need advice on damage fork and tank cb750k

Twinstar Joined: Jun 25, 2018 Posts: 31 Location: Quebec

Hello guys,

I went for a little ride today and got caught in pouring rain in the middle of the ride so I decided to turn around and head back home. As I was coming down a steep hill after a turn, the car in front of me decided to brake heavily so he could turn on another road and I saw it too late and locked both wheels only to slide and impact his trunk. I'm good but the bike now needs some work. Here's the visual damage :

- scratched stator cover
- broken right side flashers and headlight bracket
- 2 dents on tank
- bent fork tubes
- cracked throttle control

I don't really care about the stator cover as it doesn't seem to be cracked, flashers, headlight and throttle are relatively inexpensive but I'm concerned about the tank and the fork. I'd like to gather advices on what would be the best thing to do for both. For the tank, do you think those dents could be pulled out or should I just look for another tank? If I need to replace it, can I put any tanks from any cb500-1100 dohc?

As for the fork. The right side tube is visibly bent, can it be fixed or should I look into buying another set of tubes or maybe another fork completely? Would a fork from a F model or other newer honda be an upgrade I could look into? The bike is a 1979 CB750k

Cheers!

fork:
https://ibb.co/fXUH9U

tank:
https://ibb.co/dQZ0UU

Posted: Tue Oct 09, 2018 12:12 pm

Maximeg, sorry to hear about your unfortunate circumstances but happy you are alright. Those dents more than likely won't come back to perfect. Some work can be done to improve the depth but since it is creased in the dent, it's not going to come out well.

It looks like your tank is from an early DOHC, since it has emblems (missing as they might be) rather than the later DOHC with decals and a smooth surface.

I have an early 750F tank in good shape for sale, but am in the USA so shipping will be costly.
Also take a look at the forks you have, measure the tube diameter. I have a set of 750F forks in good shape for sale as well. They're 37mm OD tubes.

Twinstar Joined: Sep 25, 2010 Posts: 238 Location: Vermont

I may have a set of 1981 CB750K forks that you can have. They are straight, in ok shape, could probably use seals and bushings.

Where in Quebec are you located? Fancy a drive to central VT to pick them up?

Hawk Joined: Oct 12, 2014 Posts: 396 Location: Virginia

djf18374 wrote:

Maximeg, sorry to hear about your unfortunate circumstances but happy you are alright. Those dents more than likely won't come back to perfect. Some work can be done to improve the depth but since it is creased in the dent, it's not going to come out well.

It looks like your tank is from an early DOHC, since it has emblems (missing as they might be) rather than the later DOHC with decals and a smooth surface.

I have an early 750F tank in good shape for sale, but am in the USA so shipping will be costly.
Also take a look at the forks you have, measure the tube diameter. I have a set of 750F forks in good shape for sale as well. They're 37mm OD tubes.

A 750F tank is not the same as a K tank. This is beyond just the badges. You'll need to get a K specific tank (this also includes the L model tank). '79 thru '81 all will fit.

I also should have a set of 37mm forks free for the cost of shipping. If you are able to make the drive to get them from Adk_finn they will probably end up being cheaper.

Sorry to hear about your troubles, good luck.

Posted: Tue Oct 09, 2018 6:13 pm

I missed that the bike is a "K"

Yup, they have different tanks from the "F" bikes.

Posted: Tue Oct 09, 2018 9:12 pm

I have a spare k tank and will confirm it to be dent free this evening... but will require a full interior cleaning , sealing and new paint... unless you go will the stripped look again. I also have forks which were given new seals and other budget upgrades about 5 years ago (current status unconfirmed as they were swamped for Usd forks)

Twinstar Joined: Jun 25, 2018 Posts: 31 Location: Quebec

Wow, as a new member on this board, I'm astonished by the responses and everyone offering me parts to rebuild my bike. Thanks so much!

I did a bit of research and found this list referencing the different fork tube sizes. My bike seems to have the 35mm diameter fork so if I don't want to replace the whole triple crown then I would need to find another 35mm fork. I found one from a SOHC CB750F on ebay that looks like it would fit my bike and from a member on another forum, it also seems like it should fit the front spoke wheel and the front caliper of my DOHC K. The only thing is that the fork is 2" lower than mine but that's alright as I wanted to lower the front wheel anyway. Here's the fork I'm thinking about here

djf18374 wrote:

Maximeg, sorry to hear about your unfortunate circumstances but happy you are alright. Those dents more than likely won't come back to perfect. Some work can be done to improve the depth but since it is creased in the dent, it's not going to come out well.

It looks like your tank is from an early DOHC, since it has emblems (missing as they might be) rather than the later DOHC with decals and a smooth surface.

