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1  General Category / Photo Gallery / First peek inside the valve cover on: January 22, 2018, 10:42:24 PM
Today was wet and foggy, perfect for a nice shop project. So, shim kit in hand, I decided to check valve clearance on the CB-1 400 four. First things first, I got a good fire going in the wood stove to make sure my faithful companion Blondie was happy. She was.

Then after pulling the tank, air box, plug wires, assorted hoses and the valve cover I got my first glimpse of the gear driven DOHC goodness. The split gears are slightly offset and spring loaded to take up gear lash to reduce noise.

All 16 valves measured well within tolerance and were surprisingly consistent, even though it did not appear the valve cover had ever been off before.

It's interesting how the carburetors and intake manifolds aim in a straight line to the combustion chambers.

I had pulled the valve cover off with the radiator hoses still in place which made it much harder. So to make sure the cam cover seal stayed in place on the way back together, I drained coolant and got all hoses out of the way. That made it much easier to put the cover back on.

After getting things all buttoned up, I'm looking forward to a ride as soon as the roads dry out.

2  General Category / Photo Gallery / Re: Just received my CB-1, I'm in love on: January 22, 2018, 11:25:41 AM
....Also, I see you have Hawk GT bars on your bike. Did you need longer throttle cables?....

Thanks Paul, The hawk bars were on the bike when I bought it. I received a box of spare parts that has throttle, choke, and clutch cables so I assume they are originals and longer ones were needed, but I have not checked them for sure.

So what's the actual effect of changing the sprocket? Do you have better acceleration or a higher top speed?
Been thinking about tinkering with the sprocket size as well but Im not too sure what to go for and what to expect.

I would say the stock gearing is about perfect for 1/4 mile drag races, but for my taste is needlessly low for normal street use. Changing the rear from 41T to 37T lowers rpm 9% for a given bike speed. Now instead of turning 7,300 rpm at 65 mph it turns about 6,500 rpm, still has plenty of power, a bit less vibration, and less engine noise and wear. (This is with a 140/80 rear tire instead of stock 140/70. The oversized rear tire makes the gearing slightly higher than stock by itself.) Starting from a stop in first gear is no problem and does not require any more clutch slipping than stock.

Besides lowering rpm, a higher overall gear ratio increases the spacing between gears which I really like. With stock gearing the jumps between gears, especially 4th to 5th to 6th, felt so small I often wondered if I had missed a shift and was still in the same gear. Now the steps are more noticeable and don't feel so much like needless busy work for my left foot. I doubt top speed is much different (have not tested) since wind resistance becomes a limiting factor without a fairing.

Again, the higher gearing is just my preference as a 150# rider with no passenger, riding a spirited but sensible pace in hilly twisty areas. YMMV.


3  General Category / Photo Gallery / Re: Just received my CB-1, I'm in love on: January 21, 2018, 11:30:20 AM
How do you like the higher gearing? Nice having a little more space between the gears and a bit of an overdrive, isn't is?

Yes, I really like it geared higher. For my riding style and light weight I could even go a bit higher yet. Fourth-fifth-sixth are still quite close together, and sixth is still usable for anything over 25-30 mph. And that's even with an oversized rear tire. My speedo read 1 mph high with stock gearing, and now reads ~8% low. Just wish there was an easy way to adapt a tiny gearbox to the cable to correct it. Hmmm, there's a project there.

Is that still the stock muffler? I replaced mine with a Kerker slip-on soon after I brought her home in 1990. I run it with no packing now and as long as you don't rev it too high around town it is still low tone and tolerable. On the back roads winding her up into the meat of the powerband and hearing that exotic Ferrari sounding shriek overpower the wind noise is soooo sweet. Jekyll and Hyde.  Grin

Yep, stock muffler. I can imagine how wonderful that Kerker sounds when wound out! But I much prefer quiet exhausts both for my own comfort and to avoid annoying the public. Living on a scenic back road popular with motorcyclists, I know how pissed off I get when my peaceful surroundings are invaded by screaming sport bikes, and moreso obnoxious roaring Harleys! To each his own.

4  General Category / General Motorcycle Discussion / Re: Stuck Gas Cap - New Replacement? on: January 21, 2018, 09:38:23 AM
Anything specified for a CBR600RR should work. I bought one of these Chinese copies from ebay and it seemed virtually identical. The hinged cap did not sit quite level when locked down, but that would not be an issue with those keyless caps.

5  General Category / Photo Gallery / Re: Just received my CB-1, I'm in love on: January 13, 2018, 11:31:11 AM
After fixing the gas cap and upgrading to a Blackbird shock I've done some cosmetic upgrades and now have the bike just about where I want it. There was some corrosion and peeling paint on the leading edges of the forks and clutch cover and a few rust spots and scratches on the swing arm, so I stripped off the old paint, glass bead blasted, and repainted.


Stripping and blasting - I like how bead blasting leaves a perfect fine texture for good paint adhesion:

It was fun to get my first peek inside the engine.

