Topic: Lowering the front end '77 750 forks

[Radski]

Ladies & Gents,

need your opinion here. Im using a pair of '77 CB750K forks on my '76 frame build. I've lowered the bike by pushing the forks through the triple however bc of the stock length and the extra height of the '77 legs.... the forks end up being like 3-3.5 inches above the top triple.

Besides getting 450 forks like I've been told, I've also been told that I can cut the '77 forks, both the tube and the spring. Is this true??

What are my options in getting a lower look with out having 3" pushing through the top triple?

[scottly]

The over-all length of K7 and K6 forks are about the same. The longer fork lowers have nothing to do with how much protrudes above the top triple, but may hit the bottom triple under compression.
IMHO, it's a bad idea to lower the bike that much.

[Radski]

The over-all length of K7 and K6 forks are about the same. The longer fork lowers have nothing to do with how much protrudes above the top triple, but may hit the bottom triple under compression.
IMHO, it's a bad idea to lower the bike that much.

I totally understand what you're saying but its the look I'm going for on this bike. What are my options in getting shorter forks (internal & external) or....?

[scottly]

Not really an endorsement from me, but Wilbur likes this method:
http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-shorten-forks-td4042465.html
PS Be careful going around corners.

[Tracksnblades1]

Ladies & Gents,

need your opinion here. Im using a pair of '77 CB750K forks on my '76 frame build. I've lowered the bike by pushing the forks through the triple however bc of the stock length and the extra height of the '77 legs.... the forks end up being like 3-3.5 inches above the top triple.

Besides getting 450 forks like I've been told, I've also been told that I can cut the '77 forks, both the tube and the spring. Is this true??

What are my options in getting a lower look with out having 3" pushing through the top triple?

What exhaust are you running...?

A 4 in 1 collected directly under the engine (Yoshi style) will touch down under heavy front brake usage before bottoming the forks, if you slide them up to far.

The original F1 triples prevent sliding the tubes up to far. Their handlebar mounts places the handle bar tube somewhat over the fork tubes limiting sliding the fork tubes up until they contact the handle bars. F2/F3 mounts the bars towards the rider eliminating this.

My lifelong buddy's old 75k had handle bar setback adapters that would allow sliding the fork up as high as one wanted. But, back then the other way +4,6,8 and pull backs were in vogue.

Watch your front brake hoses and their mounts if you go low. Big bumps and hard braking can rearrange things. An aftermarket oil cooler mounted may require special attention also when going low and not limiting front suspension travel.

[Radski]

Ladies & Gents,

need your opinion here. Im using a pair of '77 CB750K forks on my '76 frame build. I've lowered the bike by pushing the forks through the triple however bc of the stock length and the extra height of the '77 legs.... the forks end up being like 3-3.5 inches above the top triple.

Besides getting 450 forks like I've been told, I've also been told that I can cut the '77 forks, both the tube and the spring. Is this true??

What are my options in getting a lower look with out having 3" pushing through the top triple?

What exhaust are you running...?

A 4 in 1 collected directly under the engine (Yoshi style) will touch down under heavy front brake usage before bottoming the forks, if you slide them up to far.

The original F1 triples prevent sliding the tubes up to far. Their handlebar mounts places the handle bar tube somewhat over the fork tubes limiting sliding the fork tubes up until they contact the handle bars. F2/F3 mounts the bars towards the rider eliminating this.

My lifelong buddy's old 75k had handle bar setback adapters that would allow sliding the fork up as high as one wanted. But, back then the other way +4,6,8 and pull backs were in vogue.

Watch your front brake hoses and their mounts if you go low. Big bumps and hard braking can rearrange things. An aftermarket oil cooler mounted may require special attention also when going low and not limiting front suspension travel.

I recently had it together and running. Rode fine and I am aware that things can get a little hairy from being so low. But honestly it still had plenty of height. 
I'm running clip ons so I have plenty of space. Besides changing to 450 or 550 forks as has been suggested, then I'd have to get a new disc and caliper and my disc currently is sweet and drilled so I dont want to spent that kinda $ on replacing the whole front end.

I have a Cycle X Sidewinder on its way to me which fits nicely kinda under but more on the side I believe. I've seen this exact setup many times. Like I
ve said my issue was that I've used '77 forks which for some reason are quite long although someone said theyre the same height as the earlier models? I dont get it then why are these so tall?

[Scott S]

 Why can't you use the 750 caliper and rotor on the 550 forks? Isn't the caliper hanger the same?

[Radski]

Why can't you use the 750 caliper and rotor on the 550 forks? Isn't the caliper hanger the same?

Some one who was telling me the fitment of the 450/550 forks said that I would have to change. I have not confirmed this nor do I have that technical knowledge. I havent looked it up yet either

[Bankerdanny]

As far as I know you can use the single disk 750 setup on 550 forks. I think it is a slight upgrade in terms of pad size. You couldn't use 77-78 F rotors and calipers, but the setup from a single disk model should work fine.

