Author Topic: Restoring my k0 cb750 (Read 21990 times)

Don R · « **Reply #25 on:** October 14, 2013, 10:35:17 am »

It may be true that you will be ahead with a different engine. A mechanic will sometimes exaggurate (sp?) to make his point. I fail to see the cylinder problem but I can see how a bent crank could wobble the bearings.

Cragdog · « **Reply #26 on:** October 14, 2013, 11:32:03 am »

So I still haven't found a rotor puller yet, anyone here have the 20mm one needed for this model (70cb750)? Also, I need to order an alternator/rotor assembly, mine is bent and beaten up... Anyone know of a good place to maybe pick one up for under an arm and a leg? Do you need the special rotor puller tool to reinstall a rotor??? Or does it just slide right on and tighten with the bolt?
Yeah, I'll post some pictures of the cylinders, they looked okay to me, let me know if anyone sees anything I don't. I did notice the the outer cylinder valves were a bit "wet" especially cylinder 4. Should I have any concerns about that?

Cragdog · « **Reply #27 on:** October 14, 2013, 11:39:01 am »

I'm still trying to figure out this photobucket thing so bear with me if I mess up adding photos. Sorry!

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Cragdog · « **Reply #28 on:** October 14, 2013, 11:45:56 am »

Here's cylinders 2 & 3.

Cragdog · « **Reply #29 on:** October 14, 2013, 11:53:19 am »

I'm getting tired of this photo issue, but if it shows up, this is cylinder 4, it was the most "wet" I know this one's a nit out of focus, sorry, but anyone see any issues here??

Cragdog · « **Reply #30 on:** October 14, 2013, 11:56:33 am »

Cylinder 4! God I hate computers sometimes!

Cragdog · « **Reply #31 on:** October 17, 2013, 12:33:42 pm »

Hey guys, does anyone here have the correct rotor puller for this model and would be willing to let me borrow it?
I can't justify spending $20 on a tool I will probably only use once... I'll send it back and it'd really help me out. Send me a PM if willing. I'm kinda stuck where I'm at until I can remove the rotor. Thanks

01Thomas · « **Reply #32 on:** October 20, 2013, 05:37:30 am »

Hi Mr. Cragdog
I believe (!) you can use the rear wheel axle as a rotor puller? Try it and tell us?

regards
Thomas

754 · « **Reply #33 on:** October 20, 2013, 07:41:33 am »

I think the pullers are as low as 20 bux. If you use the axle you may bend it. Some guys use a bolt but end must be squared up.
Why is the cylinder and head still attached?

Greggo · « **Reply #34 on:** October 20, 2013, 08:11:26 am »

I'm betting your bike has a motor in the low twenty thousands, correct? The head appears sandcast, and has the boss for the extra head bolt, but it's before they started actually drilling/tapping them.

Cragdog · « **Reply #35 on:** October 20, 2013, 12:00:22 pm »

Quote from: 754 on October 20, 2013, 07:41:33 am

I think the pullers are as low as 20 bux. If you use the axle you may bend it. Some guys use a bolt but end must be squared up.
Why is the cylinder and head still attached?

Yeah I ordered one earlier today. Hopefully shows up soon! Cylinder and head are still attached because they came off the motor that way, it separated at the base of the cylinders. I was getting some flack earlier on about taking stuff off anyway so I haven't done anymore engine disassembly. I'm also working on getting a gt550 triple 2 running at the same time so my time has been focused on that while waiting to get this rotor off. I gotta find someone with a dial indicator or buy one to figure out this crank issue anyway, I don't have any of these specialty tools so I'm waiting on that to move forward on the cb. There's always something to do between my bikes and my friends bikes that my bc isn't getting the attention I'd like to give to it. $:-\$

Quote from: Greggo on October 20, 2013, 08:11:26 am

I'm betting your bike has a motor in the low twenty thousands, correct? The head appears sandcast, and has the boss for the extra head bolt, but it's before they started actually drilling/tapping them.

Correct! It is low 20k, but it was my understanding that sandcast only went up to about 7,500 or so.. Either way this bike is special to me and I just want to feel her ride again! Makes me sad I haven't had the resources to get her running as quickly as I'd like. Fortunately my 83 shadow is holding steady as my solid everyday rider.

Greggo · « **Reply #36 on:** October 20, 2013, 01:14:09 pm »

Quote from: Cragdog on October 20, 2013, 12:00:22 pm

Quote from: Greggo on October 20, 2013, 08:11:26 am
I'm betting your bike has a motor in the low twenty thousands, correct? The head appears sandcast, and has the boss for the extra head bolt, but it's before they started actually drilling/tapping them.

Correct! It is low 20k, but it was my understanding that sandcast only went up to about 7,500 or so.. Either way this bike is special to me and I just want to feel her ride again! Makes me sad I haven't had the resources to get her running as quickly as I'd like. Fortunately my 83 shadow is holding steady as my solid everyday rider.

Sandcasting for the cases ceased at 7414, but the head and cylinders were still sandcast until the 2xxxx range, I believe shortly before the extra bolt hole was drilled and tapped. If you have later 750, compare the texture of the head and cylinders and you'll clearly see the difference. The head definitely looks sandcast.

