Date: 19-01-20  Time: 10:03 AM

Author Topic: Carb problems or is it something more?? Fazer 600  (Read 155 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.

red98

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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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