The Dupli-Color BFM0225 Medium Charcoal Metallic turned out to be a perfect match to the original color. I followed up with two coats of SprayMax 2K gloss clear coat for fuel resistance and toughness. This catalyzed clear leaves a much higher gloss than the original paint, but I like a little tasteful bling. I buffed all fasteners and clear coated most of them as well. The after:

I went ahead and replaced the chain and swapped to a 37T rear sprocket as well.

I like shiny clean hardware because.....bling!

I have Oxford heated grips on two other bikes and really like them, so......

The front dampening felt too stiff, so while I had the forks apart I used a viscosity cup to measure the current oil. It took 34 seconds to empty which is quite high compared to typical fork oils. I changed to synthetic ATF which measured 21 seconds. The front feels much more compliant now while still having good dampening.

So for now the bike is basically where I want it except for one dent in the tank. It's not bad enough to warrant repainting so I might check with paintless dent repair shops and see if anything can be done. Unfortunately due to the inside shape of the tank the dent is not accessible from inside. Anyone have experience with similar dents?

It's been great fun getting to know the ins and outs of the bike by working on it, but more so by riding favorite local twisty roads!

6  General Category / Tech Corner / Re: Gas cap help on: January 10, 2018, 12:32:32 PM
Thanks filterMan,

I didn't bother figuring out why the Chinese cap sat proud when closed, probably should have. I suspect some small dimensional difference in the latch pieces or the hinge location.

Taking the latch and lock mechanism apart is actually not too hard. You should be able to pull those parts out without removing the sealing ring/gasket although I suspect it would be easier with the sealing ring out of the way. Plus you risk tearing the seal by leaving it in place. There is a steel washer under the lip of the seal, pictured in the photos above. The washer has a notch to clear one of the latch pawls. If you have not removed the seal, lift the seal lip and rotate the washer to align the notch, then lift the washer with a small hook and tease it out from under the seal (hopefully without tearing it!) Then 3 screws are exposed. Remove the screws and the lock and latch mechanism will lift out. Note which way the key tumbler is oriented. Insert the key into the lock and pinch the latch pawls slightly together while pulling lightly on the key. Make sure the key slot is facing down, otherwise the small brass colored plates shown below can fall out the other side. Here is the tumbler part way out.

And here it is all the way out. The brass colored plates are T shaped, so with the wide ends facing up as shown in this photo they cannot  fall out the opposite side. Each is a different length corresponding to the notches in the key, so if they were to fall out you would have to find their correct locations by trial and error or studying the key notches. Best not to let them fall out!

Hope this helps,

7  General Category / Tech Corner / Re: Gas cap help on: January 09, 2018, 09:09:58 PM
OK, I received the Chinese clone CBR gas cap today and it looked like an exact copy and well made. One option I was considering was to install this aftermarket cap but swap in my lock so it would open with my existing ignition key. But after screwing it onto the tank and closing the cap, it sat slightly ajar as if not pushed all the way closed. So I went with my original plan which was swapping the Chinese cap seal into my Honda cap. Here's how it went:

The existing domestic Japanese CB-1 Type 2 cap, left, and Chinese aftermarket right.

To remove the compression ring that holds the rubber seal in place, I started by carefully prying in the V-groove of the ring at each spot where the cap casting was swaged, in order to spread the swaging a bit.

Then using the modified screwdriver with the tip bent into a slight hook as shown in a post above, I twisted and pulled to lift the steel compression ring out of the cap. Here you can see the ring is lifting out of the casting.

After doing the same on the existing cap, here are both caps with rings and seals removed.

The Chinese seal looked identical to the OEM, so after placing it in my cap I needed to press the steel compression ring down tight against the seal before swaging the ring in place. A 2" PVC coupling turned out to be the perfect diameter to press the ring tight against the seal using a woodworker's vise.

Then with the ring held tight against the seal rubber I went around the circumference with a hammer and punch to swage the ring in place.

Voila, a new seal installed in my old cap. Now to see how the Chinese seal material holds up over time.....


8  General Category / General Motorcycle Discussion / Re: Tail bag on: January 07, 2018, 12:33:23 PM
that little tail bag looks great.
yes, you lose the passenger seat but who cares, the CB1 isn't really meant to hold two 180lb you're good to go!

Looks clean, nice and tucked up against yer booty when riding. Nice job. I'm sure it even feels a bit like you have a backrest of sorts.....nice work.

Thanks VH, I've already used it for a couple of hardware store shopping trips and find it works really well. And this time of year it's really handy to be able to carry those extra layers of clothes that get peeled off as the day warms up.

9  General Category / Tech Corner / Re: Another shock question on: January 06, 2018, 08:55:02 PM
Since I shortened the Blackbird shock to just slightly longer than stock and I have a slightly oversized rear tire, I decided the side stand could best be 3/4" longer. A CBR600 stand from ebay was about 1" longer which was OK but the rod for pushing with the heel was in the wrong place plus the spring hook on the stand was also in the wrong place for correct spring tension (the CB-1 and CBR600 springs were the same length). So rather than cut and weld on the CBR600 stand I decided to add a foot to the stock stand. It is 1" thick Delrin, with the stand recessed 1/4" into it for a net increase in stand length of 3/4". Plus it gives a bigger footprint for standing securely on soft ground. Tested in damp road shoulders today and it works great!

