Topic: '74 CB750 Cafe - new guy, new project (old bike)

[Stev-o]

Note to self - oven cleaner to clean frame in a pinch!

[schmolze]

Not a ton of progress to report. I decided to do an 836cc kit, and went with one from this eBay seller: http://stores.ebay.com/cruzinimage-co1484/Pistons-/_i.html?_fsub=1783269011&_sid=526414511&_trksid=p4634.c0.m322. 'Twas pretty cheap, but appears well-made. I'm waiting now for the cylinders to be bored out.

My step-dad gave me a hand gutting the beast. Such a sorry hovel of a workshop in the basement =[


Now, I know you guys aren't gonna like this, but I've decided to use the good parts from the runner for my project. I'll be using the K1 motor (which is in GREAT shape) and frame, but most everything else will be from the K4 (former) runner.

So, here's the K4 stripped down, with clubman bars and the new shocks I'll be using (14.5", so less rake in front - note the wheels are on the ground despite the center stand).


I'm gonna use that pic to design my tank and and seat, which I'm gonna attempt to make myself out of fiberglass. If anyone wants to offer me some Photoshopped possibilities, I'd love to see 'em....

While waiting for the bore job, I've been working on the head. Did some major valve de-shrouding, kind of a "semi hemi" job. Also did some mild porting (the ports were pretty good untouched).


"Yeah, it's got a hemi" - no, not quite  Um, I didn't majorly screw anything up here, right? Never done this before...


Topside 'o the head, with valve guides removed.


Also painted the cases with Duplicolor Engine Enamel. Came out awesome, real happy with that stuff.


I've also thoroughly cleaned and inspected everything. Based on the wear, I think this engine had like 10k or less on it 


Here's a question: how the hell do I clean up my exhaust valves? All of 'em look like this, and soaking in carb cleaner and lacquer thinner hasn't done the trick. The intakes are fine. Maybe I can just leave them alone and lap them in as is?


Still thinking about oil tank locations. I want it invisible. Does the swingarm have enough volume? Maybe with some hacked enlargement?

[Stev-o]

The painted cases look great!

[BrianAdair]

For cleaning the exhaust valves, I used a razor blade to scrape the carbon buildup off, then used a brass wire wheel on a bench grinder. Try not to get on the seat part of the valve, I don't think it would hurt it much anyway but I stayed away from the seats.

[schmolze]

The painted cases look great!

Thanks Stev-O, I was pretty pleased!

For cleaning the exhaust valves, I used a razor blade to scrape the carbon buildup off, then used a brass wire wheel on a bench grinder. Try not to get on the seat part of the valve, I don't think it would hurt it much anyway but I stayed away from the seats.

That sounds like a good technique, I'll give it a shot tomorrow.

[schmolze]

I got my bored cylinder block back today:




Looks good so far, right? Unfortunately, there was a little problem with one of the sleeves: it cracked, and the guy had to grind it down.



Now, he thought I might still be OK, and that the piston travel is short enough that it won't just fall out of the sleeve. Is he right? The alternative would be to re-sleeve and bore just that cylinder. Anyone know what that would run me?

In other news, I decided to just replace my entire valve train. So, stainless valves, bronze retainers, HD springs and camchain, Webcam 61a cam. Just hope my home porting job is up to snuff...

[MoMo]

That cylinder does not look like it will work.  I think the piston comes down too far.  Mock it up back together  and check it out.  I also use a very soft wire wheel on a bench grinder-does a great job cleaning valves,  Larry

[lucky]

Not a ton of progress to report. I decided to do an 836cc kit, and went with one from this eBay seller: http://stores.ebay.com/cruzinimage-co1484/Pistons-/_i.html?_fsub=1783269011&_sid=526414511&_trksid=p4634.c0.m322. 'Twas pretty cheap, but appears well-made. I'm waiting now for the cylinders to be bored out.

My step-dad gave me a hand gutting the beast. Such a sorry hovel of a workshop in the basement =[


Now, I know you guys aren't gonna like this, but I've decided to use the good parts from the runner for my project. I'll be using the K1 motor (which is in GREAT shape) and frame, but most everything else will be from the K4 (former) runner.

So, here's the K4 stripped down, with clubman bars and the new shocks I'll be using (14.5", so less rake in front - note the wheels are on the ground despite the center stand).


I'm gonna use that pic to design my tank and and seat, which I'm gonna attempt to make myself out of fiberglass. If anyone wants to offer me some Photoshopped possibilities, I'd love to see 'em....

While waiting for the bore job, I've been working on the head. Did some major valve de-shrouding, kind of a "semi hemi" job. Also did some mild porting (the ports were pretty good untouched).


"Yeah, it's got a hemi" - no, not quite  Um, I didn't majorly screw anything up here, right? Never done this before...


Topside 'o the head, with valve guides removed.


Also painted the cases with Duplicolor Engine Enamel. Came out awesome, real happy with that stuff.


I've also thoroughly cleaned and inspected everything. Based on the wear, I think this engine had like 10k or less on it 


Here's a question: how the hell do I clean up my exhaust valves? All of 'em look like this, and soaking in carb cleaner and lacquer thinner hasn't done the trick. The intakes are fine. Maybe I can just leave them alone and lap them in as is?


Still thinking about oil tank locations. I want it invisible. Does the swingarm have enough volume? Maybe with some hacked enlargement?

You can use a wire brush on valves. they are very hard steel.
DO NOT use a wire brush on the top of a piston. It will ruin it!
The best place to put the oil tank is the stock location or under the
battery.
Oil in the swing arm has been done but presents many problems with air getting into the lines from the swing arm bouncing up and down. Hoses and fittings bouncing up and down etc., filling problems.
The angle of the swing arm would make the oil want to drain towards the rear. Just lots of problems.

The easiest way would be to add the oil tank as part of the gas tank with a small space between the two so heat will not transfer. also you would want the oil in the front of the tank so it will not be next to your body.
That oil tank gets hot very quickly.

I think the stock location makes the most sense.
Back then when the bike was made the design people were motorcycle people and were very smart about things.

Now they have car people designing motorcycle things.
The water pump UNDER the intake manifold on the Honda sport bikes
is one of the worst designs I have ever seen. Cannot see it ,cannot get to it.
The VF 1000R /F  water pump was very easy to see and work on.

[lucky]

I have seen that clutch nut tool on the internet for $20 something dollars.
Just use your hand impact driver with that tool to remove the nut.

Make sure you use GASKACINCH engine sealer between the two case halves.
Do NOT use silicone!

GASKACINCH has been around forever and is proven.

[pat english]

cool projects...and thats awesome that you made youre mom and sister carry that engine..classic.