Topic: Anyone run Weber carbs and an RC 327 cam??

[754]

Either or both together, I think 327 is the cam I have (2nd hottest)

At any rate it seemed to make really good midrange power, more tha I expected.. has anyone run these parts??

Tell me what you found.
754

[old750]

Where did you get the manifolds??? Are they just the stock ones??

[754]

Manifolds show up on ebay once in a while, and fit DelOrtto & Weber and Mikuni 2 throat.


On mine the manifolds nearly touch & have short rubbers about 1.5 in long. Were easy to find (hose size) way back but last time I looked had trouble finding, had to remove a hose layer and braid to allow enough stretch.

To run on stock frame you may have to mod a bit, my set requires air cleaner mounts to be bent up 90 deg., and air cleaners may not fit with side covers, etc..

Sacrife but I  wont use stock anymore...

[old750]

What do you search for to find the manifolds? How much do they usually go for? Anyone still make them?

[754]

Try 750 Honda manifold..or Honda Webers,  Honda 750 racing...things like that .

me and a buddy each got one a few years back..around 85-120 bux for manifold only..

Sometines there is deals on carbs in the car stuff.. but you will be buying jets and maybe venturis
..search weber carbs.. 40 DCOE is the one you want..

[old750]

I often find the DHLA 40s in ebay.com and ebay.co.uk. I'd be interested to see if I can find the manifolds for a cb750.

[754]

Ok, found an RC ENG Catalog...not sure of year, but

Vance & Hines still worked for Russ and The ATCHISON, TOPEKA, & SANTA FE are on the cover..

Here are the cam specs for 2 of the cams.. I might have the 315, will check the timig card tommorow..

RC 315 HOT STREET Strong torque curve from the ground up-------comes on low and never quits. This one makes lots of Horepower. Very good for heavy street and alterdcbikes. Our favorite in street class. Has twisted us to many national records. Very streetable. Fair idle---------quiet.

INT 55deg -85 deg EX 85 deg -55deg   lift .375 both  clearance .012 cold
 That is the cam I run..




RC 327 Full Competition----- similar to #315, but with more lift and overlap. Designed with more duration for max rev and B. H. P. on all big motors. The #1 choice for use in 1000cc motors.

Int 55-90  Ex 90-59 lift    .373int  .385 ex
clearance .012 int/.014 ex

[bathcollector]

What do you search for to find the manifolds? How much do they usually go for? Anyone still make them?

I bought my manifold setup new from Lynx in Australia, around Aus. $110.00.

[racerx95]

any way to get a copy of the RC info? I have the #327 cam in my 970.

[Terry in Australia]

I had a set of the twin throat Dellorto's on a new Lynx manifold last year, but I sold them and bought a set of Keihin CR29mm carbs instead. The Dellorto's were big heavy things with crappy linkages, so I thought they were a bit too "agricultural" for my tastes. Cheers, Terry.

[754]

Racer, they dont give much more info, I will did out my cam card today. it may have a bit of info not yet posted.

They had a 454 Top Gas cam as well that they would not publish specs for.

Ever had a motor with a mystery cam?? and have to guess at clearances??  A lot of folks are leery of big clearance but it does work if thats what the camgrinder recommends..

[mkramer1121]

RC Cam Specs:

http://www.satanicmechanic.org/rccam.shtml

[MRieck]

 .012 and .014 lash certainly has a negative impact on your total lift and duration. Megacycle stuff is all between .004 and .006 with 1 exception. Web cams are pretty much the same too. The nose of the exhaust cam does cause fast opening and the higher the lift the more you want to try and ease the opening. Still....014 is a bit overboard IMO.

[754]

I always believed what Russ said..

Mostly because it worked well, I think he knew Honda motors quite well..

[MRieck]

 I agree..they worked OK but I think it was a matter of materials and surface treatments etc. Hard weld cams are very tough (though I have seen crappy hard weld Web cams from a busa). Those big clearances certainly ease the opening but you do lose a good amount of lift etc. Combine that with the fact many of those cams were off in regard to total lift and lobe seperation. In the day RC was OK but some of the things they did are pretty funny today. Personally I always felt the Yoshimura equipment was much, much better (especially valve train components).

