Author Topic: CB550 Higher rev's (Read 9209 times)

cbrocker · « **on:** March 19, 2012, 12:04:16 pm »

I'm starting to rebuild my 75 CB550 super sport. So far I have got a new front and rear suspension, and started to build a frame jig to make a new but lighter and stronger frame. While almost nothing on the bike is going to be origanal I would like to keep to motor looking like it is a CB550 and not a hybrid. I was looking up some performance packages from Dynoman Performance and would like to use there stage 3 kit, but I would like to increase the overall rpm's. Does any one out there know of any possible way to increase the over all red line of these motors? I was reading the Honda Man's post and he was stating he could get 16,000 rpm's out of the CB750's. If this is true then the same could be done with the CB550's correct? I mean the CB550 has a lighter rotating mass compared to the 750 and with the new types of electronic ignitions and lighter engine components out there you should be able to gain something on the top end? I'm not looking to turn 16,00 rpm's but maybe 10-12,000 rpm's should be doable. Please feel free to comment. Anything at this point would help.

Bill/BentON Racing · « **Reply #1 on:** March 19, 2012, 01:21:39 pm »

They(500/550's) can spin up to 12.000+ easily.Hondaman was talking miget motors CB750's(I think) no transmission,they cut it off weld a plate,external oil pump etc,then they''ll turn 16,000!!

Bill
My little Yoshi kitted race bike(592cc) ran 12,000+ a lot!

EricHa · « **Reply #2 on:** March 19, 2012, 01:46:15 pm »

Quote from: bellcow54 on March 19, 2012, 01:21:39 pm

They(500/550's) can spin up to 12.000+ easily.Hondaman was talking miget motors CB750's(I think) no transmission,they cut it off weld a plate,external oil pump etc,then they''ll turn 16,000!! Bill
My little Yoshi kitted race bike(592cc) ran 12,000+ a lot!

What all does this entail? More than Hi-Po valve springs? I know porting and cams would be required to make power up there, but what is needed structurally?

Sam Green Racing · « **Reply #3 on:** March 19, 2012, 02:21:37 pm »

Cam and porting is one of the main things. The bigest problem when pushing the revs is reliability.
Look what sort of power can be got from a mild tuned 836 with reliability, more than the factory 750 Daytona bikes that continually wrecked the valve train because of the high revs they needed for the speed to win.

Sam.

Sam Green Racing · « **Reply #4 on:** March 19, 2012, 02:48:58 pm »

Bill (bellcow) was talking about the miget motors that Mark (Hondaman) had worked on in the day.
Billys bike was/is just a normal set up, but very fast.
Most Hondas will rev well past the point that they make max power, the dificult part is making them make power at the higher revs.

Sam.

Really? · « **Reply #5 on:** March 19, 2012, 03:01:32 pm »

Do you weld? If so, I may need to come visit you, lol.

Sam Green Racing · « **Reply #6 on:** March 19, 2012, 03:13:35 pm »

I heard he was going to use Superglue, Really

Really? · « **Reply #7 on:** March 19, 2012, 03:22:02 pm »

turboguzzi · « **Reply #8 on:** March 19, 2012, 03:32:23 pm »

put aside for the moment 16K rpm 750 motors as you are not building a midget racer.

go through the racer build threads of howell, bwaller and miine (turboguzzi) and youll find plenty of go fast tips for 500/550's. paulages has a very good thread on a hybrid 550/650 motor too. in race trim they can be pushed to more than 65 rwhp, but not really usable on the street. with a big bore kit a 55-60 rwhp motor could be quite reliable. the 500/550 bottom end is quite a bit sturdier than the 750's, you can run stock rods and stock cam tensioner up to 12K without problems.

do some reading, get yourself an idea of how much work you want to do and i am sure the "small block" guys here will be happy to help.

Sam Green Racing · « **Reply #9 on:** March 19, 2012, 03:47:59 pm »

Yo, what dyno graphs do we have for these motors in respect of the power produced in relation to the revs?

Sam.

bwaller · « **Reply #10 on:** March 19, 2012, 06:10:03 pm »

Peak power in mine was @10k. I would like to see this increase somewhat with the few small changes this year.

turboguzzi · « **Reply #11 on:** March 20, 2012, 03:23:04 am »

Sam, there are graphs in rene's and my threads.

rocker, the 500/550's have a known issue of rather small 27mm inlet valve size that severely limits breathing at high rpm, so your plan to make it peak a 12K is very optimistic to say the least.

seen quite a few dyno's of race tuned 500/550 motors, ALL of them peak slightly past 10K, ALL run out of steam by 12K.

regretfully, unless you are willing to re-angle the valve guides, the biggest inlets you can fit are 29's and even then, the small valve seat is still a bottle neck. using a 650 head is a nice work around and if you use it together with a 500 rocker cover (needs heavy welding of the head), it can be made to look almost like the original 550 head, just like you want. search for "CB500four" member's thread.

