I have an independent motorcycle repair shop and rebuild multi-carb sets all the time. However, I believe that at this point, I need a bit more information.
We currently have a 2006 GS500F with 4263 miles on the odometer in our shop that's giving us some troubles. Initially it was brought in because the owner had been deployed for three (3) years and the bike wouldn't crank over. After using a shop battery to spin the engine over, we used starting fluid and straight race gas to see if we could get the bike running. it fired up and ran, but poorly. We check the inside of the tank and it was clean. We checked and replaced all of the fuel lines from the tank to the distribution valve, then to the carbs as they were rotted and falling apart. We pulled the carbs and completely disassembled them; Hand cleaned with carb cleaner, air & wire strands thru all of the passages; Cleaned the jets, then set everything in our ultrasonic cleaner tank. When done, we rinsed the carbs in hot water, blew thru all of the passages again with carb cleaner and air a final time. We reassembled the carbs with new float needle valves and reinstalled the TPS where it was when we disassembled the carbs.
During our test ride, that's when we noticed that the RPMs would not go above 5000 RPM in 4th, 5th & 6th gears. First and second gears climbed to only about 8000 RPM and 3rd gear struggled to get to 6500 RPM.
We pulled the carbs twice ore and inspected everything, including the float height specs - all was good. I began suspecting the TPS as the culprit. However, unlike other Suzuki models that have an LCD odometer display where codes can be viewed and the TPS can be set, the GS500F has an analog odometer and no LCD display, nor a diagnostic plug to use in checking sensors and setting the TPS. The other issue, we have the Suzuki factory repair manual for the GS500F, but the book shows two (2) pin-out checks for resistance. The Ohm1 test gives a range 3.5-6.5k Ohms; the Ohm2 test gives 2.66-4.94k Ohms.
Performing the test on the original TPS, the Ohm1 test had a fixed OL reading and the Ohm2 test was .8-2.7k Ohms. That was the best reading that could be obtained in any mounting adjustment location. A new OEM replacement was purchased; Dry testing showed a fixed Ohm1 result of 4.9k Ohms with NO variation; The Ohm2 test got results of .7-6.4k Ohms. Installed on the carb set, the Ohm1 test resulted as previous, while the best Ohm2 test result was 1.6-4.6k Ohms.
The bike performed a bit better with the replacement TPS, but not much.
I don't believe that we missed anything, so I'd like some feedback from a very qualified Suzuki tech knowledgeable in this particular situation.
Thanks for putting up with my rather lengthy first post.
Quote from: MadnessMC on June 24, 2017, 06:06:33 AM
During our test ride, that's when we noticed that the RPMs would not go above 5000 RPM in 4th, 5th & 6th gears. First and second gears climbed to only about 8000 RPM and 3rd gear struggled to get to 6500 RPM.
I only read that line. The rest of the TPS and this and that its all BS Suzuki threw at the bike cos we were getting too good at fixing their idiotic carbs.
That above is a dead give away sign that you have a tiny little rip in the diaphragm that lifts the slide. Under that top.
I'd look for daylight in both of em. One you can barely see will do this exactly.
Cool.
Buddha.
There is a factory procedure for setting the TPS.
Has it been followed?......to the letter?
I don't have access to the write up with me and it will be several days before I can replicate it. From memory the WOT resistance needs to be EXACTLY 76% of the resistance at idle. The exact figures don't matter, its the difference between the two that does. Search the forum for TPS, and the various threads it turns up, you may find something of value to you.
Also the ecu is influenced by the selected gear, a signal is sent back to the ecu when 1st or 2nd is selected via the neutral switch, this is another area area to investigate and check