Topic: 1977 CB750 K7 Resto-mod, Knoxville

[enwri]

BSA M20, This came apart much easier than the cb, the crank started to take itself apart, he said it started making a funny noise after hitting 70 miles an hour down a hill, still went for months afterwards. not as user friendly to ride. people say the cb brakes aren't that good, try this thing.

Best part, an old bloke not 10km's away just happened to have a serviceable 65 year old crank lying in the dirt up the back of his garden shed, "you never know when you'll need one" he said.

[AintNoEasyWay]

Ended up taking my engine to a shop outside of Knoxville, TN called Rising Sun Cycles. The owner is a member of the same vintage motorcycle club I'm a member of here in Knox.

They just called me back today: I'll be ok with just an engine hone, but need some head work done -- intake valves are beat up & need to be replaced, exhaust valves are ok. They will clean up the seats & install new valves, plus do the necessary machine work for $390. They seems pretty steep given what a place like CycleX would do, not including shipping it over there.

But I do feel right going with Rising Sun. I'll still have to install the piston rings & button the engine back up myself. What do you guys think though?

[AintNoEasyWay]

Nice, maybe I'm better off than I realized! They should have everything ready by the end of next week. I've got to do a lot of bike detailing to earn some more cash this weekend to pay for it all, but I'm excited

[enwri]

It's happening! Wait...what? Why am I excited...   I'm gunna go do something unnecessary to mine...

[AintNoEasyWay]

Haha, have some fun enwri. It's 5 celcius here this right now & could snow some over the weekend...

[AintNoEasyWay]

So I thought the original cylinder head gaskets were obsolete, but David Silver Spares is selling this: https://www.davidsilverspares.com/CB750K-FOUR-1977-USA/part_172983/

The part number appears to match up with the number on diagrams of the head. Is this the real deal? Have the gaskets come back in stock or did I misread something somewhere?

Should I buy this gasket or something else?

[AintNoEasyWay]

Alright, ordered the rest of the gaskets I'll be needing from David Silver. Head gasket, base gasket, oil pan gasket & clutch gasket. All genuine parts according to DS.

Now all I've got left to buy are the rings. Vintage CB750 has K7 rings at a slight sale (http://www.vintagecb750.com/products/82/monthly-sales), but I'm really at a loss as to what good rings I should be looking for. Partzilla lists numerous ring options for the same standard size. What do you guys recommend? Thanks for the input!

I'm expecting to get my jugs & head back from the shop this week, so I'll finally be able to start putting things back together. Looking forward to making a lot of progress now that I'll have everything fixed up & all the parts purchased.

[AintNoEasyWay]

Just found K7 standard rings, part no. 13011-392-004, on CB750supply.com for $80 for a set of 4. The description says they are genuine OEM replacement, so I'm hoping the quality is the real deal. $80 is significantly cheaper than any other set of 4 I could find; most coming in at around $130.

[AintNoEasyWay]

Picked up my engine from the cycle shop on Saturday. The head had measurements taken, new seats cut, new stem seals installed, new intake valves installed. Had all mating surfaces checked & cylinder honed.

Now it's time to sit down next to the heater in my garage & get everything put back together.

There are still a couple things I need to grab. I want to go ahead & change out front & rear wheel bearings, & so I'll be buying some All Balls. I'm also replacing drive chain & sprockets. Bought the sprockets already but still need to get the drive chain. Also need to grab some lube for O-rings & some non-hardening gasket dressing.

Then I'm off to the races. Planning to follow the classic thread (http://forums.sohc4.net/index.php?topic=107040.0) along with lots of reading from Hondaman's book. Hopefully I can get it right the first time around.

[AintNoEasyWay]

So somewhere in the process of me taking my head to the cycle shop/them subletting it to a machine shop/bringing it back to my garage, I managed to lose one of the two engine oil jets that sit on each side of the top center of the head.

The part of obsolete & a couple forum members/threads have mentioned my best luck of finding one of these parts is to just buy a used head off eBay. Sucks that something so small will stall my progress, but MRieck is going to check for me to see if he has an extra laying around. We'll see what happens.

[enwri]

   

[AintNoEasyWay]

Fellow MRieck had a spare oil jet for me & is sending one my way. I'm in the clear & set for progress.

