Just returned from a really nice vacation on the East Coast. My friend Colin Warman in Halifax lent me this beautiful low mileage G15Mk2 and with him on his 69 Bonnie we covered some 300 kms along the beautiful Nova Scotia back roads. High light of the ride was to drop in at British Cycle Supply where Wayne showed us around. Mark, the boss, was away but he did call me to say I was welcome to visit as long as I didn’t offer Wayne a job.
Customer withT120 is having a problem. Despite both 930 carbs having the same settings one cylinder runs perfectly with a nice cookie brown plug reading and the other plug reads horribly while and lean and that side is running very hot. Recently rebuilt motor so it seems the air to gas mixture (ideally 13:1 approx.)on the problem side is way out of wack. Too much air or not enough gas.
Just like most of us do when we want to find something out or have a problem – we Google it. The advice he came up with is that the problem is a blocked pilot jet and he should run a drill through it!
Here’s the thing – for anything above 1/16th throttle opening the pilot jet doesn’t affect anything very much. The mixture is controlled by a combination of throttle cut away (the number is the height of the bridge in 1/16th’s of an inch – ie no 3 slide = 3/16″), the tapered needle passing through the needle jet, and the main jet.
If the needle jet is blocked (very common if gas has been left in the carb for an extended period) it is easy to tell – turning in and out the pilot screw won’t make any difference to the way the bike runs. And flooding needed to get it started. Hold the carb body with your thumb over the air hole at the back, index finger over the 2 little holes at the front of the slide and blast a shot of WD 40 using the red “straw” down the pilot adjuster hole. Gas should squirt out of the pick up hole in the bottom of the body. Good luck if it is blocked. Even if you poke something through the jet (not advisable) to clear it you can be sure there is more sludge in that passage which will block it again. At least the new carbs now have a clean out plug.
Back to my customer’s problem – if there are no air leaks in the inlet passage downstream of the carb, I would assume he either has a worn slide allowing air to come around the sides, an obstruction to the gas flow or perhaps wrong float height. The latter is less likely and not as much of a problem as with Mikuni VM’s which I have found to be incredibly sensitive to float height setting.
A customer asked last week what sealant he should use when fitting Norton head gaskets so I took the opportunity to ask some guys who build a lot of motors.
As has been my experience everyone I asked fits copper gasket dry. I always annealed them which I thought might have been overkill even with a new gasket however Les Emery, who worked a lot with copper and brass in his previous life at Lucas, recommends annealing new and used ones and fitting them within 20 minutes.
With the Norton motor it doesn’t hurt to put a thin ring of silicone around the push rod and oil return tunnels in the head and barrel.
With composite gaskets, if they have a copper flame ring they can be fitted dry but if it is steel you should use silicone RTV or similar.
If you feel happier using a sealant, Les uses FIXTPRO engineering grade silicone which he just dabs on with his fingers.
I always used to torque the head down and run the bike for 5o miles or so then torque it again and do the same thing at 500 miles, each time checking the tappet adjustment. This procedure is more necessary with composite gaskets which are more likely that copper to compress in use.
I’ve had some good feedback on this subject and have spoken at length with four customers who ride big mileages on classic British bikes. By far the most popular oil is 20-50 Castrol GP motorcycle oil. Two guys reported over 30,000 miles with minimal engine wear.
My friend Gil Yarrow in BC rides huge mileages on his 750 Commando and swears by a bland of 90% 20-50 GP and 10% Lucas heavy duty oil stabilizer. This he recommends for all bikes apart from late model Triumphs because the additive would not be very clutch friendly.
A couple of guys mentioned Shell Rotella T-Triple 15-40 and one engineer customer swears by 20-50 Spectro 4, which by its ads claims to have the highest content of anti wear additives.
I had a long chat with a friend who owns a machine shop and he told me the most important thing to look at when selecting an oil for our classic bikes with their flat tappets is the amount of zinc (“solids”) it contains.
Most of my riding these days is on my Kawasaki Ninja 300 and GSXR750 Suzuki both of which perform well on Castrol Grand Prix 10w40 motorcycle oil. This is designed for liquid and air (widely varying temperatures) cooled bikes. I avoid car oils because they are not generally friendly towards motorcycle clutches. I change the oil and filters once a year before putting them away for the winter.
