GS Big Block

[Guest]

That 9.20 was 25 years ago and it was a street bike. I put bars and good gas in for the track. I tried it without the bars and 3rd gear was a little scary!
Curt

It is that little scary feeling I crave so much.
A 9.90 pass was one of the best runs or most fun I have ever had on a pass I was fighting the wheelie at 1000' . I stuffed a 1400cc motor in a stock 82 1000 Katana chassis with a road racing slick on it just to see how a spare motor I built for a friend run. I only made one pass and it rained out.

 

[Guest]

That being said, It seems like a naturally aspirated 1327cc's is where I want to be from a heat/reliability/practical standpoint. Ape makes a kit for $1850, includes pistons, gorilla block, cams, valve springs and arp studs. If I go a step further and do porting and oversized valves, that should put me at a reliable +50-60hp.

Biggest concerns are transmission and clutch. What are the requirements here? Carb wise, will 1150 carbs do the trick with the right combination of jets?

You will need to build the bottom end also to handle the extra HP weld up the crank and clutch basket, APE case studs, as a minimum. As far as the carbs go that will depend on how big you port your head. In a ideal set up your carb size will be 2mm larger than your intake port. If you keep your head stock then look for a set of 1st gen Bandit 1200 carbs otherwise Mukuni RS carbs are your least expensive option.

Another option would be to put a 1989 to 92 GSXR1100 or 1996 to 05 Bandit 1200 motor in. It has less weight and a lot better head

 

[rapidray]

You will need to build the bottom end also to handle the extra HP weld up the crank and clutch basket, APE case studs, as a minimum.

I posted the above on the last page.

Another option would be to put a 1989 to 92 GSXR1100 or 1996 to 05 Bandit 1200 motor in. It has less weight and a lot better head

Another option for less expensive headwork is to put an oil cooled GSXR or Katana 1100 or Bandit 1200 head on the GS bottom end. You can go 30/26 valves in one of those heads with just a valve job. To do the same on a GS head is big valve seats at a cost of at least 600 bucks just for that. The GSXR/Katana/Bandit heads are a better port design right out of the box too. LOTS of options for a LOT of fun!!! Ray.

 

[yoshisakan]

The gsxr1100 engine is an excellent idea. I'll look more into that today. Am I going to be alright running the stock wheels with either setup? I made an appointment today to get my stock wheels powder coated, but maybe I should be looking for a different solution? I just spent $230 on pirellis, powder coating will be another $200. I hate to think 150-175hp is going to be too much for them to handle.. But it might be. I guess worst case scenario, I could send the tires back. I'm getting the feeling that i'm going to burn the rubber off of a 130.

 

[jeff.saunders]

...The turbo is probably a bad idea from a tuning perspective. The last thing I want to do is mistakenly run it lean through the powerband and melt my pistons.

Lean on any engine will kill it...

Like any performance modification, you need to setup a turbo to get the best out of it. There are pros and cons with turbo setups - and a different set of pros and cons with a big block.

The key is you need to build the motor from the ground up for both of them.

It's really down to you CAREFULLY assessing what you want from a bike, and how you will ride it. I will tell you many customers I've spoken with have regretted going too radical on engines. The bikes might be superfast, but that doesn't make them easy or pleasant to ride.

I run a turbo motor on the street (1200cc Z1). It is easy to ride, you can cruise around town without issue - but when you get on it, it is a rush... I haven't taken it through the 1/4 mile, but the bike would easily run in the 9's with the right rider on it.

The key to tuning is an air/fuel read-out. Once I added one to my turbo bike, I was able to adjust the carburation to avoid lean spots.

 

[yoshisakan]

That is a beautiful bike Jeff. What kind of rear swingarm/tire are you running there?

 

[jeff.saunders]

That is a beautiful bike Jeff. What kind of rear swingarm/tire are you running there?

The swing arm is probably an old Kosman unit - it dates to around 1980 - Steel, 2" over stock with 3 shock positions. Having the different shock position is great when turning up at a drag strip and lowering the bike in a few seconds....

The rear rim is a 'skinny' aluminum WM6 (3.5") with a Dunlop GT501 130/80-18 tire stretched on it to flatten it out. It might seem small, but it hooks up and power-wheelies in 3rd gear.

BTW, here is a short video of the bike running while we tested some of the recent changes to the bike. The air/fuel sensor was one of them (this will get replaced with a better unit when I can afford it).
http://www.youtube.com/watch?v=6ufnwhzD2Gg

 

[yoshisakan]

Very cool. Do you think I will be able to put down ~175hp with stock GS wheels? I just bought a pirelli night dragon 130 90 16. If not, I am going to skip powder coating these wheels and just get new ones.

 

[jeff.saunders]

That would be a lot of HP through a small footprint. My bike probably makes around 140hp-150hp on 5-6lbs of boost - and turbo power is not instant, so it's relatively easy on tires - plus I don't try to do drag racing starts.

I would rather have a smaller sized rear tire to keep decent handling as I ride my bike on twisty back roads much more than main highways Many of the bikes with very wide rear wheels just don't like going round corners. This gets back to you carefully thinking how you will ride - every change you make has both positive and negative consequences.

