300ex with Honda CB650SC Nighthawk engine - Almost done! - need some help

[stevensj13]

Alright guys, here I have my Honda 300ex with a CB650SC Nighthawk engine and frame. the front end of a 300ex has been remanufactured and bracketed and welded onto a CB650 frame, and the swingarm from a 300ex was a direct bolt up. Now, I have the wiring done, and other than a new chain/sprockets then its pretty much ready (haven't started it yet but thats on today's to do list). The chain for a CB650 nighthawk is like 630 or something, and the one for a 300ex is about a 520 I believe. Now, the 300ex sprocket and the CB650 nighthawk sprocket are bolth 4 bolt pattern. My question is, would the CB650 sprocket bolt onto the 300ex swingarm? I would try for myself but I don't have the wheels from the nighthawk and therefor no sprocket. I really would like to get this thing done today, test and fine tune during the week, and tear up the drag strip next weekend!

[stevensj13]

here are some pics for the interested people :beer 134736134737134738134739

[partsmaster]

Hey I'm interested! Looking good, glad 2 see someone else utilizing a streetbike powerplant. Can't help u much with the rear sprocket issue.... I'm goin a different route by shoehorning a cbr600 engine into a 250x frame, luckily 520 front sprockets are available for the cbr engine so I used that and kept the stock rear sprocket..... good luck!!!

[jb2wheels]

That's kinda wild!

Might be easier to find a 520 sproket that finds the 650 engine and use the TRX sprocket on the swingarm. These guys have pictures and measurements for sprockets.
http://www.jtsprockets.com/

Do the sprockets line up?

[stevensj13]

That's kinda wild!

Might be easier to find a 520 sproket that finds the 650 engine and use the TRX sprocket on the swingarm. These guys have pictures and measurements for sprockets.
http://www.jtsprockets.com/

Do the sprockets line up?


The sprockets line up, but there is a hump in the swingarm where it mounts that the chain rides on, so I was hoping for a tall CB650SC rear sprocket to mount, so it can clear the slider/swingarm.

[stevensj13]

Cleaned the carb and shes not running. It was a trailprotrailprotrailprotrailprotrailpro to get out of the frame, thats for sure! I'm going to play with it today. Does anyone know how to tune these four carbs?

[stevensj13]

had a very busy weekend of working on some machines and didn't update anything, but I do have an update now. I cleaned the carburators and bypassed the fuel pump with a gravity feed (stock tank, stock placement. all works, not sure why there was a fuel pump anyway :wondering). Got her running, idles great and revs right up. Great engine with no smoke either. I have decided to get custom front and rear sprockets made. I am thinking of getting the front at 16 tooth and the rear at 51 tooth, giving me more bottom end and still keeping a fast enough top speed. I might get a second lower rear sprocket made for top speed when I am murdering alky banshees on the drag strip. All and all its coming together better than expected. Need sprockets and its ready to ride! I'll have a video of the first test ride.

[RIDE-RED 250r]

Look forward to seeing those vids!

[stevensj13]

Look forward to seeing those vids!

I'll get a startup and description video today, won't be a ride video since I don't have the sprockets yet. Still, hearing it run is a blast hehehe

[badass350x]

What happened here? Did you give up?

[stevensj13]

Traded it for a very nice Jeep Cherokee