hello

thanks for all the comments.

For now I will put the 11:1 pistons in standby. I'm still not sure if I will have problems with low octane fuel with this solution.

BTW: last May I went to Algeria with my lightweight and with a friend with a modified KTM. The KTM was using an engine with 11.5:1 compression and he didn't have any problems with pinging. Only overheating… J

I will probably go moto Israel solutions but I would like to see some Dyna tests and find more comments about them.

Bernaro Feio

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bernardo feio (Portugal)
2.5 Land Rover Lightweight / BMW R80 G/S PD / Toyota HZJ 78

The KTM handles low-octane petrol pretty good, I guess a modern cylinder-head and watercooling helps. Some (all?) have a possibility to alter the ignition.

I was driving with a guy on a 640-adventure in Iceland, it overheated...

Thank you Alibaba.
I am quite illiterat when it comes to brittish measurement - I did interpret Mr Moores test too negatively.
My applogies to all for this misstake.


Bernardo I do stand firm in my primary recommendation - address oil cooling and vehicle durability/simplicity. This tuning will not be expensive if you use 2:nd hand parts.

This is a neat idea on enging cooling (I do not recommend this to you - its just a creative solution):
Photos R90W

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Drive Safely,
Albert

Hello

My needs are:

-low end torque
-ability to work with different fuels (I’m available to in some situations retard the timing if necessary)
-reliability
-(no over heating problems at low speed)
-two barrels since mine have flaking Nikasil
-a simple mechanic and simple electronics “electricity” so it can be easily fixable in the road.
-I bought the bike in the Ebay for 1800 euros. (this should be my reference when doing improvements… ) J My budget is around 600euros +/ - 20%

After all your comments I will probably jeopardy my budget in MAHLE Sport kit 1000cc from Moto Israel, for 699,00 €

(but it’s still an open issue)

One fast question: if I need to change the big end shells do I also need to change the bolts?

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bernardo feio (Portugal)
2.5 Land Rover Lightweight / BMW R80 G/S PD / Toyota HZJ 78

Good - now we have something to work with (presenting our ideas, suggestions and recommendations) -

Lowend torque:
- best torque will be with 1000cc or larger using "too small" carbs and inlet ducts (stubs).
- I have only tested the "modern" R100 with torqure max at 3000rpm once. It was good but BMW have traded off too much power to my taste. I use the old type of engins with torque max at 5500rpm - I do find that type of engine to be far better.

My personal recommendation to this is:
- dual ignition. In my R80, 800cc system, it gave me one full gearshift more power at 2000rpm, and that is a -lot- of low-end torque enhancement.
- larger, and high-flow valves. It gave me another full gearshift step at 2000rpm.
These two minute tunings/adjustments gave me from 1st to 3rd (at 5-7% up-hill) added torque.
On my R100 it is not as distinct; but it is the same ratio in added power; my R100 have a 32/10 final drive and not a 33/11 which kinds of enhances low-end torque also.
- Swap the 33/11 for a 32/10 and change the 1st and 5th gears inside the gearbox (major investment overhaul though) => 3.0:1 in 5th will be 3.01 or there about in 5th; i.e. one looses a little bit of top-speed potential (a beemer does not handle well at 180km/h and up, "so who cares?").

Wider range of acceptable petrol quallity:
- lower the compression ratio from 9.5:1 to 8.2:1; i.e. change to low-compression pistons. A neat "trick" is to simply install dubble head-gaskets (done that by misstake so I know it can work).
- dual-ignition!!! It is -so- important!
- larger intake-valves, high-flow. I have tested BugPack 45mm; sounds silly changing from 44 to 45, but it does have far more effect than what I anticipated.
- changing from 40mm to 38mm on the exhaust valves.
The change of valves enhances volumetric efficiency which does result in more engine power, but also at the same time a better acceptancy for less good fuels. The dual ignition enhances the burn-rate so radically that you should be able to run on as low as 87-90 octane (EU standard) which is close to karoseen when combined with low-ratio compression and larger inlet-valves (46/38 is what you should aim for).


OBS!
NB!
The piston heads and the combustion side of the heads -must- be grinded to be "smooth as a babys bottom"! ALL edges must be taken/grinded away, and all surfaces must be polished to "super smooth". Hot spots form at edges due to carbon deposits! Hot-spots causes pre-ignition. Pre-ignition is what determins what quallity of petrol that one must use. When these surfaces are -perfect- you can run on very low octane-


To lower the risk of overheating at low speeds, you will need to install electical fans. Tube fans or simply computor fans will do nicely. My mechanic have tube-fans on his side-car.
You could use temprature pic-up switch or a simple switch to activate the fans.

