The Kneeslider

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BMW Motorcycle with 694cc Homemade V8 Engine

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694cc cross plane V8 motorcycle engine
694cc cross plane V8 motorcycle engine

There’s an amazing amount of skill residing out there in home workshops, a great example is this BMW with a 694cc homemade cross plane V8 engine from two inline fours. According to the builder, the crankcase was machined out of a solid piece of aluminum and he machined his own cross plane crankshaft. He made new cams because the timing was wrong for a V8 and he reversed the rotation of one of the cams. Looks like Honda CB350 top ends.

I’ll see if I can get more information but the videos are included below, the first run and then installed in the bike. Sounds good, doesn’t it?

Thanks for the tip, Matt!

Videos below:

Posted on Filed Under: Engines, Motorcycle Builders

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Comments

  2. Oh hell yeah!
    We’ve all see the Busa v8s and those are neat and all but this was built by a guy in his garage. Far too cool man!

  3. It is unique in that it’s a small displacement. I like that. and that sound… it would be a shame to park it in a living room. Let’s see it in action!

  4. The engine is pretty neat, and I like the sound. It’s funny that the guy had no idea that most of the video was his butt. The good news is that he is better at producing a running prototype engine than he is at video production.

  6. Clawbrant, the CB350F inline 4 was actually 347cc, times 2 is 694cc. There was also a CB350 twin which is what you are thinking of.

  8. SO when can we buy one and how much? I like it. Sounds like a formula car when he winds it up…….

  9. your right it is always neet to see this stuff. About 15 years ago Outhouse Engineering had a V8 Suzuki,2000cc running very well in Midgets. It ran the circut for many years. (might still be going). I have seen it as a screamer and then set up to be a torquer. Very slick indeed.

  11. Amazing machining,amazing sound,like the other commenters when will it be out on the road and whenn can we buy one?WOW!!!

  13. Positively haunting exhaust notes, sent shivers down my spine and my CB500/four went whimpering to the garage!

  14. This guy would be welcome to spin a wrench or dial in the CNC in my garage shop anytime. That’s the kind of tinkering with toys that draws applause.

  17. With this level of originality and talent residing smack dab in the middle of the country, it is impossible to conceive of us getting our butts kicked by competition from overseas — yet here we sit, with sore butts!
    That wonderful lump of an engine seems to be shoe horned into the frame of an R65 from the 1980s. It would be great to see that finished bike turn up at the MOA rally in Redmond, Oregon this summer. Too much to hope for?

  18. Cooling may be an issue on the road. Too bad there isn’t a water cooled small displacement inline four that could be used. Of course, it would not have the visual impact the air cooled motor has.
    Really love the sound!

  20. I just found this sight and it realy makes me feel good about the kind words abouy my v8 project. I have been having missing out problems from the get go, I have rechecked the cam timing,ignition,built 3 intake manifolds tried different carbs and finaly I have it running like I expected it to. I will try to get some videos of the bike running down the road, and I will be sitting on my butt enjoying the ride and sound. Dennis Franz Newton,ks-1979 BMW 694 cc v8. Again, thanks to all for the encouragement.

    • I would love to know as much as you can tell me on how you designed this engine! For years I have known about making V8s out of two four cylinder motorcycle engines ever when I first heard about the moto guzzi 500 V8 and the morbidelli. I have always wanted to fabricate my own chopper and I thought ‘how cool would it be to fit a compact V8 into a chopper from two inline fours. If you could give me a little insight on how you went about doing this and some of the problems you encountered I would much appreciate it!

    • to do a project like that do i have to increase or decrease the weight of the flywheel ?? if i’am talking about a single cylinder engine to be switched to a v-twin ??

  21. This amazes me, and really awakens my soul. I love the simple SOUND of that engine. That is a true work of art, and quite masterfully done I might add.

    keep up the fine work.