Big Bore 1070cc

[HOOK74]

Hallo an alle,


Mein Mechaniker baut meinen 1991er R100GS-Motor um, der ein 1070er Siebenrock sein wird. Ich entschuldige mich für meine Unwissenheit und mangelndes Wissen. Ich bitte Sie um einige Informationen, damit ich nachlesen kann.


1) Trotz der Siebenrock-Empfehlungen möchte mein Mechaniker die Doppelzündkerze nicht verwenden. Was könnten die möglichen Probleme sein? Weniger Kraft des Bigbore-Kits, Detonation / Schlag in den Kopf?


2) Was könnte (mehr oder weniger) der richtige Quetschwert und das richtige Kompressionsverhältnis sein?


3) Ist ohne Doppelzündung eine besondere Arbeit an den Köpfen erforderlich, um eine Detonation zu vermeiden?


Sie sind auch neugierig zu wissen, was ich im elektrischen Bereich tun kann, aber ich frage im richtigen Abschnitt.


Danke



Hello to all,


my mechanic is rebuilding my 1991 R100GS engine which will be a 1070cc Siebenrock. I apologize for my ignorance and lack of knowledge. I ask you for some information so I can read up.

1) Despite the Siebenrock recommendations my mechanic does not want to use the double spark plug. What could be the possible problems? Less power of the bigbore kit, detonation / knock in the head?

2) what could be (more or less) the right squish value and compression ratio?

3) without the use of double ignition, is a particular work on the heads necessary to avoid detonation?

They are also curious to know what I can do in the electrical field but I ask in the right section.

Thank U

 

[MM]

When you combine a bigger cylinder with a serial head without machining it you make a compromise (plug & play concept) using two spark plugs.

The alternative option is to adapt the heads to the bigger diameter. As the used heads should be reconditioned anyway it is a good idea to use the second way.

Without adapting you will have problems with knocking combustion.

 

[HOOK74]

Hello MM,

thank U.

for sure my mechanic will work on the heads to adapt them to the new cylinders & pistons. so the double spark plug shouldn't be needed ... right?

 

[MM]

If he does a good job it will work.

 

[R 110 ES Peter]

Hello Hook74,

look at this:

Wer macht die Arbeiten an den Zylinderköpfen für SR Big Bore - Seite 2 (2-ventiler.de) #12

my tunig spezi told me to do this. I did it, and it was amazing. I never thougt that a 2V flat twin runs so well with a serial camshaft.

what do you mean with -detonation- ?

with best regards peter

 

[Rudi]

what do you mean with -detonation- ?

Klingeln

 

[HOOK74]

If he does a good job it will work.

...to be reserved and fair I do not mention his name (as he is known in the BMW world)...he should be competent and precise. I hope it does a good job.

 

[HOOK74]

Hello Hook74,

look at this:

Wer macht die Arbeiten an den Zylinderköpfen für SR Big Bore - Seite 2 (2-ventiler.de) #12

my tunig spezi told me to do this. I did it, and it was amazing. I never thougt that a 2V flat twin runs so well with a serial camshaft.

what do you mean with -detonation- ?

with best regards peter

I'm sorry for my bad English ...I do not speak German...

Detonation is Klingeln as Rudi wrote (thanK U Rudi)

I'll take a look at your link

thank U