CB77 1964

[Waveblaster]

For anyone that may be interested

I wanted to provide a bit of an update. A lot of progress!

I was struggling to get the fork tubes into the triple clamps. Upon closer inspection the fork shroud that fits over the bottom clamp was fouling. Inside there is a locator ring I assume to keep it centralised as theh fork travels . It turns out I had a pair of late model shrouds out of my box of parts which are smaller in diameter restricting the sliding. I was able to press out and push the correct ones in. Also the polished aluminium top steering head bracket appeared to be ever so slightly different. I managed to find the correct earlier version I think and got it together.

Here is a photo of the painted guards.






So managed to get the motor together and once the front wheel was on get the motor into the frame. Connected up the cabling and electrics. Initially had issues with one side not sparking and found the coil was faulty and swapped for a spare. Fitted carbies and the bike fired up.!

A bit of issues with high idle and the bike running away. The right side carbie slide is very worn. I can be moved with a finger through the intake side to side. I have backed off the idle on the left to drag the revs down temporarily but I have source another PW26 , from a friend at the vintage bike club which I will swap for a pw22. , hope it is a right side!

Still need to get the rear wheel sorted. I have to get the tyre off to replace a couple of stripped spokes or nipples and true slightly before replacing the tube.

I polished up the old mufflers, a buffing wheel on a bench grinder removes a multitude of sins. Tank panels need chroming sometime in the future.

I had to fit some baffles . Getting the old ones out from some other pipes was a bit of a challenge. I found wrapping fencing wire around the end and then attaching to the leg of a steel bench allowed me to use the muffler like a slide hammer. Worked a treat as they were well and truly stuck

I need to fill the forks . The manual and forum mentions 225 ml from dry. Assuming that is each fork? Or is that split between the two? Wording in the workshop manual was a bit ambiguous.

Thanks to those who have helped with questions.

Images below of progress,



rear

[Waveblaster]

So I had the local bike shop placed a tube in the rear wheel so I could do a bit of test riding. The drive chain that was thrown in with the bike turns out to be a 520 not 530 so the only chain and sprocket combo I had was a worn 15 / 42 but enough to test.

With the first ride I was happy with the transmission and clutch which seem to operate great. The engine on the other hand still needs a bit of work. It is still misfiring on the left side. I had an appointment at the local vintage motorcycle club this morning so I took it along , armed with an assortment of spares which I felt might help diagnose the issue.

There were a number of folks there attending a photo shoot and it was good having others to validate the diagnosis.

I felt it was electrical due to the intermittent nature and commonality through various rev ranges.

I tried swapping out the condenser, coil, swapping plugs, points, leads but little difference, still backfiring slightly on the left side.

It now seems it may be valve related. We checked the gap and it did appear to be set correctly and operating.

So perhaps it has not seated correctly. It also could be that with the slightly higher lift on the exhaust the valve of this particular cam shaft it is sticking a little as it is travelling further up the guide allowing some firing gases to escape.

I had the idea of attaching the timing light to the left lead and shining at the exhaust valve through the tappet inspection port.. Perhaps the strobe will show an inconsistency ....

It seems to be improving over time but possible I will have to drop the engine again.

[sarals]

The bike is beautiful!

My bike did some popping and spitting from the left cylinder early on. It has almost 300 miles on the engine now, and it's stopped doing that. Most of the unhappiness was caused by carburetion. Once that was sorted, she calmed right down.

[Waveblaster]

So a bit of an update.

I swapped the carbies left to right and the fault did not swap cylinders so I ruled out carburation .

I swapped the condenser and it stopped backfiring but would still miss

I swapped a series of coils which arrived in "box-o-bits(TM)" over but no real change. Although it did seem to run ok when cold and as it heated up became worse. Still sounding like coil.

At one stage I had inadvertently grounded the condenser lead to the points and spend some time scratching my head. Once discovered I needed to have a tea break and regroup after making a rookie error like that..

I ended up pulling a coil from a CB72 frame I have and it seemed to run better but the right began to fail. It turns out with the tightness of the coils and condenser fittings I had pulled the end of the condenser off which is epoxied on. How I dont know perhaps bumping with the ratchet while accessing the mounting bolts. Symptoms were again throwing a dirty spark at the points and missing and backfiring. I ended up swapping the second coil and condenser over and I think we have solved it. Finally.
Nothing worse than fault finding with potentially faulty components and multiple failures

I also sourced a new 530 chain and was able to fit a 15/31 sprocket combo.

Given I am a child of the 70s , I have never had any real exposure back in the day to these bikes, I found it is quite responsive and dare I say it reminds me a little of a 2 stroke in how power is delivered. I found it handles quite predictably into corners as well, I had to remind myself I still have the old tyres on.

The exhaust has quite a note to it. I was surprised even with the baffles in.

This may be old news to folks, but for a newcomer to these CBs this was a happy discovery given the work to get it here!

Still leaking out of the oil filter cover. I have found two new O rings and will have to inspect more closely for foreign matter causing issues.

[G-Man]

Greg

Sounds like you are enjoying the adventure. I had similar problems with an early CB250K2. With rust in the tank, coils shorting to the frame, blocked tank vent and other issues the bike just drove me completely mad.

In the end I sold it on without really getting it running right.

My first ride on a CB77 was when I was 14 years old and I'm still waiting for the second..... :-)

G