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L1 750 Track/Street build

23734 Views 223 Replies 16 Participants Last post by  JCW
A little background, I bought an L1 GSXr750 with a little over 2000 miles earlier this year and lowsided at the track. It was an easy lowside (at 65mph) and after a fairly simple rebuild to replace some plastics and maybe a lever I was back on the bike. Fast forward a few months and I decided I wanted to do a complete makeover, so I crashed at the track REALLY good. Managed to rash or crack EVERY last bit of plastic, bend a brake rotor, snap off a clip on, bent rearsets but the main part of the bike (fork, triples, frame, wheels, etc) survived amazingly well.

It's a work in progress and if anyone has any questions on what has gone before, I'm happy to share. Some of the highlights were an DIY FTECU flash, installation of their quickshifter, M4 Brembo brake installation with Braking's SK2 rotors. Stainless steel brake lines, Traxxion dynamics revalved and resprung forks, shimmed OEM shock and fork extenders up front, GSXR600 headers with a stainless steel stub welded to fit a DIY pie cut midpipe eliminating the cat. This ends in the stock location so I can use any of the slip on mufflers out there. Currently I replaced the rashed stock muffler with a Leo Vince slip on.

So, at the moment, I'm waiting on a superbike plastics kit from Armour Bodies. Seems they have very good reviews on their body kits. I ordered a superbike kit (one with the stock seat replaced with a one piece tail unit and a foam pad). Unfortunately, I was told it will be December before I MIGHT get it. Apparently they stock the supersport kit that utilizes the stock seat. Whatever, I'm healing from my clavicle fracture and I'm not riding seriously anyway.

I'm planning how to make the bike barely "street legal" while utilizing the race plastics. I was thinking a mini projector lights and a custom mount. I fabbed up a bracket to mount a tail/brake light sandwiched between the fender eliminator and the undersurface of the frame. I've been fortunate enough to have learned how to tig weld and brackets like this are an easy thing.
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You could have ordered something but you did it yourself in stead, way more street cred in that. Pretty badass to be honest. Given the choice I'd rather have fully functional fabbed parts on my bike that sparkly store bought stuff. That was a complex job, most people couldn't get their head around the shapes let alone measure for them. If anyone says different hand them your welder and say "Have at it". Fairly sure they will shut up quick.
Every once in a while I like to get out of my comfort zone and see what I can do.
Still have a ways to go on track, though to get where I want to be.
3 crashes and a busted clavicle, I am trying.
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If you ain't wreckin, you ain't racin.
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patched the big holes and finished the top front edge.
mounting tabs/brackets next
Still have to fix the filler cap area...
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Added front and rear mounts. It finally can be mounted on the bike!


Then bought a couple rubber stopper and hammered a nail through the top one then passed a needle inflator with a hand pump to manually pressurize the tank to look for leaks.
Rather effective. I would mark 5 pinholes, go weld them, come back and find 5 more, etc. I worked on this all day on/off. Maybe took 6-7 trips and 30+ patch welds but I got her sealed up!!




Did a little photoshop comparison between the stock and this tank.

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Damn fine work Sir. Nice trick with the air pump!

Styrofoam buck for the tank cover. I hate this stuff...
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Anyone got some fiberglass skillz?

Trying to decide if I should just coat this and fiberglass the final product or go through the mold making process... it doesn't have to be perfect.
I just put on new-to-me calipers I've had laying around last year. an older gen gp4rr.

The calipers didnt feel too much different riding around on the streets than the m4's I replaced but i had the m4 system set up and bled so well, they were the best brake system I had ever used.

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I should be arrested for how bad the bike looks, but man this thing rocks right now. Time to get my butt back on the track. I just hope I don't get too much shit for my tank...
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I also finally welded an extension to the sidestand. It's so nice to have a functional sidestand again.
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Ever wonder what galling looks like?
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This was my left engine mounting bolt... I haz a sad...

Edit- I ran a tap through the hole and it felt like I had meat left over to grip a new bolt...
One thing I've learned is to try your absolute best to line up the holes so the bolt goes in with as little resistence and friction as possible. Galling occurs with the moving friction of the two surfaces.... I'll also be using some type of threadlock or antiseize everywhere on the bike...this will help prevent some of the galling as well.
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This was the last bit of kit I said I'd get for this bike... my mod for the year.

BDK flywheel on left, Stock on right.
The kit replaces the stator case cover and stator as the new windings are much longer with thinner wires.

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Overall the flywheel weighs 1 pound less and mass is concentrated at the center vs the periphery. The new stator and cover weighs 100g more.
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This is a list I made up of the bolts and nuts M10 or larger I'm looking to change out for titanium.

Edit--- I removed and weighed all the bolts I listed and with a titanium swap I was looking at about 1# weight savings for $350+ dollars, so... I'm binning the idea. LOL.
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Heard of this trick to unload the rear suspension for a rear shock change or ride height adjustment???

I just saw that you can use a scissor jack on the rear wheel and jack up the subframe to off load the suspension to remove the bolts and shock...
I've always used the frame of my hydraulic pump press and ratcheting tie downs to lift the frame. This is so much easier and portable.

Edit- so I had to remove the plastic undertray so I didn't crush it when lifting the frame. Otherwise, the trick worked well.
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So I was reinstalling the BDK flywheel after getting all the special tools I needed and in the process cleaning the starter clutch that bolts to the back of the flywheel.
I sprayed it down with brake cleaner and when I went to shake it dry, all the little bearing/clutch pieces fell out... like 20 of them all over the garage floor.
Now I don't know how they are supposed to go back...
The starter clutch mechanism comes as a set and it's over $250.... crap
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Those little pieces are clearly sided like a cam lobe... I need to figure out which orientation.

