The Best option for engine build for GR650

[Jedz123]

Evening gents,
  I'm curious on what arrangement I should shoot for on my GR650 for maximum power. I have 2 GR650's I fully restored 1 over the winter and now it's sporting a stock exhaust.  the 2nd GR I have I want to build a light weight nimble yet peppy twin for the VT gaps I go over.  This thing doesn't need to be a speed breaker, I have 3 other bikes all liters so I don't ride the GR to impress my buddies on the flats, I would however like a top speed of about 120mph and it should accelerate there in a decent click.  My GR now with stock setup has a hard time reaching 100mph however around 55-60mph it's got plenty of guts and take turns like a champ.  I have an R6 rear shock but the frame is stock and the front forks are too... I'd like to keep the GR I restored to be the classic bike to bomb around on, the 2nd GR will be the canyon carver/ maybe track bike. My Classic GR rides like it's on rails and I feel handles just as well as my Gen 1 FZ1. I think with adequate fork upgrade and an R6 Shock for this new GR It will out handle most classic bikes it's age on the road.  If I can get the power plant to put out maximum beans it would only increase then fun factor of the bike.

  So Have at it, budget isn't too big here, maybe $1K all said and done. Should I start with a GS500 engine and augment with GR bits? or should I just use the 652cc power plant and upgrade that?

Oh pics of my twins:
My GR  in front of my ride-able Heard, A 98 Bandit 1200S, A 01 Yamaha FZ1 and the UN-touchable 08 GSX1300BK B-King... Like I said Not interested in breaking speed record with a GR... I know it's slow...

Another shot of my restored Tempter:

With the Custom 2-1 Exhaust I used and then got rid of for my ears hurt...

The new test Subject:


Oh So this is my first post too! So Hi ya'll.  I've been riding for 9 years now, put about 20K miles on a year between my machines. Love riding and can and most likely have done anything you can think of to a motorcycle... I started on a Suzuki GS750... So I needed to know how to fix it to keep it on the road so I'm pretty handy to say the least.

Thanks Guys!
  -Jedz

[Jedz123]

Ride from today Had to have a reality check and hopped on the B-12.
  thanks Guys:

[Big Rich]

Jedz!  What's up man?

The 500 bottom end physically won't fit in a 650 frame since it's longer front to rear. So you're kinda stuck with the GR bottom end. I think the easiest way to get to 120 ish mph would be to combat wind resistance. Well, that....and the intake / exhaust I mentioned on the GSR.

Welcome to the site btw!

[mennobike]

Jedz, listening to big rich is a good decision: he's got a huge thread on a 650 build he's been working on elsewhere in the thread, if you haven't given it a look you should!

Welcome to the site and good luck! 

[Jedz123]

Whats up Rich!?!?
    I'll be looking into your threads to pull up all the GR info you've compiled on your build. You seem to be the site's GR guru from searching around...
   Basically for the gap GR I'm looking to do the following:
   VM Carbs 34mm, Free flowing exhaust, Port match or if I want to spend the coin full on port and polish, weight reduction, height reduction (reduce drag), upgrade suspension, upgrade brakes and a good set of tires.
   I'm going to plug the gearing into my gear worksheet to figure out top speeds in all the gears. The gearing is ridiculously short on this bike, Stock. I think if I can raise the RPM band to the 9.5K mark I should be able to crank out 115-120mph.
   Off to do some research!
   Thanks guys!   -Jedz

[Big Rich]

Vicious rumors.... I just have a pile of Suzuki parts covered in dust....

Jedz, you've seen this site, right? http://www.gearingcommander.com/

Great stuff. I can tell you that the TU250X uses the same sprocket as a GR except for the fact it is for a 520 chain, so that might open up some gearing options for you. I don't know of a 520 sized sprocket for the stock rear GR wheel though.

[ShowBizWolf]

Welcome to the site Jedz!  Thanks for sharing, you have some awesome bikes!!