Author Topic: 78 CB750K Cafe (Read 5013 times)

atilliar · « **on:** September 22, 2012, 03:46:57 PM »

A lot of work has been done so far...

Here is what it looked like when I got it:

I first changed the suspension and changed the mac for a Kerker exhaust and had the engine gone through and had the leaks fixed (I did everything but the motor work) Got the carbs cleaned and put the stock airbox back on it and put on rear sets:

I put on the clip-ons on next and in the process had to mount the headlight onto the forks. I also removed the blinkers, relocated the horns and changed the mirrors:

Now to where I am currently. I changed both tires and raised the front end about an inch from where it was (I moved the triple trees to the top of the fork tubes):

I have a new tank and seat for it and did a quick mock up a little while ago:

As soon as I get it painted they will go on and I also have a new side cover to replace the messed up one, also waiting to be painted. My front rotor is warped so I have ordered and ebc pro-light rotor for it and will throw it on as soon as I get it. I'll be sure to up date the post when those things happen.

SOHC4 Cafe Racer Fan · « **Reply #1 on:** September 23, 2012, 08:52:39 AM »

Looking good. I imagine you had to pull the mill to fix the leaks (huge PITA). Since you are going the Cafe route, why did you choose to go back to the stock airbox?

atilliar · « **Reply #2 on:** September 23, 2012, 09:56:43 AM »

It runs better as a bike with the stock airbox. Pods look cool but they are almost impossible to tune right, have flat spots when you accelerate and are generally a pain in the ass if you don't flow the heads so it can take advantage of opening the air intake. I don't have the knowledge or ability to flow the heads myself... or a flow bench.. and don't have the cash to have a shop do it. So I'll stick with what makes the bike run the best. After all, at least as far as I'm concerned making a bike a cafe is about performance and very little to do with just looks. That's why I updated the suspension, put clip-ons and rear sets on, tires, better exhaust (oh and with that I put in the 2" comp baffles), generally made the bike run great, raised the bike back up to handle better, and so forth. The only thing I am doing for looks on this thing is the different tank and seat. They would be an improvement if it was a stock setup when I got it but as it is now I can already get into a full tuck so it's just because I like the way the Benjie's stuff looks.

The only thing that I didn't do myself was pull the engine out and the the work on it. But it needed quite a bit of work

It needed new cylinders, rings and so forth as well as the transmission shaft was bent and was even just missing some parts (some clips to hold it all in place). The guy I had do the work said it looked like some one else went into the bike and didn't know what they were doing.

seanbarney41 · « **Reply #3 on:** September 23, 2012, 10:32:19 AM »

Quote from: atilliar on September 23, 2012, 09:56:43 AM

It runs better as a bike with the stock airbox. Pods look cool but they are almost impossible to tune right, have flat spots when you accelerate and are generally a pain in the ass if you don't flow the heads so it can take advantage of opening the air intake. I don't have the knowledge or ability to flow the heads myself... or a flow bench.. and don't have the cash to have a shop do it. So I'll stick with what makes the bike run the best. After all, at least as far as I'm concerned making a bike a cafe is about performance and very little to do with just looks. That's why I updated the suspension, put clip-ons and rear sets on, tires, better exhaust (oh and with that I put in the 2" comp baffles), generally made the bike run great, raised the bike back up to handle better, and so forth. The only thing I am doing for looks on this thing is the different tank and seat. They would be an improvement if it was a stock setup when I got it but as it is now I can already get into a full tuck so it's just because I like the way the Benjie's stuff looks.

The only thing that I didn't do myself was pull the engine out and the the work on it. But it needed quite a bit of work It needed new cylinders, rings and so forth as well as the transmission shaft was bent and was even just missing some parts (some clips to hold it all in place). The guy I had do the work said it looked like some one else went into the bike and didn't know what they were doing.

good choice on the airbox, rearsets, and shocks...don't care for the Benjies stuff, but I also hate brown seat covers...and you're right!, are looks really that important anyway?...nobody can see what the bike looks like anyway when it performs as it should

madmtnmotors · « **Reply #4 on:** September 23, 2012, 12:44:16 PM »

I think the sidecover emblems are from a 77'. The 78' and 77' sidecovers were the same except for the emblems. On a side note, what are your plans for the old tank and seat? I kind of like the shape of the tail on the seat that you removed.

liPPy · « **Reply #5 on:** September 23, 2012, 01:03:53 PM »

Looking good!

How are those Raask rear sets? Any problems with comfort or functionality? I have a k8 and they are on my winter "to do" list.

Also you talk about raising the rear suspension - did you longer than stock?

atilliar · « **Reply #6 on:** September 24, 2012, 02:02:05 PM »

The Raask Rear sets are nice but the instructions are pretty worthless are were a bit of a pain to install. They work great however and are comfortable.

As far as the rear suspension goes I didn't go longer than stock I just put it back to stock. The bike had been lowered by the previous owner.

