Topic: First bike: 1978 CB750 K8. Let's turn this piece into a solid runner.

[70CB750]

I got new adjuster from Dynoman:

http://www.dynomanperformance.com/bikepages/sohc/oe.html

maybe not a bad idea to replace them all.

[therobbstory]

I got new adjuster from Dynoman:

http://www.dynomanperformance.com/bikepages/sohc/oe.html

maybe not a bad idea to replace them all.

Thanks for the link. I went ahead and ordered 8 from Partzilla last week. Hope to have this rust monster back on the road by Saturday.

Where in NoVA are you? I'm in DC but most of my two-wheel time is in VA/MD. Great roads surrounding this metropolis!

[therobbstory]

Good day yesterday. Found a like-new airbox on eBay for $12. My bike was missing one of the long nuts under the airbox. The bolt is no longer made, so I grabbed this complete airbox which is in much better shape anyway.

Also replaced all four plugs and caps. The ones I pulled were old and ugly as sin. Bike starts and idles much much smoother now.

I also replaced my #1 intake tappet adjuster and lock nut. Did a complete valve adjustment, and now she hums like a sewing machine.

I noticed some gas in the old airbox. I suspect float valves as I've been noticing some gas on them. Going to pull those today and do a complete and thorough cleaning. Will also install the seal kits I bought a few months ago.

Old vs new in the airbox photos. I sure am envious of all you guys with garages. All my work has to be done in my front yard or on the street.

[Bronko37]

Well, sh!t on a biscuit.

Noticed a hearty clatter coming from the head cover on my way home last night. Today, I pulled the tappet covers to re-adjust valve clearances and found the attached image. I can't immediately see where the locknut went, but I'm going to poke around tonight with a flashlight and a magnet.

I'd know pretty quickly if it fell into the cam chain guide, right? What other potential things should I be looking for before I replace the locknut and tappet covers, assuming I find the missing nut?

In other news, I performed all of the 3,000 mile maintenance after acquiring all the requisite tools and test equipment. Carbs weren't too badly out of sync, but I did swap out the points after losing cylinders 1/4 not too long ago. Old points were nasty. I've also got a HondaMan ignition on the way. Couldn't hurt, right?

I know that feeling. My dad was helping me work on the GL1000 and when he was removing one of the heads, he dropped the head bolt washer right down into the oil return port. Clink, clank, gone! Luckily I was pulling the motor anyway. If not it would have really sucked, a lot.

[therobbstory]

I raised the head cover up 1/4" this morning and found the tappet adjuster locknut. Crisis averted.

Installed HondaMan's transistorized ignition, and it feels like a new bike. Temps in the high teens this morning, and she fired right up. Idles smooth, and pulls steady through the RPM range. I'm a happy boy.

I broke a throttle cable last week. Pulled the carbs off to install a new one and noticed that the choke plate on #4 has a bit of flutter. Seems like the shaft bearings (if those exist; hard to see on the fiche) are really sloppy. This causes the plates to flutter. I've also noticed at low idle, under 1k, #4 carb will 'cough' a little fuel back through the intake and kill the engine immediately. Could this be valve related? ONly happens at very low idle.

Now that the engine is as sorted as my abilities will allow, I'm moving onto brakes. Ordered a steel braided line from Slingshot this morning, and will likely replace pads front and rear.

Following brakes, I think I might move onto cosmetics. The clear coat on the tank has worn in some spots allowing for new surface rust to form. I'm thinking about stripping the tank, brushing it, and clear coating. My other thought is to find a Super Sport tank, and spray it Audi Nimbus Grey. I did this with my old CB360 and really liked the look:
The Menstrual Cycle by Robb Hohmann, on Flickr

Black and gold is my other option. I love the brat look, but I also want a bike I can ride. I'm 6'2" and I just don't think a brat seat would be practical for me on long rides, so I'm trying to find a stock K8 seat to re-cover, maybe with some cool diamond stitching. There's a guy just outside DC who does great work.

Exhaust is also on the drawing board. The MAC I have on there sounds like garbage with weird harmonic resonances throughout the rev range. It's also rusty. I like the idea of a Yoshimura 4-1 with a baffle, stainless steel. Carpy has some nice looking copies. Something to look into on a rainy day, I suppose. What I've got now is functional.

Here's how she sits today.
#Blessed by Robb Hohmann, on Flickr

[SOHC4 Cafe Racer Fan]

"Menstrual Cycle" is the name of your other bike?! 

That's way beyond effed up.

[therobbstory]

"Menstrual Cycle" is the name of your other bike?! 

That's way beyond effed up.

Agreed. And it should go without saying that the woman who made me sell it is no longer in my life. 

[70CB750]

Ha, sorry, missed your reply.  I am near Warrenton, my typical joy ride is 211, 55 and such.

BTW, I like your no nonsense approach - got her running, now brakes, good job, man.

I got new adjuster from Dynoman:

http://www.dynomanperformance.com/bikepages/sohc/oe.html

maybe not a bad idea to replace them all.

Thanks for the link. I went ahead and ordered 8 from Partzilla last week. Hope to have this rust monster back on the road by Saturday.

Where in NoVA are you? I'm in DC but most of my two-wheel time is in VA/MD. Great roads surrounding this metropolis!

[therobbstory]

I spoke too soon. Impulse bought a Supersport tank off the forums yesterday. Always preferred those lines to the '77-78 tanks. I guess that means I'll need a new seat now as the SS tank is a bit longer in the rear.

[SOHC4 Cafe Racer Fan]

A few of us have used F tanks with K7 or K8 bikes. Yes they are slightly longer but look so much better.

You can reuse your seat by remounting it in the hinges slightly back.