10  General Category / General Motorcycle Discussion / Re: Tail bag on: January 06, 2018, 08:41:18 PM
Problem solved: I riveted the front straps to the underside of the seat pan, and fastened the rear straps to the cargo loops so no straps touch the paint. Added soft sponge neoprene to the bottom of the bag where it contacts the tail cowling to prevent abrasion there.

11  General Category / Tech Corner / Re: Blackbird shock install on: January 06, 2018, 08:36:29 PM
BB shock is gonna serve you well. Cheap and good alternative to the saggy original. Wink

Thanks Dash, the roads dried out today so I went for a spirited test ride of the new shock on 100 miles of deserted twisty back roads with lots of bumpy corners and no, enforcement presence. Result - I am totally happy with the BB shock. The bike felt glued to the road and stayed on its line through bumpy turns. The damping (lowest setting) is on the firm side, but better that than too weak. This shock will do the job for me for now and likely for ever.

12  General Category / Photo Gallery / Re: Cb400 fours, old and older on: January 06, 2018, 08:22:48 PM
Two mechanical jewels that were not well received by displacement hungry Americans when they were first sold here. Hard to believe that even the "modern" bike is almost 30 yrs. old.  Shocked

Yeah, since I was totally away from the sport between 1980 and 2000, both bikes seem like "current" technology to me.

13  General Category / Tech Corner / Re: Blackbird shock install on: January 06, 2018, 10:55:50 AM
Dash, do you remember how you set the damping screw? Need to back mine out, it's over damped (when did anyone say that about oem CB shock  Grin ) so curious where you went.

I set mine to minimum damping and bouncing in the shop it still seems like fairly stiff damping. But this shock is very low miles and has been sitting on a shelf for 15 years, so that might be part of the reason. The sun is out today so it's test ride time!

14  General Category / Tech Corner / Re: Gas cap help on: January 06, 2018, 10:36:41 AM
Hi Bill, good to find you on this forum site. If you read my RVF400 rebuild on BARF you'll see I went thru a gascap teardown. To get at the gasket you need not unbend the casting punches. In fact, I found them extremely brittle and broke a couple on the China knockoff that I tested on. Instead I used a flat bladed screwdriver to work under and around the rubber seal to "pry" out a metal washer (kinda like putting a tire bead onto a wheel rim) that is held in by the gasket. Once this large washer ring is removed there will be 3 screws buried under the gasket securing the rubber to the cap. Pell the rubber back and unscrew the 3 Phillips screws.

The China caps are of very decent quality esp for the price. I got a helmet lock, gas cap and ignition for $15! Shipped!

Following your work and inspired to make a few changes. Thanks!

Hi Rick, Maybe your VFR cap is different, but on the CB-1 and other CBR caps the rubber seal is clamped in place by the outer ring with the "V" shaped profile. The cap seal flares out at the bottom and is pinched in place by the ring. The 3 screws only hold the latch/vent assembly and its separate gasket in place.

You're right about the casting being brittle, and when I get my Chinese part I will just work the flat blade screwdriver with a twisting motion in the groove of the ring, to spread it and at the same time gently push the casting punches out. Much safer than tapping directly on the casting. I'll post photos back here when I have the part.

15  General Category / Tech Corner / Blackbird shock install on: January 05, 2018, 02:31:38 PM
Following morti's recommendation I decided to go with the Blackbird shock to avoid the need to swap springs with my shucked out original. The BB shock is about 3+mm longer than stock, and since I'm "inseam challenged" I really didn't want to raise the rear of the bike plus have to go to a longer side stand. The shock arrived on a rainy day, perfect for a nice shop project so I decided to "shorten" it by making an offset top bushing.

After pressing out the original steel and rubber top bushing I turned a piece of Delrin to a matching 22mm diameter. I then switched to a four jaw lathe chuck and adjusted it to offset the material 3mm off center to drill a hole for a new steel collar. The new collar is smaller OD than the original, allowing more offset.

I cut off the Delrin bushing slightly shorter than the steel collar so the mounting bolt would pinch against the collar, not the Delrin.

To make sure the Delrin bushing could not rotate in the shock eye I threaded a socket set screw through the top of the shock eye and slightly into the Delrin.

From this angle it looks like the shock body interferes with the frame bracket, but it actually has adequate clearance.

Lastly I had to grind a small notch in the lower frame bracket to clear the damping adjuster screw.

It's raining again today so I have not ridden the bike yet, but by bouncing up and down on the passenger pegs my "butt dyno" tells me it feels very good. The rear is maybe 1/4" higher but the stock side stand still works. In the future I will go from the current 140/80 rear tire to the stock 140/70 which will reduce the lean angle.

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