Author Topic: 836cc sprocket advise (Read 3247 times)

disco · « **on:** May 18, 2018, 03:19:44 AM »

I’ve got an 836cc kit in one of my 1972 CB750’s. It makes plenty of power. I generally drop it into 5th, and don’t need to take it out, unless I’m feeling like a bit of a hoon

However, I feel that it could easily pull taller gearing on the highway. Anyone got advise on sprockets for more relaxed highway rpm’s? At present I have 18/48 gearing. At 70 mph I’m indicating 5,000 rpm. However I think my repro tachometer might be reading a tad low. I think it’s doing well more than that. I’m thinking 18/45 gearing might be OK? That will reduce revs by about 7%.

70CB750 · « **Reply #1 on:** May 18, 2018, 03:38:14 AM »

I am attaching a gearing chart, it is pretty much self explanatory. Punch in sprockets and it will give you rpms in every gear.

I run 17/48, but both of my bikes are stock as far as jug size goes.

dave500 · « **Reply #2 on:** May 18, 2018, 04:02:19 AM »

if you don't spend much time on the highway leave it as is,honda got the gearing pretty well spot on,youll lose 1st and 2nd pull away power if you gear it up and youll miss it more than highway cruise if you ride with spirit.

PeWe · « **Reply #3 on:** May 18, 2018, 04:32:07 AM »

I used 17:48 with 836cc/80rwhp. That ran days on Autobahn in higher speeds. You need power when you need to pass a car.

Changed to stock 18:48 with 1005cc that produce more torque from lower.
17:48 is my recommendation, only 250 rpm more @ 100 kph/60 mph.

dave500 · « **Reply #4 on:** May 18, 2018, 04:35:21 AM »

the numbers might crunch but if you gear up itll be like starting of in second gear maybe?

disco · « **Reply #5 on:** May 18, 2018, 04:55:26 AM »

This 836cc has oodles of power. As I said I could ride it up & down mountains in 5th gear all day. I'm thinking I'll just swap out rear sprocket for a 45 tooth. I'm over being passed by the Moto Guzzis's & BMW's in our classic club, whenever there is a long straight. They have that European tall gearing for Autobarn use. I'm revving the tits off the CB750

. They go past me like I'm standing still.

The annoying part is that when we pull over for a coffee, I ask what what sort of revs were you pulling when you went past me? "Oh about 4,000" they say! They would have to be around at least 80 mph!!

dave500 · « **Reply #6 on:** May 18, 2018, 05:03:59 AM »

with all due respect disco if you reckon you don't need to shift gears you aint no way riding that bike properly,come ride with us,ill make mince meat of you and all those euro trash junkies.

disco · « **Reply #7 on:** May 18, 2018, 05:05:22 AM »

That's just rude. It was a statement that the bike makes plenty of torque.

dave500 · « **Reply #8 on:** May 18, 2018, 05:06:34 AM »

oh well,spend all day in top gear I don't give a #$%* man.

disco · « **Reply #9 on:** May 18, 2018, 05:07:52 AM »

#$%* off back to your 500 dickhead!

dave500 · « **Reply #10 on:** May 18, 2018, 05:08:09 AM »

go buy another bike if you cant keep pace with later beemers?

dave500 · « **Reply #11 on:** May 18, 2018, 05:09:06 AM »

ill see you in the twisties,along with your friends,in my rear view mirrors.

dave500 · « **Reply #12 on:** May 18, 2018, 05:10:20 AM »

jeez disco you bit hard and early!

disco · « **Reply #13 on:** May 18, 2018, 05:12:44 AM »

Mate I don't advice from a wanker like you. you're a bit full of yourself.

dave500 · « **Reply #14 on:** May 18, 2018, 05:14:09 AM »

I did start off with all due respect,and what do I get?

disco · « **Reply #15 on:** May 18, 2018, 05:16:21 AM »

Yeah all due respect then I'm gonna drop a #$%*e can on you!

dave500 · « **Reply #16 on:** May 18, 2018, 05:20:53 AM »

well look im sorry,i guess on the internet my dry humour doesn't come across as it sounded in my head,i am sorry I upset you and I hope itll go over and be forgotten from here on in?

70CB750 · « **Reply #17 on:** May 18, 2018, 05:41:13 AM »

disco cool it. Dave is a good guy, I really do not see anything that would upset you.

disco · « **Reply #18 on:** May 18, 2018, 05:48:36 AM »

Really? Maybe have another read.

dave500 · « **Reply #19 on:** May 18, 2018, 05:54:20 AM »

hey #$%* man,i already said im sorry.

dave500 · « **Reply #20 on:** May 18, 2018, 05:55:46 AM »

I sent you a pm disco saying so.

slikwilli420 · « **Reply #21 on:** May 18, 2018, 06:02:21 AM »

Well this escalated quickly! I will say that while Dave may not have finesse in his approach, he does speak the truth. These bikes like to rev and should live in the upper half of the RPM range almost exclusively. Just because you can lug around in 5th gear doesn't mean you should. With you 836 the bike comes alive above 6k or so, so ride it there. These are well built engines and can take far more than most throw at them. Start with stock gearing and go from there. Lugging the engine leads to lots of carbon buildup on the chambers/valves, which will eventually require a tear down. Rid the piss out of it, and that won't happen.

70CB750 · « **Reply #22 on:** May 18, 2018, 06:04:54 AM »

Quote from: disco on May 18, 2018, 05:48:36 AM

Really? Maybe have another read.

Read it twice, still nothing. Here, found something for you

disco · « **Reply #23 on:** May 18, 2018, 06:11:07 AM »

That's the point. I'm not lugging it. I'm Doing 70mph not km/h. Yes you're right, It does come alive beyond 6K....funnily enough I have been there! What i was getting at, is that for prolonged highway use, it does become a chore at 6,000-7,000 rpm. Hence the question only for those that actually own a 750.....who has played about with sprockets?

disco · « **Reply #24 on:** May 18, 2018, 06:11:45 AM »

#$%* off dickwAd!

News:

Author Topic: 836cc sprocket advise (Read 3247 times)