Author Topic: How to make your 77-78 CB750K handle like a MODERN sport bike... (Read 28773 times)

manjisann · « **Reply #25 on:** May 17, 2009, 06:10:06 PM »

Quote

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

Thanks, I'll read that!

Assuming my stock springs aren't at the replace me level, would the emulator be the best for handling? I guess the biggest question is, do the progressive springs do the same thing as the emulator, so one is as good as the other if installed properly?

Thanks,

Brandon

MCRider · « **Reply #26 on:** May 17, 2009, 06:28:35 PM »

Quote from: manjisann on May 17, 2009, 06:10:06 PM

Quote
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

Thanks, I'll read that!

Assuming my stock springs aren't at the replace me level, would the emulator be the best for handling? I guess the biggest question is, do the progressive springs do the same thing as the emulator, so one is as good as the other if installed properly?

Thanks,

Brandon

IMO, if the stock springs are serviceable, I would go with the emulators. THe springs are not adjustable, the emulators are, or the Race Tech ones are.

There is a safety issue here, so I am biased. I came very near death with a 60mph tank slapper on my HawkGT. THe old style forks bottomed is a serious hole, which setup the tankslparrer, and I was spit off. The boys at HawkGT.com (very similar to this forum) taught me that the emulators come very near to eliminating tankslappers. Having since installed them, the ride quality was truly enhanced. And my confidence in riding the bike hard has returned. Although my tank slapper occurred in the most benign of circumstances. Going down the road, minding my own business, dropped in a hole, on the ground hard.

So, with all that in mind, I vote for the ems first.

XN · « **Reply #27 on:** May 18, 2009, 02:24:57 AM »

FYI underbid.com has progressive springs for $60.95

Just search for 111104

They actually came from MAW so ya can't go wrong.

ev0lution7 · « **Reply #28 on:** May 18, 2009, 07:08:14 PM »

well here is a pic of my current setup i have scrubbed the EDGE of my tire... down too the tip... this is a 130/90/17 and a stock ride height bike..

MCRider · « **Reply #29 on:** May 18, 2009, 07:45:38 PM »

The kids call that last little bit the "chicken strip".

ev0lution7 · « **Reply #30 on:** May 18, 2009, 07:53:44 PM »

IMO ....

this is possible the best handling bike i have ever had or ridden... its confident... smooth ... and very neutral feeling... my friend and I switched bikes the other day (07 sporty 883 EFI) and man his bike SUCKS!!! he was amazed on how much power my bike had how nice the suspension was and the overall feel of the bike... this truely was a big compliment to me!! i'm excited the rear shocks were the icing on the cake i'm still waiting for the fork brace... and the new EBC rotor but its pretty much done...

i have the sisy bar on there for the Ride-A- Mucha (in winemucha, NV) next weekend i'm goign up with the sohc chopper guyz!!! my friend and i are going (the one with the 07 sporty) i was trying out loading up the bike with the tent and sleepign bag and what nots!

SO! is that "chicken" strip pretty close to the edge for a cb750?

MCRider · « **Reply #31 on:** May 18, 2009, 07:59:47 PM »

I love your bike and I love that you love it!

Over the years I've learned it's often best to maximize the original design through attention to detail and the best materials, rather than redesigning it and possibly going backwards.

Not always, but often.

Generally the chicken strip can only be eliminated on the track and that's with some loss of traction, so... you're doin just fine!

78CB750CAFE · « **Reply #32 on:** May 19, 2009, 06:39:03 AM »

OH MAN, OH MAN, OH MAN.....

UPS says the fork brace will be here today

I really hope a PO didn't swap out my triple trees to another years... never bothered to measure, and nothing would surprise me with this bike.
Hope they fit forks and fender....

