Topic: 1981 CB650 Performance Mods

[jpc002]

You have an extra 63hp cam?  Are you willing to sell it?

[dusterdude]

ok guys came into this late,is the 63hp motor a stock u.s. engine or was it an euro engine or was it stock in anything?

[Ibsen]

You have an extra 63hp cam?  Are you willing to sell it?

Sorry, it's not for sale. But I have sent you a private message. 

[Soos]

OK guys came into this late,is the 63hp motor a stock u.s. engine or was it an euro engine or was it stock in anything?

The 63hp is stock for all USA sohc650's.
Germany had nothing but the 50hp cam I believe.
The 650Z in europe I believe you could get either the 63 or 50hp version.


Gotta love the math with the 650....
627cc's=63hp = 9.95cc's per HP
with 65mm pistons 740cc's = 75hp....(theoretically)
Ok mabey I'm dreaming....

As compared to the 750...
736.00 cc's=67HP = 10.98cc's per HP
836cc's(same 65mm pistons) = 76hp

can't be. Or can it
Am I wrong on the assumption that the ratio would stay the same?

hey canuck, thanks for pointing that out.
a buck... what the f*** it's just a buck. Hoping it stays a buck.
Will let everyone know if it fits(if I win it)...
off to look at prices of a hot 550 cam, and see if i can compare cam info against info for the 650 cam.


l8r

[Ibsen]

Depending on the country sold, the European SOHC CB650 engine came in three different shapes regarding power output.

•   46 KW / 63 BHP / 63 PS (full power) Country Code GI, F (Germany I, France), Sweden, UK.
•   44 KW / 60 BHP / 60 PS Country Code ED (Europe)
•   37 KW / 50 BHP / 50 PS (power save) Country Code GII (Germany II)


The following table lists data about the GI (full power) and GII (power save) versions:

1979-1980 CB650z (RC03)


46 KW version:

ID: RC03 2000037-2020833
Engine ID: RC03E-2....
carbs: PD51CA (country code GI) and PD51AA (country code E,ED,F),
pn 16100-426-611(GI)/612(G1)/601(DK,DM,E,ED,F,U)
camshaft: pn 14101-426-000, cam lobe diameter 35.6mm IN and 35.3 EX
top speed: 188 km/h, 117 mph


37 KW version:

ID: RC03 3000002-3001651
Engine ID: RC03E-3....
carbs: PD51D(country code GII), pn 16100-426-691
camshaft: pn 14101-426-690, cam lobe diameter about 33.1mm
top speed: 173 km/h, 108 mph



1981 CB650b (RC03)


46 KW version:

ID: RC03 2100002-
Engine ID: RC03E-2....
carbs: VB54 B/C/D/E
camshaft: pn 14101-426-000, cam lobe diameter 35.6mm IN and 35.3 EX
top speed: 188 km/h, 117 mph


37 KW version:

ID: RC03 3100003-
Engine ID: RC03E-3....
carbs: VB54 B/C/D/E
camshaft: pn 14101-426-690, cam lobe diameter about 33.1mm
top speed: 173 km/h, 108 mph



1980-1981 CB650Ca/b (RC05)


46 KW version:

ID: RC05 2007931-2020488 (1980 CB650Ca) and RC05 2200002- (1981 CB650Cb)
Engine ID: RC03E-21....
carbs: PD50AA, PD51A/F and VB54 B/C/D/E
camshaft: pn 14101-426-000, cam lobe diameter 35.6mm IN and 35.3 EX
top speed: 178 km/h, 111 mph


37 KW version:

ID: RC05 3000002-3002110 (1980 CB650Ca) and RC05 3200002- (1981 CB650Cb)
Engine ID: RC03E-31....
carbs: PD50A, PD51A/F and VB54 B/C/D/E
camshaft: pn 14101-426-690, cam lobe diameter about 33.1mm
top speed: 165 km/h, 103 mph



1982-1984 CB650C (RC08)


46 KW version:

ID: RC08 2000023-
Engine ID: RC08E-2....
carbs: VB54
camshaft: pn 14101-426-000, cam lobe diameter 35.6mm IN and 35.3 EX
top speed: 175 km/h, 109 mph


37 KW version:

ID: RC08 3000002-
Engine ID: RC08E-3...
carbs: VB54
camshaft: pn 14101-426-690, cam lobe diameter about 33.1mm
top speed: 160 km/h, 100 mph

[mg1045]

Wow took forever to find this!

Anyways, is anyone running progressive springs, or different springs in their front end? If so where did you get them? I'm in desperate need of fork seals and I want to stiffen up the front. It really dives when I brake. Not sure if that's normal or not, but I don't like it.

[Soos]

Not sure on the springs for the front end....

But I got my stock 550 cam today...

