Rich's 81' GS450 cafe / fighter build.

[extremez31]

Hey everyone, recently I acquired a 81 GS450 for $400. I have been wrenching on cars for just about 15 years as a hobby and have gone so far as building a complete turbo system from scratch for a naturally aspirated car. In the past I've owned a bobbed Honda Rebel, and a Ducati Monster. I love the rebels simplicity and vintage look, but miss the ducati's torque and power. My goal is to somehow get the best of both worlds. I want to build a hybrid, a bike with a vintage look while adding as much modern technology as I can afford.

I've started stripping her down and cutting off tabs, need to pull the motor, remove the tank getting the bare frame and give it a good cleaning.

 

[Hornswaggle]

Good luck on the build, this should be interesting

 

[Guest]

I'll follow along on this one

That looks like an L (can't remember what your intro thread said) but it looks like it has an E/S front end on it... what size rim is on the front?

The reason I point that out is that if it's the E/S front end, you can probably do the Salty Monk brake upgrade with the single disc to have a Kawasaki twinpot caliper on there if you're looking at those sorts of modifications.

 

[D-Mac]

Hey everyone, recently I acquired a 81 GS450 for $400. I have been wrenching on cars for just about 15 years as a hobby and have gone so far as building a complete turbo system from scratch for a naturally aspirated car. In the past I've owned a bobbed Honda Rebel, and a Ducati Monster. I love the rebels simplicity and vintage look, but miss the ducati's torque and power. My goal is to somehow get the best of both worlds. I want to build a hybrid, a bike with a vintage look while adding as much modern technology as I can afford.

I've started stripping her down and cutting off tabs, need to pull the motor, remove the tank getting the bare frame and give it a good cleaning.

A lot of that bike looks like my '81 550. They really swapped stuff around in that year.

Looks like a fun project. Subscribed.

 

[extremez31]

Pete thanks for the heads up on the brake upgrade. Ill get the measurements of that wheel and report back tomorrow. These are the exact types of modifications I will be making.

I need some advise, planning ahead I want to keep the factory airbox but modify the top to fit a flat K&N filter pannel.

Inside the airbox I would like to add velocity stacks. I need to pull the carbs, clean and rebuild.

There is a debate between running pod filters on the carbs as opposed to keeping your airbox and running stacks inside. From my experience and research pod filters will make more power on a dyno but, when on the road and going through turbulent air the pod filters do not pull air in with the same efficiency. Airboxes are used by race teams, the box is meant to control the turbulence and allow stabilized air to flow into the engine. The factory airbox is restricted with a small opening, this will be addressed later in the build.

Questions:

Does anyone here have positive / negative experience with velocity stacks? If so can you please share, also include specifics ie size of runner.

I defiantly need to rebuild the carbs can someone recommend a carb kit?

Rejet kit is also in order but thats going to need to be addressed via wide-band after the exhaust is made.


Thanks in advance!

 

[Guest]

Pete thanks for the heads up on the brake upgrade. Ill get the measurements of that wheel and report back tomorrow. These are the exact types of modifications I will be making.

I need some advise, planning ahead I want to keep the factory airbox but modify the top to fit a flat K&N filter pannel.

Inside the airbox I would like to add velocity stacks. I need to pull the carbs, clean and rebuild.

There is a debate between running pod filters on the carbs as opposed to keeping your airbox and running stacks inside. From my experience and research pod filters will make more power on a dyno but, when on the road and going through turbulent air the pod filters do not pull air in with the same efficiency. Airboxes are used by race teams, the box is meant to control the turbulence and allow stabilized air to flow into the engine. The factory airbox is restricted with a small opening, this will be addressed later in the build.

Questions:

Does anyone here have positive / negative experience with velocity stacks? If so can you please share, also include specifics ie size of runner.

I defiantly need to rebuild the carbs can someone recommend a carb kit?

Rejet kit is also in order but thats going to need to be addressed via wide-band after the exhaust is made.


Thanks in advance!

I went K&N pods for simplicity, but your comments on turbulence etc. are pretty much spot on from my understanding of it. I'm contemplating some sort of side panels to block a lot of the cross winds but I haven't had any issues with that yet.

Don't buy a carb kit, get O rings from www.cycleorings.com (a member here Robert Barr runs that) and get genuine gaskets if necessary.

Check Dynojet to see if that have a kit for your carbs, otherwise use genuine jets, there's been mixed reports about the eBay kits that are around the place.

 

[extremez31]

Ok, finally got the bike to a rolling chasis, I need to start cleaning and finish grinding / removing tabs. Its terribly cold outside so I can only spend an hour or two at a time working on the bike before my hands go numb.

Pete, the front wheel is 100/90/19

Once the air filter, rearsets & seat pan come in I can start fabrication and mockup.

 

[Guest]

Good work! But where are the pic's? Noone will believe you unless they can see it

That wheel sounds like the L size wheel, but the forks still look like E/S forks.

Here's the Salty Monk ad for the adaptors for the Kawasaki twinpot calipers:

http://www.thegsresources.com/_forum/showthread.php?t=185121

Here's the thread where I took the measurements to see if it should work:

http://www.thegsresources.com/_forum/showthread.php?t=181521

Probably page 4 or 5 will be the interesting bit.

 

[extremez31]

Well, I havent touched the bike in about a week, but I have been ordering parts. Figure I share and give everyone an update.

I've ordered front clubman bars including everything that mounts to them. New lights front and back, cafe seat, battery, rebuild kit for carbs, chain tensioner, petcock, two bros carbon muffler, 1.5" stainless tubing and the part i'm most excited about. I got an insane deal for a ninja 250 swingarm, wheel rearset, master rear cylinder, caliper Shock & links for $127 shipped.

Wish me Luck!!

I have quite a few GS450 stock parts which i need to get rid of.. meaning for FREE, I hate to throw out the parts I took off the bike so if someone is willing to pick up these parts they can have em for a handshake.

 

[Cdnpt1]

Sent a PM about parts but not sure it went, where are you? Where are the pics we love?

 

[extremez31]

Forks, Swingarm and seat in place

Forks, Swingarm and seat in place

Finally, took the bike to my friends garage so I could spend some time on the bike.

Progress so far, 636 Ninja front end is on this was not a direct swap. I had to go to my local industrial hardware store with a digital caliper and sift through all the bearings until I found something that would work. The top triple bearings i found were 35x47x10 the bottom 35x55x15.

After cutting all the unwanted tabs and passenger peg supports the bike looks much cleaner.

Rear swingarm from a ninja 250 is 213mm wide measured with a digital caliper. the stock GS bearing caps are 2.2 mm thick which brings us to a total of 217.4mm. the gs swingarm pivot point needs is 205mm so I had to shave the difference off with a grinder. I put the swingarm race on a lathe and took 12mm off, threw it on the bike.

Here is a pic of the GS.

 

[Erki]

Looks good. what size wheel and tire go on that swingarm?

 

[extremez31]

The wheel tire size is a stock match. 130/90/16.

 

[Guest]

Good stuff! It's hard to tell but going by the looks of that you won't lose much ground clearance (if any) compared to stock too. I've read USD swaps tend to end up with a big loss of ground clearance, but looks like you'll be right which is great.

 

[jfman]

extremez31 : I too have bought a 636 front end for my GS400. Do you have the part numbers for those bearings or do I just need the size of them to order them?

They are the collar and balls type?(dunnu if I am using the correct term here.


Keep up the good work!