When I get my brakes (and balls) up to snuff we should see who could kill the chicken strip on our 130 tires first

mec · « **Reply #33 on:** May 19, 2009, 07:16:48 AM »

Quote from: ev0lution7 on May 18, 2009, 07:08:14 PM

well here is a pic of my current setup i have scrubbed the EDGE of my tire... down too the tip... this is a 130/90/17 and a stock ride height bike..

"How to make your 77-78 CB750K handle like a MODERN sport bike..."
http://forums.sohc4.net/index.php?action=dlattach;topic=51175.0;attach=77645;image

would be better to mount the rear damper spring the other way round...............................will help reduce unsprung weight.

mec

ev0lution7 · « **Reply #34 on:** May 19, 2009, 09:05:23 AM »

that "little" amount isnt going to make much difference for me i'm not racing my bike

78CB750CAFE · « **Reply #35 on:** May 19, 2009, 03:16:23 PM »

My Tarrozi brace came in today, went on smoothly, and made an INCREDIBLE difference!
Tracking and control greatly improved, an over-all more "solid" feel, and considerably less bar vibration and hand numbness are the first impressions I have after about 60 miles today.
Tomorrow I am going to raise my front end a little, I currently have the top tree about 1.25" down, I will probably go to between 1/2 and 3/4 inches of drop... just fine tuning.

So far well worth $100

aussie · « **Reply #36 on:** May 22, 2009, 03:54:18 AM »

Reading this post with interest, i may be able to help a few blokes out that don't want to spend any money on springs.

A trick we use and a lot of suspension shops use is, cut off the progressive part of the spring.Then cut a piece of electrical conduct, ( heavy wall and the same approx diameter of the spring) to the same length as the piece cut off and reinstall ( you can play around with different lengths of conduct,to tailor how firm you want your springs). Only if you are going to use emulators.

I have to laugh thou, when some have said there CB is the best handling bike they have ever ridden.

Retro Rocket · « **Reply #37 on:** May 22, 2009, 04:50:11 PM »

Quote

I have to laugh thou, when some have said there CB is the best handling bike they have ever ridden. Grin Grin Grin

Spot on Aussie, it takes quite a bit of work to make these bikes handle well and even the best handling 750 will not compete with a modern sports bike.

Mick

turin39789 · « **Reply #38 on:** June 09, 2009, 05:58:29 AM »

I'm running an F3 frontend for the dual discs, does anyone know of an emulator for these forks? Racetech only lists the F starting in 79, not 78 - will the K emulator work?

MCRider · « **Reply #39 on:** June 09, 2009, 06:25:39 AM »

Quote from: turin39789 on June 09, 2009, 05:58:29 AM

I'm running an F3 frontend for the dual discs, does anyone know of an emulator for these forks? Racetech only lists the F starting in 79, not 78 - will the K emulator work?

Bummer hadn't noticed that. Still the fiche lists the important parts of the 78 K & F as the same, dampers, springs, etc. Worth giving RaceTech a call. They are really hyping their involvement in Vintage /AHRMA applications, so I think its a website oversite.

With the emulators, one effectivley disables the stock damper rod by drilling huge holes in it anyway.

Seems from reading and cross-reading that all 35mm damper rod forks of that era may take the same emulator. Would be good to get some confirm on that and not just guess.

HavocTurbo · « **Reply #40 on:** June 09, 2009, 09:25:16 AM »

FYI

Progressive doesn't sell straight wound springs to just any dealer. They will have to be special ordered for each application and can cost more than stock replacements.

So if emulators aren't in your design the standard progressive rate springs will work just fine.

Also: Evo if you are in need of a damper I might be able to get a set-up for you. I'll need fork OD and a specific length for mounting.

78CB750CAFE · « **Reply #41 on:** June 12, 2009, 11:13:02 AM »

FYI

Progressive doesn't sell straight wound springs to just any dealer. They will have to be special ordered for each application and can cost more than stock replacements.

