GT650r hard starting

[Michael]

Hello.  I have a 2007 GT650r, and it seems hard to start.  I have a Lithium battery and had it tested, and it’s charged and strong.  The bike cranks over, but starts hard, when it does.  It does, however, usually fire right up if i put a jump starter on it.  I’ve had advice from a Hyo mechanic (semi-retired) and he seemed to think it was carbs not cleaned enough.  Namely the starting circuit/pilots.  I’m leaning towards possibly electrical, because again, if i put on a jump starter, it fires right up.  My reasoning is that if it was the carbs, it would still be hard to start even with the jump.  But i’m open to suggestions that i’m wrong.

Wondering if anyone has any thoughts/ideas/experience with this particular problem.   Possibly be the regulator, or stator?  Or both?

I just want a bike that starts reliably.

Thanks for any help at all.

[Simon]

I’m not a fan of the lithium batteries being fitted to bikes that don’t have them as standard they require a slightly different charging setup, one of the things to check is the coils & if standard the plug caps which at that sort of age can cause all sorts of problems.

[Michael]

Than you Simon.  I’ll take a look at the coils and plug caps.  I know I bought coils, but i can’t remember if i got around to changing them out.  It does run fine once started, it”s just a hard starting bike.  I haven’t had many this hard to start.  I know the Lithium takes different charging rates, but from what I could tell, they do alright in vehicles.  The upside is the lighter weight, smaller size, and increased power density.  But still, I may just get an AGM and see if it’s better.  I appreciate the input!

[tonyw]

Hi Michael,
I have similar problems here in Finland with my 82 year old dads GV650, but only when the engine is warm. A cold start is not an issue at all. I renewed the battery, checked all the wiring for corrosion and changed to a thicker ground cable. New solenoid, rectifier, and even starter motor. Finally I renewed the stator about a year ago. The stator was burned and it finally worked. Now this summer 2025 it has the same symptoms again. It still charges the battery well (about 13,5-14V) and when I crank the bike to start it, the battery’s volts doesn’t sink below 10,5V. This means, what I understand, that the stator and rectifier are OK. Somewhere I read one commenting about Hyosung, that they are where sensitive to wrong valve clearance. I’m now planning to the check the valve adjustment, since I can not find the problem on the electrical side. We have tried many battery’s so I don’t believe it is the battery that causes the problems. I don’t know if this is any help for you, but now you at least know that there are other Hyosung riders battleing with same kind of problems. About the valve adjustment, I guess the clearance might be too big, which makes the valve open a bit too late, which makes the cylinder to keep compression longer and in that way makes cranking the engine more difficult for the starter motor.
Regards, Tony

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