Author Topic: How to make your 77-78 CB750K handle like a MODERN sport bike... (Read 28811 times)

ev0lution7 · « **on:** May 10, 2009, 10:42:31 PM »

1. Install ALL BALLZ tappered roller bearing kit in the tripple tree
2. Install HONDAMAN.. Oil lite bronze swing arm bushing kit...
3. Change Fork oil (i used 10W Motul Fork oil.. but see notes)
4. Check and or REPLACE wheel bearings.. (you wouldnt one of these failing in a HIGH "g" corner

)
5. Install Progressive front fork springs...
6. Install Fork Brace... (Fastfromthepast.com #22-0037)
7. Install Progressive rear shocks (12 series or equivelent)
8. Install Dunlop D404 tires (130/90/17 Rear or 100/90/19 Front) you can go stickier but they wear out faster!
9. Inflate tires.... (37-40 PSI rear) (28-32 PSI front) depends on rider weight (see notes)

NOTES:

Fork oil is a personal setting you will need to adjust amounts and WEIGHT for rider weight and comfort i'm about 190lbs. so 10 weight is about right...

as far as wheel bearing go i just replaced all of mine while i had the wheels off just as a saftey measure my bike sat since 92

they were cheeeep!!! only about $5 ea so i went ahead...

tires... those tire sizes made a really positive feel to the bike... its very responsive and very stable at TON UP and above!!!! and i chose dunlops due to price/ value.. i could of gotten a V rated tire that was stickier but they dont last as long...

Tire pressure... i've been fighting weird handeling on this bike for a month now and finally i tried running the tires at 28-30 psi like the book says and have been fighting wobble and unstable leans and the rear of the bike feeling like its slidding out .... so i tried 40PSI and in the rear and checked the front (30psi) and BAM the rear end feels GREAT!!! no more wash out feeling and it feels really stable...

as far as shocks go for the rear you will have to play with pre-load for your weight and style...

overall my bike looks like an OLD stock cb750 but it handels like a NEWER modern sport bike...

everything i've done keeps the bike looking original but still is more modern.. my dream bike was the HONDA 919 but i could have a reliable cb750 for $400 and some fixer up parts and bam looks sorta like a 919

i realize that you can put rear sets on install clip-ons or low profile bars ect.... but that is not what i wanted i like the STOCK look but with a more modern flare... again these mods are what i did on MY bike you might want to change some things to make it more suitable for your weight and style of ridding this should be taken as a guideline... not set in stone.... take in to account that i'm not a profesional suspension setup guy i just used OFF the shelf parts and got the bike ridding like a cruizer down the freeway and keep up with the BIG BOYS in the canyons!! this bike HAWLS A#@ it feels super smooth @ 2x times posted in turns and OVER!!! it pulls T0N UP easy and SMOOTH heck i pulled over 95 in a 55mph turn and it just got it up like no problem i had to blink and do a double take... and i just couldnt believe i was on a CB750.... it was crazy .....

enjoy!!! PM me if you have any questions!!!

seaweb11 · « **Reply #1 on:** May 10, 2009, 10:51:22 PM »

Add a steering damper and your done

ev0lution7 · « **Reply #2 on:** May 10, 2009, 10:56:01 PM »

http://www.spec2.com

the PN# FS4 $129.95 for the fork brace

well i havent used a stearing dampner for mine yet but its next on my list... i'm not sure now that i inflated my rear tire to 40psi that i need it... it feels SUPER stable and smooth in the corners i hit some huge bumps and dips and choppy pavement and it NEVER wobbled in 16 miles of solid FLOGGING in the corners!

but i will try it for sure!

I will note that i'm running just about everything stock... (stock bars, pegs, ect...) besides the above mentioned parts

eurban · « **Reply #3 on:** May 13, 2009, 07:03:47 PM »

Good info! Couple of things. . . . . .

Consider upgrading your front fork's internals to a "modern" setup with a cartridge emulator kit. Properly set up front forks with springs, fork oil level / weight and an emulator will transform both the handling and comfort performance of our dinosaur front forks. Racetech (www.racetech.com) can provide the emulator kit, single rate springs and oil recommendations. Mikexs (www.mikesxs.net) offers a less expensive emulator kit for the xs650 that some here have found to be suited to the 750s forks. Never heard a full report though. I have used the racetech product on an old Kawi with excellent results. I will be upgrading my GL front end with emulators as soon as i can find the time and $.

Perform a careful front to rear alignment. My 78 project bike's alignment marks on the swingarm are a good bit off. Using string looped around the front and rear wheels it is possible to do an accurate alignment that assures that the rear wheel is pointed straight ahead. This can make a noticeable improvement in handling.

Setup up your suspension for sag etc. Go here for a good write up: http://www.yssusa.com/suspension_problems.html

If you really want "modern" handling then consider rear shocks with more adjustment and performance. YSS, Worksperformance, Wilbers, Hyperpro, and Racetech etc make shocks that will allow you to adjust preload, compression and rebound.

