BMW R 26 1959. Where has the Power gone ?

Begonnen von Pederkr, 29 April 2018, 16:47:46

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Pederkr

Anyone who has a good idea. Now my R 26 is on the road again after rebuilding. But it seams to have lost some power in 4 gear. Ignition is Vape, ignition time is 7 degrees before top in ideling check whit stroboscopic lamp.
Karburator 1/26/55 is rebuild after factory spec, needle, jet, jet stern o.s.v.
New valve valve seats valve guides new bore and 69 m/m piston. (izetta)
Very god compression and cylinder head gasket is the silicon type from Ullis. Cylinder top has been straightness 0,5 m/m but a alu gasket has been put under cylinder to get the same stroke again.
The engine revs good, is fairly quick getting up thru 1,2,3 gear but nothing seams to happen in 4 gear. Topspeed whit me (100 kg ) in the sattele is 95 km/h Topspeed whit my friend Egon ( 70 kg) is 95 km/h :-) so i dont have to lose weight. I have read somewhere that if the exhaust is not original, it can lose 15 km in top speed, but i am not sure. What to do, fiddling whit ignition timing or bigger jet or ????. Please give me an idea.

Pederkr



krhoff

Hi Peder,

Here are a few comments. Note that I am by no means an expert.

IGNITION:

Check that the points gap is correct. The correct gab is written in the R26 handbook. If you change the points gap, of course you need to adjust the timing again afterwards.

Test the advanced ignition at high revs using strobe. Compare this number to the R26 handbook. This number of degrees is more important than the one at idling.

Make sure the centrifugal timing advance mechanism unit is working probably. Check the springs and maybe add some oil on the moving parts. If you do, use an extremely small amount of oil and wipe of all excess. You do not want oil splashing around in the generator.

Try adjusting the ignition a few degrees more retarded than the R26 handbook. Say, 2-3 degs more retarded. Modern gasoline burns quicker, which justifies the later ignition. It has been mentioned in other topics in this this forum.

SILENCER:

If you want to find out if the problem is the silencer, there is a simple procedure. Remove it and go for a noisy ride and see if it changes anything. If so, you may modify the silencer by drilling some larger holes. This is explained in another topic in this forum.

MAIN JET:;

You may try to install a main jet one size above the factory spec. This is sometimes a way to get the last few %'s of power.

OTHER:

Make sure the brakes are not "dragging".

Make sure that the key is installed firmly and do not cut the power due to vibrations.

Make sure that the gasoline can flow at the required rate, i.e. check all filters and similar.

OldsCool!

Hi Peder,

krhoff already gave well advice. If you strobe the ignition at higher revs, the "F"-Mark should be rather in the lower part of the viewing hole -> that's the few degrees more retarded.
If the idle timing is no more that perfect at late marker ("S"), don't bother in case it runs ok.

Another aspect is the engine rework. In case you renewed the piston and rings and bored/honed the cylinder, you need to run-in the engine for the first at least 1000km before you can expect full power. Do not forget to change oil after first warm-up, 50km, 100km, 1000km etc... to remove particles from run-in.

BR Steffen
Ich bin auf dem Dorf aufgewachsen. Ich wurde nicht erzogen, ich habe ÜBERLEBT!

Pederkr

Hi there.

Thanks for the advice. My bike is running whit this kind of ignition

http://www.powerdynamo.biz/eng/systems/7383/7383main.htm

So i do not have many options to adjust but after the markings. The advance timing is electronic adjustable.
But i think the "monkey" is in the ignition timing, so i will try to make som F adjustment in 700 km time, when i reach 1000 :-)

Anulu

#4
Sorry me english is terrible.

Look at the dip switches!!!!

Factory is all dip's on(!)



You must turn the switches ,,off" or :
,, on-off-on-off"

Did you know what i mean?


An die deutsche Fraktion falls ich aus dem
uralten Schulenglisch Käse zusammengewürfelt habe, übersetzt mal bitte.

Die UPD wird werksseitig mit den Dipschaltern auf ,,On" ausgeliefert.
Das ist laut Powerdynamo eine 2-Taktkurve!


Ich hab mich fast blöd gesucht bis Rolf mich durchs Telefon gezwungen hat noch mal zu prüfen wie die stehen!
Gruß Manuel



Rock or Bust!

Pederkr

#5
Manuel, you made my day.
I did have some form for suspect for this setting.

I will try, and return whit reply

Thanks thanks thanks

Anulu

#6
Thank you.



Only a Lucky Strike or in German: ,,Schwein gehabt"

I write with Powerdynamo in Berlin about the settings.

The answer from Powerdynamo:

,,Hallo Manuel,

diese Kurven sind für die BMW 4-Takt Motoren geeignet:

1) 1,2,3,4 auf OFF: 9 Grad Frühzündung bis 1200 U/min und dann auf 38 Grad bei 3000 U/min

2) 1,2,3 auf OFF und 4 auf ON: 9 Grad Frühzündung bis 1200 U/min und dann auf 34 Grad bei 3000 U/min

3) 2,3,4 auf OFF und 1 auf ON: 9 Grad Frühzündung bis 1200 U/min und dann auf 38 Grad bei 5000 U/min

4) 2,4 auf OFF und 1,3 auf ON: 4 Grad Frühzündung bis 800 U/min und dann auf 34 Grad bei 2500 U/min und dann auf 40 Grad bei 3500 U/min

--






PS: i Drive with ,, all off"

Gruß Manuel



Rock or Bust!

Pederkr

All off :-)
What's your top speed then ??

Anulu

Dont Ask....

300ccm but max 105kmh ( last year)

but why.... ???


And than:





This year i drive äh... mean, fly with Warb III



Gruß Manuel



Rock or Bust!

Pederkr


Anulu

Good luck and please tell us the result and Vmax
Gruß Manuel



Rock or Bust!

Pederkr

VOLL GASS

It worked, the problem i solved. It's very windy today in Denmark, but whit the wind in my face 95 km/h and whit the wind in my back 115 km/h measured bye GPS and in a upraised driving position. But best of all it feels like it has a lot of power in the middel range.
It was the ignition regulator, who had a wrong base setting.
Ich bin so sufrident  :D

So once again thanks for reply and good advice, i am now riding into the sunset whit a smile on my face

   

Anulu

Very good.

Yes the weather hear in Eckernförde is always too! storm, rain , storm, rain.....and ⚡️⚡️.
Schleswig Holstein-Summerweather.

We are Neigbors.

Id like the Powerdynamo too on my ,,Deathstar"

Gruß Manuel



Rock or Bust!

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