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  #1  
Old 19 Oct 2010
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BMW high compression ratio pistons (11.2:1)

Hello

I’m planning an expedition with a R100GS. The bike has high compression ratio pistons (11.2:1)

Will I have problems with sahara fuel? The normal pertol is 95 octant or lower?

I normally travel with diesel LRs so this problem never cross my mind

tks
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Old 20 Oct 2010
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...are you really sure about that?

Do you have 4-valve technique on the airhead?

Above 10.5:1 on an airhead is pushing it... and above 11:1 is adviced against by all sources I have have found...

It is -not- possible to run on poor petrol with that high compression ratio... you should seriously consider changing to stock 9.5:1 or even the 8.2:1 version to minimise overheating risks and allow for usage of low and poor octane petrol... there is a reason for why the Egypt Police ordered a special version of the R80 engines... 44/40 valves with Bing 40... equates about 7:1 allowing for EU 87 octane petrol to be used...

Let us know -exactly- how your engine have been modified. It is possible that my comments above may not apply - it depends on exactly how the conversion to 11.2:1 have been made.
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  #3  
Old 20 Oct 2010
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Are you sure 11.2:1 is correct? I would have made a compression-test to check it.

Personally I would never used anything higher then 9.5:1 on bike intended for traveling in areas with poor fuel. It's probably a bit on the safe side but on the other hand you can get a very powerful engine with 9.5:1.



Quote:
Originally Posted by dc lindberg View Post
Let us know -exactly- how your engine have been modified. It is possible that my comments above may not apply - it depends on exactly how the conversion to 11.2:1 have been made.
Yes, please tell us!
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  #4  
Old 20 Oct 2010
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hello

I have a normal 2 valve airhead and I need barrels (they have some scratches) and pistons + pistons rings

“It is -not- possible to run on poor petrol with that high compression ratio” I full agree with you if you keep the same combustion chamber shape.

http://www.moorespeed.co.uk/bmw-engine

High compression ratio pistons
Designed by Richard Moore in collaboration with Omega pistons, these high compression pistons offer the most cost-effective (and easiest) way to boost power. The dyno charts show the solid increase in both bhp and torque achieved simply by slipping in these new pistons (use your existing piston rings if in good condition) – an extra 8bhp for a couple of hours work! Combine them with a free-flowing Moorespeed air filter conversion, and gain an extra 2bhp (see also Moorespeed Tuning Kit section).”


I still don’t have the pistons installed but I have the same doubts that you have (that why I have I posted where)

Yesterday I called Richard Moore from moorespeed and I had a long talk with whim. He has a looong experience in motorsport and in BMWs air heads. He seems a very well formed fellow and not just a curious.

We said that his pistons here used in several African races with out problems. He also has some bikes that were used in Africa tours also without problems.

He says that eventually if the fuel is very low in octane level you should delay a bit the timing to avoid some knocking.


Personally I would never used anything higher then 9.5:1 on bike intended for traveling in areas with poor fuel. It's probably a bit on the safe side but on the other hand you can get a very powerful engine with 9.5:1.”


What solution do you use? Siebenrock replacement Kit?

thanks
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Old 20 Oct 2010
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I can't see that Richard Moore claims hat the pistons will give you 11.2:1 and I would have expected much better dyno-runs if they did.

There are some discussion about his pistons (and my old setup) here: Power piston kit - ::. UKGSer.com .::

Quote:
Originally Posted by bernardo feio lightweight View Post
What solution do you use? Siebenrock replacement Kit?
I used a Siebenrock upgrade kit (800cc -> 1000cc) and a few other modifications for 60kkm. The kit worked nice and will probably be re-used on my second R80.
Right now I use a setup based on narrow 1043cc cylinders (from Mahle/HPN). I spend quite some time thinking about what compression-ratio to choose before I ended up at 9.5:1.
The bigger bore increases the risk for pinging so I also installed dual-plugging.
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Old 20 Oct 2010
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Hello

The compression ratio of Richard M. pistons is not written in his web page but he told me that by email and confirmed that yesterday by phone.