MCRider · « **Reply #4 on:** May 13, 2009, 07:52:28 PM »

Quote from: eurban on May 13, 2009, 07:03:47 PM

Good info! Couple of things. . . . . .

Consider upgrading your front fork's internals to a "modern" setup with a cartridge emulator kit. Properly set up front forks with springs, fork oil level / weight and an emulator will transform both the handling and comfort performance of our dinosaur front forks. Racetech (www.racetech.com) can provide the emulator kit, single rate springs and oil recommendations.

SNIP

+1 on the emulators (and everything else said, but especially the emulators.) Keeps stock appearance but vastly improves the front fork. Not only for performance but for safety.

The pre-cartridge forks could bottom, with deadly tankslapper results. Don't ask me how I know. The emulators are proven to greatly reduce this.

Good work EVO on this thread and the braking thread. Thanks!

ev0lution7 · « **Reply #5 on:** May 13, 2009, 08:34:42 PM »

well yesterday i setup for a 95+MPH run though a 35MPH corner (down hill left hand turn...)

so i downshifted held the rev's countersteer'd in and hung on and WOW i was supprised i drug the peg (left side) (2nd time that day) and it still wanted to go MORE after i left the turn!!! it was CRAZY!!! smooth

ya i know emulators will make a big difference... but you guys are missing the point i did these mods on the CHEAP! not with some race budget... and the average joe is not goign to know how to setup his suspension "right" i was just pointing them in the right direction to get things "happy"

noisebomb · « **Reply #6 on:** May 13, 2009, 10:06:11 PM »

Thanks for the info. I wasn't sure if I should go through with the fork rebuild, and the steering bearings, but this post convinced me.

eurban · « **Reply #7 on:** May 14, 2009, 04:52:22 AM »

Quote from: ev0lution7 on May 13, 2009, 08:34:42 PM

ya i know emulators will make a big difference... but you guys are missing the point i did these mods on the CHEAP! not with some race budget... and the average joe is not goign to know how to setup his suspension "right" i was just pointing them in the right direction to get things "happy"

Race budget?? Actually it sounds like you have spent some good $ on your swingarm rebuild, tires, rearshocks, fork brace etc etc. Check out the emulator kit at the Mikesxs site . .$50. Looks to be a copy of racetech's products. If it works like the racetech's products it should provide ample bang for the buck. Also the average joe doesn't know how to maintain / rebuild a 30 year old motorcycle, but if they choose to buy one they will typically learn. Setting up your suspension and performing a careful alignment isn't particularly difficult; the info is out there and the process would likely be easier than a carb rebuild for the average joe. Well worth the time in my experience.

Buber · « **Reply #8 on:** May 14, 2009, 05:02:51 AM »

Quote from: ev0lution7 on May 10, 2009, 10:56:01 PM

well i havent used a stearing dampner for mine yet .....

Just being picky

- it's steering damper.

ev0lution7 · « **Reply #9 on:** May 14, 2009, 03:44:14 PM »

most of the stuff i did was pretty easy with hand tools

the swing arm hondaman did for me
and the roller bearings were easy
the fork springs i put in while the bike was on the side stand
tires were pretty easy i took them to a shop...

most things i've done on a budget 1 step at a time..

78CB750CAFE · « **Reply #10 on:** May 15, 2009, 12:35:26 PM »

aside from the Hondaman swing arm mod and fresh wheel bearings, I am running everything you mentioned (still waiting for fork brace... grumble grumble) and the difference is night and day.

+1 bazillion on the following mods:
Race Tech emulators
Progressive suspension springs and shocks
All Ballz bearings

I also rock air caps on my forks for further fine tuning
AND... DON'T FORGET TO TRUE, TENSION AND BALANCE YOUR WHEELS CORRECTLY!!!!!

78CB750CAFE · « **Reply #11 on:** May 15, 2009, 12:36:47 PM »

speak of the devil...
Just got an email from Fast from the Past saying my fork brace is on the way!!!!

YAYYYY!!!!!!!!

manjisann · « **Reply #12 on:** May 17, 2009, 08:35:15 AM »

Great post, getting ready to redo my 650, want to keep the stock look sorta but with modern safety. You mentioned $5 for the wheel bearings, were these the sealed ones like All Ballz has, or the old bb ones? Where did you get them?

The oil in the forks, is it the higher the number the stiffer it will be, or the other way? Where does one pick up the progressive springs for the forks? I've seen replacement springs on Z1's site, but I think they are just stock replacements.

My rims are DID, so no spokes. To "true" them am I just looking to be sure that the rear wheel is straight with the chain tensioners?

If you had to choose between the emulators and the progressive springs (budget you understand) which is gonna give the biggest improvement?

Sorry for the barrage of questions, and thanks in advance for the help.