just a friendly general tip: from your posts, it sounds like you dont have too much experience tuning motors and yet, you are already talking about not only building a 550 that revs to 12K but also making a frame from the ground up,etc. Take into account that just building a race bike with a stock frame took me something like 400-500 hours. just saying this so you dont set yourself too difficult targets, bite more than you can chew and then become disappointed when you cant finish a project. we had quite a few guys that romped into hipo with big plans to build the fastest sohcs out there that quietly disappeared, never to be seen again....

my 0.02

MRieck · « **Reply #12 on:** March 20, 2012, 04:32:00 am »

I agree about the intake valve....it is the main obstruction. Kibblewhite make s a1mm OS intake for the 500/550. As I have said before, if you bore the seat to 90% of the valve OD you will pick up some CFM quickly.

Sam Green Racing · « **Reply #13 on:** March 20, 2012, 05:17:56 am »

Take a listen to this little motor, have a guess what the motor revs to when he blips the throttle.

Supercharged CBR250R initial startup & run

Sam.

Really? · « **Reply #14 on:** March 20, 2012, 08:50:55 am »

you can now. You have hit the magic 5 post!

turboguzzi · « **Reply #15 on:** March 20, 2012, 10:16:06 am »

Quote from: cbrocker on March 20, 2012, 08:35:00 am

Thanks for the heads up. I was was just asking a simple question about the 550, and if i need to use the 650 head and other components that i will. No one needs to assume that I'm some "rookie with a big dream". I've built more rotary, large piston, diesel, jet engines and full tube chassis race cars than motorcycles so any help here is great news for me. Here is one of the cars that I helped build its a RX3 3/4 tube chassis with a 3rd gen. RX7 motor with plenty of getty-up. Its under the user name of 13BTXR3 in you tube. Sorry I cant post external links.

sorry CBrocker, didnt mean to offend, I knew i run the risk that you might be an expert builder under cover, but unless you tell us about yourself and your background like you did now, it would have been hard to guess from your questions.

As far as I know, only member mec has really built a performance frame from the ground up in this forum (as well as amazing hipo motors, slipper clutches and what not) so thats the main reason why i told you about the risks of taking on too big a project. not many have done this in this forum,

Good luck with your project then!

MRieck · « **Reply #16 on:** March 20, 2012, 10:45:54 am »

I can tell you the 650 head has much better intake ports than the 500/550.

Tews19 · « **Reply #17 on:** March 20, 2012, 11:16:27 am »

Engine revving video is sick! How high did the RPMS go to?

Sam Green Racing · « **Reply #18 on:** March 20, 2012, 01:26:55 pm »

Quote from: Tews19 on March 20, 2012, 11:16:27 am

Engine revving video is sick! How high did the RPMS go to?

That's for you to guess but you will be really supprised.

Sam.

turboguzzi · « **Reply #19 on:** March 20, 2012, 01:29:06 pm »

Quote from: cbrocker on March 20, 2012, 11:08:13 am

Not knowing the 650 layout is it better to simply swap the head or the crank, jugs, and head? Or better put can you swap only the head and in put in after market pistons, or is that not possible?

here's a link to the guy running a 650 head that looks like a 550's....

http://forums.sohc4.net/index.php?topic=63938.0
unless you are limited to a stock 550 head by vintage racing rules, cant see a reason NOT to use a 650 head, specially in a street big bore motor

Tews19 · « **Reply #20 on:** March 20, 2012, 01:44:55 pm »

Quote from: SamCR750A on March 20, 2012, 01:26:55 pm

Quote from: Tews19 on March 20, 2012, 11:16:27 am
Engine revving video is sick! How high did the RPMS go to?

That's for you to guess but you will be really supprised.

Sam.

Ah with that response probably 10k. Secondly, you are mean!

bwaller · « **Reply #21 on:** March 20, 2012, 04:21:04 pm »

Seems to me the stockers redlined at 18K or thereabouts.

Sam Green Racing · « **Reply #22 on:** March 20, 2012, 04:27:51 pm »

That's about right Brent. Tews, just 7,000rpm, I was supprised and I've buzzed one.
They will spin up to over 20,000rpm.

Sam.

Bill/BentON Racing · « **Reply #23 on:** March 20, 2012, 05:50:19 pm »

Ya'll SICK,but we could have a beer or two!

Got a NOS 650 head '79 if interested.PM me.Bill

Tews19 · « **Reply #24 on:** March 20, 2012, 07:43:41 pm »

AH I didn't mean to offend Sam. I know nothing when it comes to performance.. I'm still in the " these are so cool" phase for the SOHC's. But the 31 page thread CR thread has got my attention. It will take me a while to read all.

News:

Author Topic: CB550 Higher rev's (Read 9209 times)

cbrocker