Topic: CB550 Cafe done but so am I

[dirtroad]

Hi there everyone,
Ever since I joined this forum I've been pretty much leaching, learning and trying. Thanks a lot for that, I've learned a stack. In essence everything I needed to go from a lump of metal destined for the recyclers to something I'm proud of.
After the initial tweaking and timing she started up and the thrill of taking her down the road is, well was, indescribable. Since I've gone through two carb kits, different float valves etc but just can't stop the issues with flooding, overflowing, "not flowing", some flowing etc etc. Thing is the 550 model I have does not have the removable carb float valve seats like other models have. It seems even with new float needles she still leaks.
Anyway guys long story short, what alternatives have you tried in terms of different carbs etc. CR are cool but way expensive. Are there more "robust" carbs from other model that will fir the 550 perhaps.
Thanks to all again for your valuable wisdom. Even if she never runs again I'll put her above the fireplace mantle and look at it, it is art after all.

[strynboen]

the 78 k3 have differens float height..from others 550..... but fine rust in tank can make it overflote..even they are korrekt adjusted..mine got first fine...when i  got a rust free tank...it took me month to get it to run...but now it are daily runner ..work perfekt every day..a joy to run

[Stev-o]

Wow - is that the same bike? Very nice.

When I had my 550F,i also had carb issues. Ended up buying a set of K carbs and ran better.

[TwoTired]

You have the PD carbs.  While the float valve seats aren't normally replaceable, the seats can be "lapped" to match the needle point profile.

It involve taking valve lapping compound and putting some on the valve seat, then twist or "worry" the valve against the seat so they create a seal between them.

Also, note that the floats at set to 14.5 or 12.5mm rather than the 22mm of the earlier style.  And be certain that the floats aren't upside down.  Check out the latter chapters of the Honda shop manual for better detail on the PD carbs.

Lastly, DO check the carb bowl stand pipes for cracks.  You may find that the float valves aren't the source of the leak.

[dirtroad]

Thanks for the advice. The tank I made from scratch and it is a composite fibre and epoxy (fuel resistant) so rust can be eliminated. The only thing I haven't checked is the possible cracks in the stand pipes. I've done the rest with intermittent results which I know only proves that something is intermittently wrong, right?
I'm definitely looking at getting a more reliable setup. This forum is swamped with the same issues I'm having and I can only be presumptuous to think that more folks would appreciate a no-nonsense get up and go setup.
I'm as old school as the next guy but just thinking out the box a bit, would it be feasible to use 4 separate carbs? It shouldn't be too difficult to come up with a similar mechanical setup to control simultaneous throttle operation, fuel supply would be simple really and the cost compare to a CR setup would be way lower.
Does the carb have to match the engine exactly or does the engine "use" whatever fuel volume is available during intake? I have quite a bit of experience with Briggs&Stratton 4 stroke small engines and it seems you can fit pretty much any carb as long as the mixture is ok, would this apply to a motorcycle as well or are there some "mathematics" related to stroke, cc etc

[65Ch3v3LL3]

Convert it to fuel injection! I'm converting my CB 650 so I don't have to deal with carbs either.

[strynboen]

fuel indjektion ...new problems are  on vay...the 550 dont make power inof for elektric pump..and elektronic kontrols..
this old caburetors work fine..when they first are there..

[TwoTired]

Thanks for the advice. The tank I made from scratch and it is a composite fibre and epoxy (fuel resistant) so rust can be eliminated. The only thing I haven't checked is the possible cracks in the stand pipes. I've done the rest with intermittent results which I know only proves that something is intermittently wrong, right?
I'm definitely looking at getting a more reliable setup. This forum is swamped with the same issues I'm having and I can only be presumptuous to think that more folks would appreciate a no-nonsense get up and go setup.

I forgot to add before, that you seem to have done a very nice resurrection on your bike.  It isn't my style.  But, still obviously better than when you got it.

The stock carbs ARE extremely reliable when in proper working order.  Perhaps if you approach the man hours that where put into the stock carb development, you'll have something that works as well.

The forum seems to collect "problem children", and/or people that lack knowledge and experience working on these bikes.  We can usually help those who haven't given up before a solution was found.

Cheers,

[Syscrush]

I'm as old school as the next guy but just thinking out the box a bit, would it be feasible to use 4 separate carbs? It shouldn't be too difficult to come up with a similar mechanical setup to control simultaneous throttle operation, fuel supply would be simple really and the cost compare to a CR setup would be way lower.

What are you talking about?  The stock setup is 4 separate carbs.

Does the carb have to match the engine exactly or does the engine "use" whatever fuel volume is available during intake?

Carb too small = loss of peak hp.
Carb too big = bad throttle response, excessive fuel consumption, lack of power, difficult tuning.