[AintNoEasyWay]

Anyone have advice on cleaning/restoring front forks? What should I use to clean mine up & what should I expect to replace/upgrade. With the engine out of the bike, I'd like to go ahead & tend to these to make sure I'm getting optimal performance out of them.

[Stev-o]

Polishing the lowers front forks is popular and looks great.  I'd also plan to replace the springs, seals and oil, pretty basic.
I put Progressive springs in my K4 earlier this year. 


http://www.ebay.com/itm/Progressive-Suspension-Fork-Springs-111104-Pair-/191056101424?pt=Motorcycles_Parts_Accessories&fits=Year%3A1977%7CModel%3ACB750K&hash=item2c7bd4c030&vxp=mtr

[SOHC4 Cafe Racer Fan]

If you end up needing new upper tubes (if the tubes are pitted where they travel into the lowers), you can get new ones from Forking by Frank. Cycle X may have them too.

[AintNoEasyWay]

Awesome. Thank you, guys.

[SOHC4 Cafe Racer Fan]

If you forks are pitted above the area where they travel into the lower forks, some people have sanded and polished the pitting (even painting the surface).  If the travel area is pitted, however, it will destroy your fork seals (like sandpaper).

[AintNoEasyWay]

If you forks are pitted above the area where they travel into the lower forks, some people have sanded and polished the pitting (even painting the surface).  If the travel area is pitted, however, it will destroy your fork seals (like sandpaper).

I do have some rust on my right fork that I will try to clean up. I'll post a picture for you guys to see when I get home later.

[AintNoEasyWay]

Alright, guys, here's a photo of the rust on the front right fork below. It doesn't look bad to me, but I don't know if it's still progressed enough to do damage in the fork. What do you guys think? I used some aluminum foil & water to clean the surface rust & now the photo shows what's left.

Also, I am trying to clean up my head & cylinder. I bought some regular O'reilly's degreaser, some ZEP purple, and S100. Thus far I have actually been able to get a good amount of grime off the two parts with just a tooth brush, scotch brite pad, & WD40. The exhaust ports on the head will be very difficult to clean though. Are all of the above products still safe for me to use if I leave the springs, valves, stem seals in the head while I clean? I don't have a way to take out the springs, but want to be sure that the valve stem seals aren't damage from the cleaners/ degreasers.

I'll be rinsing everything off & then blow dry with an air compressor. Let me know if this is okay. Thanks!

& happy Thanksgiving.

[enwri]

When you mentioned that you have some pitting on the fork I thought maybe you could get away with cleaning them up a bit. Now even I would have to draw a line at that, sorry.  That's a bit beyond polishing. Or throw a set of boots over them and try to avoid any motocrossing. They will jump ok, the landings can be a little heavy though.

[Stev-o]

Time for a new set of tubes. May as well change the springs too, if you havent done it.

[AintNoEasyWay]

Alright I'm on it. Will be a while until I can get those forks rebuilt as that's just another expense to add to the rebuild.

I have a new Tsubaki cam chain I'd like to install for my engine rebuild. Do I need to break open the crank case in order to install it? Maybe a newb question, but I'm not seeing how to install it otherwise.

[Trad]

Alright I'm on it. Will be a while until I can get those forks rebuilt as that's just another expense to add to the rebuild.

I have a new Tsubaki cam chain I'd like to install for my engine rebuild. Do I need to break open the crank case in order to install it? Maybe a newb question, but I'm not seeing how to install it otherwise.

You can get a soft link for those chains and order a good rivet tool like the Motion Pro Version. I just did this on my cb550K rebuild. Easy as pie.

Nice looking bike man!

[AintNoEasyWay]

Alright I'm on it. Will be a while until I can get those forks rebuilt as that's just another expense to add to the rebuild.

I have a new Tsubaki cam chain I'd like to install for my engine rebuild. Do I need to break open the crank case in order to install it? Maybe a newb question, but I'm not seeing how to install it otherwise.

You can get a soft link for those chains and order a good rivet tool like the Motion Pro Version. I just did this on my cb550K rebuild. Easy as pie.

Nice looking bike man!

Thanks a lot, Trad. I don't own a rivet tool/chain breaker yet & definitely need one for putting my new drive chain on anyway. Is this the one you're thinking of?: http://www.motionpro.com/motorcycle/partno/08-0058/

[Restoration Fan]

Oh, come on, Nate.  Go ahead and break open the cases.  What could go wrong?   *says the guy about to help his son put the cases back together for the 4th time*