I am a fan of car alternator conversion with belt pully. Those start at about 40A. A standard Audi 100 or Saab 99/900 55-70A from the 80:ties will do just nicely.
The car alternator have a fan that aids in cooling the engine; more on the side it is mounted of cause. And because one takes out the original generator it opens the front for better air-passage which also enchances engine cooling.
http://www.webstruktur.com/svea/board/artik/bilgen.html
http://www.webstruktur.com/svea/board/artik/mont_bilgen.html

More engine oil does aid in cooling the engine as does lower compression ratio as does larger inlet valves.

I like oil-coolers - but installing an oil-cooler is trading off some of the reliability. Oil-cooler is kind of necessary in really warm areas... Catch 22 situation -...

Consider -retro- tuning away from the electronic ingnition trigger unit (ITU) to a braker-point can. Mind you - I drove close to 300 000km before a secondhand ITU broke (hallsensor failiur); so they are -very- reliable. You could consider a dual-hallsensor ITU from Motobins though -

A replacement 1000cc siebenrock kit is -very- nice. You will be amazed how nice they are -
The light-weight pistons make the engine more rappid/snappy. The engine tends to run a bit cooler - my guess is that the lower piston weight may have this as a nice sideeffect.
However... this is a 9.5:1 kit, i.e. a 70bhp kit, and I have recommended that you drop the top-end power from 70bhp to about 60bhp and then tuning it up by changing the valves and installing dual-ignition which I guess will give you about 65-67bhp on a 60bhp base.

Simplifying electronics really means dropping the poor standard alternator for a pully drive car-alternator. Spare-parts all over. (Riding in west Africa means that you should perhaps look at french alterntors?).
Braker-point canister instead of the electronic ITU. Dual ignition in parallel like Daniel Dicke presentes = if one set of coils break, you simply continue drive (happened to me once in heavy rush-hour traffic jam down-town on a road with no side-lanes).
I.e. "retro" tune the ignitionsystem; or carry one spare ITU and at least one spare ICU (ignition control unit).

Problem:
- 600EU will not cut it -...
The suggestions above will set you back about 1500-2000EU in parts...
You need to make compromises -...
As a compromise I would strongly recommend 2nd hand 8.2:1 pistons and barrels. This gives you room for head-overhauls (i.e. dual ignition conversion, Derdickes solution, Q-techs is not anywhere within reach).
There is no room for a spare ITU nor a spare ICU.


Now I look forward to read what other riders recommends

__________________
Drive Safely,
Albert

Hello

Thanks for your very interesting answer.

I rebuilt “my” heads not so long ago so I will not change them now. But a good idea will be to clean them and polish the combustion chamber.

Were can I find “free flow” photos of inlet and exhaust ports? Is it normal to cut part of valve guides?

Since my bike is a R100 I already have 40/42 mm valves. As I wrote I will not change them (at least now) but I will analyse the possibility to install dual plug if I notice some pinging.

The references to improve cooling are quite interesting but as you suggest in the past I will apply where the KISS strategy. If I notice any high temperatures I will analyse the possibility of installing a bigger oil cooler.

Now I’m being a lazy mechanical engineering: did you calculate the compression ratio decrease when using 2 head gaskets? This is a very good idea since it’s a very simple “do it in the field” change if I start to have problems with low octane fuel. Is it possible to put a head gasket in the base of the barrel? This would have the same effect but will not compromise pressure escape…


bernardo feio

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bernardo feio (Portugal)
2.5 Land Rover Lightweight / BMW R80 G/S PD / Toyota HZJ 78

Rather than use two head gaskets, why not install a cylinder base spacer. these are made by BMW and cost very little. Originally designed to overcome pinging.

I do recommend the 8.2 :1 pistons, I had these in my stock r80rt and they worked perfectly with all fuels I tried to use.

to get extra power use 'tame' cams and ensure the engine breathing is easy.
That way you have power on hand at normal driving speeds and revolutions, not just at high revs.
remember if your engines natural breathing is poor, increasing the compression >ratio< may not actually increase combustion chamber pressures by much at all.

Having done all this, where do you propose to use the extra 10% of power ??
30hp will easily let you cruise at 85mph.

As you seem to have your engine apart at the moment why not play safe, fit secondhand standard barrels and pistons then after you trip modify your engine in whatever way you want and sell the standard parts. I would also keep the engine standard in other ways, carbs, air filter etc, they might not give the most exciting performance but reliability is more important where you are headed.
I have never had much problem with standard parts on my R80GS despite having run it on 80 octane in Egypt and something equally awfull in Iran, although the latter was only 1.5 pence per litre.