Running really rough below 3,000 rpm

[quixotic]

Is it possible the boyer ignition plate is not centered in the bean can. Does the boyer have 2 magnetic sensors and are they exactly equal distances from the cam.  

I suppose anything's possible with the Boyer.  I wasn't too impressed with the design or the instructions.  The stator plate (I assume that's what it's called) was similar to the stock mechanical unit in that the two screws that went through the bean can were used to hold it in place.  Now, whether the plate is perfectly perpendicular to the sides of the bean can is another matter; it's just made out of circuit board material, so it's not nearly as robust as the stock unit.

Yes, it does have the two magnetic sensors.  I'm not sure about the distance to the cam, but it seems that they're made to signal to two metal prongs that stick down from the stator plate.  I think the only adjustment possible would be via any gap in the bean can where the two screws go through to hold the stator plate (ie, loosen the screws slightly and see if the can will allow some extremely tiny movement of the plate) (and maybe also to confirm that the plate is perfectly perpendicular to the can).

[quixotic]

I just came across another bit of weirdness.  I adjusted the throttle stop screws so that there was a bit of a gap (0.03 mm's) when the throttle was off (there was none before).  After that, I very slowly increased the throttle to about 1,500 rpm.  So far, so good.  Then, just above that, the rpm's (on the tach and the engine) would race up to about 4,000 or 5,000 -- even though I had only just increased the throttle by a tiny notch.

I'm not sure if that symptom was there before the throttle stop adjustment or not, since prior to that, I may have just been blipping the throttle instead of very slowly increasing it.  I guess I'll know for sure later today, when I take the bike out on to the road.  

[Bob_Roller]

You need to perform a carb synchronization, with a manometer or gauges connected to the carbs .

Do this on an engine that is at operating temperature, not a 'cold' engine .

[quixotic]

Well, I disassembled both carbs and gave them a good cleaning.  Then I made a manometer and did the synchronization thing.  I found that the butterfly stop adjustment at idle and the cable housing adjustment around 1,400 rpm went well, but that the idle mixture adjustment was a bit more of an art (whether I'll eventually master it is anybody's guess).  

Occasionally though, when I blipped the throttle, the rev's would climb up to an indicated 5,000 rpm and stay there.  My hunch is that it's got something to do with the Boyer ignition that I installed a short time ago.  I've also had problems with the tach, and although I've been able to tune to the idle mark on the flywheel, I've been unable to tune to the advance mark (can't seem to hold the throttle steady enough).  Plus, I've consistently heard what sounds like marbles in a tin can when accelerating on the highway.  This all leads me to believe that the Boyer unit is the culprit.  So I think my next task will be to reinstall the stock timing unit and see if those issues clear up.  

[Barry]

This all leads me to believe that the Boyer unit is the culprit.So I think my next task will be to reinstall the stock timing unit and see if those issues clear up.  

I think that's a good plan as the ignition has to be known good and timing correct before you can finalise the carb settings.

[georgesgiralt]

Hello !
Start by checking the valve clearance (it has a big influence), then check spark plugs, points, and advance system.
Only then you can synchronize carbs and set idle richness.
As for the throttle, you should buy the screw to set the throttle handle where you want it.  
It is item # 26 on the right handle fiche for model after 81 (I hope the previous model had the tapping for the screw...)

[quixotic]

Hello !
Start by checking the valve clearance (it has a big influence), then check spark plugs, points, and advance system.
Only then you can synchronize carbs and set idle richness.
As for the throttle, you should buy the screw to set the throttle handle where you want it.
It is item # 26 on the right handle fiche for model after 81 (I hope the previous model had the tapping for the screw...)  

Thanks Georges.  Yes, that has all been done.  

The good news is that now I've taken the Boyer ignition out and reinstalled the old mechanical system, my tach is working again.  And no more knocking during acceleration.  

And with that and the carb balancing, the bike is now running better than it did at any time since I bought it 5 weeks ago.  

There's a bit of fairly loud valve chatter above 4 or 5,000 rpm on the right cylinder, so I'll probably re-check that.  But all in all, I'm a happy camper.

[georgesgiralt]

Well, glad you've a running bike ! summer is coming !
The noise could be due to pitting at the rocker tip. (making the valve to re-close a bit after opening a bit).
Some workshop can re-polish the tip and harden it back but it is becoming somewhat of a lost art.
You could start searching for a couple of non pitted rockers.... Or a wizard...

[Bob_Roller]

When you are checking the valve clearance, check the gap of the rocker arm and the blocks at each end .

Too much clearance will give you more valve noise/clatter .

[Luca]

Nice tip Bob, I'll have to do that myself from now on.

Also, Quixotic, congratulations!  Now that your engine has smoothed out, you can play with the inevitable higher end vibration (around 5K) by adjusting your motor mount torques.

[georgesgiralt]

Hello Luca,
Could you explain the torque influence ,
I've always bolted my engine "by the book" so I will enjoy learning a new trick to try on my poor R65  
Thanks a lot in advance !

[Luca]

Play with your torque values... a little up, a little down.  Supposedly each engine/frame combination is different, so you will have to tinker yourself.  I'm doing some experimenting myself.  45 ft/lbs front and 40 ft/lbs rear seems to have a narrower high speed vibration (The 65-75mph buzzing that turns many people away from the R65) than 55/50 or 50/45 torque values.

I've been meaning to put a thread up asking what people would consider the minimum safe motor mount torques.

[Barry]

I've been meaning to put a thread up asking what people would consider the minimum safe motor mount torques.  

I'd use the 85 on torque values as the low end limit.  Forget what they are exactly but a fair bit lower than the earlier figures.

The best explanation I can think of why toque values have an influence (and I believe they do to some extent) is that the high frequency buzz happens to be at revs where the engine vibration resonates with the natural frequency of the frame. Back In the day when special builders swapped vibratory Brit engines and frames it was well known that the same engine could feel quite different according to the frame it was installed in and that must have been due to coupling and resonance effects.

Changing the torque values may alter the coupling between engine and frame which perhaps moves the resonant frequency and amplitude around a little.