum.  It's the butterfly/linkage that needs bring back to the datum, by resetting them, i.e. level of Hg, then balance all the others, 4-3 then 1-2 then 1-2 & 3- 4.   Just about every TPS has been moved and in my experience just about every bike I've worked on the carbs are out of balance!               


Something that just caught my eye, you say 4-3 first, is there any particular reason for that order?
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Re: Carb problems or is it something more?? Fazer 600
« Reply #22 on: 24 January 2020, 07:22:42 AM »
4 is where the TPS is, as I said it's the datum just where I start.  That said as mentioned the datum has nearly always been moved, in which case I get the carbs pulling 240mmHg and then adjust to each other, which is the balancing act, once they're all pulling 230 -250mmHg and are balanced I check the TPS.  If it's out I move until it's back in spec, it's now back as the datum, going forward this is where you start i.e. if this carb is pulling 230 -250mmHg at the start move 3 to match it and 1-2 to match 3-4.

Better still but beyond most owners and stealers is a gas analyzer attached to the downpipe.       
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YamFazFan

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Re: Carb problems or is it something more?? Fazer 600
« Reply #23 on: 25 January 2020, 10:26:31 PM »
On average, how often would you expect the carbs to require rebalancing?
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Gnasher

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Re: Carb problems or is it something more?? Fazer 600
« Reply #24 on: 26 January 2020, 11:55:57 AM »
They shouldn't need totally rebuilding, short of a few 100k.  They only wear short of that due to lack of maintenance that being, change of air/fuel filters, keeping the linkages clean and lubed and too much fiddling by people who have no idea of what they're doing. 


The amount of carb issues and damaged I've seen due to owners/stealers would stagger you :eek  You can get the odd diaphragm degrading but it unusual in my experience. I see bikes I've been looking after for 30 plus years, some of these are 80k plus bikes still running perfectly on the original crab internals.
« Last Edit: 26 January 2020, 11:58:53 AM by Gnasher »
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