[Terry in Australia]

I've gotta agree with Mike, what was "state of the art" in the 1970's has been pretty much eclipsed now.

I was watching a car racing programme last weekend and they were racing old Ford and GM "musclecars" of the early 1970's, and the commentator said that these engines are running up to 200 BHP more than they were back in the day, due to modern technology applied to very old machinery.

Only problem of course is that like our old bikes, the rest of the vehicle needs to be suitably modified to handle all that extra power, but of course "classic racing" rules don't allow a lot of mods, so these cars get scary when you're feeding 750 BHP thru "period" Hoosier or Mickey Thompson race tires. Sure is exciting to watch though, ha ha! Cheers, Terry.

[MRieck]

I've gotta agree with Mike, what was "state of the art" in the 1970's has been pretty much eclipsed now.

No.......It's been sucked into a Black Hole Terry.

[754]

Well if it is outdated, then a modern cam and headwork should get a few sohc's in the 9's in sorta streetable trim...

 except.....

nobody that I am aware of has been pushing development forward by much for a few decades...

 if you think  you have a fairly quick sohc goe to  Dale Walkers Holeshot Performace sight and see if you can get close to his times...!!..... from the 80's...

[Terry in Australia]

Well if it is outdated, then a modern cam and headwork should get a few sohc's in the 9's in sorta streetable trim...

 except.....

nobody that I am aware of has been pushing development forward by much for a few decades...

 if you think  you have a fairly quick sohc goe to  Dale Walkers Holeshot Performace sight and see if you can get close to his times...!!..... from the 80's...

Well Mike Rieck has a Dyno card that says he's getting 98 reliable rear wheel BHP on his street bike mate, I don't know about 1/4 mile times, but I'm sure that double the original rear wheel BHP is a respectable effort? I think Mike has got as few tricks up his sleeve that fly in the face of what was common way back when, ha ha! Cheers, Terry. 

[MRieck]

Well if it is outdated, then a modern cam and headwork should get a few sohc's in the 9's in sorta streetable trim...

 except.....

nobody that I am aware of has been pushing development forward by much for a few decades...

 if you think  you have a fairly quick sohc goe to  Dale Walkers Holeshot Performace sight and see if you can get close to his times...!!..... from the 80's...

Some recent "tricks" are 5mm valve stem conversions using a 34mm intake valve. It fits on a stock early F/ stock K seat easily. Other tricks involve opening the port throat diameter to 90% of the valve diameter. Of course there is zero deck etc but that isn't very "new". Various coatings are worth 1 or maybe 2 HP. McGrews one piece cam chain tensioner is a big step forward. Tuner set ring gaps and modern pistons that allow for tighter skirt to wall. Etc.
  Rick Stetson (Harry's Machined Parts in Massachusetts) had the fastest/quickest N/A, non alcohol, carburetor CB I know about in the 70's. I believe it ran 9.12 for its best time in the late 70s. He had stuff like .100 positive deck height, very large Ti valves, a cam set up known only by him and one fella at Megacycle, valve to valve clearance of about .030 etc etc. It was the fastest and quickest CB in the USA for a long time.

[Sam Green Racing]

Hi Mike, what sort of chassis was this guy running ? (bars slick)

Sam.

[754]

MRieck,
 Are you modding other valves or are they biult for the CB? is stock stem 6mm or ?? Can you tell me more about the cam tensioner.

Anyone been running raised ports or billet head, that sort of thing?

A local guy here started building big singles out of H-D twins..950 cc.. blown with fuel injection, nitrous. He ran  155 one way at Bonneville.. first time out (salt was  bad this year) made some of the twins look bad.

Cant wait to try my 750 out on the flats...

[MRieck]

MRieck,
 Are you modding other valves or are they biult for the CB? is stock stem 6mm or ?? Can you tell me more about the cam tensioner.