I got mine on ebay from a dealer who custom ordered them for someone who bagged on them...
Paid less then the standards go for and they were made for someone who weighs the same as me, so I scored big time

caferacer750 · « **Reply #42 on:** July 06, 2012, 07:31:30 AM »

i add a steering damper and all the other part listed and wow the bike is great

Itwillbefun · « **Reply #43 on:** August 30, 2012, 10:21:35 AM »

Quote from: caferacer750 on July 06, 2012, 07:31:30 AM

i add a steering damper and all the other part listed and wow the bike is great

Which damper did you go with?

Justin

lucky · « **Reply #44 on:** August 30, 2012, 03:18:51 PM »

Quote from: caferacer750 on July 06, 2012, 07:31:30 AM

i add a steering damper and all the other part listed and wow the bike is great

Only the "modern" sport bike needs a steering damper because the rakes are so steep. 24º in some cases.

The CB750 never needed one . It is not an issue.
The CB750 had 3.7 inches of trail. 27º-28º rake depending on model and year.
It had enough offset too.

Retro Rocket · « **Reply #45 on:** August 30, 2012, 04:10:26 PM »

Quote from: lucky on August 30, 2012, 03:18:51 PM

Quote from: caferacer750 on July 06, 2012, 07:31:30 AM
i add a steering damper and all the other part listed and wow the bike is great

Only the "modern" sport bike needs a steering damper because the rakes are so steep. 24º in some cases.

The CB750 never needed one . It is not an issue.
The CB750 had 3.7 inches of trail. 27º-28º rake depending on model and year.
It had enough offset too.

Lucky, i understand that you try to help with your advice but thats not correct, the K's had under 4 inches of trail which isn't much at all. I have owned some very well set up Honda 4's and i can tell you from personal experience that a steering damper is a great addition on these old bikes. It matters not what the offset numbers are when looking at the way the front end behaves, its all about trail, there are modern sport bikes with less rake but look at the offset and they are relatively small numbers like 30-35mm, that brings trail back to around 4 inches + which is critical for stability. My old 1988 gsxr1100 had nearly 4.5 inches of trail {116mm}and came stock with a steering damper. You only need to experience a tank slapper once on one of these heavy old girls to understand the benefits of a steering damper. I use them on ALL my old Honda's... You'll also see that in later models, Honda decreased offset which added trail, they did this for a reason....

MCRider · « **Reply #46 on:** August 30, 2012, 04:50:35 PM »

Gotta go with RR on this one. A steering damper is a huge improvement on a CB750. Personal first hand experience.

Just don't use it as a substitute for everything else being correct. But once that's sorted, add a damper and enjoy.

On many models (my CB750K2) there is a threaded lug on the lower triple tree for the damper.

On my 1968 CB77 there's a factory steering damper. Hardly a modern sport bike.

DORIGTT · « **Reply #47 on:** September 04, 2012, 08:32:06 PM »

What size tire should I run to 'handle like a MODERN sport bike...' on my '73 CB750?

MCRider · « **Reply #48 on:** September 04, 2012, 08:41:28 PM »

Quote from: DORIGTT on September 04, 2012, 08:32:06 PM

What size tire should I run to 'handle like a MODERN sport bike...' on my '73 CB750?

You are limited by the rim widths. If stock, a 100 on the front and a 120 on the rear is about tops. If the bike is otherwise un modified, I'd go with a 90 on the front and a 110 on the rear.

mac_48 · « **Reply #49 on:** October 05, 2012, 12:44:37 AM »

I am thinking about going with emulators, dual discs, etc. for my front end, but why not just go with a gsxr front end instead? Is the price difference really all that much when you add up the cost for dual discs, emulators, etc. to upgrade the front end? I haven't gone through the pricing of it all but it seemed like it would end up with not that much of a difference... also, are the aftermarket triples for these bikes strong enough that you don't even need the fork brace? I am completely new to these bikes so excuse me if I am way off here....

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Author Topic: How to make your 77-78 CB750K handle like a MODERN sport bike... (Read 28773 times)

ev0lution7

ev0lution7

ev0lution7