Topic: 1981 CB650 Bobber

[Calaya]

Hi, everyone.  I'm a new member to this site, as I recently got a 1981 Honda CB650 that I'm turning into a bobber for my step-son.  Through Google searches I was directed to this site and found a lot of info to be helpful, especially in the beginning stages so I thought I'd become a member.

I got the bike for free but it set outside (in Michigan), uncovered for about 8 years.  In addition to the rust, we discovered that one piston ring was seized but everything else looks good.  No excessive wear or metal shavings in the engine and it looks surprisingly clean ... although the bike has only 8300+ original miles on it.

I look forward to corresponding with many of you and appreciate any info/expertise you can provide.

Tony

[SOHC4 Cafe Racer Fan]

Welcome, Tony.

After you've made 10 posts, you will be able to post photos.  I suggest you get some posts done, so you can put up some photos of this bike in this thread, and keep track of your project on it.

There are several hybrid 650 engine in 550 frame builds and others with just 650s. 

In addition Tom Witt both here and on the 650 forum is extremely knowledgeable of the 650 and parts out bikes often for VERY fair prices.

You should download the factory service manual on this site, print it out and put it in a 3-ring binder for your garage.

Free bikes (especially ones sitting outside for years in weather) can end up costing more $ than expected.  Be systematic about it and do the 3000 miles service -- checking all mechanical and electronic systems one at a time to arrive to a running, reliable bike.

ALSO -- you might re-name this thread with a name about the bike, even 1981 CB650 Bobber . .  so it's easy to recognize

[Calaya]

Thanks for the info.  I changed the title as you suggested.

Having restored a 1975 CB750 with my dad years ago (that was in better shape than this 650), I told my step-son that it'll probably take more money than the bike is worth but, it's a fun project that we (along with my father-in-law) can work on together.  It was that project with my dad that got me into riding and hooked on bikes and so I'm hoping to share that experience with Christopher.

I ended up purchasing a manual but will certainly benefit from the knowledge of people on this forum.  My first question is related to a wheel swap (Comstar instead of spokes).  Is this the right folder for something like that?

[SOHC4 Cafe Racer Fan]

Which specific model do you have?  If you have spokes, it sounds like you have a Standard.

The 1980-1982 Standard model featured 4-2 exhaust pipes, a black plastic headlight bucket, and wire-spoke wheels. The Custom model featured 4-4 exhaust, Comstar wheels, a chrome headlight bucket, and in 1981, dual disk front brakes and air assist forks.

This was my beat down '82 when I bought it:


You should be able to swap wheels from different CB650 models.  The air assist on the forks was an interesting idea, but most people I've heard from say that the air assist forks do not hold the pressure very well, and swap the caps to conventional caps.

How are you planning to bob the frame?

[Calaya]

It's the standard model, based on the description you provided.  I hope to swap out the (badly rusted) spoke wheels with the Comstars from that same year (single disk brake).  The manual indicates that the Comstars are tubeless but I think I read somewhere that they, too, are bias ply/use tubes.  Can you confirm?

Currently, we have the engine apart, down to the pistons, and I plan to take off the wheels, shocks, handlebars and forks this weekend and then begin prepping things for sandblasting.  We already have the color scheme:  satin black and silver/aluminum, and I hope to paint the frame in the next week while waiting on engine parts. (One piston ring was seized.)  We don't plan to modify the frame but I'm hoping to customize the seat pan to make it look more like a Corbin Gunfighter.  I know to purists that won't really be a bobber, but it's a nice compromise ... and gives him the option for strapping a bag to the seat or maybe a short ride for a passenger.

[SOHC4 Cafe Racer Fan]

It's the standard model, based on the description you provided.  I hope to swap out the (badly rusted) spoke wheels with the Comstars from that same year (single disk brake).  The manual indicates that the Comstars are tubeless but I think I read somewhere that they, too, are bias ply/use tubes.  Can you confirm?

Currently, we have the engine apart, down to the pistons, and I plan to take off the wheels, shocks, handlebars and forks this weekend and then begin prepping things for sandblasting.  We already have the color scheme:  satin black and silver/aluminum, and I hope to paint the frame in the next week while waiting on engine parts. (One piston ring was seized.)  We don't plan to modify the frame but I'm hoping to customize the seat pan to make it look more like a Corbin Gunfighter.  I know to purists that won't really be a bobber, but it's a nice compromise ... and gives him the option for strapping a bag to the seat or maybe a short ride for a passenger.

The 80s Comstars should be able to run tubeless.  And you can use more modern rubber, too.

[Calaya]

Thanks, again, for all of the helpful info.  Now that I have a few posts under my belt, I thought I'd share a pic of the bike.  Most people will probably think that I'm crazy, as it'll take more money to fix it up than it'll be worth but it's got an interesting back story and gives me, my step-son, and father-in-law an opportunity to spend time together working on a project that we all enjoy.

[JimJamerino]

You got a free stick with it, too!

Good luck with your project!

[Calaya]

Hi, again, everyone.  Haven't been on the forum for awhile due to family illnesses and home repairs.  (Seems like it's always something, eh?!)

I'm moving forward with the project but have another question.  (One, of probably many more to come):  What is the distance in inches from the bottom of the triple tree to the top of the fork seal?  I took apart the forks and, while there are a few small nicks near the bottom, I was told by someone at the local Honda dealer that it should be ok to reuse them as long as the nicks are not in the area of the seal (which may cause them to leak).

Any help you can provide is always appreciated.

[Calaya]

Still working on the CB650 rebuild (mainly one day on the weekends) and finally have the engine out of the frame and have sandblasted about 1/2 of the parts.  Hope to have the rest done this weekend.  Discovered that the exhaust probably needs to be replaced and had to order aftermarket master cylinder and perch, as well as the clutch perch.  Hope to find out about the integrity of the fork lowers today via my local Honda dealer.  (They have a slight gash where I think the fork seal may rest so I may be purchasing new ones.)  Got the new wheel bearings, fork stem seals, chain, and brake pads and hope to have the wheels (minus tires) done by next weekend.

Also, we decided to paint the engine using Eastwood 2X engine paint.  Have heard various things about VHT and POR-15 but thing Eastwood will best suit our needs.

[754]

If the lower has a gash where the seal goes that can be fixed.

[Calaya]

Thanks for that info!  I took it to my local Honda dealer and they think that it's nothing to be concerned about, too.  So, it's on to the powdercoater next week, provided I can get everything sand blasted this week.

[Calaya]

Well, I didn't do much work on the bike during the summer but, in early Fall started where I left off.  I should have it as a roller by next weekend and thought I'd post a couple of pics of the progress.  Once I get it as a roller, I'll take more pics ... and then start on the engine.  I hope to have the bike ready to ride by next April (2018).

[Calaya]

Been awhile since I've posted pics of the progress (or even worked on the bike) so I thought an update was in store.  Hope to be putting it all back together in the next month or two.

[Calaya]

Most recent pic

[Gurp]

Love that you're still at it. Even if it is very intermittent. I habe a bike like that.

[wolf550]

the reverse comstars look good.
even have em on my 550 with the front.