'63 r60 losing power after warmed up

sherman980
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Re: '63 r60 losing power after warmed up

Post by sherman980 »

Dumb question... Are you sure the gas cap is venting? ....
Thanks.
Chuck S

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jwonder
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Re: '63 r60 losing power after warmed up

Post by jwonder »

Ziggy wrote:
Sat Nov 07, 2020 7:25 pm
I am going to take the advance off tomorrow and inspect. While it is still on the bike are there any simple diagnostics I could do to determine its general condition? And, once off, will overly worn lobes be obvious?
The way that I found to be the best to check it is as follows:

1) take the condenser wire off the points.

2) Connect an ohm meter set for continuity to the terminal where the condenser wire goes and to the block. Make sure you have a meter that beeps when it has continuity so you can verify listen for the beep.

3) Remove the spark plugs.

4) Slowly turn the motor with the kick starter and find out where the beeping stops. Thats the point at which the points open. It should be at the "S" line. Do the same thing for the next cylinder and re-test. If it is far off you have differential timing for some reason to be then inspected. I find that putting the kick starter all the way down at the bottom of the stroke I can use the foot peg and my hand to really control the movement very finely.

See my video at: viewtopic.php?f=7&t=16364 for a look at how I do it with the beeper. This shows the lobe height as well, but you really don't need to go that far to measure the differential timing and see if you have a problem.

Good luck,

James
James Wonder
1967 R69S, 1966 R50/2, 1965 R27, 1963 R27, 1952 R51/3 and 2018 R1200GS
Long Island, New York

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jwonder
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Re: '63 r60 losing power after warmed up

Post by jwonder »

sherman980 wrote:
Mon Nov 09, 2020 7:50 am
Dumb question... Are you sure the gas cap is venting? ....
That is NOT a dumb question. Fuel flow is a possible cause, either non-venting cap or clogged filters, but I am fairly sure he checked the filters already.
James Wonder
1967 R69S, 1966 R50/2, 1965 R27, 1963 R27, 1952 R51/3 and 2018 R1200GS
Long Island, New York

sherman980
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Re: '63 r60 losing power after warmed up

Post by sherman980 »

"....but I am fairly sure he checked the filters already."

Clogged gas filters tend to slow fuel flow immediately. You likely wouldn't get a mile or two at speed before you noticed the float bowls running too low. A gas tank with a cap that isn't venting properly that is less than full (plenty of air space in the tank) will allow the bike to run like normal for quite a while before the vacuum in the tank builds enough to actually cause poor running. It would be easy for a bike with a poorly or non-venting cap to go 10 or 20 miles (or more) before you might notice.

Easy enough to check. Fill the tank say 2/3rds full, tighten the cap, and then drain it through the petcock. Check the fuel flow when you start and again every few minutes. If you see a slow down, open the cap and see if it improves things. You can do the same thing when you're riding. When you notice the loss of power, just open the cap and see if things improve - it might take 20 or 30 secs or maybe a bit more, but you'll know pretty quickly.
Thanks.
Chuck S

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Ziggy
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Re: '63 r60 losing power after warmed up

Post by Ziggy »

Advance appears to be working properly. Springs seemed a bit tired, so replaced them. Timed the bike again and S and F marks appear at idle and full advance in inspection hole. Bike starts nicely, goes well. Move through the gearing up and down until the bike is presumably good and warm - roughly 15/20 minutes and then the power loss sets in, top of 2nd ask for more and it just doesn't transfer power with increased throttle. So new points, new condenser, new Emerald Isle coil, properly gapped points, seemingly properly timed ignition, properly timed magneto, good compression. I ran the bike with magneto exposed, Richard at Benchmark said that this would rule out coil involvement if the problem persisted, and it did (I assume this test was to run the bike in a way that the coil would not heat too much) So I am left with a bike that gets going great cold, and then does not want to go well at all when warm. It has never outright died, but a lot of limping back and no clear direction to go at this point. I have given thought to the clutch, but wouldn't a worn/slipping clutch show itself differently, as in, why would the bike go along fine and then once warm, then have clutch issues. Grasping at straws. Thanks for all the previous responses, and any more that might help me dial in what is the root of the problem.
JF Rogers
'63 r60/2
Scituate, MA

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Bikesmith01
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Re: '63 r60 losing power after warmed up

Post by Bikesmith01 »

Hey Ziggy.
Apologies if I just missed it (This thread is getting long!), but I haven't seen if you've given a really detailed description of your symptoms. I know you're getting power loss, but how exactly does that manifest? When warm is the bike idling well? Then when you twist the throttle, what's the response? Does the engine sputter and cough? If so, is it only initially? If you hold the throttle at, say, 2000 RPM does the engine smooth out after a second? Does it keep doing the same thing? Does it get worse? Maybe the engine is completely smooth, but just totally gutless?

Is the problem exactly the same regardless of load? Does it do the same thing with the clutch disengaged or with the bike in neutral? Do you have the same issue if you very slowly increase the RPMs from idle?

If your engine is having its problem and you release the throttle does it go back to a smooth idle? Immediately?

Any other detail you can think of to throw in might be the one that gives somebody here their AHA! moment.

-Jon
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Jon the Bikesmith
1959 BMW R60
1940 Royal Enfield WD-C/O
1942 Chevy 3/4-ton special Flatbed
1985 BMW K100RS
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312Icarus
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Re: '63 r60 losing power after warmed up

Post by 312Icarus »

Stranger things have happened, but consider a pair of new plugs. Speaking of plugs, what do they look like when you pull them? Also check plug gap, carbon fouling. ONe more final idea (at this point) Are you running ethanol free fuel? Is it possible the fuel is beginning to boil giving a vapor lock? (I assume you have checked carb to head gaskets?)

Icarus

Jim D 5112
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Re: '63 r60 losing power after warmed up

Post by Jim D 5112 »

You may want to read the thread from November -19-2017 called R69S Starting Issue. In it is a post about the proper grounding for the magneto and taking that whole area apart to insure good electrical ground contact. There is also a thread called Magneto Anomaly from around September -6-2016 that also talks about the grounding of the magneto near the end of the thread. When the unit warms up the resistance builds up causing problems with the condenser and points.

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Slash2
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Re: '63 r60 losing power after warmed up

Post by Slash2 »

Jim D 5112 wrote:
Tue Nov 10, 2020 8:36 pm
You may want to read the thread from November -19-2017 called R69S Starting Issue. In it is a post about the proper grounding for the magneto and taking that whole area apart to insure good electrical ground contact. There is also a thread called Magneto Anomaly from around September -6-2016 that also talks about the grounding of the magneto near the end of the thread. When the unit warms up the resistance builds up causing problems with the condenser and points.
I’ll second this suggestion.

By losing power is it possible you’re dropping a cylinder?

Richard at Bench Mark works suggests assembling the mag body with “no ox” (an anti oxidation compound) to ensure proper grounding.

I’m chasing a very similar issue and my next step is to tear the entire mag down, clean again, and reassemble with no-ox. My bike starts easily cold, runs beautifully for about 20 minutes and then begins dropping the right cylinder. 1965 BMW R69S.

Will post any relevant updates.
64' R60/2 - 66' R27 - 51' R67 - 68' R69S
88' R100RS - 06' K12R

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Ziggy
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Location: Massachusetts

Re: '63 r60 losing power after warmed up

Post by Ziggy »

I will look back to those 2 threads, and Slash 2, very interested in anything you find. As far as I can tell, both cylinders are firing when power loss occurs.
JF Rogers
'63 r60/2
Scituate, MA

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