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68Mm 1098 Twincam


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#1 Dingus

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Posted 19 January 2017 - 07:58 AM

Hi all, 

 

After two years of research, I'm about to launch into an ambitious (and weird) project: A 1098 bored to 68mm with a twin cam head and twin Webers. I know its an unusual combination, but I think the specs will work really well and it'll be a fun little fast road/sprint engine and should get close to 100BHP. I've used this forum a lot and hope to contribute instead of just leaching info from the more knowledgeable.

 

 



#2 minifreek1

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Posted 19 January 2017 - 08:25 AM

What head are you using....?

 

BMW bike head maybe...?



#3 Dingus

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Posted 19 January 2017 - 08:51 AM

8V K100 (Couldn't make the 16V fit well enough on the smallbore block)


Edited by Dingus, 19 January 2017 - 08:53 AM.


#4 Alex_B

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Posted 19 January 2017 - 10:39 AM

Why not use the 1275 as a basis? The 1098s don't have nearly as much potential due to the weaker cranks, they shouldn't be used above 6000rpm regularly and I suspect the BMW head needs to run higher rpm to get the most out of it.

#5 Dingus

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Posted 19 January 2017 - 11:05 AM

That was my plan, but 1275s are getting hard to come by in Australia, and will set you back around $2000 for a 'sold as is'. I already have a 1098 and the extra $2000 will easily cover the cost of strengthening internals. I'll have the rods heat treated, lightened, polished, then shot peened, and the crank wedged and nitrocarburised (and/or the journal radii shot peened) then all dynamically balanced. Add in a centre main strap and a 6500 redline and I reckon it'll be fine.

 

Also, I'm a pigheaded dude and now that I've decided to go down this path I'm sticking to it. :D  


Edited by Dingus, 19 January 2017 - 11:20 AM.


#6 nicklouse

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Posted 19 January 2017 - 11:17 AM

why not a 998 crank then?



#7 Dingus

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Posted 19 January 2017 - 11:33 AM

998 crank is a possibility, it would only be 110cc less in terms of swept volume. I have an A+ 998 and a 1098 A to choose from, and Vizard cautions about A+ cranks and issues surrounding the rolled fillet radii. 

 

The 998 stroke is closer to the BMW K100 stroke as well which would mean the cam is probably going to work better with the 998. Hmmm... 

 

Uh also, I don't know how this works, but can I add this thread to my thread in 'Projects', because I think we've moved pass the introductions right?


Edited by Dingus, 19 January 2017 - 11:36 AM.





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