“1043cc cylinders (from Mahle/HPN).”

Can you give me more information about that? Part numbers, piston rings, prices…

If you prefer please send me a PM to:

bernardofeio @ yahoo.com.br

thanks
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  #7  
Old 20 Oct 2010
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BTW:

any comments on this kit?

[url=http://www.motoren-israel.com/products/en/Shop/Engine/Cylinderkit/Sportkitt-1000cc-75mm-kuerzer-MADE-IN-GERMANY.html]Sportkitt 1000cc, 7.5mm k
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Old 20 Oct 2010
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Mr. Moore may be a excellent engineer, or a good con artist...
His site looks so much like the old catalogues from Luftmeister and CC in California... The pistons do look very smart. Keihan carbs - quite interesting. I will study his site later - my curiosity have been awakened

What is your budget?
How much may the conversion set you back (cost)?
=> gives us an idea of what to suggest, recommend and advice about.


If you want to play it as safe as possible, I would recommend that you get a set of 8.2:1 BMW original pistons with squissband (those perform just a little bit better than those without, in my opinion).
Perhaps you will have to buy pistons for steel-lined barrels and pistonrings for the nicasil barrels that your model have; that's how I had to solve high-compression on the 800-system. Works nicely - no problem.

Currently I am running 1000cc replacement Siebenrock pistons - love them.
But (!) - that is 9.5:1 and as I pointed out above; I would recommend that you do not choose the high-compression solution.
The Siebenrock pistons are about 50gr lighter than my Velonlia 10.5:1 pistons. The Venolia pistons are about 70gr lighter than stock (if I recall correctly) - and runns very smoothly once warm; far nicer than the heavy lumpy unbalanced original pistons.
If you go with 8.2:1 original pistons - balance them (!) and the conrods => the engine runns far better if you do.



Should you want high-compression - study carefully what Alibaba and Mr.MR writes!

My personal experience with high-compression is; good power, good mileage, a ... lot of garage time and heachache figuring out what broke and why. Since I ride in an area where high-octane petrol is available I want the high-compression; but should I ride in areas with questionable petrol, well... I would study closely how the Egyptian Police set up their special R80's!!!

Remeber - as compression raises... so does engine heat... The mileage differens is not -that- great that I would sacrifice/risk durability...


Good - to excellent engine/oil cooling should be your focus as well as looking at the most optimal solutions for keeping the engine running.

The hall-sensor pick-up (ITU) is a source of concern. The braker-point canister used on the late 70:ties models may be an option to consider. Braker points take little room, a spare hallsensor-canister is kind of bulky and difficult to mend on the road. I read here on H.U. about a year ago about this tip on the braker-point option - if I recall correctly VW 1200 (beetle) braker-points fits. You need to check that though - I might remeber it in-correctly.

If you want more power... you could install a turbo or super charger...
Seriosly - keep everything as light as possible and as close to stock as possible, or rather "retro-convert" to more simple and easy solutions for best road-side repairability.
*
Apply KISS strategy; "keep it simple stupid" - That will save you from a lot of trouble and headache
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  #9  
Old 20 Oct 2010
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Quote:
Originally Posted by dc lindberg View Post
Mr. Moore may be a excellent engineer, or a good con artist...
Quote:
Originally Posted by dc lindberg View Post
His site looks so much like the old catalogues from Luftmeister and CC in California... The pistons do look very smart. Keihan carbs - quite interesting. I will study his site later - my curiosity have been awakened

Quote:
Originally Posted by dc lindberg View Post
What is your budget?
How much may the conversion set you back (cost)?
=> gives us an idea of what to suggest, recommend and advice about.



600 euros?... but I also need some barrels (can be used)

Quote:
Originally Posted by dc lindberg View Post
My personal experience with high-compression is; good power, good mileage, a ... lot of garage time and heachache figuring out what broke and why. Since I ride in an area where high-octane petrol is available I want the high-compression; but should I ride in areas with questionable petrol, well... I would study closely how the Egyptian Police set up their special R80's!!!



