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Review of L2 GSX-R750 and a potentially complex issue

3495 Views 53 Replies 7 Participants Last post by  craigfer63
Hi everyone. As you all know I'm new to the forum and I would like to post a little review of the limited time I've had with the bike so far.

A little about me. I've been riding for about 15 years now. But haven't been to the racetrack yet (planning on that within the next 6 months). I also haven't owned many bikes but I started off on a Kawasaki ZZR250, then upgraded to a 1999 Yamaha R6, then a 2013 ZX6R (new) and now a 2012 GSX-R 750. I've had small rides on a 2013 Triumph Daytona 675, 2015 Yamaha MT-09 and a 2018 Honda CBR1000RR. Again, I've mostly ridden street but I am fairly confident in handling the bikes at high speed and through corners (as far as street riding goes). I also like working on my own motorcycles because I just don't trust the dealers unless I can't fix something due to lack of resources.

With that out of the way let's move on to my small review. Five days ago I went for an inspection of the bike it looked clean and seemed well taken care of, hence I purchased it. It has the following mods on there:
-Full Yoshimura R77 (??) exhaust
-ECU and dyno tune (130hp apparently)
-Aftermarket grips
-Bonamici Racing brake and clutch levers
-Clutch switch mod for clutchless start (throws an FI light but more on this later)
-Techspec tank pads
-Fender eliminator

I've since ridden the gixxer 750 only 3 times since then, including riding it home from the inspection. Today I went for the longest ride (about 40 minutes) with my wife on the back. It feels great to ride and it's not an overly aggressive body position. I can actually flat foot the bike which is neat. I've changed the shift pattern to GP shift as that is what I had on the ZX6R, which helped solve an issue I had with the gear lever placement as I was riding today. It goes well but I find the power is lacking which must be due to the clutch switch issue I've been reading about on this forum. Brakes feel good for the street and stop really well. Handles corners well enough but I think after changing to new tyres, it might be better at this. Overall a great bike and not many complaints.

Now comes the issue I'm having. From what I understand, removing the clutch switch forces the bike to use a neutral map and therefore it loses power. According to the guy I bought it from it has been tuned, but the throttle still feels choppy, almost the same as if it was from the factory. Because of the aftermarket levers, there doesn't seem to be a mounting point on the bike for the clutch switch. But it has been zip tied to a harness with 2 wires connecting to it (see picture)

Automotive tire Automotive wheel system Gas Auto part Pipe

I want to fix this up and put the clutch switch back where it belongs so that the bike can run as it was intended. I really don't care that I have to pull in the clutch to start the bike. That FI light annoys me (I don't have the dealer switch to pull the code) and I feel the lack of power is due to this issue. So the problem for me is two fold. 1. improve the bikes performance and 2. get rid of the FI light. The issue I'm having is where can I mount the switch and which wires do I connect to the switch?

Now to be clear, the bike runs smoothly and without issue despite the FI light coming on. I could leave it as is but I feel like I'd be gaining so much more if I could resolve this issue.

Any help would be greatly appreciated. Thanks for reading :)
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WOW what the F%&#k is that ? No bare wires on your bike ! The clutch switch, like all the sensors on your bike talks to the ECM. Clutch in and out, tells the ECM your in neutral. You can take it off, but you need to press the switch to tell the ECM. Or delete it from the ECM.
Dealer Mode Switch here
Need to fix any FI codes.
Shift light setting in Owners Manual.
You need Workshop Manual.
No sorry. Search for one or buy one very important to keep your Gixxer in running condition.
Did you follow the Owners Manual when setting shift light ?