 

[yoshisakan]

Yeah I mean as it is, sometimes I drop a gear and fly on the highway, but I have to slow down in the turns because my suspension and current tires are old. I think in highway pulls, these tires should be fine. Taking off from a red light, they'll probably light up before pulling a wheelie.

 

[rapidray]

You should SERIOUSLY be looking at suspension & BRAKE upgrades before you throw hp at your bike! A good way to DIE if not!!! Ray.

 

[Guest]

You should SERIOUSLY be looking at suspension & BRAKE upgrades before you throw hp at your bike! A good way to DIE if not!!! Ray.

+1 on that


Yoshi,
How old and what kind of tires are you running around on now?

 

[yoshisakan]

I'm sure i've mentioned it a few times in this thread, but currently im running on some old ass pos tires that are who knows how old. I just bought a pair of Pirelli Night Dragons. We'll see how they hold up this weekend.

 

[Guest]

A lot of good advice from good people. I did the Gsxr oil in a GS 1186cc big valve cam motion cams 38mm carbs its 150+ rwhp. That parts easy. I admit it was very sketchy on the biasply tires and original suspension & brakes.Getting proper brakes and tires required upgrades to suspension wheels & brakes that takes more work.Trying to run with modern 1k bikes that weigh around 430lb with a GS that are about 550-575lbs not easy. My bike is down to 465lbs so I'm close to them. Gearing make a huge difference as to acceleration rate. I say build what you want just match the rest of the bike to the amount of power it makes. Good luck and post lots of pics. And big tires only helped my bike turn quicker and more stable Andy

 

[rapidray]

A lot of good advice from good people. I did the Gsxr oil in a GS 1186cc big valve cam motion cams 38mm carbs its 150+ rwhp. That parts easy. I admit it was very sketchy on the biasply tires and original suspension & brakes.Getting proper brakes and tires required upgrades to suspension wheels & brakes that takes more work.Trying to run with modern 1k bikes that weigh around 430lb with a GS that are about 550-575lbs not easy. My bike is down to 465lbs so I'm close to them. Gearing make a huge difference as to acceleration rate. I say build what you want just match the rest of the bike to the amount of power it makes. Good luck and post lots of pics. And big tires only helped my bike turn quicker and more stable Andy

Nice looking bike Andy. It has the wrong motor but still looks nice! LOL!! Ray.

 

[yoshisakan]

A lot of good advice from good people. I did the Gsxr oil in a GS 1186cc big valve cam motion cams 38mm carbs its 150+ rwhp. That parts easy. I admit it was very sketchy on the biasply tires and original suspension & brakes.Getting proper brakes and tires required upgrades to suspension wheels & brakes that takes more work.Trying to run with modern 1k bikes that weigh around 430lb with a GS that are about 550-575lbs not easy. My bike is down to 465lbs so I'm close to them. Gearing make a huge difference as to acceleration rate. I say build what you want just match the rest of the bike to the amount of power it makes. Good luck and post lots of pics. And big tires only helped my bike turn quicker and more stable Andy

Wow, that is a beautiful bike! What did you do as far as wheels, brakes and suspension? I haven't been able to find much information on these upgrades. I'll post some pics of my bike this weekend after I get the new tires on. I finally got rid of the stock ape hangers and put some nice bars on there.

 

[Guest]

The front is 93 gsxr750 straight bolt on had handlebar mounts welded on top. Rear is 95 gsxr100w that required changing the pivot bushings up to 25mm adding upper and lower shock mounts. Not sure what year the wheels are they were the same for several years on 750 and 1100s but I think they came off the 95 1100

 

[Guest]

Nice looking bike Andy. It has the wrong motor but still looks nice! LOL!! Ray.

Thanks Ray if wrong means easy to install lighter no RR problems and a unbelievable price then yes its so wrong. I tell ya one thing when the tach gets to 7500rpm you better have a good grip on the bars

 

[yoshisakan]

Thanks Ray if wrong means easy to install lighter no RR problems and a unbelievable price then yes its so wrong. I tell ya one thing when the tach gets to 7500rpm you better have a good grip on the bars

-- And you'd better hope your welds have good penetration on the steel.

 

[Guest]

A lot of good advice from good people. I did the Gsxr oil in a GS 1186cc big valve cam motion cams 38mm carbs its 150+ rwhp. That parts easy. I admit it was very sketchy on the biasply tires and original suspension & brakes.Getting proper brakes and tires required upgrades to suspension wheels & brakes that takes more work.Trying to run with modern 1k bikes that weigh around 430lb with a GS that are about 550-575lbs not easy. My bike is down to 465lbs so I'm close to them. Gearing make a huge difference as to acceleration rate. I say build what you want just match the rest of the bike to the amount of power it makes. Good luck and post lots of pics. And big tires only helped my bike turn quicker and more stable Andy

I don't care what anyone says that motor look like it belongs there. The whole package looks great nice job.
And you did all that for close to what it would cost to build a big 1400cc motor. You can get those Bandit motors for around a grand sometimes less


I am curious what does the 1100/1150 motor weigh?
I know the GSXR1100/Bandit1200 motor weighs in at around 175lbs without the alternator.




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