As for the rear seat I am open to getting rid of it once I have changed everything over to the new stuff.

atilliar · « **Reply #7 on:** September 24, 2012, 02:05:30 PM »

Update:

On my way back from a ride today, as I was pulling into my apartment complex, the bike died and wouldn't restart. Right before it died it started running poorly. I'm thinking it is electrical as when I try to start the bike I don't get any spark. So I'll start going through that soon. What a pain...

madmtnmotors · « **Reply #8 on:** September 24, 2012, 05:35:57 PM »

I documented the process I used to refurbish the wiring harness of one of my current projects in another thread:

http://forums.sohc4.net/index.php?topic=113099.msg1271887#msg1271887

atilliar · « **Reply #9 on:** September 24, 2012, 06:32:33 PM »

Thanks mad I'll look at that. I did test the battery and found that it was just dead. I did a partial charge (enough to crank it) it and put it back on a voltage meter and found that before I cranked the bike it read 12.02 volts and when I cranked it it went down to 11.8. I revved the motor and it didn't change. The voltage stayed the same. I'm thinking that the charging system is bad.

Any thoughts?

madmtnmotors · « **Reply #10 on:** September 24, 2012, 06:50:51 PM »

Charging system issues could definitely cause the problem you describe. The battery is also part of the charging system and must be fully charged as well as be able to hold a charge. The alternators on these old bikes do not use a permanent magnet like newer charging systems do, but instead use an electro-magnet (field coil) that requires a full 12 volts to generate the magnetic field. I.E. a weak battery will never charge.

There are some static tests that can be done with a meter, so crack the manual and start probing! Electrical troubleshooting often requires determining what it's not.

Factory manuals can be found here: http://www.sohc4.net/index.php/cb750/cb750k/books-manuals-guides/

Keep us posted!

atilliar · « **Reply #11 on:** September 24, 2012, 06:55:46 PM »

That's good to know and I'll definitely keep you posted.

Thanks.

atilliar · « **Reply #12 on:** November 30, 2012, 05:44:35 AM »

Okay I got my issues all sorted out. I had to replace a burned up wiring harness and a rectifier. The stator was fine (thank goodness). Now the bike works great! No issues at all!

Now on to the asthetics. I hope I can get my new tank and seat painted and put on soon. Then I'll be at least as close to done as I can think of... for now... untill I want to dump some money into a big bore kit, cams, and have the heads flowed... Maybe mag wheels... or a gl1000 front end swap....

atilliar · « **Reply #13 on:** November 30, 2012, 06:09:55 AM »

Oh... I forgot. I got a new front disk rotor from ebc. It's very nice. So Hopefully I'll be getting that on soon. Had to buy a torque wrench... actually as I have tackled this project I have bought a lot of tools....

Now I just need a new set of pads and I can hammer that out. I'll make sure to post some pics of the new progress soon.

atilliar · « **Reply #14 on:** December 02, 2012, 10:23:47 AM »

Got the new pads on order so I should have the rotor on this coming week. Also I could use a decent/ clean front K fender if anyone has one.

Thanks.

SOHC4 Cafe Racer Fan · « **Reply #15 on:** December 03, 2012, 01:32:02 PM »

I was told that they no longer make an EBC rotor to fit the 69-78K models. Is this a bolt on replacement?

atilliar · « **Reply #16 on:** December 04, 2012, 05:32:45 AM »

Yeah EBC still makes one. Dynoman sells one. I haven't put it on yet but it's supposed to be just a bolt on replacment. I'll be sure to take some pics when I get them on and update the thread and talk about any issues (if any).

lucky · « **Reply #17 on:** December 06, 2012, 11:48:42 PM »

I like the rear tail section and lights you have installed.
Also I like the gold highlights on the air filter box.

Contrary to what many say the 1978 Cb750 can be made to run right with pods and aftermarket exhaust.
It is easiest if you get new slide needles with the 5 grooves on them. You can use 1976 needles also.

You would use 120 mains and #42 idle jets.
Clip on needles would need to be one groove down from stock.

atilliar · « **Reply #18 on:** December 08, 2012, 01:19:37 PM »

That's great to know, Thanks.

atilliar · « **Reply #19 on:** December 10, 2012, 01:22:07 PM »

Got the rotors and pads on yesterday.

New pads are still braking in but I can feel an improvement already, and of course it solved my issue with my other rotor being warped. That was my first time ever doing that so I'm pretty pleased how smooth it went.

racinchase · « **Reply #20 on:** December 10, 2012, 03:16:35 PM »

Looking great. It that the stock front fender?

atilliar · « **Reply #21 on:** December 11, 2012, 06:08:08 AM »

Thanks. And no, it was from a Kawasaki. The previous owner did that. I'm currently talking with another board member about getting a stock one. It wouldn't be so bad except they had to bend it and force it to fit and it shows up close.

atilliar · « **Reply #22 on:** December 12, 2012, 12:10:00 PM »

I just bought a new (to me) front fender for the bike from a forum member. Should be here on Saturday. I look forward to getting that on.

atilliar · « **Reply #23 on:** December 14, 2012, 05:35:06 AM »

I polished up the aluminum while bored at work (the perks of working at a bike shop!) and went to a local bike night last night. First time I have really taken the bike at any sort of bike gathering and it got the attention of everyone there.

Everyone was looking and admiring and asked questions. Pretty good feeling when people notice and acknowledge the work I've put into it. I'll post pics of the bike all polished up when I get home tonight.

atilliar · « **Reply #24 on:** December 14, 2012, 04:32:32 PM »

As promised:

News:

Author Topic: 78 CB750K Cafe (Read 5013 times)