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L1 750 Track/Street build

23732 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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That was harder than I thought. but turned out a little better than expected.
I retained all the bolts, both dowels and the speed sensor. I dont think any meaningful rigidity was lost since the two biggest forces acting on the cover were are on the top half of the case cover. most of the material was removed from the bottom half.
I could remove more, but will probably just stop.
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Stock cover for comparison
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what a waste of an hour or two... lol!
My carbide burr must be dull AF, cause it took quite a bit of pressure to cut the case. After getting the holes big enough, the best thing to remove case material was the angle grinder and a grinding disc. That cut like butter. Mg is embossed on the inside of these covers but it doesn't feel as light as I thought magnesium would. maybe it isn't what I think it means

I'm waiting on a few things to button up the alternator and rear brake setup. Can't wait to weigh the bike again. I was at 356#'s before the tank but after the core moto wheels. I've managed to save minuscule amounts of weight from the steering damper (nonelectric replacement), rotor Ti bolts, lighter clipons, tank with sato quick release front mount, race gen, lighter sprocket, lighter axle, marginally lighter rear brake set up and a handful of aluminum and ti bolts here and there, nothing crazy. I'm hoping I see <350... that would be a great number to hit.
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got my moly grease for the sprocket and starter reassembly.
Local autostore only has the low content moly grease like stalube... these are like <3% moly. Honda used to make a M60 60% moly paste. They changed this to M77 which is not 77% or even 60% moly anymore. These days I get my moly grease and spline moly from TSmoly. They sell a spline lube 60%, TS-60 spline grease, and a 70%, TS-70, I use on the axles, nuts, bolts etc that dont need loctite. Prevents galling, a real thing :(, and protects again corrosion. You get a jar or big tube for almost the price of honda's smaller-than-a-travel toothpaste 2 oz tube. But then again, you don't use too much per application...

Another issue with the BDK generator. The rubber grommet sits WAY too tall for the case opening and looks a little narrow to me...
I'm afraid this won't seal properly... Might not even install flat. I sent an email to BDK in England, my 3rd email for unrelated questions over the past month, and NONE have been answered. Tried to call once as well. Truly a crap experience with support.
With all the issues I've run into I absolutely can't recommend this product and I haven't even tried it yet...
Maybe they expect the end user to be a race team that can troubleshoot their poor product fit and finish and no support... I don't know... I can't get someone to answer my questions.

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It's not even wide enough...
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Maybe it's supposed to smush and widen???? I don't know... I can't talk to someone about it.
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Rear brake mock up and fitting done.
The max disc thickness for this caliper is supposed to be 4.5mm but all gixxer rear discs are 5mm. 5mm disc JUST BARELY fits with the pistons all the way back and pads in but it dragged. (At least I know I'm spot on with shimming the bracket with the 1.5mm shim.) I had to sand the pads down just a smidge, only 5 thou, to get the wheel to spin freely.
reused the stock grommet holder and mocked up a temporary one at the end of the swingarm. It looks good... i'm happy.
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Front sprocket installed... You can lose SO much weight (well... maybe 1+ pounds) with a 520 sprocket and chain swap... at the cost of accelerated wear of the rear aluminum sprocket.
1/3 of a pound off stock in the countersprocket alone with the ultralight Renthal steel sprocket, Ti nut, aluminum spacer and aluminum bolt for the speed sensor "wheel" (not installed in pic)

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I think I'm gonna finally replace that exhaust hanger. Really liked the short run of Sato hangers but none for this bike...
I'm gonna take a flyer and try to see if an '06 model will work. Called Sato and they have a couple sets lying around with a small discount. These were made to go with their high mounted exhaust they used to make a long time ago. No longer making them so they didn't plan on selling these.
They maybe too short but I could possibly weld an extension if needed. We will see...


Edit- I just found somewhere online that the spacing for the exhaust bracket is 63mm for the 2006 600 and 70mm for the 2011+ 600/750 and certain 1000's. Looks like the torch is coming out... :(
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The bracket was nice... but too short and not pointed in right direction.
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I felt destructive...
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We will see if I can weld titanium. Plan on putting a slightly large diameter ti tube that will slip over the Sato tube to connect the back. Then bend the front one to weld to the back.