I have an early 750F tank in good shape for sale, but am in the USA so shipping will be costly.
Also take a look at the forks you have, measure the tube diameter. I have a set of 750F forks in good shape for sale as well. They're 37mm OD tubes.

Thanks for the insight, I'll definitely try pulling the dents to see how much I can remove, might try to cover the rest up with bondo and paint it but I'd rather replace it and keep it as a spare. I'd definitely take your F tank if it can be fitted to my K without too much effort. As for the fork, as mentionned above, I think I need 35mm for my bike.

adk_finn wrote:

I may have a set of 1981 CB750K forks that you can have. They are straight, in ok shape, could probably use seals and bushings.

Where in Quebec are you located? Fancy a drive to central VT to pick them up?

very nice of you to offer but the 1981's seems to be 37mm diameter and I would optimally need 35mm to keep my triple crown.

Alt1 wrote:

A 750F tank is not the same as a K tank. This is beyond just the badges. You'll need to get a K specific tank (this also includes the L model tank). '79 thru '81 all will fit.

I also should have a set of 37mm forks free for the cost of shipping. If you are able to make the drive to get them from Adk_finn they will probably end up being cheaper.

Sorry to hear about your troubles, good luck.

I've looked at pictures of cb750k and cb750f tanks and the difference seems to be very minimal. Can you tell me if the cb750f tank would fit with my cb750k grommets up front and the mounting bolt under the seat would line up or are they different length?

mwe wrote:

I have a spare k tank and will confirm it to be dent free this evening... but will require a full interior cleaning , sealing and new paint... unless you go will the stripped look again. I also have forks which were given new seals and other budget upgrades about 5 years ago (current status unconfirmed as they were swamped for Usd forks)

I'll look forward to your answer. Thanks alot!

Posted: Wed Oct 10, 2018 12:36 am

Fork tubes can be straightened. Finding some place that can do it could be a problem. Good luck.

Hawk Joined: Oct 12, 2014 Posts: 396 Location: Virginia

maximeg wrote:

Alt1 wrote:

A 750F tank is not the same as a K tank. This is beyond just the badges. You'll need to get a K specific tank (this also includes the L model tank). '79 thru '81 all will fit.

I also should have a set of 37mm forks free for the cost of shipping. If you are able to make the drive to get them from Adk_finn they will probably end up being cheaper.

Sorry to hear about your troubles, good luck.

I've looked at pictures of cb750k and cb750f tanks and the difference seems to be very minimal. Can you tell me if the cb750f tank would fit with my cb750k grommets up front and the mounting bolt under the seat would line up or are they different length?

The front grommets should line up okay, the length of the tank is not the same.

In regards to the SOHC tubes and compatibility brakes etc, anything can be made to fit. However, parts should be plentiful on these forums or ebay.

I double checked and I do have two 35mm forks but I'll have to locate the fork bodies as they were separated. If I have the bodies and you want them, they are likely from an F bike that had the dual front brakes. So you would have empty holes on the one side.

Posted: Wed Oct 10, 2018 2:53 am

I straighten fork tubes as long as there is no bulge on the tubes and no flaking of the chrome. Generally the bulge will be right under where the lower triple clamp holds it.

I can generally straighten them for about $85.00 if they come to me already apart. If you send them still together then it is a T&M job.

Peace, Jim

Twinstar Joined: Jun 25, 2018 Posts: 31 Location: Quebec

Alt1 wrote:

The front grommets should line up okay, the length of the tank is not the same.

In regards to the SOHC tubes and compatibility brakes etc, anything can be made to fit. However, parts should be plentiful on these forums or ebay.

I double checked and I do have two 35mm forks but I'll have to locate the fork bodies as they were separated. If I have the bodies and you want them, they are likely from an F bike that had the dual front brakes. So you would have empty holes on the one side.

I assume the F tank is the longer one as it appears slimmer than the K. I could only go maybe a 1/4" longer before I'd need to re-fabricate a seat so I guess I'll definitely need a K tank if I'm looking for an easy fix. I'll try to pull the dents out of mine this weekend and see if I can save it.

As for the forks, I'm very thankful you are offering me yours but I don't want you to get into the hassle of finding the bodies and boxing them to ship up to me if you don't want to. The ones I found on ebay amounts to a bit less than 100$ shipped to me and all I'll have to do is change the seals and the oil so I can deal with that unless you really want to get rid of yours Wink

JJam wrote:

I straighten fork tubes as long as there is no bulge on the tubes and no flaking of the chrome. Generally the bulge will be right under where the lower triple clamp holds it.

I can generally straighten them for about $85.00 if they come to me already apart. If you send them still together then it is a T&M job.

Peace, Jim

Hey Jim, thanks alot for offering but I think it would be less hassle to just switch out the forks lowers completely for now. I might get back to you later on if I decide to fix my bent forks! Cheers