Throttle Body Tuning

Originally Posted by Craig380

It's a RIGHT pain in the backside to get to. I managed to avoid dismantling by turning mine using a pair of LONG tweezers, I was just able to get enough grip to turn the screw a couple of degrees at a time.

As I mentioned above, the adjustment is very sensitive, you won't need to turn the screw more than 45 degrees. Even a 30-degree turn might do it. The fast idle cam only needs to move the main throttle plates a tiny amount to give the correct idle speed.

Grrrr, tantalisingly close with my long nosed sparky’s pliers. Close, but no cigar!

The whole mechanism needs a good clean on my bike, so I’ll take the air box off and do it properly in the next couple of weeks.

Many thanks for your help, it looks quite straightforward once I sort out the access.

Addendum: I suppose I’m slightly looking for a problem that may not be there! The K6 starts easily and ticks over from cold - just not exactly the way the good book tells us it should. I could just ignore it and enjoy riding the bike a bit (and it is good fun)


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Originally Posted by Craig380

It's a RIGHT pain in the backside to get to. I managed to avoid dismantling by turning mine using a pair of LONG tweezers, I was just able to get enough grip to turn the screw a couple of degrees at a time.

As I mentioned above, the adjustment is very sensitive, you won't need to turn the screw more than 45 degrees. Even a 30-degree turn might do it. The fast idle cam only needs to move the main throttle plates a tiny amount to give the correct idle speed.

Success at last! This morn I tried a bendy screwdriver like this:



There was just room to insert it between the steering head and air box with the tank raised:



And then (this was a fiddly bit, be patient) guide it into the fast idle adjustment screw using another long screwdriver so it slides into the slots:



Once engaged it was quite easy to move the screw in 1/8 of a turn at a time - starting the engine to check each time - until the cold tick over speed was up to 1800 RPM.


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An addendum: I started my K6 from cold this afternoon, it now ticks over at 2000 RPM from cold with no throttle and settles down to 1300 RPM from about 25C - and stays there - just about perfect, thank you for the advice Craig380.

Also Sarries won the European Cup again, all in all a pretty good day


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[Craig380]

If only all fixes were that easy

Originally Posted by Craig380

If only all fixes were that easy

Yes indeed, but credit to you: this just proves one should try the easiest (and cheapest) fixes first.

I’m nothing but impressed with my 134,000 mile K6 - with a bit of fettling everything works


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One last post to round off this thread. Adjusting the fast idle so that it works absolutely as Suzuki had intended 13 years ago has been bizarrely satisfying. I don’t think the engine has run as it does now for many years (it was a commuter bike, as long as it started and ran that was fine). Now I get a puerile satisfaction when I press the starter with no throttle, it fires on the first turn and ticks over perfectly at 2000 RPM before settling down to 1300 as it warms up.

I’ve borrowed a very capable manometer (well, actually 4 of them in a nice case) to balance the throttle bodies, so I’ll probably do that little job next week. I’ll give the area between the cylinders a bit of a clean up with Screwfix degreaser at the same time, which will also be quite satisfying.

AO.


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[R1ffR4ff]

I think you've done great work bringing the bike back to good condition and I wouldn't be surprised if you get at least 200,000 miles out of the engine

Properly balanced fuel bodies/carbs should be the icing-on-the-cake

and get you the power and fuel returns the bike deserves.

Originally Posted by R1ffR4ff

I think you've done great work bringing the bike back to good condition and I wouldn't be surprised if you get at least 200,000 miles out of the engine



Properly balanced fuel bodies/carbs should be the icing-on-the-cake



and get you the power and fuel returns the bike deserves.

Thank you.
I’ll balance the throttles next week.
Best wishes,
AO


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