Brandon

MCRider · « **Reply #13 on:** May 17, 2009, 09:25:16 AM »

If I may: higher number = thicker oil.
progressively wound springs = progressivesuspension.com and their many distributors.
CHoosing on a budget=springs and oil.
Emulators should be accompanied with new springs. = higher cost.
RaceTech recommends straight wound springs with emulators as the progressivity comes from the emulator.
Save up for the emulators if possible.
IMO YMMV

78CB750CAFE · « **Reply #14 on:** May 17, 2009, 10:20:52 AM »

In my opinion I think if your stock springs are within spec, get the emulators, and fresh springs when you need them.

real budget improvement would be new seals, dust caps and oil.

MCRider · « **Reply #15 on:** May 17, 2009, 10:28:25 AM »

Quote from: 78CB750CAFE on May 17, 2009, 10:20:52 AM

In my opinion I think if your stock springs are within spec, get the emulators, and fresh springs when you need them.

real budget improvement would be new seals, dust caps and oil.

Yup

noisebomb · « **Reply #16 on:** May 17, 2009, 01:44:58 PM »

So, concerning the front springs, how do you check them to see if they are "in spec"?

manjisann · « **Reply #17 on:** May 17, 2009, 01:55:23 PM »

Well, thats cool, the one guy had the emulators listed at 59.99, and springs were more than that. Does anyone know if the XS650 emulators would work in a CB650? It also talks about drilling the damper rod, can anyone shed some light on that? I'll have to measure my springs, already got the kit to do the seals as one side is leaking.

Thanks,

Brandon

MCRider · « **Reply #18 on:** May 17, 2009, 02:23:15 PM »

Quote from: noisebomb on May 17, 2009, 01:44:58 PM

So, concerning the front springs, how do you check them to see if they are "in spec"?

THe length. My Clymers lists the CB750 "replace if less than 495mm".

MCRider · « **Reply #19 on:** May 17, 2009, 02:25:33 PM »

Quote from: manjisann on May 17, 2009, 01:55:23 PM

Well, thats cool, the one guy had the emulators listed at 59.99, and springs were more than that. Does anyone know if the XS650 emulators would work in a CB650? It also talks about drilling the damper rod, can anyone shed some light on that? I'll have to measure my springs, already got the kit to do the seals as one side is leaking.

Thanks,

Brandon

There is a discussion with diagram and example on this thread. THe idea is that you render the existing damping worthless.
http://forums.sohc4.net/index.php?topic=43972.msg457451#msg457451

noisebomb · « **Reply #20 on:** May 17, 2009, 02:26:11 PM »

Thank you sir. Guess I should measure the old ones before I buy new ones.

MCRider · « **Reply #21 on:** May 17, 2009, 02:34:09 PM »

Quote from: noisebomb on May 17, 2009, 02:26:11 PM

Thank you sir. Guess I should measure the old ones before I buy new ones.

THing with factory suspension componenets of that era, they were mostly junk in the showroom, front and rear. If you have any miles on it at all, 10,000+, its a safe bet they need to be replaced. But doesn't hurt to measure and do the drill.

What I dislike about many of the manuals numbers, they are the "replace at" number. THey don't tell us what a new one should measure so you can judge how much service life may be left. The difference between new and actual, relative to the replace at number.

noisebomb · « **Reply #22 on:** May 17, 2009, 02:42:07 PM »

Fair enough. So, according to what you are saying, if going the emulator route, which I am, the Progressive springs are not ideal?

MCRider · « **Reply #23 on:** May 17, 2009, 02:59:45 PM »

Quote from: noisebomb on May 17, 2009, 02:42:07 PM

Fair enough. So, according to what you are saying, if going the emulator route, which I am, the Progressive springs are not ideal?

http://racetech.com/HTML_FILES/EMULATORGV.HTML

That's just something on emulators.
TO your question, I can't find where I read it, but Race TEch suggests and sells straight rate springs with their emulators. The emulator gives the progressivity.

Since you may not buy from Race Tech, I don't know what the other brands of emulators may suggest. I think that Progressive Suspension sells both progressive winds and straight winds. But you'll have to check.

I don't think it could hurt to put a progressive wind in with the emulators. I'm sure someone has done it.

noisebomb · « **Reply #24 on:** May 17, 2009, 05:38:57 PM »

So, to follow up, I did a bit o' searchin' on the web, and everything I found supports the idea that mixing progressive wound springs AND valve emulators is not a great idea. It evidently makes the forks feel "mushy" (quite the technical term). The progression of the springs and the emulators cancel each other out.

Race Tec sells straight rate springs based on your riding style and weight for @ $110. Not too much more than the progressive ones.

Just in case anyone else was wondering...

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Author Topic: How to make your 77-78 CB750K handle like a MODERN sport bike... (Read 28811 times)

ev0lution7

ev0lution7

ev0lution7

ev0lution7