Topic: Hot street 650 motor help

[trueblue]

I'm wanting to build a hot street engine for my 650z, I already have 61mm forged wiseco pistons and another head to play with.  What head work would you fellas recomend for this engine, I have access to a flow bench and full engine machine shop. Also what cam options are available? and thirdly what will I have to do to the carbs once I'm done, will rejetting work or will I have to go to a bigger bore carb? I am a diesel mechanic by trade, but have never built a hotted up motor, other than a couple for mates who had already done all the leg work and all I had to do was assemble a box of bits. Any help would be appreciated.

[CBJoe]

I would recommend starting with this thread.  Much of this type of info is written up very well here.

http://forums.sohc4.net/index.php?topic=40414.0

Cheers, Joe

[trueblue]

I would recommend starting with this thread.  Much of this type of info is written up very well here.

http://forums.sohc4.net/index.php?topic=40414.0

Cheers, Joe

Thanks Joe I have already read that thread numerous times, the bottom end work is pretty elementry.  What I am after is some more info on the power making bits, ie heads, how much port work if any, sizes of valves etc etc, cam options and where to get them, then what to do with carbs, will they need rejetting or will I need to aquire different carbs etc. After all there is more to making more power than just fitting bigger pistons.

[CBJoe]

Cool... so if you've got that down... you're well past my knowledge level  Have to let someone else chime in for more technical info.

You might look into CB750 carbs for more performance options... i believe that member Soos had some luck with that specifically on the 79-80 650 model that used the mechanical carbs (PD).  Here is mentioned some specifics about the 750 carbs with the 650.  also mentions use of the Kawasaki ninja CV Carbs.   

http://forums.sohc4.net/index.php?topic=54073.msg582537#msg582537

I remember that Soos had a number of threads on running different carbs on the 79/80 CB650.

Regards, joe

[trueblue]

Thanks for your replies Joe.  Surely someone out there knows what cams options are available for these engines and what headwork achieves the best results .

[cb650]

Not many cam options anymore.  You can get a hot 550 cam for 300 new or have yours reground.  The 650 was considered outdated so not many companys made parts for them.  i was even surprised jardine made a header for them.

[trueblue]

do you know how a hot 550 cam compares to a standard 650 cam? I saw a post a while ago that had the stock 650 cam specs, but I have spent the last 2 nights searching for it but haven't come up with anything yet

[cb650]

it had 1 mm more lift.     at web cam I think.

[trueblue]

sweet thats an extra .040" lift, I really need to find the specs for the 650 cam before I can order another cam, especially if I can't buy a 650 specific one, just to make sure I won't be going backwards from where I'm at