Edit--- yeah!! Just found this

They actually sell just the one way clutch center section (pictured) by itself on amazon.
But all I needed was the orientation.
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Installed the flywheel and there is a slightly uncomfortable amount of side to side (axial) play in the starter gear behind the flywheel.
Off everything came again... I think it MIGHT be normal, but I want to be sure before the locktite sets.

Emails sent off to BDK.

Update- No response from BDK... Not unexpected to be honest. These race parts are usually buy at your own risk...
I refitted the stock flywheel and measured the play. About 1.3mm.
The BDK flywheel had 2.5mm of axial play in the starter clutch gear.
I'm not sure if putting in a shim or thrust washer would be the right thing to do... I'll mull it over for a couple days.
Send one more request for info...

Update- No response... I give up.
I'm planning to shim the space between the starter gear and the flywheel. Rather than behind the flywheel. I bought $40 worth of thrust washers/shims from mcmaster carr and am trying to see which one is the closest fit (25mm shaft vs 1" shaft and different OD's) and best material (spring steel, bronze, graphite containing, corrosion resistant). My main concern is the vibration that a "loose" fitting "washer" will do on the shaft turning at 14,000 rpms.
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I feel like cutting open the front sprocket cover so you can see some of the sprocket and chain.

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purely cosmetic thing... Tony Elias Yoshimura gsxr1000 SBK on the left. stock 750 on the right...

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This one practically gets rid of the entire cover and speed sensor.
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If anyone is interested... I may have worked out a way to convert the rear brake to underslung for the 2011+ 600/750.
The only place I could find that makes a direct replacement adapter is from England and it's almost $900 for the entire quickchange rear. Which is about the going rate comparing to Fast by franks.

Again this is 99% cosmetic, IMO. Rear tires changes would be easier... But ultimately, a single piston sliding 30mm is gonna perform better than a lot of these micro rear calipers even if they have brembo in red and are "carved from billet."

Im still collecting parts and taking measurements but here's a gsxr1000 and a stock gsxr600/750 stock rear caliper bracket side by side.
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I asked a couple bike builders and racers... most of them told me to just stick with stock. About half say they don't even use the rear brake... Cross another mod off the list...
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Some reason this is satisfying to me. spooned on a lightly scrubbed SC1 rear and test fit the rear wheel with some new parts.
Sry cant embed video.

I am finishing up the underslung caliper conversion for the 11+ 650/750 because well I started it. You can do it for under $300 with a cast brembo. Here's how... the gsxr1000 09-16 caliper bracket is the same as the 11+ 600.750 bracket EXCEPT the axle center is 25mm instead of 28mm. A 09-16 gixxer thou brembo bracket kit and a metal sleeve to sleeve down the axle hole from 28 to 25mm and youre set.
Unfortunately, I was informed brembo stopped making that specific gixxer thou bracket and the kit is unavailable from the factory... you might be able to find leftover stock somewhere. There are also copycats on the internets however some may require a little lateral shimming to get perfect. Superbike unlimited offers one availabe to order in 2-4weeks. I have a sneaky suspicion it is the Taiwanese sourced brackets however I trust Superbike umilimited's products as they are involved with and put their parts on actual race bikes.

I ended up with a Taiwanese bracket off ebay (that required a 1.5mm shim from Mcmaster carr), sleeve from amazon and brembo caliper. The cast brembos are only about $180 and @ 34mm are probably well sized for the 14mm stock rear master.
You can find billet brembo rears ranging in price from $400-$1500 dollars but that's more for show, not for go realistically. OPPracing has probably the best website for listings for you to window shop. A totally cool caliper is one with TWO inlets FOUR pistons in TWO separate circuits. So you can hook up your thumb brake and rear brake to the same caliper but have completely separate systems? LOL!
(I found one seller on ebay selling 64mm brackets for the 1000... vs the regular 84mm brembo kit)

Best prices right now are overseas unfortunately... even with shipping. Caprimoto and a place I've never heard of before genial moto have some great prices. Make sure you know your credit card foreign currency transaction fee and figure this into the purchase price as well. The higher the price the better the saving buying from italy at the moment.

The video above is with the bracket and shim installed. Awaiting the caliper and i guess I'll need a longer brake line.
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One last tidbit... a cbr600rr 05-12 rear axle is the same diameter and just a smidgen longer than the 600/750 axle. They are interchangeable as long as you get a thick 25mm washer on the end of the axle for the nut and are not hamfisted when tightening the axle down as the flats on the other side maybe like 0.5mm shorter so they can dig into the soft aluminum axle stock sliders a little more than stock. When I mean thick washer I mean like you will likely need several washers. I bought an aluminum spacer 25mm at 1/4" thick and filed the OD down to look nicer. the axle thread and nut is 22mm but the 25mm part of the axle extends like 1-2mm past the axle adjuster plate so a 22mm washer will bind on the axle before tightening down the swingarm if that makes any sens at all...
this is the cbr600 axle, stock axle adjuster, aluminum spacer and oem replacement 22mm ti nut
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I found this out in my research into Ti axles... omg... I bought the cheapest used axles off different model years cbr1000; cbr600, zx-10r that I looked up had the same axle size 25mm and measured their thread lengths and overall lengths. the honda 600 was closest. The other manufacturers BMW, yamaha, ktm use different sized rear axles.
But it also give you a cheaper option for a replacement if you are needing one used on ebay.
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Stock rear caliper is light as f!!!! 375g without pads!
That's lighter than all the brembo calipers billet or cast unless you go crazy expensive with just miniature pistons.
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