[therobbstory]

You can reuse your seat by remounting it in the hinges slightly back.

Ah, genius. Will do that as a temporary solution.

Here's the tank:


Paint will be coming off ASAP. If it's not too hideous under that swastika (!!!), I'll just rattle can some clear on it until I can get it into a proper paint shop.

It's 16°F in DC right now. High of 61 next Saturday! Hoping to get out for a long cruise finally.

[seanbarney41]

You can reuse your seat by remounting it in the hinges slightly back.

Ah, genius. Will do that as a temporary solution.

Here's the tank:


Paint will be coming off ASAP. If it's not too hideous under that swastika (!!!), I'll just rattle can some clear on it until I can get it into a proper paint shop.

It's 16°F in DC right now. High of 61 next Saturday! Hoping to get out for a long cruise finally.

lol, I saw that tank elsewhere on the forum, and initially, kinda liked the design.  Then thought to myself, "Hey, that kinda looks like a swastika!", just as I read this post.

[therobbstory]

Tank arrived last week from a forum member. While waiting for brake parts to arrive, I've begun stripping the tank. Temps poked into the 60's here yesterday which means my stripper could do its work.

There are three spots of bondo but the dents don't appear too severe. My plan was to strip the tank and powder coat it clear, but I'm reading a lot about how that won't prevent rust. There are a few bits of rust inside the tank, but I think I can take care of that with some vinegar and an old bicycle chain.

[therobbstory]

A bare metal tank covered with powder coat will not rust. I'm uncertain who would have said differently. Color is immaterial to powder coat's protection. Perhaps they were referring to the interior of tank left bare without a liner???

Looking back, I think I was finding more info about spraying clear coat as opposed to powder. I couldn't find much on the longevity of good clear powder coating. I'll get on the horn with a few local shops tomorrow to get some ideas of what I can do.

[SOHC4 Cafe Racer Fan]

Gone is the swastika and "animal"!

[therobbstory]

Gone is the swastika and "animal"!

Ahhh, actually I left the Animal glyph. I feel like there's some good mojo in there and it needs to stay.

[greyghost18t]

There is some good information on this thread! I am watching this because I too am building my 78K.  The honda man ignition, can it be used with the moto gadget stuff though?

[SOHC4 Cafe Racer Fan]

I do like the "Animal" graphic on the filler door.  It does provide some character.

[therobbstory]

There is some good information on this thread! I am watching this because I too am building my 78K.  The honda man ignition, can it be used with the moto gadget stuff though?

I went through your build thread the other night, and I'm pretty sure that's what made me decide to go with a raw tank. Kinda reminds of The Rocketeer in a way.

No idea about the Motogadget compatibility. I imagine it'd work, though. The control module wouldn't know the difference between breaker points and transistor switching.

[greyghost18t]

I am up in the air about the raw tank.. i like the raw look..but then i see some amazing paint jobs and makes me second guess.. now i am thinking about an early to mid 70's tank or a F tank because of this thread.

[Restoration Fan]

There is some good information on this thread! I am watching this because I too am building my 78K.  The honda man ignition, can it be used with the moto gadget stuff though?

Sure.  I don't see a reason why not.

[greyghost18t]

Thanks for the responses - Didn't mean to hijack your thread.

[therobbstory]

Stellar weather this weekend, so I got out on the road with some friends. Rode DC > Frederick, MD > Baltimore, MD, DC yesterday, about 150 miles of country roads.

Some things I noticed:

When pulling in the clutch and coasting, I felt and heard a little k-chunk k-chunk sound. I know what bad wheel bearings feel like on a 15lb bicycle, and this felt like the same thing but increased by a magnitude of 650lb motorcycle with rider. I'm going to order some replacement bearings. All Balls seems the way to go from what I've read.

I'm also going to swap the chain and sprockets for peace of mind. There was considerable slack when I bought the bike, so much so that it would slap the swing arm. Not sure if that was a stretched chain or just poor maintenance. The drive drain sounds really noisy despite cleaning and lube.

Fork seals are leaking so much oil, I wonder if there's any left in there at all. Even small bumps at speed would send a shockwave down my spine. I've got the seals, I just need to engineer a way to hold the front end off the ground. I don't have a garage, so I may attempt the cymbal stand hack I saw in another thread.

The engine ran great all day, though! Most of my riding has been stoplight to stoplight in the city, and I rarely get to stretch it out in 5th gear. Cruising down the Baltimore Washington Parkway at 70-80mph was a real treat. Especially with a new headlight

In other news, I found a local powder coater who has grand ambitions for my raw tank. Should be able to get that to him this week. Still need to figure out a seat solution. Stock one is all ripped up, but functional. I'll likely move the hinges back to accommodate the super sport tank until I think of a better idea for replacement.

To recap next steps:

• Replace fork seals
• replace wheel bearings, front and rear
• replace chain
• replace sprockets
• install shorter clutch cable
• powdercoat new tank

Here are a few photos from yesterday.

[therobbstory]

You would be well-served to also replace the steering head bearings while the forks are apart. Butter smooth, and not jolts when riding or steering  All Ballz makes those too

Will do, sir!

Just came back from a quick ride. Noticed a little bit of smoke coming out of the crank case breather tube which exits next to my muffler. I know these 78's had some kind of smog pump under the battery tray. This seems to be bypassed on my bike. The tube comes out the top of the breather cover, under the tank, and exits down under the bike.

Is the smog pump (correct me if it's called something else) essential? Should I reconnect this? And what could be causing the smoke? Oil level seems normal and I haven't had to add any since changing it about 500 miles ago.

[Stev-o]

Smog pump?  I don't think so.