The Honda CB350 basket case

Honda CB350 Road Racer Project
The bike could be described as a Honda CB350, a Replica CYB350, a Cafe Racer, Boy Racer, Road Racer, Clubman or just John's Honda.

April 2001

Progress this month:

Adjusted the valves
Installed the standard advance unit and points plate
Cleaned out the Carbies and polished the tops
Fitted the motor to the frame
Test fired the engine - on the 1st of April no less
After 2 years of looking, finally obtained a 4LS 200mm front drum

One side of the 200mm 4LS drum	200mm brake plates
One side - part assembled after cleaning	The other side

Building the top end and getting it set up correctly was a lot of fun.
Things I learnt about Honda 350 motors:
Putting the pistons in the hole was easy - although the manual indicates "push the rings with a screwdriver" was a bit of a worry. I used the plastic handle from a tooth-brush so as not to scratch anything. The barrels would not sit flat on the base gasket - the new O rings hold them up and allow them to move causing you to think something is wrong.

After lapping in the valves with fine paste and checking that they will seal (spray some penertrating oil up the ports and make sure it does not leak past the seats) the head just drops on. Bit of a fiddle to get the CAM chain and guides in the right place as the barrel and head go on, but do it slowly and everything will fit into place.

Not many people seem to know HOW to install the CAM - all my cam bearings show signs of hammer damage - seems to be "if it won't go in, smash the bearings with a big hammer till they give in and stuff the cam chain and destroy the bearing surface as the cam is forced into place" - there as some real metal butchers out there.
For the record - IF the cam is installed correctly, ie. left piston at TDC (LT on the index marks), the cam wheel has the horizontal line and the 'L' at the the top, the pin on the timing end of the cam is at 12 o'clock, AND the motor is then turned back (clockwise) 90 degrees so all the cam lobes are away from the rocker arms (the cam pin will be between 3 and 4 o'clock), the rocker arms will slip in and the cam bearings will slide into place using nothing more than finger pressure. This just happens to be the same point the motor is set to when adjusting the cam chain tension. You can see the correct point while the top is off the motor - all 4 valves are closed and all 4 rockers move. (Remember where this point is so that if a motor is to be stored, you can park the cam here to keep all valves closed and the pressure off the valve springs.)

Week 1:

Ignition setup - I used the standard points and advance unit - however, people seem to mix and match components from different models. One engine has the advance unit, points plate and rotar stamped 286 while another has 286 on the rotar and 312 on the points plate and advance unit. A bit of checking shows the 312 set belongs to the CB360. I would expect a different advance curve between CB250/350 and the much later 360 with the 360 being 'softer' as it has a lower peak revs / redline. As I don't have the facilities to find out the differences, I will use the known CB250/350 parts.
Actually getting the LF point set was difficult - as the mark was approached there is a tendency to jump past the point requiring a rotate backwards and another try forwards. The RH cylinder has one of the valves about to close and the valve spring pressure pushes the cam forward and off the LF mark - all caused by the large cam lobes I have on this cam. Another area to watch is the points cam lobe - it can be installed 180 degrees out. Makes setting the points correctly very difficult - you can actually set the points to fire at the correct location (LF for the left points but the points plate is way round from where it should be) - and watch out for the flames. As a guide, the points should be roughly vertical - if they are not, the cam may be out 1 tooth on the sprocket or the points cam is out. (A quick cheat - on the back of the advance unit is a cutout for the peg on the camshaft. The indicator mark on the points cam is on the opposite side or 180 degrees away. With the stator mark at LF, the camshaft / advance location peg will be at 12 o'clock and the points cam setting indicator mark is at 6 o'clock)

Points are set, valves are set, put some good oil in (you did remember oil didn't you?), fuel in the bowls - kick it and scare the hell out of the neighbours - forgot - I only have straight out 2 in to 1 pipes, but I fitted a 2 stroke baffel into the pipe. 3 prods and we had lift off.

First big disappointment - my very nicely heat-resistant painted cases are not fuel resistant. Can't burn the paint but petrol lifts it straight off.
Second disappointment - running very lean. I will have to pull the carby apart and blow the air through it again - must be some crap in there somewhere.

Good thing was it didn't get hot enough to lock anything up and the cam / rocker gear didn't seem to be noisy. Checked the timing with the timing strobe - close enough on both sides at idle. Must have the settings about right on the first go. Wonders will never cease.

Week 2:

Suzuki 4LS front end has arrived. Has a new Akront 18" alloy rim and heavy duty spokes. All alloy bits need cleaning and a bit of polish. After test fitting, was surprised the hub width was the same as the Honda. Looked too easy - just a threaded sleeve for one side to adapt the axel to the Honda legs. Too easy - one brake plate is 5mm wider than the other which puts the wheel off-centre. Decided to modify the legs to centre the wheel - the wheel is far more difficult to replace than finding another set of legs if the modifications don't quite work.
A bit of trimming and a spacer for the opposite side and everything is centred nicely. Honda torque arms fit as do the Suzuki brake cables and lever.

Week 3:

After much engine testing, have decided to remove the race cam and replace it with a standard cam. At low revs, there is not enough air flow to pull fuel into the engine. With big cam overlaps, there is not enough vacume to get airflow across the primary fuel ports and the engine runs very lean. Seem to be OK at higher revs as would be expected when the cam starts to work. On a race engine this would not be a problem as the engine should not spend much time below 5,000 RPM, however, for a roadgoing engine, I think it would end up either overheated or siezed. Motor out, top off, change the cam and hope that solves the overheating.

Week 4:

Standard cam has been installed and the motor is back in the frame. Still looking at ignition systems. Yet to decide if the standard coil and points will stay or if I will go to full electronic - have searched the Internet for suitable systems and have found some curcuits to "roll your own". Everything I have looked at (commercial or kit form) seem to be unusually large and therefore difficult to hide.

Back to work tomorrow - so that's it for this month. A lot of progress for the month. We are just heading in to our winter months - I think it will be about 12 weeks before it warms up again. Should be enough time to get the beast finished before it warms up again and I want to hit the road.

No work for May as I am getting my Wolseley 4/44 ready for the 2001 Wolseley National Rally. The car is not fully restored yet - still lots of bits and pieces to fit. Bikes are so much easier - smaller parts and less of them. The rally is for full week with visitors from out of state. The last time I went on this rally was '95 in Victoria (about 700 miles from home), but this time it is here in my home state. Should be a lot of fun.

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Contact Information

Electronic mail address
jmiller@brisnet.org.au

Web addresses
http://www.brisnet.org.au/~jmiller/
http://www.brisnet.org.au/~jmiller/honda
http://www.brisnet.org.au/~jmiller/matchless/
http://www.brisnet.org.au/~jmiller/hmccq/
http://www.brisnet.org.au/~jmiller/wolseley/
http://www.wolseley.asn.au/

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Last revised: April 22, 2003.