Perfect fit!
The lobes are in the right positions, the journals are the right diameter and the corect location for use in a 650 head...

now to find a gently(yeah right) used 550 cam that is as wild as the 550 cam's go.


l8r

[mg1045]

I was pretty sure it would fit. I've been keeping my eyes open for a perf. cam and I'm not sure it'll happen. May have to wind up sending a cam out and getting it reground or built back up and custom ground. I'd like to find out if a regrind would help. It should give a few more mm of lift. I've got an extra cam or two I believe, and if I ever get a paycheck that's worth a damn I'll send one out. I'll check around here with a few machine shops and see what they say.

What about springs an retainers? Does anyone know if they are good enough, or if better ones are available?

[Will McD]

Hey, I'm a newbie, and i just bought a pair of K&N pods for my 82 cb650 and i cant get them on. I read someone cut the boots to make them fit? Do you have any pictures of where you cut the boots and how well they are clamped on? Is it possible to get them on without cutting. maybe removing the carbs?
also, How much did you pay for your pods? I thought they were ridiculously expensive but after much research i came to the conclusion that there are no other K&N pods that will fit, so i didn't really have a choice (especially since i bought the bike with crappy "uni-filter" pods already on it)

[Frankenkit]

digging up another zombie thread since I've seen so many new 650 owners and some of these threads REALLY get buried.

[martino1972]

funny thing is,that while we get seen as less then a 750  rider...the numbers between a 650 and a 750 are not that far apart...a 650 does even better in hp to cc's.... we should be the most popular out there...

[Frankenkit]

it's just that the 750s were made over 10 years...
650s?  well... there's THE 79. The 80 which is the bastard child of the 79 and 81-82...  and the 81-82 which were the more advanced ones... then the nighthawk family.

[MJL]

I can tell there was a big improvement in my '81 650 when I went to 4-1 exhaust and a jet kit.

IIRC Dynojet made the jet kit. It came with new needles and other things I think. Stock needles are non-adjustable.  I know I'm one or two notches up from the bottom.  I did run pod filters for awhile. There was no noticeable improvement over the stock airbox w/K&N, other than more intake noise. 

Hopefully this summer I can throw it on a dyno and see what it puts down.

[cb650]

With the 4-1 you loose lb's also.     

[Soviet1942]

Bumping the #$%*, any new news on performance mods other than the dynojet and exhaust? Reading through the thread it seems to have only confused my about the 550 and '79 650 cam. 

[paulages]

The "HOT" 550 is 1mm more lift than the stock 650.   Dont know what its worth but shouldnt need any mods to the rest of the 650 valve train.



                             Terry

Can anyone confirm the fitment of a "HOT" 550 cam in a cb650('79) head?

l8r

 

i have a megacycle 126-21 cb550 cam in the 650 head i use on the 718cc cb550 (i couldn't resist making that confusing  ). 363/259 lift/duration.

[Soviet1942]

^^ Wait...what? 

[cb650]

The 550 and 650 cams are interchangable.  Use the cam gear from the motor you are using.   And the tack and drive gear will need to be matched to the cam.  As for the perf youll just have to decide what you want
.

[Soos]

The "HOT" 550 is 1mm more lift than the stock 650.   Dont know what its worth but shouldnt need any mods to the rest of the 650 valve train.



                             Terry

Can anyone confirm the fitment of a "HOT" 550 cam in a cb650('79) head?

l8r

 

i have a megacycle 126-21 cb550 cam in the 650 head i use on the 718cc cb550 (i couldn't resist making that confusing  ). 363/259 lift/duration.

YEAH!





Of all the "upgrades" I have experienced...

- I like the 750 carbs the best.

- a 4-1 helps a LOT.(weight reduction I suspect more than anything)

- Ok one better than 750 carbs, 61mm overbore pistons.
(or 62mm, or 64mm, or 64.75mm, or 66mm even!)

- using a K&N stock airfilter replacement.

- the air filter cover mod.

- Gearing will affect how your bike runs as well(mainly acceleration from a standstill)

- Another mod I like - a slotted cam gear. That one has WAY more effect than I thought possible.

- I modified a Dyna2000 once, and FRIED the entire wiring harness(along with nearly everything else electrical). While it was running however I enjoyed it.
Too bad I spent all that time on $400+ just to have it get fried.

- Dyna coils.... Cannot say whether they are a "upgrade" or not, but new coils is NEVER a bad thing when considering using 30'ish year old coils.



l8r

[Pinhead]

Hmm I honestly wonder how much HP the 4-1 exhaust actually frees up (other than weight). The 4-2's on my '79 rusted right between the "collectors" and the mufflers so I chopped them off and installed 12" straight pipes (2" ID) which seemed to help quite a bit... But that could still be attributed to weight reduction.