It was really nice to see some noob JTKMs practising at Clay on Friday who were either first or second time out but, in the damp conditions, spinning was inevitable and I found myself becoming the Push Start Guardian for the morning. I didn’t mind, it’s a JTKM Dad rite of passage 😉 Each time I helped a Dad get their lad going, I’d look around to see him on the floor as his lad drove off(!) so here are my tips on how to start and direct drive engine without tasting the tarmac…
Firstly, it’s documented in way more detail than I will offer on Karting1.co.uk in their post ‘How to Bump Start a Kart‘. I’ll just summarise the basics and the golden rule:
In your pit bay, you need to properly prime the carb. To do so:
- Disconnect the short piece of fuel hose from the small overflow tank
- Disconnect the long piece of fuel hose from the carb
- Blow into the short hose until fuel runs out of the long hose (that is connected to the fuel tank but no longer connected to the carb)
- Reconnect the long hose to the carb
- Remove your spark plug (but leave it in the spark plug cap and sat on top of the engine to avoid any potential for electrical damage)
- Remove your airbox
- Cover the carb with your hand and rock the engine-side rear wheel back and forth to draw fuel into the carb until you feel the fuel on the hand covering the carb
- Your preparation work is done – you’ve done your bit to ensure that there is minimal air in the system. Optionally, you are ready to fire up the engine with a handheld starter if you seek additional piece of mind. Obviously, you want to replace the spark plug before doing so (and you will find that you will leave it out and you will look daft when you try starting your driver – it’s just one of those noob things!).
Now push is going to come to shove, quite literally so with the kart on the grid…
- Get the driver to lean forward (it helps lessen the mass you’ll be lifting)
- Hold the rear bumper in the right hand (which will be doing most of the lifting)
- Hold the back of the seat with the left hand (which won’t be doing much lifting)
- Lift the kart – you don’t need to lift very high, in fact the lower the better
- GOLDEN RULE: LOOK UP, NEVER LOOK DOWN!!!
- Run as fast as you can for 5-10 yards
- Drop the kart down
- Keep pushing until it picks up. Driver will need to feather the throttle pedal until the engine starts to pick before accelerating away.
An engine with a properly primed carb should not require ‘choking‘ but an unwilling engine can be helped by the driver placing their hand over the airbox trumpet momentarily to increase the fuel to air ratio. Do this too much and you will flood the engine!
There is one other tip that I found helped us greatly (when we bought the kart it took a long run to get going and, after this tweak, it took a matter of yards). It’s a little more technical so please seek expert advice if you are unsure!
You can help yourself by ensuring that your carb butterfly is slightly open so that, when you hold it up to the light, you can just see daylight around the outside of the butterfly. This is the butterfly:
It is adjusted by the idle adjust screw as illustrated on p27 of Tal-Ko’s BT82 Parts and Drawings Guide. It’s worth emphasising that inappropriate changes to carbs can be seriously damaging to your wealth! Again, if in any doubt, please ask a more experienced TKM mechanic.
Hope this helps!