GS Big Block

[stetracer]

Just my opinion, but it strikes me as risky to dump big money into a high HP air cooled engine. Get stuck in traffic, pick up some crud in your jets, get an air leak in the carbs, etc, and the engine will cook from all the heat. There's a reason modern high performance bikes are water cooled.

A modern engine will need modifying also to get 180hp at the rear wheel also.
I am building or collecting parts for a 225hp N/A 1340cc Bandit and I could buy a brand new Busa for what I am spending on this bike but it will be a brand new bike also just an older style that will fool a lot of people. My build budget on this project will be in the 12 to 13 grand range with over half of that building the motor. Oh and did I mention that I do all my own work so there is no labor figured in on this build. I am using all new parts on the motor build except for the cases and head casting

[yoshisakan]

Would it be a better idea to turbo a smaller displacement motor? I have a t22 sitting on my desk at home collecting dust. No shaft play.

Maybe I could just slap some low compression pistons in my current block, change out the valve seals, weld a custom turbo mani and use some 1150 carbs? Thoughts? I think heat wise, it would probably generate a lot less at idle than a higher compression engine.

[kawfeedave]

A lot of good thoughts in this thread, but all this talk about 2013 type HP out of a motor with 1982 type tires and brakes seems a little short sighted. Maybe a lot short sighted.

For the price of building the motor/clutch/trans, you could buy any number of used bikes that will be close in power/performance. Anything with 150hp, that weighs 100lbs less with modern, wide rubber will eat a GS for lunch.

Add in the cost of upgrading the wheels/tires/brakes/suspension, and you have even more bikes to choose from with even more power to be had.

If you love the GS, then build it. Just be ready to eat 75% of the build cost for lunch if you choose to sell the bike, as we have seen many, many times in the past. If you do build it, post video of the beast, I would love to see it.

[rapidray]

Would it be a better idea to turbo a smaller displacement motor? I have a t22 sitting on my desk at home collecting dust. No shaft play.

Maybe I could just slap some low compression pistons in my current block, change out the valve seals, weld a custom turbo mani and use some 1150 carbs? Thoughts? I think heat wise, it would probably generate a lot less at idle than a higher compression engine.

A turbo IS the easiest way to make a lot of power if you don't know how to build cylinder heads. It will only build REAL heat when it's on boost so that is an advantage. You still have to do everything else you need to do to build either motor correctly. Studs top & bottom, crank work, trans work, cams, valve springs, cam chain, pump gears, pistons, big oil cooler, etc.... THEN the cost of the turbo setup is MORE than a good cylinder head for the big motor build. A 1200cc turbo will do 200-220 RWHP easy. Heat is an issue once you spool it up & plumbing the thing is an issue too. 6 to 1, half a dozen to another. EITHER motor is a BLAST!!! Ray.

[bellucci]

I rode my 1327 for 3 years on the street... They do get warm. But like Ray said,Torque is a blast...If you want to see what it cost in 1990 dollars and see the dyno numbers, type in historical documents into the search button. It dynoed at 180 back then... And its still running in my drag bike. I had a off brand turbo that was a blast on the street. XS1100 with 20 lbs of boost with a shaft drive. At the track it ran 9.20's with bars and 125 octane fuel... Those were the days.
Curt

[stetracer]

A lot of good thoughts in this thread, but all this talk about 2013 type HP out of a motor with 1982 type tires and brakes seems a little short sighted. Maybe a lot short sighted.

For the price of building the motor/clutch/trans, you could buy any number of used bikes that will be close in power/performance. Anything with 150hp, that weighs 100lbs less with modern, wide rubber will eat a GS for lunch.

Add in the cost of upgrading the wheels/tires/brakes/suspension, and you have even more bikes to choose from with even more power to be had.

If you love the GS, then build it. Just be ready to eat 75% of the build cost for lunch if you choose to sell the bike, as we have seen many, many times in the past. If you do build it, post video of the beast, I would love to see it.

For what it is worth I don't sell my bikes so resale value is of no concern to me. My 85 GS1150 I have owned it since 1990 with no plans on ever selling it. As far as far as power it has more than enough to eat any newer stock bike for lunch. With the cost of the bike I would say I have a little over 6 grand into it so not a ton of cash to be wasted . I wonder what a high 8. Second GS1150 street bike would sell for? I know not what I have into it.

[stetracer]

I rode my 1327 for 3 years on the street... They do get warm. But like Ray said,Torque is a blast...If you want to see what it cost in 1990 dollars and see the dyno numbers, type in historical documents into the search button. It dynoed at 180 back then... And its still running in my drag bike. I had a off brand turbo that was a blast on the street. XS1100 with 20 lbs of boost with a shaft drive. At the track it ran 9.20's with bars and 125 octane fuel... Those were the days.
Curt

9.20's with sissy bars.😂 Try high 8,s with no bar street tire bike now your talkin power. Sissy bars aren't all bad they have their place. Even I have a bar bike for bracket racing

[yoshisakan]

During the course of this conversation, I have researched many different bikes, suzuki m109r, vrod, vmax, triumph 3 etc. I'm sorry to say but all of these bikes leave a lot to be desired in the appearance department. I'd much rather invest in my GS and have a great looking bike. As a side note, i have a 1973 datsun 240z in my garage, it's another lifer. When you put money into these kinds of vehicles, its a given that you're going to lose your ass if you try to sell them.

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.

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?

[rapidray]

Stock carbs will work but will limit the REAL power that will be available. For a 1327-1400 I would use RS40s or FCR41s. Stock carbs would choke the potential real HP. Ray.

[bellucci]

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

[stetracer]

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.

[stetracer]

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.