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Discussion Starter #1 (Edited)
2002 GSXR 750 1x Owner (Me)
80K miles (freshened up at 50K) Lots of street miles/track days/WERA, but haven't really ridden it in years because of problems.

Current aftermarket parts on the bike: BMC Race filter (Clean), Yosh full exhaust, 1/4 turn throttle, chain/sprockets, Disconnected Power Commander III.

I have the factory service manual, and have always felt like I'm a decent mechanic but have a basic understanding with electrical issues.

Compression: 180-190 on all cylinders, Wet compression 200-210. (Using a harbor freight C-tester)

The last time I really was able to ride it successfully was about 2013.

My current problems:
1. I put new (stock) headlight bulbs back in and cycled the key. LOW beams and speedo were on, but when I clicked the HI beams I lost all lights and the speedo. Found and cleaned corrosion on the wiring harness under the air duct and now my lights work, but my speedo only lights up (no tach/or gauge information, just the backlight) I cannot find any other corrosion and also tried swapping the ECM but no change. Ideas?

2. I believe the bike has electrical issues because of poor running conditions (bike runs better when cold, but horrid when it gets hot). I replaced all injectors/coil packs/plugs/sensors/ECM/fuel pump/Stator/Rectifier/Battery with no luck. I have used 2x multimeters all over the bike. The original stator was good on Ohms, each leg was 22v at 5k, and was charging the battery at 14.2-14.5. The problem was when it hit 150 degrees exactly it would overcharge 14.7-14.9 and start running a lot worse including dropping the idle rpm from 1200 to 1000. I replaced the stator, rectifier, and battery with all of the OEM parts just like it had in it. THE NEW PROBLEM. New stator will hold 14.2-14.3 constantly until I take it down the road then it starts running bad so I come back and read the battery and its only putting out 12.7 (not charging). All plugs and contacts are clean. Any Ideas?

3. I thought I smelled burning coming from the top of the motor near the coil packs so I pulled the plug off the back when running. 2x out of the 4 will almost let the engine die and 2x have an almost in noticeable change like they are bad. So I swapped them with each other and with 2x other sets I have and get no change almost like the harness is bad. I checked the voltage on each coil pack while running and they are all within spec per the service manual. Ideas?

4. With the airbox off there is a very fine white vapor/smoke coming from the crank case breather. Ideas?
 

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SuperMod of the North
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Damn, you got a lot going on here. OK, I am not a tech guy but here goes...hopefully one of the tech Gods comes along and helps out here. I know rectifier location on some of the models caused a problem due to being located in a hot area, it was common to move them around to the clutch side of the bike away from the headers where they got some air flow. I don't think this was an issue with the 2002 though, it was later if I recall. Heat is resistance, I would be checking all connections and grounds. If you have all new OEM parts you should be rockin, there's something going on in the infrastructure here. I would go back to the harness...again...once John logs in here do what ever he saysl
 

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Discussion Starter #3
I have 2x rectifiers which both check out based on 2x multimeters, and the location is at the back left of the tail unlike the 06/07 GSXRs. Thanks.
 

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!. keep wiggling wires until the gauge lights up it may have a loose connection at the rear of the gauge. (check every fuse as well)
3. fire the bike. keep testing each header as it warms with misted water or laser temp gauge. If it starts to malfuction or miss, you will be able to tell which cylinder is misfiring.
Then its on to why its misfiring.
Ill keep thinking about the rest maybe RV6 will chime in he is really good at internet diag.
:devil
 

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Discussion Starter #5 (Edited)
The engineers here said the same thing about the speedo, it either has to be a corroded pin which I missed or poor contact at the forward harness. All fuses are good.

I have done the header test several times but unfortunately they are consistent until it gets to 150 degrees then everything goes nuts. I will try again for giggles. The engineers also suggested that maybe the harness is just done and I need a new one. Even though the harness is stock its not in great condition from age, heat cycles, and racing. Thanks.

