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2015 V Star 950, 2013 Suzuki S40, 1967 Yamaha YSC1, 2022 KTM 690 SMC-R
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Discussion Starter · #1 ·
I have a 2015 950 with Ivans tune. It runs and idles fine, but I notice when coming to a stop when I fully release the throttle and squeeze the clutch, the RPMs bog down so much that the engine is on the verge of shutting off. Is this a common issue?
 

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2015 V Star 950, 2013 Suzuki S40, 1967 Yamaha YSC1, 2022 KTM 690 SMC-R
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Discussion Starter · #4 ·
^ Good question, I almost never use neutral. But when it just starts and idles in neutral or in gear, it runs just fine, its the immediate off throttle RPM drop once the bike is nice and warm that seems to be excessive.
 

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It also how Ivan has idle set on the flash and throttle off fuel setting. I would call him and have him look in his records, another thing is run some seafoam , you my have a little build up not giving you enough fuel in throttle off.
 
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i don't have Ivan's, but i experienced something similar out of nowhere a couple years back for a minute. my '09 950 would actually die if i let the RPMs drop too low. bike was around 80k miles at the time i think. pretty sure it was bad gas or buildup as @Jspree suggested because it just kind of cleared up on its own. i may have put in some seafoam as well.
 

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2015 V Star 950, 2013 Suzuki S40, 1967 Yamaha YSC1, 2022 KTM 690 SMC-R
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Discussion Starter · #8 ·
Ok, so I don't ride the 950 too often, but now with the colder weather I'll be riding it a lot more since its got the most wind deflection vs my other bikes. I took it for a long ride to a job site 70 miles out, and did some testing on the road. Doesn't matter what speed - squeeze the clutch and let go of the throttle and the RPM drops so low that the engine shuts off every other time, if not 2 out of 3 times. If it doesn't die, after a few seconds of running too low the RPMs gradually rise up to normal range. I'll call Ivan to ask if he can assist.

The only mods are Ivans flash and Cobra intake, no exhaust mods.

Ivan said to check the TPS, the voltage at idle should be .67 to .68V
 

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2015 V Star 950, 2013 Suzuki S40, 1967 Yamaha YSC1, 2022 KTM 690 SMC-R
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Discussion Starter · #9 ·
Its been raining for 5 days straight, so I wasn't able to do anything, except when it stopped this afternoon for a couple hours. I pulled the bike out to mess with the TPS. According to the manual, there are two parameters on the TPS - voltage adjustment, and resistance.

The voltage is adjustable by spinning the TPS with volt meter attached to it to set the voltage between .067 and .073 volts with the ignition on. That is not a simple task as the plug is on top of the TPS, right under the tank. But I see the TPS is set right in the middle from the factory, with a paint mark over it, so I don't think it's out of adjustment.

The second parameter is resistance, which must be 3.08-5.72 kΩ, and if it's out of range, then the TPS needs replacing. I removed the TPS, and hooked it up to my multimeter, and it was showing 0 resistance, once in a while fluctuating up to .50, to .75, and even up to 1.00, but mostly stuck at 0. Unless there is something wrong with my multimeter, the TPS is certainly faulty.
 

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Discussion Starter · #11 ·
Got a new multimeter today, tested the resistance and its well within spec at 4.17kΩ. There is no easy way to test the voltage, I'll have to come up with some sort of leads tomorrow and try and test it.
 

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Discussion Starter · #12 ·
So I was trying to cheat and adjust the throttle cable to where the throttle would stay slightly open, but this doesn't seem to be an option. I can adjust the cable where it is very tight with no slack at all, but it doesn't start to turn the throttle plate. I need to play with it and see if I can do this cheat on the throttle body side.

However, I just read in the manual that spart plugs require replacement ever 8000 miles or every 12 months. My bike is a 2015, I bought it in the summer of 2020 with under 1,000 miles. I have no idea if the original owner ever replaced the spark plugs, but right now the bike has 6k miles, I've never replaced the spark plugs. Do they really need replacement every year? Could they be contributing to my low idle?
 
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