Thought some might be interested as this guy seems to do quite a few BMW rebuilds
BMW R100 Siebenrock BIG Bore 1070cc Engine Rebuild
- Thread starter Bigcats
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I reckon Mikeyboy should get down to the gym and then do a video like that 
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I don’t need to go to a gym.
I’ve never yet found a customer willing to pay for a 1070.
Happy to be corrected,
£2 k for a 1070 kit
That’s before you strip the existing motor and address anything.
My customers have generally gone down the route.
1001 cc omega race pistons.
Moorespeed cam,prob 328
Moorespeed heads/ valves.
Either dellorto carbs or reworked bings.
Even if you go down the 1070 route,
The heads and carbs will ultimately limit power output.
I’ve never yet found a customer willing to pay for a 1070.
Happy to be corrected,
£2 k for a 1070 kit
That’s before you strip the existing motor and address anything.
My customers have generally gone down the route.
1001 cc omega race pistons.
Moorespeed cam,prob 328
Moorespeed heads/ valves.
Either dellorto carbs or reworked bings.
Even if you go down the 1070 route,
The heads and carbs will ultimately limit power output.
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I will add,
Lightened and balanced crank ,flywheel etc will all add to the the power,and cost.
But why bother,why bother with the 1070?
Do you really think you’re that good.?
.
Lightened and balanced crank ,flywheel etc will all add to the the power,and cost.
But why bother,why bother with the 1070?
Do you really think you’re that good.?
.
I put a 100cc SB big bore kit on an R45 a few years ago. With the ratio at the bevel drive made for the 450cc and weight of the bike, it was a torque monster. Very minor tuning required.
A lot of fun. Probably not for the average Airhead rider though
A lot of fun. Probably not for the average Airhead rider though
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That blew upI put a 100cc SB big bore kit on an R45 a few years ago. With the ratio at the bevel drive made for the 450cc and weight of the bike, it was a torque monster. Very minor tuning required.
A lot of fun. Probably not for the average Airhead rider though
( dropped exhaust valve )!! New owner just received his new Siebenrock kit which he will fit over the winter.
Ouch...That blew up
You really have to keep an eye on modified engine. You need to check valves frequently. Especially the guides for play. It was a sewing machine when I had it. When was that ? 3 years ago ??
SteveHop
Registered user
Isn't a 1070 big bore kit a bit OTT for a old airhead ?
Perhaps for a fast handed amateur. But not if you know what you're buying and how to maintain a modified vintage. The crank and transmission on an R65 Motor are more than up to the task.
He's just dropped a valve. I think probably easily prevented if serviced accordingly for its vintage and modification. Likely a failed valve guide. It would have been smoking and burning oil. Probably mis firing too.
To drop the valve, you would've had to be oblivious to that.
Last edited:
"We're having a bigger displacement, by having a longer stroke"
The swept volume has nothing to do with the length of the con rod - the bloke's misinformed.
The longer rod was due to the piston crown height being shorter on the Siebenrock piston.
The swept volume has nothing to do with the length of the con rod - the bloke's misinformed.
The longer rod was due to the piston crown height being shorter on the Siebenrock piston.
SteveHop
Registered user
But you must be able to push through more torque then the transmission and final drive were ever designed for ? I know airheads were over engineered but by how much ??
It's a well tried and tested modification. It's nothing new. They're been fitting them for many years and many people have done a lot of miles without issues.
Will it put more stress on everything over the years. Well yes. Of course.
But for most, it's really not an issue.
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1070 motors are rare because it’s very expensive,
With few benefits without a lot of other expensive mods to get the best out of it.
The other mods make for a decent motor on their own
With few benefits without a lot of other expensive mods to get the best out of it.
The other mods make for a decent motor on their own
I'll second what mikeyboy says. It's not worth the cost unless you're already committed to some kind of rebuild or customisation.
Just buy an R100..
In my case, it was for an R45 that I'd bought cheap and I just wanted to do something daft with it.
And obviously I wasn't paying anyone else to fit it.
It's an very well made kit. Top quality. If money is no factor and you want to upgrade a smaller capacity bike that you're sentimentally attached too, then there really is no replacement for displacement
Just buy an R100..
In my case, it was for an R45 that I'd bought cheap and I just wanted to do something daft with it.
And obviously I wasn't paying anyone else to fit it.
It's an very well made kit. Top quality. If money is no factor and you want to upgrade a smaller capacity bike that you're sentimentally attached too, then there really is no replacement for displacement
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