754 · « **Reply #37 on:** October 20, 2013, 01:20:32 pm »

Start looking at. It like this shop time is 65.00 an hour or a lot more..
Sooo buying the odd tool for 20 bux.. (That you will probably use again).. Is going to be a worthwhile investment..
I think all heads are sandcast till at least in of K2, if not further..and the hole is drilled, not tapped.

Greggo · « **Reply #38 on:** October 20, 2013, 01:44:17 pm »

Quote from: 754 on October 20, 2013, 01:20:32 pm

Start looking at. It like this shop time is 65.00 an hour or a lot more..
Sooo buying the odd tool for 20 bux.. (That you will probably use again).. Is going to be a worthwhile investment..
I think all heads are sandcast till at least in of K2, if not further..and the hole is drilled, not tapped.

The hole in the head is drilled, and the hole in the cylinders is drilled, and tapped, no?

This is from the SOOC site:

I believe this later casting commenced in the area of VIN 149xxx and ran until VIN 22xxx. After this VIN, provision was made for an additional bolt in the casting to answer an oil seepage problem, which was characterisitc of these early engines. I also understand about this time, all heads were manufactured using a die casting process in lieu of the sand casting process used up unitl this time. Certainly, there is no mistaking the sandcast heads from die cast heads.

I think there's an extra X in that first figure, which would indicate the bolt boss appeared around 14,900.

754 · « **Reply #39 on:** October 20, 2013, 03:47:56 pm »

I noted the casting info on the heads, so you are saying approx 14,9 -22, have an undrilled boss that could be cut for the hole?

Greggo · « **Reply #40 on:** October 20, 2013, 05:34:17 pm »

Quote from: 754 on October 20, 2013, 03:47:56 pm

I noted the casting info on the heads, so you are saying approx 14,9 -22, have an undrilled boss that could be cut for the hole?

Exactly.

Cragdog · « **Reply #41 on:** October 21, 2013, 10:19:27 am »

Where exactly is this extra bolt hole you speak of? I find this interesting, I always thought the heads looked to be a different casting, but I know little of casting in general.. Good info guys, thanks!

Greggo · « **Reply #42 on:** October 21, 2013, 07:18:09 pm »

Quote from: Cragdog on October 21, 2013, 10:19:27 am

Where exactly is this extra bolt hole you speak of? I find this interesting, I always thought the heads looked to be a different casting, but I know little of casting in general.. Good info guys, thanks!

The boss is just below the cam chain, but the hole isn't drilled. Earlier heads don't have that casting at all, as shown in the second picture.

Cragdog · « **Reply #43 on:** October 23, 2013, 01:50:45 pm »

Hey guys, does anyone know where a good place to get the left side alternator cover that fits my k0? I found a couple NOS ones on eBay but for $369!!! I am in no position to pay that much and there's gotta be some other options out there right? Thanks again for all your help.

Greggo · « **Reply #44 on:** October 23, 2013, 01:59:04 pm »

I have a couple from later years, but they're not perfect. I'm also not sure if there are subtle differences between them, and the K0's. They would both clean up with a sandblasting/primer/paint job.

Cragdog · « **Reply #45 on:** October 23, 2013, 05:04:46 pm »

So the puller came in today! But I still can't seem to figure out why the rotor isn't coming off, even used my impact wrench and the thing ain't popin off. Anyone have any insight on this? I must be missing something...

Cragdog · « **Reply #46 on:** October 23, 2013, 05:58:14 pm »

Strike that, reverse it.
My wrench was underpowered, came off after a few more tries. Still gotta wait a couple days for the dial indicator to come from harbor freight so I can measure the runout on the crank. Any of you know what measurements I should be looking for once I get there?

754 · « **Reply #47 on:** October 23, 2013, 08:53:39 pm »

After you torqued it up, strike it with a hammer. Hat is why I hate the axle idea.
Zero runout on crank, well maybe a thou or two.
Now that rotor is off use an elastic or something to hold a pencil or straw, and see if you have visible runout.

Don R · « **Reply #48 on:** October 23, 2013, 09:45:13 pm »

I had a left side cover all punched in at the bottom. I took the coil out and used a small hammer and flat drift pin to bump the dents out then filed and sanded it smooth. I could see micro cracks on the bottom, maybe heat would have helped with that. Anyway I JB welded it on the inside and it looks great. No one had looked at the bottom of it yet.

edwardmorris · « **Reply #49 on:** October 24, 2013, 09:44:44 am »

Quote from: 754 on October 23, 2013, 08:53:39 pm

After you torqued it up, strike it with a hammer. Hat is why I hate the axle idea.
Zero runout on crank, well maybe a thou or two.
Now that rotor is off use an elastic or something to hold a pencil or straw, and see if you have visible runout.

754, I can swear I saw a project thread here, where someone used a gear puller like this one

http://www.menards.com/main/tools-hardware/automotive/tools-shop-equipment/8-gear-puller/p-1965378-c-9113.htm

to remove the rotor. I saw this at my local menards, will this also work or should it be avoided? Same price as the actual thing, but easy to just go pick up.

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Author Topic: Restoring my k0 cb750 (Read 21990 times)