Anyone been running raised ports or billet head, that sort of thing?

A local guy here started building big singles out of H-D twins..950 cc.. blown with fuel injection, nitrous. He ran  155 one way at Bonneville.. first time out (salt was  bad this year) made some of the twins look bad.

Cant wait to try my 750 out on the flats...

That 5mm conversion is available from Kibblewhite. It includes guides, springs , Ti retainers, keepers and the stainless valves. The stock stem is about 6.5mm. I'm sure you know the value of a light valve train especially when used with rocker arms. Open the intake throat to 90% of the 34mm intake valve and you start to move some air with a good port). The tensioner is available from M3 Racing  http://www.m3racing.com/. Look under CB750 parts. It is a pretty simple piece really....much better than the old Yosh steel wheels etc. He also lists the 5mm kit but it is  a bit expensive there. SamCR750 and I are running the 5mm kit. Sparty, Terry, Sam and me are running the tensioner. There may be others too. Another very important item is a Dyna 2000 digital ignition. It is simply fantastic. I have had the exhaust ports welded a bit but the ports is so small it's tough to raise the roof. On the intake I have not epoxied one (I've done 4 valve heads) because I always felt the port volume was pretty small. I really flatten and widen the floor on my Stage 3 port. I do have to epoxy the intake spigot on that port because it gets very thin. That port can pull around 130CFM @ 28" with a 33.5 valve @ .400 lift if I remember correctly. It will pull even more with a 90% throat. The stock port maxed at around 95CFM @ 28". I haven't flowed a CB head in a while because once you get the shape...well....you got it. Like Terry said....mine makes and honest 98HP to the rear with a 915 kit, pump gas and electric start. The dyno is not a "happy" one either. Those big Cobra engines were honestly lucky to hit 90HP and they had a good bit more displacement then mine. Paulpages had a discussion with a guy who had a Cobra and he did not believe him when he said mine made 98 (his made 89). I sent a dyno copy to paulpages, he gave it to the guy and he never said a thing. I'll be the first to say it is no mean trick to get 100HP to the rear wheel under 1000cc on these engines and have it idle, not detonate, be electric start and generally well mannered.

 PS   155mph out of a single is a good number especially with a bad surface.

[754]

Thanks for the info. My buddy tried to dyno his 1080 but said they had trouble calibrating.. used I think  a Kawi  as a baseline or comparison (not sure how it works) think he was in the 90,s

The guy with the Harley single has a dyno and will probably let me use it a bit.

Interesting he said that big single dynoed 80 something horse before he left w/o Nos.  He is running an aluminum fairing of his own design.. I said it would have to be pretty good design wise to hit that speed. He built a 250 twin last year that did a 133mph one way ( discovery Channel Build-off) It dynos over 85 hp.
 He is hooked and after going there this year, I can see why.. its time a single-stick gets out there..

 Years ago a guy from BC ran a 750 on the salt, I think he ran 149 ish.. was in Street Chopper years ago..

[MRieck]

Thanks for the info. My buddy tried to dyno his 1080 but said they had trouble calibrating.. used I think  a Kawi  as a baseline or comparison (not sure how it works) think he was in the 90,s

The guy with the Harley single has a dyno and will probably let me use it a bit.

Interesting he said that big single dynoed 80 something horse before he left w/o Nos.  He is running an aluminum fairing of his own design.. I said it would have to be pretty good design wise to hit that speed. He built a 250 twin last year that did a 133mph one way ( discovery Channel Build-off) It dynos over 85 hp.
 He is hooked and after going there this year, I can see why.. its time a single-stick gets out there..

 Years ago a guy from BC ran a 750 on the salt, I think he ran 149 ish.. was in Street Chopper years ago..

You're welcome 754. I'm very free with info. As you so correctly stated.....this is old stuff. The neat thing is there are some great tweaks. I love that. Please feel free to ask me some ?'s. I have to assume you are an older guy with experience for sure. Welcome to the board.
  Mike