Idle Screws

KTM 2 Stroke/Keihin PWK – Easy Adjust Idle Screws

Finally a proper idle adjustment screw for your 2 stroke KTM that can be turned by hand – even with gloves on.

Used & endorsed by multiple winners of the Scottish Expert Enduro championship – Richard Hay & Derek Little who have both very kindly allowed me to quote them:

Derek Little:

“1st impressions are that it’s really useful and well made. I thought it was basically a screwdriver to adjust the existing screw, but quickly realised it was to replace it. Works very well and is easy to adjust with gloves on etc.

I was riding at the weekend with a few pals and 2 of them had jetting issues, which the quick adjust would have made much easier. The standard plastic screw is very easy to round off and almost impossible to turn by hand, so this is a definite improvement. The air screw and idle jet make such a big difference to bottom end performance that its worth paying a bit of time and attention to sort it out. This tool makes that job much easier.

It will also let everyone know you take jetting seriously and you’ve spent a few quid on some bling that works.”

Richard Hay:

“It’s dead simple and just works. To start with I was a bit sceptical, normally I set the bike up and that is that! However after fitting the screw I have found it quite handy. I quite often like a higher tickover on special tests to stop you dropping the revs too much so now its easy.

It also makes it easy when the temperature changes to do some tweaking. The million dollar question is would I buy on and the honest answer would have to be it depends on the price. it isn’t going to make you go quicker, jump higher or turn faster…. But it does save you raking in your toolbox for a screwdriver, sometimes when you really don’t want to be.”

Why do you need one?

1. Warming up

Engine idle speed varies as the bike heats up to normal operating temperature. If the idle speed is correct when fully heated up it’ll be lower when the bike is warming up causing it to run poorly or stall.

Simply start the bike from cold, turn the idle screw in by 4 flats (360 degrees) & leave it to warm up quicker & smoother on its higher idle. When you’re ready to ride turn the screw back 4 flats to return it to its original idle speed. This is easily done with gloves on & takes seconds.

2. Altitude changes

2 strokes are very sensitive to climate & temperature changes & even one big hill climb can alter the way a bike runs. You can compensate for this by raising the idle speed so that the bike doesn’t constantly cut out but without the hassle of digging out a screwdriver every time, this job literally takes 2 or 3 seconds with the Easy Adjust Idle Screw.

3. Normal riding

The climate conditions can change from day to day so your bike can be running spot on one week & not so good the next. This can cause the bike to not idle high enough & cut out on tick over. The last thing you want to do is stop to dig out a screw driver. Again a 2 second job with the Easy Adjust Idle Screw. I know some ‘experts’ re-jet their bike for every outing but I’m sure I’m not the only one who does this twice a year for summer & winter.

3. Racing

Top racers often like to increase the tickover on special tests to reduce any chance of the bike cutting out, now its a quick easy job.

CNC precision manufactured to the highest ISO 9001 standards in the UK by highly qualified senior engineers using high grade aluminium & can be fitted in seconds using the standard spring, just apply a spot of copper grease on the threads.

One modification we have made has been to the spring seat, we found that some bikes were running with the standard idle screws so far in that the spring was almost coil-bound, especially in colder temperatures, so we have moved it 1mm further out to allow for this. This doesn’t affect bikes that don’t have this problem as the spring has plenty of travel.

Apparently the original M5 plastic idle screw from the Keihin PWK carburettor (KTM part number 54631219100) has been fitted to the vast majority of 2 stroke KTM’s since around 1996 but please check for yourself before ordering.

We have found that some of the smaller PWK carbs (under 36mm) have the fuel inlet pipe in a different position which does not allow this idle screw to fit. Please compare your carb to the one in the picture to check this before ordering. We have an alternative now available, please email for details.

You also find certain ages of Japanese motocross bikes have the same carburettors fitted. I’m fairly sure if it’s a Keihin PWK it’ll be the same idle screw but if in doubt just ask.

Available in polished alloy or a choice of 6 anodised colours to co-ordinate with your bike.

Please email me at or phone me on 07775 603320 if you wish to place an order or require any more information.


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