[Radski]

As far as I know you can use the single disk 750 setup on 550 forks. I think it is a slight upgrade in terms of pad size. You couldn't use 77-78 F rotors and calipers, but the setup from a single disk model should work fine.

thats the issue with forum suggestions...sometimes you get spot on, and sometimes you may get slightly jumbled info. Thanks for your input

[754]

Early 450 forks lowers and brakes, same as 750 to end of 72, tube length for 450 , slightly shorter.

[Tracksnblades1]

I recently had it together and running. Rode fine and I am aware that things can get a little hairy from being so low. But honestly it still had plenty of height. 
I'm running clip ons so I have plenty of space. Besides changing to 450 or 550 forks as has been suggested, then I'd have to get a new disc and caliper and my disc currently is sweet and drilled so I dont want to spent that kinda $ on replacing the whole front end.

I have a Cycle X Sidewinder on its way to me which fits nicely kinda under but more on the side I believe. I've seen this exact setup many times. Like I
ve said my issue was that I've used '77 forks which for some reason are quite long although someone said theyre the same height as the earlier models? I dont get it then why are these so tall?

That sidewinder looks Sweet on cyclex web site. Looks like an old RC sidewinder with a modern muffler section instead of the classic full length megaphone. It looks like it has large primaries.  If you have a spare minute, measure the primary pipe's outside diameter for me. I've been measuring different headers primaries for comparison.

You can drop the rearend too. May help keep your fork geometry closer to stock. My buddies old 75k had the 16" rear wheel and lowering brackets on the factory shocks with a custom chain guard. I'd use shorter shocks nowadays, and check your chain and factory guard for interference.

You can remove the springs up front to mock up your bottomed out clearances. You can deflate your front tire some to get real precise.
 Logged

[madmtnmotors]

Not really an endorsement from me, but Wilbur likes this method:
http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-shorten-forks-td4042465.html
PS Be careful going around corners.

I am using this method on my drag bike. I am currently running a 2" spacer (effectively shortening the forks 2") but I did not cut the spring. This makes reassembly a little tight, and you have to be aware of the preload when disassembling forks done this way, but the extra preload on the springs helps prevent the shorter travel from bottoming out.

EZPZ 

[Radski]

Not really an endorsement from me, but Wilbur likes this method:
http://vintage-and-classic-honda-s.456789.n3.nabble.com/How-to-shorten-forks-td4042465.html
PS Be careful going around corners.

I am using this method on my drag bike. I am currently running a 2" spacer (effectively shortening the forks 2") but I did not cut the spring. This makes reassembly a little tight, and you have to be aware of the preload when disassembling forks done this way, but the extra preload on the springs helps prevent the shorter travel from bottoming out.

EZPZ 

excuse my ignorance...I'm not 100% on how the internals work, but how does adding a spacer but not shortening the springs give you a shorter fork? I'm confused.

[WhyNot2]

I just changed to a set of CB550 forks.

Lots of headache gone.

[scottly]

I'm running clip ons so I have plenty of space. Besides changing to 450 or 550 forks as has been suggested, then I'd have to get a new disc and caliper and my disc currently is sweet and drilled so I dont want to spent that kinda $ on replacing the whole front end.

Like I
ve said my issue was that I've used '77 forks which for some reason are quite long although someone said theyre the same height as the earlier models? I dont get it then why are these so tall?

The 550 fork tubes are about 1" shorter than the 750 tubes. I've had 750 K1, K7, and F2/F3 forks on my bike and they are all very close to the same length. Measure from the axle center-line to the top of the tube (not the top of the cap). Should be a touch under 30" IIRC.

[scottly]

As far as I know you can use the single disk 750 setup on 550 forks. I think it is a slight upgrade in terms of pad size. You couldn't use 77-78 F rotors and calipers, but the setup from a single disk model should work fine.

thats the issue with forum suggestions...sometimes you get spot on, and sometimes you may get slightly jumbled info. Thanks for your input

Your K7 caliper will mount onto 550 fork lowers with no problems. You must also use the compatible 750 rotor. 

[754]

You have a damper rod with bumper  spring. The top of  It's at the the bottom of your fork tube. Now push your forks down 2 inches..  then if you could install a spacer , it would stay there. .. the fork could not go back up the 2 inches
 So take forks apart , install the 2 inch spacer... now your spring will be sticking out of the top,  compress that enough to start your fork cap, once that is installed fork is 2 inches shorter, and has 2 inches less travel.

[madmtnmotors]

excuse my ignorance...I'm not 100% on how the internals work, but how does adding a spacer but not shortening the springs give you a shorter fork? I'm confused.

You have a damper rod with bumper  spring. The top of  It's at the the bottom of your fork tube. Now push your forks down 2 inches..  then if you could install a spacer , it would stay there. .. the fork could not go back up the 2 inches
 So take forks apart , install the 2 inch spacer... now your spring will be sticking out of the top,  compress that enough to start your fork cap, once that is installed fork is 2 inches shorter, and has 2 inches less travel.

This.

The location of the spacer limits the extension of the lower section by the amount of the spacer length.