carb balancing?

[Dead Eye]

I may as well have

I'm certainly out of commission for a few days, the bike probably longer...

http://foc-u.co.uk/index.php/topic,8908....l#msg92310

[JoeRock]

[quote author=mickvp link=topic=8911.msg92244#msg92244 date=1375541910]
if you wind all 3 screws in/out, the overall vaccuum should move?

For some reason I hadn't considered this... must be my bad day

Punkstig - I was using very little pressure as I know that if you push down it affects the readings and always blipped the throttle between adjustments

Unfortunately the bike and I had a slight accident which resulted in the front end being destroyed on a ride this afternoon so it seems all my fettling was in vein as its off the road until I can fix it up  :'(
[/quote]

It doesn't matter mate what they're on as long as they're all close!

[mickvp]

It doesn't matter mate what they're on as long as they're all close!

The Haynes book of lies says all 4 reading when balanced should be between 230 to 250 mmHg.

[elbrownos]

Seems pointless to specify something that can't be adjusted

[darrsi]

Would it not indicate that something is amiss if you're not within spec?

[Yamazer-92]

I can't remember what numbers the gauges were at when I was doing it, it was 20 something but in the instruction booklet it said that it doesnt matter what number it is at particularly as long as they are all level and within 1-2 cm of mercury. Mine is running nice and smooth now but have I done it wrong by not getting it within 230mm or whatever it is?

[darrsi]

I can't remember what numbers the gauges were at when I was doing it, it was 20 something but in the instruction booklet it said that it doesnt matter what number it is at particularly as long as they are all level and within 1-2 cm of mercury. Mine is running nice and smooth now but have I done it wrong by not getting it within 230mm or whatever it is?

It's in relation to the measurements listed on the Carbtune, not a physical cm of the rod.


It should be within 10mmHg (dunno what that means?) so would actually need to be within two of the smaller lines.


Okay, just learnt that Hg is the chemical symbol for mercury, i never knew that! 

[mickvp]

Hg is the chemical symbol for mercury, it just means the vacuum required to displace 10mm(3) of mercury.

As I said earlier, I was under the impression if you moved all 3 screws an equal amount, you could achieve the overall level of vacuum as laid out in the Haynes manual. I'm not sure how much it matters though, although mines is where it should be.

[darrsi]

Hg is the chemical symbol for mercury, it just means the vacuum required to displace 10mm(3) of mercury.

As I said earlier, I was under the impression if you moved all 3 screws an equal amount, you could achieve the overall level of vacuum as laid out in the Haynes manual. I'm not sure how much it matters though, although mines is where it should be.

Yeah, my photo' on the previous page puts mine in the good books too, although i've adjusted it again since then and it's even better now.


Took the bike out for a spin today after refitting my Moto GP exhaust and it felt and sounded awesome, and was pulling like a train. 

[Dead Eye]

Well mine was running better with them all balanced correctly (even with the low vacuum) up until my little fight with a corner...

[nick crisp]

When I've balanced carbs in the past, I've just been concerned with getting a level reading across all four, and didn't used to worry too much what that reading was. With wear and tear on higher mileage engines, I believe it would become more difficult to ensure that the actual reading would be perfect anyway. The goal is to get the bike running as smoothly as you can and not worry too much about whether or not you are perfectly "on spec". Obviously if you are no where near the recommended settings you may have another problem, but this would probably manifest itself in other noticeable symptoms anyway. I also seem to remember that you usually have one "reference" carb, and I seem to remember that this one doesn't usually respond in quite the same way as the other 3. But it's a while since I've done this myself, and perhaps my memory is a little cloudy.

Actually, come to think of it now, on some bikes the reference carb is not adjustable?

[darrsi]

When I've balanced carbs in the past, I've just been concerned with getting a level reading across all four, and didn't used to worry too much what that reading was. With wear and tear on higher mileage engines, I believe it would become more difficult to ensure that the actual reading would be perfect anyway. The goal is to get the bike running as smoothly as you can and not worry too much about whether or not you are perfectly "on spec". Obviously if you are no where near the recommended settings you may have another problem, but this would probably manifest itself in other noticeable symptoms anyway. I also seem to remember that you usually have one "reference" carb, and I seem to remember that this one doesn't usually respond in quite the same way as the other 3. But it's a while since I've done this myself, and perhaps my memory is a little cloudy.

Actually, come to think of it now, on some bikes the reference carb is not adjustable?

I wonder if that's carb #1 then, 'cos it didn't appear to move much when tweaking it?

[nick crisp]

If there is a reference carb on the FZS, surely it must refer to it in the manual? Again, this is from a rusty memory, but usually I think it's 2 or 3. But my experience is also with older Kawa***i fours (z650s &c) so may not be 100% relevant here.

[darrsi]

I think it just said balance 1 & 2 first, then 3&4, then balance them together to level them all from memory.

[Dead Eye]

There is no reference carb on the Fazer as all 4 are adjustable. A reference carb is usually used when each carb is independently adjustable of the others. On the fazer, there are three adjustment screws, but each affects at least 2 carbs. So as we know; Left balances 1 and 2, Right balances 3 and 4 and Middle balances 1+2 against 3+4

[davec]

Just balanced my carbs,did it because I had some clutch rattle which annoyed me, and it has completely eradicated it.The carbs weren't that far out but that small adjustment has made all the difference.Money well spent.