Hi all. Looking for recommendations for a dyno centre who would be up to the task of setting up my GK73A SP. Ideally Yorkshire / North. It's back together and running but i guessed the jetting and it needs some work, very hesistant between 8 and 9k in taller gears and seems slightly flatter up top than it used to.

Thanks

What spec is the bike and what jets do you have? Any dyno centre can do the 73a but it takes time/money to change jets at the dyno centre because of labour to faff around with the air box etc.
Best to get it as near as you can yourself if you are able to, as they're quite tricky to tune if not in std form.

moforockband wrote:What spec is the bike and what jets do you have? Any dyno centre can do the 73a but it takes time/money to change jets at the dyno centre because of labour to faff around with the air box etc.
Best to get it as near as you can yourself if you are able to, as they're quite tricky to tune if not in std form.

It's got SP airbox and 4-1 (straight through can), non SP carb bodies so no bungs (SP bodies were butchered). SP needles and tubes, 105 mains. Carbs have had all seals done and been unracked to fit in ultrasonic bath.

If you have fitted non sp carbs you will have gone from 33mm to 32mm, not a huge difference. It may hamper top end very slightly, and it may even improve low mid range running due to higher air speeds.
105 mains may be too small for the 4-1, and you may have to richen slightly. Mine does run very lean on WOT through the mid range but then richens out on top. You may find say a 110/115 dynojet main jet will get you the results. Mind though that the snorkel in the air filter (do you have it fitted) will match the 105 main jet on the original set-up.

My spec;
'89 GK73a sp (60 hp ish at rear wheel dynojet dyno)
RC98 S+B pod filters
Stainless 4-1 with yoshi can.
std 33mm carbs with 120 Dynojet mains. needles on richest clip.