We were looking for a suitable 50 weight oil (my first choice for the Norton twin as previously mentioned) to offer to our customers. Castrol do make Grand Prix in a straight 50 but it is very expensive. On the advice of our local oil rep we settled on Kendall GT-1 however an engineer customer has been very critical of it and recommends Spectro.
For the primary chaincase (other than of course Triumphs which breathe their motors through there) we sell a Kendall non-detergent 20 weight oil and customers seem to be happy with it.
I’d really like to hear opinions on this subject, especially from people who ride big mileages on classic bikes and are able to assess wear on eventual teardown.
As an aside, I have been recommending customers put a small amount (say an egg cup full) of 2 stroke pre-mix oil in every tank of gas. It will keep the gas taps working well – they were designed to be used with gas which contained lead and sulfur for lubrication – both of which have since been removed. It will also extend the life of your inlet valves.
One more ramble and then I’ll get packed up for the CVMG Paris (Ontario) Rally this weekend. We have some TY Yamaha trials bikes here which we run on pre-mix. Unlike the 4 stokes in which we religiously load up with Star-Tron or other stabilizer before laying them up for the winter, we don’t bother with the TY’s and they always start up fine in the spring…..
When this subject comes up at swap meets and shows I am perplexed by the variety of opinions and everyone seems to think he is right. One dealer customer is getting very frustrated with problems with Norton rebuilds and is switching to USA made Hastings rings if he has any problems. Interestingly the “Hepolite” pistons sets supplied by Wassells presently have Taiwanese pistons (well received by customers) with American Hastings rings. The JP Pistons we sell (Australian) used to use Hasting rings but have switched to Indian made type with which they are enjoying good success.
I must admit I don’t ride long distances on Classic bikes these days but I am going to pass on some of my experiences from the 60’s and 70’s when I used British bikes as my daily riders. I will follow this up in a day or two with some modern day thoughts and advice.
My new 1966 T100SS seemed to burn a pint of oil every 300 miles and when I mentioned it to the dealer he told me new Rolls Royce’s burned a pint every 100 miles and I shouldn’t be concerned. It seems to me that vehicles in general back then burned oil and it was quite normal to check the oil and quite often top it up every time you filled up with gas. Modern vehicles (at least mine) use next to no oil. My Ford van has over 200,000 miles on it and doesn’t need topping up between oil changes. I sincerely believe that how a motor is driven in the first 500 miles has a huge effect on longevity and oil consumption. Keep the motor revving freely, don’t race it or lug it. Use as little choke as possible (extra gas washes the oil off the cylinder walls) and shut the throttle fairly frequently. High revs and fast riding/driving too soon will get you a motor which will use more oil I believe.
My main riders were an AJS 33 and A 1969 Commando Fastback. Both these motors I rebuilt a few times (mainly due to that infamous timing side crank bearing) however I had the cylinder bored twice on the 33 and once (I think) on the Commando. Probably on the advice of a mechanic friend, I ran the motors in on 20-50 and did experience heavy oil consumption in the first 500 miles. I would then change to a straight 50 and had no more oil consumption problems. These motors were designed to burn some oil initially and the ring of carbon created around the outside circumference of the top of the piston would help seal it up. Read any handbook from the 50’s where it covers de-carbonizing (de-coking) the motor – a normal routine procedure for the hands on owner back then. It is stressed that when removing the carbon from the top of the piston you should not remove it from the outer circumference or increased oil consumption will result.
We sell a lot of terminals and wire (in all the common colours) for customers who are repairing or making their cables. We recently had a complaint from a customer that the new wiring harness we had sold him had crimped, not soldered terminals.
Many years ago a very well respected engineer and British bike mechanic told me that good crimping was preferable to soldering as there would be less likelihood of the terminal breaking off. Our UK wiring parts supplier told me recently that the vast majority of his customers prefer the crimp their terminals these days.
If crimping bullet type terminals it is most important to choose the correct sized terminal to suit the diameter of wire being used. This is not as important if you soldering.
The next revision of the Walridge catalogue, which we are presently working on, will include more terminal types together with suitable crimping tools.