Hey guys. I'm new to this forum, so I hope I'm posting correctly and such... Pretty cool site you all have going on here btw... Recently picked up a Suzuki GT250 1974 and am currently getting it ready for an MOT (Service check nessesary for insurance) after its been stored away for many many years (it has gone 30.000km). I got it fixed up and also took off the carbs for a good clean (only done this a few times before, so i far from an expert, or know what issues to keep an eye out for). I got it started (It fires up on the first kick, with the choke) but here is the problem . It fires up to a ridiculously high rpm, then slowly drops down a bit 4000-5000 rpm. Once warm I remove the choke and it falls to about 2000rpm where it flutters up and down quite a bit. If i adjust the idle setting any lower, to say 1500, it dies. If I give it a tiny bit of throttle, its revs up but comes down slow. If i give it a lot of throttle and release immediately, it revs up to red zone on its own, hangs there for far too long and drops back down slowly. It is as if there is an invisible hand holding the throttle open, despite the fact the throttle handle having returned to its original position. Now if i get on and ride it, when i bring it to a stop it wants to die immediately. I have to keep my hand on the throttle and hold it at 2000rpm to stop it from cutting out. If i try and ride it like a "normal" bike it would rev up like an airplane getting ready for take off, and I would probably be embedded in the side of a building somewhere. I am open to suggestions and possibles fixes. Any ideas would be much appreciated.
Hi Xeqter. Are your cables free, not binding at the splitter/joiner (where the one cable splits into two) as this sometimes causes similar to what you describe. Also look at sticking slides or air leaks around the intake rubbers.
Same as Murdo...welcome and give those carbs a good clean while you're checking there are no leaks around the boots.
Hey guys, thanks for the replies and the welcome There are not any (obvious) leaks, as i sprayed the outside with carb cleaner and there were no jolts in the rpm. As far as i can tell and feel the cable does not bind. It has been given ample amounts wd40 as well since that was my initial thought. The carbs were given a good clean and were not that dirty to start off with. With regard to the sliders, i will have to take off the airbox and check that. Will update on that as soon as i have had the chance Thanks
I concur with Murdo on this one as it happened to me on my GT250X7. When you remove the tank there very little room to spare as you have a wiring loom and of course your throttle cable with splitter. Mine became jammed on a metal tag attached to the frame, can't tell you how much damage was done, give it a quick check just to be sure. Also, welcome to the forum.
Loving the support and feedback guys... How about this approach? -Pull the tank and check the sliders for response and synchronization. (What am i looking for in response? an immediate smack down of the sliders upon release?) -Check the cables. -Replace the tank and leave the filter off and see if I still have the same response and sync. (That should be able to rule out the tank jamming the cable, right? Had a mate suggest the sliders may be worn out causing the symptoms i am experiencing, is that possible? Hope that is not the case cuz that would mean complete carbs and sliders replacement :/ However the sliders dont look anything like the sliders that show up when googling worn sliders.
I was about to suggest looking at the slides, make sure they are clean, from memory there is a brass screw that can be removed from the carby that shows the alignment mark for the carby at idle, make sure that is set !!!
Hey Kiffsta, thanks for the hint... i have uploaded an explosion diagram of the carb, it would be a great help if you could point me in the right direction. These carbs are kinda new to me.
Ok... bad upload. hope its ok to put up a link instead. http://www.suzuki-gt.co.uk/images/Reference Library/122 GT250KLMABC.pdf Page 48 "Fig. 8 Carburator (GT250K,L)
correction, the brass screw removes to set the oil pump, the idle is set from the screws on top of the cap, this is the plug I was referring to:
Apart from the obvious cable issues that have been mentioned. Ignition timing first. Too much advance can hole a piston very quickly on a two stroke. Clean the points, gap them and use a dial gauge to set the piston position. I have always used a cigarette rice paper to determine 'opening'. Two strokes are very, very sensitive to ignition timing and mixture. I would not even turn the ignition on without setting the ignition timing first. This is what a genuine spark plug hole dial gauge looks like. The piston position is determined with one of these. Nothing else is acceptable. The other thing that may be occurring is that the crankcase seals may be on the way out. That can lead to 'dieseling'. When this occurs turning off the ignition has no effect. It will just run until it has no fuel. cheers Blair
