Author Topic: Just joined the CR29 club (Read 7601 times)

Captaindonutbikes · « **on:** July 28, 2010, 04:36:58 AM »

I am running a cb 550 k3 and just took delivery of a brand spanking set of smooth bores.

offered them up and they are well out for the standard rubbers, do i need to change the rubbers/intakes or move the carb bodies in ?

cheers in advance

Sam Green Racing · « **Reply #1 on:** July 28, 2010, 05:33:03 AM »

No doubt you will get a reply during the night from one of our American brothers.

When is your website going to be up and running and how's the Italian bird making out.

Sam.

Captaindonutbikes · « **Reply #2 on:** July 28, 2010, 07:10:47 AM »

italian is super fine, but getting impatient.

(she is pretty good tho)

so whats the deal with the rubbers bro ?

the 550 k3 does not line up, and i have seen on other threads people running different rubber mounts for the carbs.

what are these ?

cheers

Captaindonutbikes · « **Reply #3 on:** July 28, 2010, 07:14:07 AM »

tried putting this on the english forum but it has disappeared !

Sam Green Racing · « **Reply #4 on:** July 28, 2010, 07:17:56 AM »

It's off line at the moment and I don't know anything about the smaller 4s.
You'll probably get a reply later tonight when the US guys get home from work, it's 9.15 in the morning over there.

Sam.

Sam Green Racing · « **Reply #5 on:** July 28, 2010, 07:23:14 AM »

Check out this thread, it might be of some use.

http://forums.sohc4.net/index.php?topic=42903.0#top

Sam.

Captaindonutbikes · « **Reply #6 on:** July 28, 2010, 07:26:00 AM »

CB750 (SOHC) VM29/A2HSM set of 4. 005-026
For mounting aftermarket performance carburetors to CB750 (SOHC) from 1969 to 1978 SOHC models.

think these are the ones i need but not sure, shall wait for the american guys to answer.

Captaindonutbikes · « **Reply #7 on:** July 28, 2010, 11:01:26 AM »

BUMP!

MCRider · « **Reply #8 on:** July 28, 2010, 12:05:28 PM »

Quote from: Captaindonutbikes on July 28, 2010, 07:26:00 AM

CB750 (SOHC) VM29/A2HSM set of 4. 005-026
For mounting aftermarket performance carburetors to CB750 (SOHC) from 1969 to 1978 SOHC models.

think these are the ones i need but not sure, shall wait for the american guys to answer.

I may be way off base here, but as an owner of VM29s they are not the same as the CR29s, pretty sure. Don't know about the rubber manifolds though.

Captaindonutbikes · « **Reply #9 on:** July 28, 2010, 12:19:48 PM »

yep just realized what i had posted. thanks any how

fastbroshi · « **Reply #10 on:** July 28, 2010, 08:28:28 PM »

You might wanna PM member Goddfrey, he's got some on his 550. Sounds like a custom job though (quote from Goddfrey in the Inspiration Gallery:

"The build is shown here: http://www.vinmoto.org/gallery/v/VinMoto-Garage/album03/Godfferys-Garage-123/Richards-Cafe-project/
I also had questions regarding the CR carbs, It took some doing to get SUDCO to make a set for the CB550 and get the intake mainofolds right (had to use CB500) but I'm loveing them & just need to tweek the jetting now. Call Mike "AKA Dude" at 1-414-588-3106 or cycletunewisconsin@sbcglobal.net"

Captaindonutbikes · « **Reply #11 on:** July 29, 2010, 05:19:49 AM »

link does not work

Godffery · « **Reply #12 on:** July 29, 2010, 10:13:31 AM »

Quote from: Captaindonutbikes on July 29, 2010, 05:19:49 AM

link does not work

Try this one:
Café overkill project http://tinyurl.com/23udf4f

turboguzzi · « **Reply #13 on:** July 29, 2010, 11:13:17 AM »

running 29's on my racer which has essentially the same head as yours and you'll definitely need to craft custom inlet stubs to fit them.

most do a big flanged thing on a lathe.

you might find pics of such setup in my cb500 racer development thread and in howell's posts.

Is it a street bike? If yes, then I am not sure about the wisdom of running CR29's on the street on a 500/550, specially with stock porting, cams and compression. They might work well on street 750 but on a small block 500/550 you'll need to pull pretty high rpm to get flow speed (and response). Hope I am not spoiling your party....but you better hear that now than after doing all the work.

