I was always into the Aircoled RD’s of that era as a youngster but many of my mates had GT250’s
The two things that stick in my mind were the kick start is on the wrong side and I could never master that, and they rattle like a good’un even when new.
If it’s got a quiet engine there’s something wrong with it…lol;)
Lovely bikes though and almost capable of the magic ton in stock trim, despite all the stories to the contrary;)
Im amazed you found one, would have thought they all died donkeys years ago. Passed my test on a GT250 in 1980 and did alot of riding on that machine.
Reliable, great gearbox and good fun, handled ok too and I can still remember kick starting that two stroke into action and zipping about on it. I traded up to a BMW R100RS after a couple of years which was nowhere near as much fun.
if the owner has fitted K&N filters the carbs will need sorting out and this is likely what he is hinting to because since fitting them the mixture is all wrong and now it likely doesnt run very well.
If you fit different air intakes to any two stroke the fuel air mixture will be changed, this will affect the performance of any highly strung 2 stroke…likely the heads will need taking off to check if the pistons have a hole developing, if the mixture or timing is wrong they can and do burn a hole in the piston. Very common…(taking the heads of is easy of course)…if its a 77 it likely does not have the ram air system…think it was about 76 when Suzuki decided it didnt work and they dropped it. Makes taking the heads off easier too…
Basic rule of thumb is if you fit a free flowing air filter, ie K&N’s you will need to up jet the engine, change the needle position and maybe even chnage the oil pump or fuel oil mix if done manually… to achieve the right tickover and make it run right from then on is pure trial and error unless someone else has done it already…what you will likley do is make an already thirsty bike even more thirsty and with very little performance improvement, and you may even ruin the performance. Thre is a lot of work that you can do to a 2 stroke but I dont recomend doing it and the gt250 has no history of being heavily modded so there are no stats to play with…ie no one before you has made all the mistakes already…
If you can take it back to standard it will run cleaner, better, longer…standard exhausts as well if possible but a good set of expansion chambers will improve performance on standard carbs with a couple of jet size increases…if they are properly designed but it is unlikley that you want to pay upwards of 600 quid for a good set of pipes…get originals and there will be some about.
If its a project you can go many ways but if you want to drift from original I would focus on the frame. I would get the engine as original as possible, maybe with expansion chambers but then work on the body and mechanicals susch as, change the front forks from a later model bike, find a swing arm that fits it and change that and get new springs for the rear…maybe change the bars and the seat…or place it in an rg250 frame and have a real hybrid…
Oh one last thing the front disc brakes dont work very well so be very careful, you will have to learn rear wheel braking techniques…
with 32bhp its not ultra fast compared to modern bikes but is relatively light and with the handling sorted can be a lot of fun…and a lot safer than a 175bhp 1 litre sports bike…just for comparison an rgv 250…four generations on (x7,rg250, rgv250) has 65bhp …double the gt250…how technology moves…
ooh forgotto say that i also have a few spares, mostly for the gt380 and 550 but some parts are non model specific from the 70’s so let me know if you need any bits…and no i dont have the original air box but watch ebay and keep an eye out for the bits…