Edit- LOL, I priced out what I would need to weld this- new gas lens, furick cup for titanium, titanium welding rod, some 3/32" tungsten, titanium 5/8" tubing and some scraps to practice on. well more than $100. really closer to $200 since some of the comsumables come in packages.
Price to make this out of steel from scratch- some 1/2" 0.03" wall mild steel tubing, 5/8" tubing... everything else i have. $10
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Bleeding the rear brakes that are completely empty... new or rebuilt.
because there is no rear master cylinder bleed screw, you HAVE to bleed at the MC banjo first otherwise you will never get the caliper to pressurize fast enough.
Ask me how I know...
Re wired bike a little today. Cleaned up some of the "temporary" connections I made 2 years ago when I removed both side switchgear, no lights except a projector type LED. The clutch switch is the only thing remaining on the left and there is a woodcraft keyless ignition bypass with a 4 button race pushbutton unit on the right for ignition power and starter and menu up/down. I had to wire a switched power to run the race regulator rectifier... I made it more difficult than it needed to be but it is done.

I also wired a cheap little volt meter. since the race alternator doesn't charge much under 5k, I'll need to keep an eye out on the battery level.
Depinned and removed a couple circuits from the front wiring harness to unused lights and steering damper control. Really buggered the dash connector, but got them out.

Managed to pull a cam position sensor wire right out of the connector. Spent a night digging the pin out and trying to reassemble the mangled pin onto the remaining bit of wire.

Because I removed the electronic steering damper and O2 sensor. I needed to flash the ecu to deactivate these at the ecu level. Tried to connect with the bench flashing unit from FTECU.. last time I did this was 2 years ago. Couldn't for the life of me get it to connect. I borrowed my son's school laptop and figured it out finally. Very counterintuitive how to download/read the ecu to file but it worked... 2 hrs of wasted time but It's DONE.

Filled the tank with a gallon of mildly stale gas and turned the ignition on a couple times to cycle the pump. Everything looked normal except for the low fuel light. But that's because I removed the fuel level sender. Wouldn't work on my homemade tank.

Will try to start it tomorrow!
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348 pounds in track trim. No lights or side stand. 1 gallon of gas (measured) so about 342 with a dry tank.

Started fine with a topped off battery.
With the race gen, I'm still able to maintain 13v on the small Lithium battery charger at idle. It seems the reg is starting to charge at 4000rpm.

When the fan kicks in volts drop to 12v on the charger and it starts to hit the limit as far as maintaining charge.

Took about 10 min to recharge after letting bike fully warm up, fan kick on and off. Then shut off.

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Took me a long time today but managed to pump out an exhaust hangar in steel.
I bought 1/2" tubing but I liked 3/8" better. I had some laying around from the tank.

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The hanger in thin tubing steel is so light, I think I'll pass on fixing the titanium one for now. another 1/2 pound right there.
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Spent the afternoon/evening metal gluing this little bracket together.

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glad that's over with.
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My Shoei helmets are 6 and 15 years old and the liner is disintegrating on the RF900.

I read that EPS foam doesn't age or breakdown and is very resistant and long-lived. And the 5 year rule for helmets was something Snell just made a general judgement call on. I do not believe there is a 5y rule in europe or other countries. With the great prices from Chromeburners and the relatively high $ to Euro rate, I couldn't pass up getting a new fangled lightweight racing helmet.

Based on availability and some random criteria like shell sizes, weight, optics/vision on racetrack, compatibility with glasses, I narrowed my choices to the Scorpion Exo R1 and the LS2 thunder both carbon. Because I bought from Europe, they won't have DOT stickers so technically they are track only.

I've kinda come to the conclusion that many of these full face helmets are close enough that you could do just fine with any of them. Fit and minor feature difference are probably what differentiates most of them. I've learned while I have an oval head, it's closer to the round oval than long oval and probably why I get headaches in the narrower helmets. And why I tend toward Shoei. Problem with Shoei was I felt the top of the helmet cut off my view on the track in a tuck and with the back protector on. I wanted one that had better upper field of vision.