TG

bwaller · « **Reply #14 on:** July 29, 2010, 11:49:10 AM »

I have to agree TG.

I can't understand how 29's an a stock 550 would be very streetable. I could never get a mostly stock one to run decent with Keihin 28mm (stock CB750) carbs back in the day. These 29's are night & day ahead of the 28's.

Godffery · « **Reply #15 on:** July 29, 2010, 12:18:32 PM »

Oh man 29's... I missed that little detail; Yes, I agree; 29's would be way too much. I'm running the CR26's on mine and that's with a hotter cam.

BTW; as for the spigots, I talked to the dealer / shop I got my Carbs from and he said that he DID turn them down on a Lath to modify the fitment.

bwaller · « **Reply #16 on:** July 29, 2010, 12:28:51 PM »

That makes more sense.

Howell · « **Reply #17 on:** July 29, 2010, 12:49:54 PM »

Quote from: bwaller on July 29, 2010, 12:28:51 PM

That makes more sense.

To fit the CR's on the CB500 head you have to buy or make new intake manifolds.
But we did some more work to fit them.
On our racer we use them of Takegawa made for Honda minibikes.
See the pictures how they are fit.

Godffery · « **Reply #18 on:** July 29, 2010, 12:50:13 PM »

Another update:
I looked a little deeper into those intakes I used; I was totally wrong! I got them mixed up with some others I had on the shelf; there from a 1978 550. http://www.bikebandit.com/houseofmotorcycles/1978-honda-motorcycle-cb550k/o/m9449 NOT CB500...! man I feel like an idiot. The 77-78 are shorter & don't have the tuning ports because Honda used different Carbs for those years. http://www.vinmoto.org/gallery/v/VinMoto-Garage/album03/Godfferys-Garage-123/Cafe+Overkill/DSC+274.JPG.html

Captaindonutbikes · « **Reply #19 on:** July 29, 2010, 03:34:56 PM »

so drilling and tapping the manifolds are the best way for doing sync on these problematic bad boys ? i know they will be a nightmare in this current set up but its a start!

would it be worth running a 650 cam with them ?

the list goes on.

thanks everyone for your as always invaluable help

Captaindonutbikes · « **Reply #20 on:** July 29, 2010, 03:42:37 PM »

oh and for the ~~non believers~~ i quote traveller:

'so, 120 mains with velocity stacks and an open 4-1 are good on an otherwise stock 550!'

Godffery · « **Reply #21 on:** July 29, 2010, 11:28:53 PM »

Yes I think installing the tuning nipples were a must but not because I think there problematic, I'm just kind'a anal.
I've here real good things about the 650 cam trick, the only draw back is that you have to use a CB750 tach because the tack drive gear is different.

As for the main jets, 120's work well in stock Carbs with velocity stacks and an open 4-1. as for the CR Carbs, probably closer to 110 or so, I'll let you know when I get mine dialed in.

Captaindonutbikes · « **Reply #22 on:** July 30, 2010, 04:24:45 AM »

cool.

the tuning nipples are because there are no vacuum points on the cr's to do sync right ?

Captaindonutbikes · « **Reply #23 on:** July 30, 2010, 07:54:09 AM »

Carbs all fitted, must have been having one of those f*ckwitt days, thanks for everyones help.

Just need to know about drilling the manifolds ?

Godffery · « **Reply #24 on:** July 30, 2010, 09:34:23 AM »

Right.

The only thing critical is to make sure there positioned as not to interfear with the mounting and easy reached for plugging in the vacuum gauge. As for the Nipples them selves; I got mine at Dennis Kerk.
If you have never drilled & taped, you may want to have some expert help with that part.
Also, using blue lock tight when installing them will insure a air tight seal on the threads.

turboguzzi · « **Reply #25 on:** July 30, 2010, 11:12:40 AM »

I've done two racing seasons with 50$ swapmeet 27mm VM's (not even smoothbores) on my 500, the bike put down 60 rwhp on the dyno and indeed, according to Mikuni's tuning guide 27 would be otpimal size for 15 or so hp per cylinder. They know their stuff

Two years ago I switched to CR29 and to this day, I am not sure if they've added much on top end, my guess is maybe 2-3 hp, but midrange repsonse is nowhere as nice as it was with those cheapo 27's. really miss them everytime I power out of a hairpin

and that's with a tuned to the max racer, 12.5:1 CR, wildest megacycle cam, stage 3 ports, SW springs, ti retainers, etc.