The last time the motorcycle ran good was around 2012-13 in the Tahoe area of Nevada. I did several long trips through the mountains into Cali then one day my wife and I were riding it up the mountain, and where I would normally be in 5th gear I had to drop it down to 3rd because of power loss. At this point I started throwing parts at it. What lead me to believe it was electrical after time was the dimming of headlights and the speedo when the engine would slow down at stop signs which is why I replaced my stator/rec/battery (all OEM). Now that I have found the corroded harness at the front it no longer does the dimming but still runs like crap (I'm suspecting the harness).
 

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Have you gone through your ground connections? Because almost all of our ground points are aluminum, they tend to get very corroded on a regular basis. One other thing, The whole 150 degrees thing is screaming crank or cam sensor. Crank is usually the guilty culprit. It is consistent with almost all of your symptoms... Not unheard of to get a bad electrical component right out of the box...
 

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Discussion Starter #7
CKP looked good and same for CPS. I recently pulled it apart again once I had the head vacuum tested and to make sure the cylinder walls/ring gap were good. Everything checked out but just for giggles I replaced the CKP and CPS (I now have duplicates of everything on this bike), valve cover, all gaskets, plugs, swapped coil packs around, timing chain, guides, and cam chain tensioner. The bike acts no different now than when I had problems with it in 2013. It will pull hard to redline but has a lot of vibration and runs bad when hot as if cylinders aren't firing (this includes bucking/surging when at a constant lower speed). When I plug the Power Commander up it begins the surging/bucking and is not ridable unless the rpm is over 3500.
 

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Hmmm, Could this be a timing issue? I'm not sure how smart the '02 ECU is, but, here's an out there theory for ya. Bad temp sender to the ECU, ECU thinks it's over heating, throwing into a "limp" mode. I really don't think that system is that sophisticated, but... The automotive industry has had this "feature" since the 90's...
 

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Discussion Starter #9
Timing has been gone through multiple times and had new parts multiple times (new cam chain, tensioner, cams, CKP, CPS, and ECM). If it were timing it most likely wouldn't start let along go up to redline. My temp sensor has me at 180 unless in traffic then up to 200-220 (fans on by that point). I have had other bikes go into limp mode and this one doesn't do it.
 

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Discussion Starter #10
Update as of yesterday:

-Crank position sensor resistance is 217. Suzuki says 70-220 ohms. Can someone check theirs to see what a normal CKP is, I am worried that with the high resistance then adding engine heat it might be the cause of all the issues as Spyder13 stated even though I replaced it (used one).

-Coil packs are 14v ish across all 4 during cold temps but once the bike gets hot the battery goes from 14.2/3 to 14.5/7 and the coil packs go to 14.22.

-Found a burnt pin in the speed harness up front but no change one cleaned. The speedo needle and display still doesn't work.

-Going to pull the entire harness today or tomorrow.

Any suggestions would be great.
 

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Had the same issue in regards to the speedo on the 05 im working on. Turned out to be the orange wire with blue tracer in the harness coming from the speedo back to the main harness.
Concentrate on that wire when you unravel the outer shrink wrap you might find the problem in the wire or the pin connection at the flat clear connector to main.
(not sure if your wiring will be the same color dont have a manual for that model, but it may be.)
 

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I'm a tad confused by some of what I've read here. I hope this helps instead of adding to the confusion. This is derived mainly from the 1000's. But there should be lots of commonality with 600/750.

The tachometer lead from the ECM to the cluster is Y/Bl (yellow with blue tracer) on all that I'm aware of. The big connector in the fairing is the first place to look. After that, check the contacts at the cluster connector and at the ECM. If you've been racing it, you may have removed an ECM lead like that for the EXCVA. If you didn't plug the empty hole, moisture can condense inside the connector and badly corrode the pins & contacts. So take a look. But if there was corrosion there, you'd generally have many other problems. If your multimeter will measure frequency, you can check the Y/Bl lead while the engine is running. 1000 RPM is 17 Hz. No guarantee but I seem to recall that it's a square wave that jumps between 0 and 12 V.

