R65 Resurrection

[Matt Chapter]

I would suppose that the back brake is the essential one to have working - I think the bike even past its uk MOT with the front brake not lighting the brake light - possible?

The front brake provides the vast majority of braking power, moreso as you brake harder and the weight transfers forward.  Ideally both should light the lamp, but if I had to pick one I'd pick the front.

Can't speak to the legal thing, but here in Texas they asked me to use the front and rear brakes separately to show the light.

[Barry]

For motorcycles built before 1986 there was no requirement for the front brake to operate the brake light so it might not fail an MOT if it didn't work. A knowledgable tester might augue that if it's fitted it should work but how many testers are going to know 40 year old bikes in that detail.

[TomHoldom]

New spark plugs leads installed and initially still not starting.
After recharging the battery and trying again that evening there was initially nothing, but then in frustration I tried I little throttle and bingo, it started. And ran nicely and was able to turn choke off (although still not able to idle) - went for a very nice 10km run.
Could this be related to my idling problem (i.e. that it won't idle at stand still stalling even when warmed up, though with a tiny amount of throttle it idles v. smoothly)?

today's update - now won't run at all with out choke, and then with limited power.
checked both idle jets which were clean - time to take the chokes apart?

As always thanks for any suggestions
(b.t.w. new tyres fitted - thanks to Georges Giralt for the advice on choice and Tony Smith for the wheel removal technique)

[TomHoldom]

Well this appears pretty serious and may explain all the issues I've been having.
Whilst removing my plugs to check again whether they were fouled, I noticed something in the combustion chamber! see photo.
Is that a piston ring thats come off? - pretty serious. Obviously I won't try and start again until I've had some feedback from here.....

[wilcom]

Well this appears pretty serious

I have no depth perspective but looks like a valve. What ever it is your quote is right on !!

[Barry]

It's normal to be able to see the valve through the plug hole - unless of course it's no supposed to be open at point in crankshaft rotation.

[TomHoldom]

It's normal to be able to see the valve through the plug hole

aha, so this might not be the disaster I feared? Shall I try and gently turn the rear wheel and see if it moves?

If this simply the valve then any ideas on my earlier issues (quoted below) would be appreciated

New spark plugs leads installed and initially still not starting.
After recharging the battery and trying again that evening there was initially nothing, but then in frustration I tried I little throttle and bingo, it started. And ran nicely and was able to turn choke off (although still not able to idle) - went for a very nice 10km run.
Could this be related to my idling problem (i.e. that it won't idle at stand still stalling even when warmed up, though with a tiny amount of throttle it idles v. smoothly)?

today's update - now won't run at all with out choke, and then with limited power.
checked both idle jets which were clean - time to take the chokes apart?

As always thanks for any suggestions

[Barry]

aha, so this might not be the disaster I feared? Shall I try and gently turn the rear wheel and see if it moves?

Yes and I'd do it with the rocker cover off so that you can see the rockers and valve move together which will eliminate the valve sticking open.

I've forgotten what you have done so far but it would be good to measure the valve clearances at the same time to check they haven't closed up.

[TomHoldom]

Hi Barry,

Took the rocker cover off, mostly ok - made a couple of small adjustments to the clearances:

These are my outstanding issues (that I'm aware of....)
1/ not starting unless I give a little throttle
2/ not idling (when warm). Though with a tiny touch of throttle it idles nicely - slow and smooth
3/ right plug sooting up a little / left side possibly running hot

Once its running it seems to run quite well......

[TomHoldom]

After reading Steve Doyles doc. on tuning Bing Carbs, I adjusted the throttle adjust screw following this advice:
"use a thin piece of paper between the throttle adjuster screw and where the screw touches the throttle lever. Set equal opening of the butterflies here. Tighten / loosen the screw until it just grabs the paper. 1/2 to 1 turn tighter (clockwise) is about idle speed."

and this has fixed my idling problem - hopefully I haven't just masked another problem.