A well known effect of over carbing is the WOW! when they finally start working at higher rpm, but that's more because the hole they create in the midrange than any real top end gain.

So here is the graph, but dont let the facts confuse you

TG

ps - i hope its clear that I want these "used" 29's for my coming 750/810 racer build, will make captain an offer when he gives up on them

Captaindonutbikes · « **Reply #26 on:** July 31, 2010, 09:07:17 AM »

did it this way. used the vacum screws of the PD's

all mounted up and ready to go.

comparison shot

just need to sort out the throttle cable length.

if any one can help ? too long and have read that the KLE650 throttle cable set works ?

Captaindonutbikes · « **Reply #27 on:** July 31, 2010, 09:09:14 AM »

TG i have a set of PD's going

but the cr's are all mine !

akabek · « **Reply #28 on:** April 01, 2013, 08:23:20 AM »

This is an old post but it is in line with my question. I recently completed a 592 big bore on a 1975 CB550F that is also running a CB650 cam, ported head, valve job, 4-1 exhaust, electronic ignition etc.

The carburetor I am using is a Keihin CR29. The rubber intake boots were mounted to the intake manifold first. When I installed the carb to the boots the two inner rubber boots do not go on as far as the outside boots on the carburator mounts. Is there a way to get a better fit or would I have to get some machining work done? A earlier thread mentioned using 77/78 (shorter) intake manifolds with CR29s but I do not understand how that will make difference.

FunJimmy · « **Reply #29 on:** April 01, 2013, 09:48:34 AM »

Quote from: akabek on April 01, 2013, 08:23:20 AM

This is an old post but it is in line with my question. I recently completed a 592 big bore on a 1975 CB550F that is also running a CB650 cam, ported head, valve job, 4-1 exhaust, electronic ignition etc.

The carburetor I am using is a Keihin CR29. The rubber intake boots were mounted to the intake manifold first. When I installed the carb to the boots the two inner rubber boots do not go on as far as the outside boots on the carburator mounts. Is there a way to get a better fit or would I have to get some machining work done? A earlier thread mentioned using 77/78 (shorter) intake manifolds with CR29s but I do not understand how that will make difference.

;
I think the shorter 77/78 manifolds provide sufficient room for pod/frame clearance.

akabek · « **Reply #30 on:** April 01, 2013, 10:51:01 AM »

Ah...I missed that part.

I am running Steel Dragon stacks with BBR filters and the setup fits although the outer filters are pressed against the frame. I just cannot get the rubber boots to seat evenly across all 4 carb mounts. When I mount the boots to the intake and carb and than install the assembly I cannot line the bolts up to mount it to the head....

FunJimmy · « **Reply #31 on:** April 01, 2013, 01:07:42 PM »

Quote from: akabek on April 01, 2013, 10:51:01 AM

Ah...I missed that part.

I am running Steel Dragon stacks with BBR filters and the setup fits although the outer filters are pressed against the frame. I just cannot get the rubber boots to seat evenly across all 4 carb mounts. When I mount the boots to the intake and carb and than install the assembly I cannot line the bolts up to mount it to the head....

Wish I could help, but I went the custom manifold route with my CR's

Godffery · « **Reply #32 on:** April 04, 2013, 10:02:10 PM »

I've made some shorter Spigots to solve the problem with it hitting the frame ..
http://www.vinmoto.org/gallery/v/VinMoto-Garage/album03/Godfferys-Garage-123/album185/Keihin+CR26+Carburetor+Kit+for+1974-1978+Honda+CB550/550+spigots+010.JPG.html

turboguzzi · « **Reply #33 on:** April 04, 2013, 11:17:02 PM »

are the carbs spaced to match the stubs? guess so, just making sure? but surely CR work best when used with custom inlet manifold

not that hard to them on a lathe

akabek · « **Reply #34 on:** April 14, 2013, 07:20:57 PM »

I ended up removing the carbs and attached the boots to the carb first. Than I mounted it to the intake and they just slide right on. I guess leaving them mounted for a few weeks stretched them out and the warmer temperature helped as well. I took the bike out for a short ride and wow...I can't wait to finish breaking it in. She really kicks in on the power band. I can hammer on the throttle and there is no hesitation whatsoever. The only thing I have to work on is the idle. It does not like to idle below 2000RPM.

News:

Author Topic: Just joined the CR29 club (Read 7601 times)