Quote:
Originally Posted by dc lindberg View Post
looking at the most optimal solutions for keeping the engine running.


? I didn't understand you now...


Quote:
Originally Posted by dc lindberg View Post
The hall-sensor pick-up (ITU) is a source of concern. The braker-point canister used on the late 70:ties models may be an option to consider. Braker points take little room, a spare hallsensor-canister is kind of bulky and difficult to mend on the road. I read here on H.U. about a year ago about this tip on the braker-point option - if I recall correctly VW 1200 (beetle) braker-points fits. You need to check that though - I might remeber it in-correctly.


braker-point canister?... what is that? I also didn’t understand you on this…

Quote:
Originally Posted by dc lindberg View Post
Apply KISS strategy; "keep it simple stupid" - That will save you from a lot of trouble and headache


That I use almost always. If you look to my signature you will notice what kind of vehicles I use in my expeditions.... very simple and basic

thanks for your very interesting answer...
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Old 21 Oct 2010
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The kit from Motoren Israel will set you back around 950€.
It's 699€ for the kit, 55€ for the pushrod-tubes, 15€ for inserting the pushrod-tubes, 75€ for the pushrods, 45€ for bolts and 35€ for the gaskets.


The kit is from Mahle and usually their products are nice. I have no experience with the kit but I do have some experience with Motoren Israel.
It might be a smart idea to get in touch with them and tell them what you are looking for. Silvia is a friendly guy and he has given me many good advices through the years.

Lindberg mentions heat as a possible problem with a modified engine and he might have a point here. The problem with air-cooled engines is that there is not much cooling when you ride really slow (technical sections or rush-hour). This is not a major concern for equipment used under racing-conditions because they keep the speed up and gets better air-flow.
My bike ran hotter with the modified Siebenrock-setup and an oilcooler then it did as a stock R80 (without a cooler), but it never gave me any kind of problems.
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Old 21 Oct 2010
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Hello

Thanks for your answer Alibaba. Your comments are very important because of your African travel experience with these bikes!

Does any one know what are the power/torque claims for the Moto Israel 112011 piston kit 1000cc -7,5mm



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Old 22 Oct 2010
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Quote:
Originally Posted by bernardo feio lightweight View Post
Does any one know what are the power/torque claims for the Moto Israel 112011 piston kit 1000cc -7,5mm
You can ask Silvia at Motoren Israel but I don't think he will know.
Usually people change a lot in their engines when they rebuild it so it's hard to tell..
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Old 31 Oct 2010
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I just studied Mr Moores homepage/Dyna test.
Technical

THAT I did miss reading from the beginning.
I am NOT one bit impressed!
60bhp and 6kg torque - on a 1000cc engine?!
I do see notions of 66bhp and 7.6(?)kg torque - but it is very hard to read his test papers (too low resolution).

Anyway, you do get FAR more power by simply installing stock 9.5:1 pistons and old 44/40 valve heads with bing 40. That should give you 67-70bhp and about 7.4kg torque.
And he is asking 400 EU for such a "crappy" kit?!

With the low compression pistons: 8.2:1 and bing 40 you should have 60-65bhp, and about 7kg torque.

38mm exhaust. 40mm exhaust does not give you more power, rather you loose a bit of lowend torque.

11:1 would theoretically give you about 80bhp and close to 8kg torque - but to be sure you need to test it.

1100cc kit from 7-stones or the tunings done by Motoren Israel will give you >>80bhp. Those who have that kit describe it as -powerful- and -fun- to drive.
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  #14  
Old 1 Nov 2010
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If you click at the graphs you will get better resolution.
He claims:

Standard R100: 51bhp/ 47Ft/lb (64Nm)
Omega long skirt: 58bhp / 53Ft/lb (72Nm)
Omega long skirt with different filters: 60bhp/ 55Ft/lb (75Nm)
Omega with long rods: 63bhp / 57FT/lb (77Nm)

I think the numbers for a standard R100 looks about right. Like you I'm not impressed by the results for the Omega pistons, with such an increase in compression I would have expected more.
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Old 1 Nov 2010
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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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