Slow throttle response on low throttle – GT250Ri
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Bike Model = : GT250Ri
Hello, I have a weird issue which points me into a wrongly set up TPS, but I wanted to post it here in case someone can share some other idea.
When accelerating, especially when already at speed, the first inch of the throttle (not the freeplay) makes the bike drop speed a little bit more than the natural deceleration without throttle, like if it went too lean, and then after a second or so it corrects itself, and it starts accelerating, kind of harshly.
It’s something I guess I could live with, but this makes it uncomfortable when driving at constant speeds at low throttle, since I have to always be correcting for this issue.This slow reaction doesn’t happen if I open the throttle more than an inch or so, like in situations when I want to overtake or accelerate faster, etc.
So, to summarize:
– I get up to speed
– Release the throttle and let the bike slow down
– Want to just maintain low speed so open throttle lightly
– Bike “goes lean” and slows a little bit faster (barely noticeable, but I can feel it) for a second– Bike abruptly accelerates after that second.
– This doesn’t happen when I open the throttle more aggressively -
Hmm in Spain, go find this bottle (this exact bottle) and get 2 of them (yes 2 of them)
https://www.halfords.com/motoring/engine-oils-and-fluids/fuel-and-oil-additives/wynns-formula-gold-petrol-treatment-500ml-166754.htmlDrive with both bottles filled in the tank and also about half a tank of E5 fuel (5% ethanol? here it’s called premium fuel in UK) as the cheap ones (standard fuel) %10+ ethanol is just not good on Hyosungs , although it will run E10 fine but nothing positive for any vehicle using too much ethanol but i am digressing.
Observe her, the idea is to try clean out your entire fuel system critically the pump and the injector. I know myself that when i increase the throttle, the pump gets louder , what if your fuel pump has some kind mini-delay to the throttle response or the injectors are waning ? TPS would be the last thing we check but it is also worth checking to make sure it is in OEM specs with your multi meter as per manual guidance.
If the tank is nearly empty, siphon the fuel out of the tank carefully, and inspect your fuel pump or the fuel strainer being clogged, it gets clogged eventually causing the pump to work harder than it needs to or slightly less pressured fuel going to the injectors.
Least if the 2 bottles get used on the tank, its one less maintenance thing to do knowing you had the bottles try to clean out the fuel parts.
Another tip , spray carb cleaner (be wise! ⚠️🔥) around the intake pipes , so see if there is an air leak (even a tiny bit) , these O-Rings eventually do need replacing to keep things optimal:
Intake Pipe O-RING (Inlet Boot Seals) x2 – GV125 GT125 RX125 GV250 GT250 Hyosung
Also , check your ISCV O-ring on the airbox, like this example below:
GV125s idle speed when hot / ISCV problem (Idle Speed Control)
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I’ll try and find that exact bottle here, but its going to be hard. If not I’ll try with something similar.
My first suspicion going into the tps is because the bike is really low mileage, just 7K km, so having a faulty pump or injectors seem more improbable in this case, but yeah I wont disregard it and will check everything you mentioned, thanks.
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Funily enough, my bike doesn’t have any tps even though it’s and EFI, one less thing to check, I guess. I did find a loose airbox tube to the intake, which I have tightened correctly, and I took the time to change sparkplugs too. The issue seems to have improved, but I don’t know if it’s a placebo or not. Did have the chance to spray brake cleaner to check for leaks since I didn’t have any, but will probably do that, and if I find anythin,g I will check it and if not I will just assume this is the normal harshness o the bike
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Funily enough, my bike doesn’t have any tps even though it’s and EFI, one less thing to check, I guess. I did find a loose airbox tube to the intake, which I have tightened correctly, and I took the time to change sparkplugs too. The issue seems to have improved, but I don’t know if it’s a placebo or not. Did have the chance to spray brake cleaner to check for leaks since I didn’t have any, but will probably do that, and if I find anythin,g I will check it and if not I will just assume this is the normal harshness o the bike
You’re on the right track! 🙂
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