The speedometer and odometer get their information from the speed sensor. The leads at the sensor connector are B/R (12 V supplied by the cluster), B/W (ground), and P (the sensor signal to the cluster, it's B between the connector and the sensor). The B/R and P run through the big connector to the cluster. So there could be problems at the speed sensor connector, the big connector, or the cluster connector. Obviously the various wires can also be failing if the wire bundles were scuffed. The service manual shows how to test the sensor.

You could also open up the cluster case and look for corrosion.
 

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Discussion Starter #14
I will have to keep searching for the wire that's causing the trouble.... more on that later.

Here is where I am with the engine trouble:

I had the airbox off and decided to cover each individual throttle body with my hand. Cylinders 3 and 4 almost choke the bike out, and cylinder 2 comes close but not as much suction. Cylinder 1 has almost no effect as if there is a vacuum problem. I had a machine shop vacuum the head for leaks and they said it was good. I have completed many compression test all of which indicated good rings but will attempt a couple more just because I'm losing my mind. The throttle body vacuum lines appear to be clean and good. When I put the head back on I did a valve adjustment with the correct set of feeler gauges. Anyone have a clue where it could be pulling air from? It definitely sucked my hand to the top of the throttle body but it didn't choke the engine.
 

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Have you checked the throttle body synchronization?
 

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Discussion Starter #16
No I have never had one done or done one myself even though it seems like a simple process. I have spare throttle bodies and since I don't have the sync tool I could try swapping them out. I did notice something strange with mine. If I role the throttle forward it lowers the idle and tries to kill the bike. What I found was that the mount on the TB where the cables attach (brass) was/is bending and seems to allow the butterfly's to close more. How strange is that. Could a throttle sync impact the bike that much especially when it runs much much rougher at hot temps? Each header pipe seems to be heating up at the same rate and all 4 plugs look the same but are a little blacker than I would like. more of a dry black than a wet black. (PC3 is disconnected)
 

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Sync is really only important at or near idle. Anything much more and the small difference in throttle plate position is not important. Unfortunately for troubleshooting purposes, intake leaks act about the same way.

Just swapping in another throttle body is really not the best idea as you don't know whether they are synced after you put them on.

It's crude but you can use the hand on the throttle body method to sync them also. It is not real accurate but my guess is that your bike is pretty far off.

You can also look at how much each throttle plate is physically open. That may give you an answer also.

Check the connection mechanism between the throttle bodies and make sure nothing is loose or missing there.

Getting a slight idle change by pulling the throttle back is not very unusual but I wonder if the #1 throttle plate is totally closed and the idle speed stop screw is not even touching the arm.
 

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Discussion Starter #18
When I move the butterflies they all appear to be perfect which is why I have never synced them. I have had the motor out 3 times and the TBs off more times than I can remember. I will look at the screws and their position. I don't remember any weird positioning though.

For vacuum I would think, rings (well I have done multiple compression test), valves (I had a machine shop pull vacuum on them and check the straightness), then I checked the valve clearance before putting the valve cover on and changed out the shims as appropriate per the service manual. That would leave spark plug crush washers, TBs, and valve cover gaskets?
 

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Spray some TB cleaner around the intake manifolds while it's running. Have you taken the rubber intake manifolds of lately? I had a lot of corrosion where they clamp to the head once. Was chasing an idle issue for a whole season before thinking of pulling those bastards off...
 

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Discussion Starter #20
Intake boots are clean and clear. I swapped/cleaned them when I swapped the heads, and also sprayed carb cleaner around all of them to check for leaks (no leaks). I have been chasing a vacuum problem this whole time and its affecting the bike at all rpms. If I keep my palm on the top of the #1 TB the bike has a pop every 1.5 secs exact.
 
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