R69 not running right

[R50Bill]

well he is telling you right about fouled plugs and today's fuel

From my Newbie thread:

I'm wondering if you should revisit you're starting routine. Each bike requires just a little different process depending on the state of tune and carb setup. How much to tickle, how to use the throttle, etc. I've finally settled in on a good routine on my R69S. A couple of things that I do that, I hope, helps it start. After I tickle each carb, I kick through 3-4 times, key off and throttle closed. Then I turn the ignition on and with little to no throttle, kick it...it usually starts first or second kick.

Kurt in S.A.

It woiked!

[redavide]

So far I've checked floats, advance weights, condenser, petcock, plugs, cleaned out float chamber and everything seems OK. As already suggested I suspect the problem is related to a vacuum formed in the gas tank which prevents fuel from going down to the carbs smoothly.

I've noticed that if I run the engine with the petcock closed to empty the carbs of fuel, when I re-open the petcock I can hear fuel flowing down to the carbs in a slow gurgle and then if I quickly open the gas cap the fuel starts flowing very noticeably faster and easier.

My question now is: how does air get into the top of the tank to prevent the vacuum from forming? My cap has a rubber gasket around the inside and screws on very tightly -- there's no way any air's getting in the tank unless you unscrew the cap. Does anyone know of another type of cap that somehow allows air in? Is there some other reasonable method of creating an air flow?

[schrader7032]

I have a cap I bought from Vech and looks like the original. It has no openings on the top. It seals down fairly tight...it's got a cock gasket IIRC. My guess is that the air gets in by going between the cork gasket and the outside edge of the metal cap. Then it goes through some openings that are behind/above the gasket, hidden from view. It has to vent because I've never had a problem with a vacuum forming in the tank.

Kurt in S.A.

[EuroIron]

there is absolutely no reason to have any such suspicion as it is quite easily diagnosed

run it without a cap

if that cures it

you found your problem quite simply

then simply drill a hole in your cap and live with it or get a new one

[niall4473]

The cap breathes through the two holes that the locking ears are pressed out of, and the multitude of holes around the periphery where the two pieces are swaged together underneath. This works perfectly as long as the seal doesn't mask them over, see my previous reply.

[vonkas]

I rode my R69 about 100 miles today. It ran perfectly except for three short periods...

my take: when it sputters, stop engine and immediately close fuel tap. Open float bowls and check fuel level - this tells if you have a flow restriction or stuck float with subsequent over supply.

However my bet is that your ignition points are dodgy. Nowadays the quality of aftermarket parts is questionable. The points can 'stick', meaning they do not rotate frreely on the axes or the spring is obstructed. I have also had problems with the nylon cam wearing very quicly, especially with new points - some seem to settle down once worn in. ALso the spark bypasses on the coil can be too closely adjusted, handbook says 11mm - but that is the shortest distance between anything and the terminals. On reco coils the terminals may be out of place and the spark jumps to another palce than the brass pointy thingies.

All of the above can depend on temperature and be intermittend, with a tendency to getting worse.

I have fixed my sputtering problems by observing the above and taking the mechanical igntion parts off the engine, freeing everything nicely and lubricating all moving surfaces with thin oil. Make sure the felt is in place and touches and is well lubed - I use 2.5W shock oil and refresh it every service.

Let us know what you find..

Jim

[redavide]

I took the bike out for about 30 minutes the other day and it just generally ran really rough -- missing, sputtering and giving a kind of pushing/pulling feeling.

The fuel flow from the petcock is strong (more than 100cl/15 seconds as per Duane A's recommendation). I inspected the floats and they appear to be in good working order. I took off the front engine cover and ran it in the dark -- no visible sparking at the points or anywhere else (except a bit at the generator brushes at higher RPMs).

Question: If the condensor is bad, will there definitely be sparking at the points or not necessarily?

Spark plug leads are brand new and the screws holding them to the coil are tight. When I inspected the plugs (which are brand new), the gaps were correct, but they had a lot of fluffy black carbon on them. I cleaned them off and the engine ran a bit better afterwards but still very rough.

Question: Is the carbon on the plugs a result of the rough running or possibly a symptom of the problem? Also from one of the replies above, someone wrote that "the plug is a NGK BP6HS and the gap is .020" Once they get fouled they are NG." Is this true? Should I buy new plugs? Also, what is the correct gap? .020 is smaller than what the owner's manual suggests.

I also noticed that where the spark plug leads attach to the coil, the bare wire comes out below the small brass cylinder that the wire mounts to. The space between the pointy brass part below and the end of the spark plug lead is considerably less than 10mm.

Question: The suggested measurement of 10-11mm is from what point to what point exactly?

Any thoughts are appreciated.

[schrader7032]

It is my understanding that the condensor is designed to smooth out the voltage spikes at the points. If a condensor wasn't working, I think you would see some sparks and the points wouldn't last as long...the surfaces would become pitted very fast. If there's any doubt, replace the condensor.

The saftey gap of 10mm is to anything... If the wire from the spark plug lead sticks through the post significantly, then the 10mm should be measured to that. The spark will jump to the closest point and the exposed end of the wire could be that point.

Kurt in S.A.

[bombard4101]

I had a similar problem with my '66 R60. When riding, it would suddenly start to sputter and miss a bit like it was runnig out of gas. The problem was in the key switch at the headlight, it would work its way up just the tiniest little bit (you can't see it) and the bike would "shut itsefl off" just for a second. I'd push down on the key and all would be well. I've read of this problem and the solution is to rebend the contacts in the headlight. Mine was so minor, that now I know what to do and just touch the key once in a while. I've already had the switchplate out of the headlight once during restoation, and didn't really want to risk breaking off tha tabs just for this. Don't ask me how I figured this out, but it works. Keep it simple before tearing everything apart. Don't forget, you are dealing with basically a tractor engine.

[niall4473]

When riding, it would suddenly start to sputter and miss a bit like it was runnig out of gas. The problem was in the key switch at the headlight, it would work its way up just the tiniest little bit (you can't see it) and the bike would "shut itsefl off" just for a second. I'd push down on the key and all would be well.

You lot must be very brave if you ride these bikes out on the road without a rubber band over the key, I wouldn't, even if the switch and key were new, and stayed down, in fact the practice used to be so universal here that until I was about 14 I thought that was how it was intended to be!
Also, if you don't have the rubber band (cut from a 4.00 inner tube), what keeps water out of the switch? Here in the UK, and most other places where the authorities put salt on the roads in winter, your switch would rot away in one winter if you didn't keep it out.
Here are two good examples, on this pristine, original, low-mileage R60.