We need the FI code to proceed.
K7 750 here.
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Your slipper clutch is working, and gives you a smooth transition when down shifting. Rev matching protects the engine from damage. Slipper clutch is adjustable but yours sounds right. here is the L2 slipper clutch.
The adjuster bolts #22 (3), rest on the clutch driven cam #19. When down changing cams #18 and #19 lift the clutch pressure disc (plate) #15 .
You can see these adjusting bolts #22 (3), through the inspection hole in the clutch cover. OEM is 3 threads showing above the locknut.
2 1/2 threads showing gives more slip. (if you go in too far, clutch will slip under acceleration !)
3 1/2 threads showing gives less slip. Good thread here.
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Clutch Switch is an on / off momentary switch. So you are saying with this switch depressed the bike works well ?
What readings are you getting when you test the Gear Position Switch, as per the workshop manual ?
On all the wiring diagrams I can find these Clutch Switch wires are Black / yellow and Black / White. Is this correct ?
My first impression of your problem was dodgy wiring, and it still looks like this ?
Have you traced these 2 blue wires back to the harness ? What does their other end look like ? They just don't look like Suzuki wiring.
You have to get your sport bike to a track day. If you have access to a Race Track. It is like night and day. The sport bike is designed to do this. It is like riding from your house to the end of your street at 100 mph. (170 k) In 3rd gear !
I'm still using the rear brake, in braking area, at least when the rear tire touches, it grabs a little. I'm trying everything to get me stopped !
Front brake hard, rear brake full, body sitting up straight in the air stream, matching down changes hard with revs low. MOUTH OPEN 😯 fingers crossed 😁 Turn in, trailing off front brake, last.
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Yes, you can see this watching Moto GP races. Of course these guys are pros and work very hard to keep the bike straight and settled.
The physics is obvious, under braking the rear is lightened and with the rear wheel off the ground, the rear of the bike wants to overtake the front.
As all bikers know when you lock the rear wheel on a slippery surface, the rear comes out, then the rider automatically corrects the slide with steering and body movement.
Sitting up and moving your weight to the rear can settle the rear.
Just before you come off the front brake, use your forward inertia to move into position forward for the turn.
There are lots of youtube vids on this.
Oh and yes, having only two wheels means the bike will slide out from under you sooner or later ! For me in my old age this means the race track insures I wont hit any foreign objects, cars, trucks, trees, barriers, with my head. (y)
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The situation / feeling you are getting, from the rear wheel under braking, can be caused / fixed by suspension setting. Assuming you have your ride height and sag set, there is lots of info on this, search.
And your suspension is set to standard, (which Suzuki went to a lot of testing to find this)
Try adding some Rebound to the rear shock. Go 1 click in (harder) at a time, do not go past 5 clicks in.
Make a log book of what your doing and how your bike feels with each change. (y)
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Changing your own tires is hard core ! I have been changing my own tires since I was 10, on pushbikes and dirt bikes.
I have every tire lever, spoon and device known to man but it is still a battle of whit's, 😡🤬 So attempting to gouge my way through my Gixxer rims, I'm reluctant. 😆
Let us know how you go.
Patience is the answer. when there is air in the system it will be in multiple places. so the master cylinder piston is pushing against air.
This is what is driving you crazy. 😆
A simple analogy is when you put the garden hose on the tap. When you turn the tap on, the water starts coming out in a broken flow, until there is a solid flow.
A simple way to bleed brakes is the gravity method. Keep the reservoir full at all times.
Open all bleed nipples and watch brake fluid running out. When there is a solid flow from all nipples, the system is full.
Of-course this would get brake fluid everywhere but you get the idea.
Using your bleeding hose on the further est nipple, watch the fluid run out, the air will be coming out here, but under gravity it will be slow and had to see. Let a reservoir full through, then to each closer nipple in turn. Good luck.
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Thanks for good pics.
Once a year minimum. Racers will bleed brakes every meeting. I would bleed mine every 4 track days. Noted in log book, date and Km's.
I have a cheap syringe (fleabay) that I use to remove old fluid /crud from reservoir before I start bleeding. No use pushing that shit through the system.
Mark your Brake fluid bottles with date, 1 year, bin it.
Mark where your Master Cylinder Banjos are now, with a white marker. So when you undo them to move them you will have a starting point.
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