Topic: Just joined the CR29 club

[turboguzzi]

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]

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]

TG i have a set of PD's going  but the cr's are all mine !

[akabek]

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]

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]

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]

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]

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]

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]

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.