CBF500 2004 carb heating pipes

[RogerD]

Hi
I have not long bought the bike and for some reason the carb heater pipes have been disconnected and blanked off by the previous owner.
I can’t contact the original owner so does anyone have any suggestions why the pipes might have been disconnected?

At present the pipe from the water pipe and the pipe from the cylinder head have both been blanked off. Am really tempted just to get new pipes and reconnect it, but would prefer to know why the carb has been isolated.
Any help would be appreciated.
Thanks. 
Roger

[Simon Davey]

Being of an age and having heated carb's, as mine is too, it's quite possible/likely that at some point they were blanked off for diagnosis, or because of some misconception. 

I would reconnect them, carb icing can happen in the summer,as well as cooler weather. 

If the bike runs badly because of it, you'll have some investigation to do. 

[RogerD]

Hi Simon

Thanks for the reply. Hadn’t come across carb icing so will look into this.

Many thanks.

Roger

[Hairsy]

Simon's right. The most likely reason for blanking them off is that someone was working on the carbs to resolve a problem. It's a right pain when you have to drain the coolant every time you pull the carbs.

 

If it's running Ok then it would probably be sensible to connect them back up again.

[RogerD]

Hi Hairsy

Thanks for the reply. Time for some new pipes, and see what happens - can always take them off.

It runs “okay”, pulls well enough, but I find it is not as smooth as I would like when held at a constant rev, eg when going slowly through traffic. It doesn’t stall or anything, but it’s as if the revs are fluctuation slightly. I have had the carbs looked at, and supposedly balanced, but something just doesn’t quite seem right.

Bit reluctant to start pulling anything apart as I don’t know what I’m looking for, and equally don’t fancy it going back to the garage for another “blank cheque” experience.

Thanks again.

Roger

[Simon Davey]

17 minutes ago, RogerD said:

 

It runs “okay”, pulls well enough, but I find it is not as smooth as I would like when held at a constant rev, eg when going slowly through traffic. It doesn’t stall or anything, but it’s as if the revs are fluctuation slightly.

 

I had this with my bike (ZZR1200), People thought it was funny when I said my bike bike wouldn't run slowly enough. 

One shop mechanic who spent a considerable amount of time telling me how well trained, and how many decades experience he had, stripped and put the carb's in the ultrasonic cleaner. It was barely any different. It was much faster from 4k to 11k, but he didn't sort it. He told me to just ride it faster. 

 

Took it elsewhere where I got "yeah, we do this all the time, leave it with us". So I did. It cost just under £400, they replaced all 4 idle jets, seals and O-rings. Now it's literally perfect, I love it. 

Probably better that it wasn't running so well when I bought it, as I hadn't ridden for 24 years

[Mississippi Bullfrog]

7 hours ago, RogerD said:

Hi Hairsy

Thanks for the reply. Time for some new pipes, and see what happens - can always take them off.

It runs “okay”, pulls well enough, but I find it is not as smooth as I would like when held at a constant rev, eg when going slowly through traffic. It doesn’t stall or anything, but it’s as if the revs are fluctuation slightly. I have had the carbs looked at, and supposedly balanced, but something just doesn’t quite seem right.

Bit reluctant to start pulling anything apart as I don’t know what I’m looking for, and equally don’t fancy it going back to the garage for another “blank cheque” experience.

Thanks again.

Roger

They can feel a bit hesitant on light throttle in low gear due to being tuned to run lean. So long as it pulls cleanly when you open the throttle a bit more I wouldn't worry about it. 

[bud]

Being a 2004 model the carbs shouldn't be as effected by emissions. But being twenty years old the pilot jets can corrode inside. They are so small that it can make quite a difference to low speed running.

The first up to quarter throttle is mainly controlled by the pilot jet. So @Simon Davey could be on the right track.

What exactly did they do when looking at the carbs?

Edited January 5 by bud

[Mississippi Bullfrog]

2 hours ago, bud said:

Being a 2004 model the carbs shouldn't be as effected by emissions. But being twenty years old the pilot jets can corrode inside. They are so small that it can make quite a difference to low speed running.

The first up to quarter throttle is mainly controlled by the pilot jet. So @Simon Davey could be on the right track.

What exactly did they do when looking at the carbs?

Lean burn designs were around well before 2004. 

[bud]

yes they were. But emissions didn't really start tightening up till 2007 with Euro 3.

[Mississippi Bullfrog]

3 hours ago, bud said:

yes they were. But emissions didn't really start tightening up till 2007 with Euro 3.

We are at cross purposes,  I didn't mention emissions. Just that the stock tune does run lean at light throttle settings. It's a characteristic of the bike. It's predecessor,  the CB500 did the same.

[RideWithStyles]

Euro 3 for bikes was about way prior to 2005. most Cars were at e4 back then, nearing the Euro5.

Last of the Euro 4 bikes 2019.

Both of Which dragged on for a lot of years.

 

how or what they did to get that was up to the manufacturer and the base design from the vehicle -bike or car.

My bike was the last of the carbs of that model Suzuki bandit 650 and apparently still ok (may need a test if it’s questioned but it’s bog std so all good) for the shite hole called khans zero playroom.

 

MB is correct they did and still do play with the design and settings (analogue,digital or material) to achieve the pass, as the test is only at certain speeds and gears still.

 

Anyway back to the OP - If this was a summer bike and/or the heater broke or pipes split they more than likely just deleted the system and blanket it off as for their use case it didn’t matter and just complicated things. Might have been raced/tracked? 

another thought of it not quite right might be is a tiny air leak or if the exhaust isn’t standard post set to the carbs or has the baffle removed? That’s can be enough to throw it off, even if it was an early injection bike let alone a carb one with questionable history?

The OP hasn’t said much of the bike to really nail down a good cause.

Edited January 6 by RideWithStyles