The carbs that will work best with these bikes, and the best ways to set them up and troubleshoot are well understood by experts on this forum and at good bike shops all over the place.  Bring your thinking back in the box for a bit, take some deep breaths, and I'm sure you'll be able to get the help you need to get that bike running as good as it looks.

[Syscrush]

Convert it to fuel injection! I'm converting my CB 650 so I don't have to deal with carbs either.

This is a beautiful example of false economy.

A vehicle that's got EFI stock is easier to tune in many ways than one that's got carbs.  However, the idea that fitting an EFI setup to an old vehicle that doesn't have the plumbing or room for a fuel pump to run correctly, or an electrical system that can properly drive an EFI fuel pump and injectors is off-base.

There are a lot of good reasons to switch to EFI, but simplicity or ease of tuning are not on the list.

[Tews19]

Hey ya'll, I continue to learn from all of you on this site and TT is the man when it comes to 550 knowledge.

 Anyone notice how the pic looks fake? EHHH, prolly my own bias from all those South African emails i get saying I won their 15 million dollar lottery that I never registered and onoy takes me a few hundred dollars that i shoudl wire promptly or my lottery winnings go to the next person.

Nice build.

[dirtroad]

Jeez bit of animosity against us folks here in deep Afrika!! Tews19 I take offense to your notion of a fake pic..wtf. and also ignorance towards those lottery spam which originates in Nigeria my friend which is in Africa yes, not South Africa! I think your comments are uncalled for, at least in this section of the forum list. I'd love to debate with you in the prober forum category but here's one for you, South Africa has a better credit rating with the WB than the USA, go figure.

It seems my post was clearly misunderstood, I didn't mean to challenge any experts, wisdom or such, just asking if anyone has ever thought about  " what if we did this or try that, new ways of doing things, be inventive man"... I understand that the first knee jerk is to defend the beloved SOHC technology and that some might have very high emotional attachment to that. Respect for that!

Perhaps I chose the wrong place to ask such an out of the box question, sorry guys.

[Tews19]

Oh man it was all a joke.  If you would like I can remove it. If you notice I did say nice build at the end, guess dry sense of humor doesn't resinate well typing. Sorry though

[Syscrush]

It seems my post was clearly misunderstood, I didn't mean to challenge any experts, wisdom or such, just asking if anyone has ever thought about  " what if we did this or try that, new ways of doing things, be inventive man"... I understand that the first knee jerk is to defend the beloved SOHC technology and that some might have very high emotional attachment to that. Respect for that!

OK, I hope that my post didn't sound like I have any emotional attachment to the SOHC technology, because I don't (although I know that plenty here do).  The fact remains that there's a tremendous body of knowledge around the stock carbs and getting them to work, and as a result that will be the simplest approach.  Also, it seemed to me that some of your questions belied a lack of knowledge/info about carbs, which is why I'm suggesting taking the simplest route.

Perhaps I chose the wrong place to ask such an out of the box question, sorry guys.

I think you asked in exactly the right place.  I also think that you got some info and advice that could be quite helpful.

[65Ch3v3LL3]

Convert it to fuel injection! I'm converting my CB 650 so I don't have to deal with carbs either.

This is a beautiful example of false economy.

A vehicle that's got EFI stock is easier to tune in many ways than one that's got carbs.  However, the idea that fitting an EFI setup to an old vehicle that doesn't have the plumbing or room for a fuel pump to run correctly, or an electrical system that can properly drive an EFI fuel pump and injectors is off-base.

There are a lot of good reasons to switch to EFI, but simplicity or ease of tuning are not on the list.

In my case I have more experience working with EFI than I do with carbs so it works for me. The electrical issues are easy to overcome with modern stators and rotors and actually the fuel pump issue isn't a huge problem either with a in-tank pump placed into a surge tank that is fed from the main tank. I wasn't seriously suggesting it in this case but it can be done and isn't as bad as one might think. Personally I like the fine tuning control of the ignition and fuel that can be had with the EFI setup. I know you can do the same with points and carbs but environmental variables change too often for it to always be optimal. And that's just my .02 

[Syscrush]

In my case I have more experience working with EFI than I do with carbs so it works for me. The electrical issues are easy to overcome with modern stators and rotors and actually the fuel pump issue isn't a huge problem either with a in-tank pump placed into a surge tank that is fed from the main tank. I wasn't seriously suggesting it in this case but it can be done and isn't as bad as one might think. Personally I like the fine tuning control of the ignition and fuel that can be had with the EFI setup. I know you can do the same with points and carbs but environmental variables change too often for it to always be optimal. And that's just my .02 

I agree that EFI is just better in almost every regard, and I love seeing the EFI conversions.  I'm just saying that converting a carb bike to EFI is not an easy path to a properly-fuelled bike.  Have you seen any of the threads on here about it?  Some very good work has been done in this area.

[Flick]

WOW, what a transformation...