Some questions re Keihin carb rack cleanup/repair

I suspect these same carbs were used on some 80's kawasaki's...KeiHin and bore measures 32mm at the carb holder end.

I'm hoping to get this 81 Honda CB650 running right and cleaned up in time for xmas gift to my younger brother.

The small plastic 'T's that distribute the fuel between the bowls are broken, and before I try to fabricate something, I'm wondering if anyone has discovered an inexpensive and readily obtainable replacement for these. They are something like $23/each from Honda and I need two of 'em.

I've worked on the MIC VM and BS series but these KeiHins are fresh meat and wonder if there are any tricks or gotchas I need to be aware of before digging into them.

I did find some 3/8 wall reinforced fuel line with 1.5" ID that looks like the makings of a set of fine new carb holders. Under $6/foot at the auto parts store.

The packaging suggests this red stuff is OK for fuel as did my buddy at the auto parts store. Any related experience to the contrary is most welcome.

Summary:
What to do about broken 'T's?
Red RTV in fuel?
Early 80's vintage KeiHin trix?

You might look up WiredGeorge. He worked on my Keihins.

Not sure which Keihin carbs are on the Honda you refer to. In any case, you would do well to remove the fuel pipes before making decisions on how to repair them. Many "plastic" pipes are actually aluminum clad in the plastic and the big scary cracks don't actually effect performance of the fuel pipe. I am pretty sure the CV Keihin series as well as the CVK have aluminum pipes clad in plastic stuff but I am not sure what carbs you actually have. Look at the pipes or post a pic... You can tell by looking at the ends of the pipe. I can't recall ever seeing an all plastic fuel pipe or tee.

There is a number stamped on the outside of the right hand carb. If it is a 1981 it should be VB44A (CV carbs), if it is an earlier model it will be PD50 A or B (piston carbs).
You might be able to repair the T, but it is common that they crack up over the years. I would replace them.

And no, the Keihin carbs used on the CB650 was never used on any Kawasaki model. But CV carbs simulare to the VB44 was used on the early KZ400 models.

And one more tip: When you mount the carbs back on the bike, be very careful with the plastic part for the choke mechanism located between the carbs. It breakes easily, and it is very expensive, if you can find a replacement.

Post edited by: ibsen22000, at: 2005/11/24 17:29

Thanks.

I will watch for the plastic bit on the choke, if it is still there...Don't recall seeing one when they came off.

Yes, T's are plastic. They are CV carbs but they are up at the workshop and I'm 42 miles away so no numer at this time. The slides have a flat area on them and the vacuum chambers are cylindrical. IIRC, two screws hold the cap on the vacuum chamber.

I guess I could turn some brass tubing to the OD and braze up some T's. Was hoping to find an auto part for a couple of bucks that would work.

-Duck

Yes, I know how the carbs look.
It is possible that I'm mixing the two types of carbs regarding the plastic piece for the choke mechanism.
On the piston carbs it is located between carb #2 and 3, on the rear. It is the black piece on the picture.

Post edited by: ibsen22000, at: 2005/11/24 19:05

This forum software sucks:evil:

I don't have a close up of your carbs, but this is how they look.

Yep, that's them on the bike.
Nice looking bike too.
Ever notice how tiny the muffler outlets are when sitting next to a cb750? They are about half the diameter!

My main complaint with the forum software is that the followups are not collapsed. Could be that I've not figured it out on the client end, but it's really difficult to go through the forum and look at topics when every followup is there as well.

I'm running the old PHP forum stuff for my daughter to keep up with friends. She's doing a year at an architecture school in Paris. Don't know what prompted the change here but also have no experience running with this many users and this much traffic.

-Duck

Duck wrote:

Yep, that's them on the bike.
Nice looking bike too.
Ever notice how tiny the muffler outlets are when sitting next to a cb750? They are about half the diameter!

-Duck

That bike was up for sale on Ebay a while back.

In many ways the 650 is a 550 bored out to 625cc, but with a different cylinder head with larger valves and a different camshaft. The top end will bolt straight on to the 550 bottom end, but the camchain are different. The 550 had a single row cam chain,while the 650 have a HyVo camchain. And the 650 have got a primary chain tensioner that both the 550 and 750 lacks.
The 650 is probably the best SOHC Honda made.

I feel like an idiot.

I promise, no more questions unless the thing I am working on is in front of me!

The T's are not fuel distribution, they are bowl vents. I got the carbs on the bench yesterday and took a look in prep for a trip to the autoparts store. Went a head and cleaned them up without disassembling the rack and just left the vent ports open.

Experimented with using 1.5" ID fuel line for carb holders. It doesn't grip the necks well enough and works off with vibration. Will try making a ring out of solid copper wire to fit in the groove on the carb and head port necks and give a bit more grip once the hose is clamped.
Also, the fuel line is slightly smaller OD than the OEM holders and the OEM clamps can't be used. If I can find some narrower hose clamps to use in combination with the ring, it might work.

-Duck