This is a common one and I’ve addressed it before. A couple of people have had problems this week with twins running on one cylinder or misfiring on one and think they need to buy a new Boyer kit. This can not be a problem with the Boyer which fires both plugs together.
First thing – swap the plug leads and plugs over. If the problem stays on the same side the cause must be carburation or mechanical malfunctions on that cylinder. If the problem goes to the other side the cause must be faulty HT windings in the coil, faulty HT lead, plug cap of spark plug.
3 enquiries about this for concentric Mk1 carbs in one day so best reply here.
I really wonder about carb “rebuild kits” – people think they can get one of these kits Amal offer and it will magically make their carbs like new again. Most used Amals I see
have been so used and abused they are junk and I hate to see people waste their money.
In all honesty and responsibility I prefer to level with customers rather than rip them off with something which won’t solve their problems.
Only if the slide to body wear is still OK and the pilot circuit is completely clean – MUST pressure check from all 4 directions -then you can go with the following:
New needle jet – this is the highest wear part in the carb and is usually overlooked!
New needle if original is worn or damaged (usually not) but check 2.67″ long so a previous owner has not fitted the wrong one. 4 Strokes all use part no 622/124
Gasket and o ring set
Stay up float kit
New viton tipped aluminum float needle – only use in concentric carbs, stick with the brass type for monoblocs.
If you have one of the very early carbs with a screwed in rather than pressed in pilot jet, my advice is get a new carb, don’t try top fix it. This is discussed in detail in an earlier blog.
Frequently asked for my honest opinion!
That’s a hot potato and there are all sorts of opinion on the forums.
I’ve had A65’s and Norton twins drop a pint every 2 days and yet run perfectly fine. In fact I had an email from my friend Gary at SRM saying that while most of these bikes wet sump badly after they have done a few miles, back in the day we hardly noticed because we rode them almost every day.
The only valve we do is 99-Us/s ($114.34 Canadian) with either 5/16 or 3/8 fitting for the oil pipe. These are made in stainless steel in Wales by a company which makes parts for Boeing. I have sold literally hundreds of them and only one engine blow up reported – the guy had forgotten to tighten the lower hose to the valve and it sucked air. One local dealer buys two or three every month.
Opinions differ – Les Emery (Norvil) says he’ll sell you an engine rebuild kit with the valve because you will need it!
Would I fit one to my bikes? In all honesty no. With Norton twins (other than 72/3 750’s) if you get the drain plug/ filter assy with the little drain plug in the ,middle it makes draining the sump an easy thing to do.
1. always park the bike on the centre stand
2. when you switch the motor off, press down on the k/s lever till you feel compression
3. run the bike on straight 50 oil (remember to warm it up before riding).
The only one currently available is 54202275. This causes concern with Triumph and BSA Triple owners because it is narrower than the ones originally sold with the bikes. It is OK to use 54202275 and it will work fine as long as you space it to run centrally in the stator.
Been asked a couple of times recently for torque specs on wheel nipples. I have never personally used one and neither has our wheelbuilder. I put the question to Central Wheel Co in the UK and they tell me that in over 100 years of wheelbuilding they have never used a torque wrench.
I don’t knock torque wrenches and find them very advisable on modern bikes. Nevertheless I do remember a question to one of the bike mags years ago when a writer was asking for the head bolt torque specs on (I think) a very early A10. The answer was that the A10 was invented before the torque wrench. Basically an experienced mechanic can fasten up most of the nuts and bolts very successfully by feel.
Back to wheels, my thoughts are very well known in that it is not a job for the inexperienced. OK have a go if you like but for goodness sake have an experienced wheelbuilder check it afterwards. The main thing is to get even tension on all spokes and this is easily checked by spinning the wheel and tapping a wrench against them to make sure they all sound the same. Uneven tension will quickly lead to spoke breakages.
As for build – aim for getting it within 40 thou (3/64″) excluding 2″ each side of the weld.
New product coming soon – self balancing inner tubes. These have special magic beads inside them and they do really work. Unfortunately not yet available in 325/350X19 & 350/400X18 (the two sizes we sell the most of) but we are working on it.
This is the regular driver’s footrest fitted to all 350 – 750 AJS & Matchless machines (other than competition models) from the early 1950’s thru to 1968. Been in very short supply for a long time so we got 200 made (powder coated) and they are selling well. $60.45 Canadian ($48.36US at today’s rate) each.
Been asked for these a lot!
We now have a source – 2-3 weeks to get in, part no 02-2794. These are good quality reproductions, polished aluminum complete with end caps studs and nuts. $285.57 Canadian each – that’s $228.46US at today’s rate. This rate is likely to change any day due to strengthening Canadian dollar.