Are these CR's 29's?

Hi Guys, I bought these CR special's off someone here maybe a month ago and just barely started to get into them. I was told they are 29's. So would they measure 29mm at the throat where they go into the rubber carb holders? I have never had a set before but they measure 33 at the opening. Is this normal for 29's or are they 33's? I just have a crappy harbor freight caliper so I'm not sure. I'm not sure what the deal is with all the green fuel squid, that seems a bit unnecessary but that's another issue. They are nice and clean inside upon my first inspection, haven't checked what size the jets are yet.

Should measure 29mm ID at the throat

Any other distinguishing features or any differences between the sizes?

No offense baldy but that doesn't help at all. They seem like they might taper? I asked is the 29mm where they meet the rubber holders? Your answer didn't clarify anything.

If you measure 33 mm on the rubber boots side you have 33 CR´s not 29 CR´s.
A crappy harbor freight caliper gauge have no 4 mm measurement error.
Pics a welcome with caliper gauge on rubber boots side port.

You need to measure the narrowest part of the carb bore which will be the actual venturi where the slide is.
This is the size of the carb.
These, like most carbs ( unless they are straight bored/modified ) taper down to the venturi from the air filter side and back out again to the boots.
I know the 33's measure 35.5 at the boot.
They also should have the bore size ink stamped on the bodies so maybe that is still visible somewhere.

KZ802 wrote: So would they measure 29mm at the throat where they go into the rubber carb holders?

Keihin calls the removable aluminum tube on the engine side a "spigot". These are often internally tapered, so they have a different inside diameter at either end. This allows the same set of carbs to be adapter to different bikes with different mounts and different port diameters.

So you need to remove one spigot and measure the inside diameter on the carb side (the threaded side). This should match the diameter of the carb bore and should tell you the size.

They also often have a "29" stamped in ink on the engine side. up near where the throttle shaft goes through the body. But since it's ink it may have been washed off at some point.

The the bottom of this page has show a table of spigots for the CR carbs, with the ID for both ends and the OD.
www.jetsrus.com/carburetor/carb_keihin_C...oded_view_parts.html

I was hoping something like this was the case. Upon further inspection it looks like I have a set of 29's. It looks like they have been around the block. Thanks DOHC I have been trying to look up everything I can about these carbs and I have not come across this info yet. The ink stamp appears to be long gone so measuring was my only option. I can see where they have different reference marks which I assume are to fit to different bikes. Someone either added or lost some washers along the way, too. Next I will see what I have for jets, and most likely some velocity stacks.

On CR's you do not have to use three inlets for fuel. Either use the center inlet, or use the outer two. You can eliminate a lot of unnecessary plumbing that you have now on those carbs.

If you have a single outlet petcock, just use the center inlet. If you have a dual outlet petcock, I would use just the two outer inlet tees then.

CR's are great carbs once you get them dialed in.

I use the outer two fuel tees on my CR's.

Thanks Dr., I was thinking that. I am using them on my 76 KZ900 so it has the dual petcock. Do you have a good source for parts for them or any tips on using them?

I use Sudco for all my Keihin parts. They are the master Keihin importer for this country. They now sell customer direct at real retail prices. Unlike my local dealers who want 40% more than I can buy it from Sudco for!!! Their online catalog has all the parts breakdowns, and the part numbers you will need!!!

I would replace the o-rings around the float needle seats, and the o-rings that go between the screw in spigots, and carb bodies first off.

Don't know what to tell you for jetting on the CR29's, I run CR33's on my bikes. The last time I jetted my CR's in, I had them off and back on the bike like 12 times or so. But now they are spot on across the whole RPM range!!!!

Good luck!!

Yeah I have had them off and back on a number of times now. Luckily that's not bad without an airbox. I think I am still really rich. The PO must have had them on a much bigger engine I made a huge leap down and I am still way off. I can get it to run at like 2000 rpm but if I touch the idle lower than that it just stumbles and dies. Where did you get the cap for the center fuel inlet? I can't find anything like that anywhere. I had to put a long piece of hose on with a bolt in it so it wouldn't leak. I hope you don't say sudco my carbs have a sudco sticker on them I should have looked there first!