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+--- Thread: Carb problems or is it something more?? Fazer 600 (/showthread.php?tid=81376)
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Re: Carb problems or is it something more?? Fazer 600 - His Dudeness - 23-01-20
(23-01-20, 08:14 PM)Gnasher link Wrote: 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.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?
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!
Re: Carb problems or is it something more?? Fazer 600 - darrsi - 23-01-20
(23-01-20, 08:14 PM)Gnasher link Wrote: 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?
Re: Carb problems or is it something more?? Fazer 600 - Gnasher - 24-01-20
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.
Re: Carb problems or is it something more?? Fazer 600 - YamFazFan - 25-01-20
On average, how often would you expect the carbs to require rebalancing?
Re: Carb problems or is it something more?? Fazer 600 - Gnasher - 26-01-20
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.
Re: Carb problems or is it something more?? Fazer 600 - Disorderlypunk - 27-01-20
i proper balancing is always worth the money - especially after a rebuild - mine were out by a mile once i finally got the carbtune a few years ago
a bench balance can be close but a proper job is always a benefit
Re: Carb problems or is it something more?? Fazer 600 - darrsi - 28-01-20
(27-01-20, 07:30 PM)Disorderlypunk link Wrote: i proper balancing is always worth the money - especially after a rebuild - mine were out by a mile once i finally got the carbtune a few years ago
a bench balance can be close but a proper job is always a benefit
I would hazard a guess that a lot of people don't even know what a carb balance is.
When i first used my CarbTune kit not only did it make a big difference in general running, but it was kind of satisfying the fact i'd done it myself.
Maybe it could be improved even more if done by a shop, but as long as i made sure all other related components were in good shape before giving it a go, like plugs, filters, TPS, etc, then i was more than happy with the results.
Re: Carb problems or is it something more?? Fazer 600 - Dman2019 - 17-05-20
Thanks all for your advice, had 3 test rides now and it all seems to be back to normal.
I readjusted the pilots back to factory settings and retuned the carbs and it seems fine.
I tested the electrics and changed the ht caps, leads and regulators, when i put a multi meter over them there seemed to have different reading, thought its better safer than sorry
Re: Carb problems or is it something more?? Fazer 600 - singhangad - 29-06-20
Sorry to hijack the thread
I have the exact same issue on my bike with 150 000 miles on it. My question is what are you doing about it? Are you still just riding it or have you taken the head off to change the piston rings? I am thinking if its worth the effort or shall I just use it for as long as it goes.
(21-01-20, 06:22 PM)His Dudeness link Wrote: 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?
Re: Carb problems or is it something more?? Fazer 600 - Trebor69 - 15-08-20
(16-01-20, 08:03 AM)darrsi link Wrote: 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.
[size=1em]The TPS outer case unplugs, it's a bit fiddly, i normally gently use a flat key to unhook it.[/size]
[size=1em]With key in ignition switch it on (don't start engine).[/size]
[size=1em]Unplug the TPS [/size]
[size=1em]The rev counter needle should go to 3000rpm.[/size]
[size=1em]Then plug it back in and the needle, if positioned correctly, should land on the 5000rpm mark.[/size]
[size=1em]If it goes to 0rpm or 10,000rpm it needs adjusting back to 5000rpm.[/size]
[size=1em]If it goes back to 3000rpm it's totally knackered.[/size]
[size=1em]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.[/size]
[size=1em]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.
[/size]
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
Thanks for this, mine was reading 10000........may be able to smooth out the idle now