I picked up the LS2 after trying on the scorpion at a local store. It was fine, just a little tight in the temples. No taxes, no economy shipping charges over $375, shipped in TWO DAYS!!! with upgraded priority fedex which was like just $5 more than fedex economy. That was insane. I can't get mail from UPS/FEDex/USPS that fast inside the US.
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World's jankiest 750 is back to life. Installed a pressure switch to the rear MC for a brake light signal, changed the oil and fired her back up. Re-upped my insurance and took it around for about 1/2hr and everything is running good. Nothing fell off yet.

The race alternator is going to be a big PITA on the streets. If you are thinking about it for your streetbike, forget it. I have a small led spotlight up front and an even smaller led taillight drawing a minimal amount of amps, and even then, when I stopped at the gas station it wouldn't restart. lol.
The bike charges fine >7K rpm. It barely charges at 4K. Anything under, you are running the battery down.

I am running Driven clip ons this year. I don't know if I posted that earlier. They are those tangent tube clip ons that brings bars a bit closer to me.
Everytime I get back on this bike after some time off, I think I can't ride this thing...
But it quickly comes back and I'm at least decent on it.
Plan on trying to get out as much as I can early this year.
Trackdays later in the summer.

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Getting used to the race alternator... If you get on any kind of highway, you are golden. More than a few minutes in city/red light or bumper to bumper traffic, it's risky.
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Last I measured, the bike was 50#'s less than stock. I thought it might be a good time to look at spring rates again.
A couple seasons ago I put in 0.95 fork springs to replace the 0.9 as I was bottoming out the forks. I also sent the used penske shock I had to turn one racing and he didn't bother changing the spring it came with.
Now I know I've checked what that Ohlins spring was but didn't realize until now it's on the rather soft side. Even with the 50# weight loss. Spring is 01093-31/95 which is a 150mm length, 47mm ID spring with a 95N/mm (542N/mm) rate. racetech recommends a much higher rate 575-630N/mm)

I think I am going to replace one of the forks legs' from a 0.95 back to 0.90. That'll give me a 0.925 kg/mm front.
And swap out the soft rear spring to 575 from hyperco.

This seems to be more in line with what racetech recommmends on their on line spring rate look up tool. And jives with penske's chart.
installed the .90 forks springs tonight. The springs were easy. The hard part is always that frickin front wheel. The pit bull stem stand just gets in the way enough to make pulling out the axle a pain. After the fork is off, to remove the cap, remove the spring recheck oil level and replace everything only takes maybe 10-15min. running an oil level of 130mm with some cartridges from traxxion.
I decided to keep the 95N/mm rear spring for now. We will see how this combo works.
The issue i hope to fix is that I just can't get any decent compression travel on the brakes. That means no help with steering (reduced rake) and a lack of feeling of how hard i'm braking (dive).
Corner exits seem to be ok on this shock/spring rate. Squat can be tuned with swingarm angle/rear ride height or preload changes.
Lol... came out this morning and noticed the throttle cables are routed wrong... crap
Off comes the wheel again.
Just scored me a complete set of oem fairings from a 21 bike with matching tank!!! pristine with 400miles.
This makes me almost as excited as any performance mod I've done. I remember the bike being SOOO nice with OEM clothes on.

And on the crazy side... I found out I could save a few more grams switching the steel airbox shoulder bolts (6) with aluminum bolts with lightweight spacer instead. I'm going to do the rear rotor bolts and front axle pinch bolts and reweigh the bike.... I want to reach 150kg sooo badly.
Dealing with some major stiction issues on the front forks... >10mm.
Not sure what to do with this if anything.
I've tried to true up the forks several times without results.

.9 front springs working well, I'm getting good front end travel on hard brakes. Now I know why people run high front ride heights.
My brother shipped his Ural to me from California since he's moving to a small place in texas and doesn't have storage for the bike.

The bike is fun. Kinda like a ride in one of those mobile amusement parks, marginally fun and oddly dangerous.

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But the really cool thing was the couple of Arch motorcycles that were going across the country to their new owners.

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The fully compressed beautiful Ohlins forks were hurting my eyes. The picture doesn't capture the beauty and extent of the cnc machining everywhere on the bike.

BTW, reweighed my bike and I'm at 340 pounds dry! Could I lop off 10 more pounds? Unlikely...
I have some ideas though.
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Love your work.

Would it be easier at this stage for the rider to lose 10# ? Power to weight ratio needs to factor in the rider.

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