Reply To: GT250 EFI DSpec Stalls at Idle after Warm Up
Hi Joe,
Thank you for the update. I followed your instructions and checked out my ISC valve. I removed ISC from the airbox and turned ignition “ON”, it unscrewed itself completely and flung the parts because of the spring pressure. I put it all back together and re-installed it.
fyi, According to a Hyosung tech on Facebook, our bikes have one TPS on the ‘front’ throttle body if you look in between the two throttle bodies. It indirectly reads both TBs because the second TB is supposed to be synced to the first TB from factory (bad design but that is how it is). I zeroed out (closed) both the throttle bodies and started the bike (based off of ISC only). It started and idled rough, did not respond well to throttle. Then I bypassed the ISC temporarily, by blocking off the two vacuum tubes, to make the bike idle and respond to throttle based off of throttle body settings only (like it was before I found out the ISC bypass). With the front throttle body closed and rear throttle body slightly open, seems like we’re back in sync (or close to it) the bike idled well and responded to throttle like it should (I should just leave it here and enjoy the riding season, but curiosity is a bitch).
At this point, I lock the TB settings right there and introduce the ISC back into it. The bike starts, revs high for a few seconds and then settles down around 1600 rpm. Now I’m riding it normally, with some occasional sputtering/bogging when taking off from lights. It does not stall, idles well and I am givin’ her the beans.
Next plan is to finalize and fine tune the TB sync using a manometer (using a T-fitting with ISC vac lines) and checking ISC operation on/off throttle (I think my ISC is not responding fast enough when I go on throttle and try to take off).
Hope this helps!
Regarding your question about the fuel filters for our pumps, there are brand new replacements available on Ebay, that can be installed without replacing the pump. Check link below: https://www.ebay.com/itm/161494487889?fits=Make%3AHyosung&itmmeta=01HW3FJGZVNMV5P4P6M7RAW72A&hash=item2599d25351:g:3rUAAOSwDthiIWeq&itmprp=enc%3AAQAJAAAA0BLOBSeT%2BNNUM73lPj14WcgjCK%2BSphXINUci%2Fk8kwybi6TS9DAc%2BFkD8v8%2BjoXn9sNSyUnU7ntfpPPoKuOI7VkPbXzMBH%2BqrtXMQvrMZZ%2B%2Fof7QFWBFu1bnMQ%2BRWKian%2Fj3F6Yi1dQ8fjzg%2Fz32wmAP3HhJovy1fgjsc8r%2BGKtRJ4DR%2Ba%2FD3XAVCjopjY8mshXcGjzEHOcErST2oceAkzllwFcuLDwD65ARkU0dWcAMJ44hJfkuTHMGyMJpZob8Def6H6ljpQkiqW0kP2psfYdE%3D%7Ctkp%3ABk9SR4SQyu_gYw