Topic: Re: No longer new to SOHC/4's... but still got a few questions.

[RatRacer]

I have owned several bikes, none of them newer than 1982, but I am new to SOHC/4's.

Last summer I bought the '79 650 in my sig for $500.  The bike had no handlebars (but oddly enough all of the handlebar controls were still attached at the other ends), and the seller didn't guarantee that it would run.  All it took was a stick of 7/8" pipe, a battery, and some fresh gas to get it back on the road!

While I have the bike in my warm basement for the winter I'm going to fix it up a little better... there are just a few questions that I can't seem to find the answers to:

1) I bought a front brake reservoir to replace the original cracked one but I can't get it to seat on the master cylinder housing properly.  Is there some sort of trick to popping these things in?

2) My front brake seems to drag.  I've never had to work on brakes before so I have no idea where to even begin troubleshooting.

3) What is the tooth count for the stock front and rear sprockets?  What (if any) high performance options are available?

4) My stock exhaust is broken (on both sides) right behind the operator's pegs.  I understand that this is a common problem on these older bikes, yet the only replacement 4 into 2 systems that I have found are from 'MAC' and their quality seems to be marginal at best.  Does anybody know of another option?  I'm not particularly fond of 4 into 1's... they always seem to sound tinny and they aren't symmetrical on the bike.

5) Even with new plugs, my bike does not like to start cold and often needs to have the choke on full for several minutes to warm up to operating temp.  Are these machines just cold blooded or could there be something else wrong?

6) One of my screw sleeves that holds the air filter cover on is loose in the filter's mounting box.  The exposed head of the screw turns, but it won't come out because it's sleeve it goes into is stripped out and it just spins around inside the bike.  Is there a non-destructive trick to getting that sucker out of there so I can get to the air filter?

Sorry that was a lot of questions.    I just have one more: Is there anybody else up here in Michigan's UP?

[KingCustomCycles.com]

Is a 79 CB650 SOHC? 

[RatRacer]

Yes it is, and other than the ascetic modifications listed in my sig, it appears to be completely stock/original too.

[Alan F.]

Start by downloading a manual for your model, it'll have specifications on stock sprocket tooth count and all.

The manual will have a good breakdown of your braking system, how it comes apart and what may need to be replaced or adjusted.

The air filter screw sleeve, if it's what I'm thinking you mean can be removed by using a Dremel tool with a cut-off wheel to grind a slot into the end of the sleeve that you can get a flat blade screwdriver into, savvy?

Lots of sohc4's are cold blooded, cleaning and rebuilding your carbs, plus a full complete tune-up may help. The each different model has its own special circumstances though.

Exhausts, check for good used ones in your local parts shops, craigslist, ebay, local forum members, etc.  They're out there.

$500 for a running bike with a title is not a bad score, learn to use the search function and read as much as you can.
Cheers.
Alan F.

[RatRacer]

Ok, I found the manual.  A nice bit of lite reading for tonight...

Yes, the air filter screw sleeve is what I'm talking about.  Unfortunately it is the bottom sleeve that is messed up so I'm either going to have to be real creative or I'm going to be pulling the whole bloody box out this weekend. 

I cleaned the carbs after I had the bike for a few weeks and that did help.  I guess I am just a little surprised that my old Iron-Head was easier to start than a Honda!

Unfortunately there is nothing 'local' up here in the great white north.  The Honda shop in town is nothing like the huge mega-dealers they have elsewhere.  Support for these older bikes is almost zero.  I've only found one other Yooper on this forum and they run 550's and 1100's.  Apparently the 650/4 is a bit of an odd duck.  I'd be a little uneasy buying a used exhaust anyway because whats stopping it from rotting out in the same spot a few years down the line?

[RatRacer]

Update on my progress:

Q1: Apparently a little Vaseline is the key to popping brake reservoirs back on.

Q2: It seems a master cylinder cleaning/rebuild is next on my to-do list.

Q3: The teeth on both sprockets are in very good shape and compared to my Ironhead, this 650 is already a rocket.  Conclusion: If it's not broke, I'm not going to fix it... for now. 

Q4: I found a set of stock pipes in relatively good condition on craigslist for a little less than what I paid for my whole bike.  Haha... no.  A MAC 4-into-1 it is, I'm thinking black headers with a chrome can.   This will be a good excuse to put rearsets on too!

Q5: I went over the carbs about as thoroughly as is possible without completely disassembling them and they appear to be pretty darn clean.  I don't know the conditions of the jets, but the bowls and slides were almost spotless.  I'm going to run a good dose of Sta-bil through them when I fire it up in the spring.  A new air filter couldn't hurt either.

Q6: I managed to coax the air filter screw sleeve completely out of the air filter housing.  A heavy spritzing of PB Blaster got the screw and the sleeve separated.  Now I have to figure out a way to put the air filter screw sleeve back into it's stripped out housing and keep it there.  I was thinking epoxy unless someone has a better idea.

It looks like the air filter hasn't seen daylight in a very long time.  Completely blackened.  No wonder the bike was cold blooded and felt a little bogged down at times.  I'm just surprised I was getting around 50 mpg's with it so clogged.

Does it seem like I'm on the right track??

[Old Scrambler]

Your on the 'right track' and just take your time to get all the info from this site. You might feel like your in lonesome country but when summer arrives and you have your bike running good........others will be looking for your advice.

[cookindaddy]

Hello Ratracer!

It definitely sounds like you are on the right track. Lotsa details. You seem to be suitably methodical.

My 750 sohc is definitely not cold blooded. It starts with the briefest tap of the starter button. It took a bit of TLC to get it to that point but it can be done. And it is a blast to ride!

Good luck and welcome!

[RatRacer]

So I was the lead bike escorting Godzilla through the northern tip of Michigan's lower peninsula where I hit a patch of gravel and dumped my bike.  I'm fine and other than a broken peg and a big dent in my tank, the bike suffered no damage that wasn't scheduled to be fixed this winter anyway.  Other than a busted master cylinder, the bike would be completely ride-able if I just bent the bars back.

So as I sit here resting my road rash I started thinking about how I am going to tackle this obstacle.  According to my wife, I need a break from riding so it's not like I don't have time for a project!  Even thought I put a good bash in the tank, I still have a nice little platform to build upon.  The carbs are nearly perfectly sync'd, the clutch grabs strong, the frame is solid and true, and it has the cleanest set of Comstar wheels I've ever seen.  The crash bent the handlebars (which I never really liked) and finished off the master cylinder (which leaked like a sieve even after two rebuilds).  A lite engine re-build and cleaning with all new seals and piston rings couldn't hurt and there are a few rusty spots on the frame I'd like to clean up.

I'm thinking about a complete tear down and resurrection as a full blown Cafe Racer.  Silver frame to match the engine, key re-location, re-designed clubmans (I didn't get the angles right the first time), cowled rear seat, smaller but brighter LED lights, and a bobbed rear fender.  Unfortunately quite a few of the stock components on my 650 are plastic and won't look right on a Cafe so here we go again with the questions:

1) Could the metal handlebar controls from an older SOHC/4 work on my 650?  Any un-related aftermarket components that might also work?

2) Besides keeping track of my nuts and bolts, does anyone have any SOHC/4 engine re-build tips?

3) Anything else I should do while I have her on the operating table?

4) I don't think I'll get too carried away... but what about a pair of small turbochargers? 

Thanks again as always!