My outstanding issue now is the right side misfiring and constantly sooting up that sparkplug. This is what I'm thinking as my next steps:

- possibly running rich (turn in mixture screw (clockwise)) ?
- check float level: A too high fuel level is likely to cause an excessively rich mixture, which quickly fouls the spark plug.
- possibly weak spark resulting from dodgy coil (I'll swap coils and see if it stays on the right side)
- check the choke operation on the carby that is on the side that does not fire up when cold.

Do these all sound like sensible things to investigate?
Thanks for your thoughts....

[Barry]

My outstanding issue now is the right side misfiring and constantly sooting up that sparkplug. This is what I'm thinking as my next steps:

- possibly running rich (turn in mixture screw (clockwise)) ?
- check float level: A too high fuel level is likely to cause an excessively rich mixture, which quickly fouls the spark plug.
- possibly weak spark resulting from dodgy coil (I'll swap coils and see if it stays on the right side)
- check the choke operation on the carby that is on the side that does not fire up when cold.

Do these all sound like sensible things to investigate?

Float level is first thing to check before any other adjustments are done on the carb. Making sure the enricher is correctly assembled and fully shuts off against the stop is essential too.

I doubt it's the mixture screw if it's close to the base setting of 1/2 a turn out but worth a try if you first make reference mark so you can get it back to the base setting. Yes turn in to weaken.

Quickest ignition check is to swap the leads over from one cylinder to the other without disconnecting anything except pulling the caps off the plugs. If the fault then moves to the other cylinder you can narrow it down my swapping leads at the HT coil. There is no need to physically move the coils.

[TomHoldom]

Float level looks ok, although I'm finding it difficult to assess accurately due to the spillage I get due to the angle (RHS 13.13 degrees, LHS 17,3 degrees off horizontal), but with a funnel set up underneath, when I pour the spillage back in they are near to 24mm.
Certainly when the float is level with the carb body the flow stops.
Could the difference in mounting angle of the carbs be significant?

The choke on the misfiring side was a touch off the stop tab when fully off, but I have adjusted that now (which now means that the fully open is a touch off that tab, but I guess this is less critical?)

Swapped which coil is connected to which spark plug (with new leads), and I don't think anything has changed - i.e. still misfiring on right side.

I checked the idle jet again which was clear.

Might be worth opening the enricher bits on the right carb?

When checking the spark on the right side, the engine runs on the single left cylinder, but not the other way around.

When I run the bike now, it seems ok at low throttle, but when I open it up I can really feel the lack of power.

A few days ago it was running better, I would say to full power - I went on a 30km round trip with a 1/2 break in the middle with no problems, apart from the fact left side was hotter than the right, and the right spark plug was sooting up, which made starting difficult the next day

Any thoughts for next steps appreciated as always

[Barry]

when I pour the spillage back in they are near to 24mm

Anywhere between 22-24mm is fine provided the floats are known good i.e. they are new or you have weighed them.

Could the difference in mounting angle of the carbs be significant?

Not particularly as the main/needle jet are on the central axis so not really affected by the tilt in fuel level.

The choke on the misfiring side was a touch off the stop tab when fully off, but I have adjusted that now (which now means that the fully open is a touch off that tab, but I guess this is less critical?)

Agreed.

Might be worth opening the enricher bits on the right carb?

I think you have to in order to eliminate from enquiries.

Any thoughts for next steps appreciated as always

In principle it's simple; good compression, good spark at the right time and the carbs set correctly should make it run properly.

[TomHoldom]

Once started it seems to idle quite nice and evenly, so I thought I would check my main jet / needle jet as it is after about 1/4 of the throttle when it seems to struggle (on the right side?).

This wasn't blocked but I did notice a couple of things which may offer a clue as to the problem.
1 - a little bit if oil around the air intake tube - is that normal?
2 - the needle appears to be slightly offset from the centre of the combustion chamber / needle jet assembly.....? see photo

any of that helpful?

edit - on looking at the needle again, it has some play in its mounting, so moves easily to be centred.

[TomHoldom]

and a photo of the oil on the air intake...