Point-Seven-five wrote:Not sure how to do it on a fuel injected engine. 

In days past we tuned with plug readings and timed test runs, changing carburetor jets, ignition timing, and spark plugs.

chris846 wrote:With the airbox & exhaust mods you've got, you should still be able to get the bike to run just fine with everything as standard. That's what you should aim for to start with - if it isn't running properly don't rush into thinking you need to 'tune' it to cope with your mods. It's much more likely to be a 'normal' problem that a K can encounter. This approach (and the guys on this forum, naturally) will help you troubleshoot anything you come across.

Once you've got it running 'normal', then you can explore the various tweaks.

Easy does it eh?

(And then we'll talk about swapping your crank for a lighter one - 1.2Kg makes a lovely difference!)

MartinW wrote: First check and adjust the valves, and check the compression and spark plugs. All the 2v Bricks have a built in check system to check your mixture. With the idle set to run at 1000 RPM press the green starter button. The revs should either rise slightly or stay the same, if it rises significantly or the engine dies the mixture needs adjusting. This is done with a 5mm Allen key through a rubber plug covered hole in the RH top corner of the airbox. This can be done by either using an exhaust gas analyser or the lean drop method. The balance between the throttle bodies can be checked with either an off the shelf 4 gauge manometer or home made version. I've never had to adjust the timing. Never play with the throttle body screws covered with the blue paint.
Regards Martin.

92KK 84WW Olaf wrote:If you have removed the right hand side box have you have also removed the air flow meter [MAF]??

Have you swapped out the original K Bosch system [Jetronic LE]?

Its outside my area of knowledge but as far as I know you can't have one without the other.

chris846 wrote:Ref. post 7, we could be at crossed purposes, if the bike won't idle then I'd be looking at such things as the breather pipe leak already mentioned, or leaks around the rubber throttle body/cylinder adaptors if they've been removed and replaced during the rebuild - they go hard and in my experience they won't seal without RTV where they mate to the cylinder head. I wouldn't be twiddling the AFM bypass screw until I knew that everything else was okay - there'd be no point and you'd just be adding to the list of 'things-I've-disturbed'. Likewise the brass bypass screws in the throttle bodies, although you can use these to fault find: with the engine running on a closed throttle, carefully wind them in (counting the turns!) and then back out again. If this doesn't alter the tickover, then you've got an air leak - either the rubber adaptor, or the throttle plate (somebody's been at the blue-painted screws!).

MartinW wrote:You should find the adjustment screw for 5mm Allen key on the top RH corner of the MAF.
Regards Martin.

chris846 wrote:I modified a K100 similarly to you - binned the air filter housing (the 'right-hand box') and left the AFM out in the breeze with a cone filter stuck on its end. My exhaust was the standard headers into a collector and a straight through silencer. Your bike should run and tickover just fine with similar mods.

Yes, you might have some room for fine-tuning the AFM to get an ideal mixture at tickover, but it should still run and tickover with the setting it was previously on.

The adjustment screw in the AFM is a simple bypass/bleed screw - it allows a small amount of air to bypass the flapper vane, which turns the potentiometer and informs the ECU how much fuel to inject. The flapper vane itself still opens on tickover and allows metered air into the engine - so opening(unscrewing) the bypass screw just adds unmetered air to the mix and so weakens the mixture. It is a very minor effect, only noticeable at tickover and just off tickover. Once the throttles are open and the engine is drawing in two thousand revs worth of air, the small amount of unmetered air flowing via the AFM bypass screw is immaterial in comparison.

The brass screws on the throttle bodies work in a similar way - they allow a small amount of air to bypass the throttle plates. This is what allows the bike to breathe enough to tickover, when the throttles are closed. The brass bypass screws are important because, with the best engineering in the world, the throttle plates leak a tiny amount of mixture, each by differing amounts. Bear in mind that a throttle is just that - when that engine is ticking over you are strangling it almost to death - it's sucking air in from wherever it can get it. The brass screws are used to balance the air flows in the individual throttles, which is necessary for an even tickover. Their effect is lost almost as soon as the throttles are open, even a small amount.

The blue-painted link screws between the throttles are a very different story - they keep the throttles flowing even amounts of mixture up to around 1/3 throttle, after that, their effect diminishes. They have the biggest effect on clean, smooth running at part throttle.

Hope that helps.

chris846 wrote:I was trying to say the opposite - I don't think your exhaust is the reason for it running on two/three cylinders.

Check sparks.

Check injectors - whip the fuel rail off and position the nozzles to squirt onto kitchen roll. Hit the starter for a couple of cranks and the damp circles should be the same size - remember you are playing with petrol!

If okay, see if it starts to run more evenly as you crack open the throttle. This could indicate an air leak.

- I'm assuming that you haven't altered the bypass screws from prior to the rebuild?

chris846 wrote:That seems to make a case for it being the exhaust, but my own experience says otherwise. Maybe try back to back exhaust swaps - that should be fairly easy?

chris846 wrote:The AFM bypass screw and the brass bypass screws have nowhere near enough effect to richen the mixture throughout the range. There's postings about resetting the potentiometer inside the AFM, and another way is to overpressure the fuel delivery with an adjustable FPR. I've done both, but I do have a wideband Lambda and gauge fitted so's I can see what's happening. 

I still run the bike on standard settings.

If I were in your garage now, having done what you've already done with swapping back to the standard can, I'd still do a straight back to back swap to convince myself.

MartinW wrote:What happens when you press the green start button with it idling at 1000 RPM. What do the plugs look like.
Regards Martin.

MartinW wrote:Read post #3.
Regards Martin.

MartinW wrote:For the test to work the idle has to be set at 1000RPM or over or the starter motor will engage. The green button once over 1000RPM enriches the mixture. The 5mm screw adjusts the mixture. When pressed the revs should stay the same or rise very slightly.
Regards Martin.

MartinW wrote:For the test to work the idle has to be set at 1000RPM or over or the starter motor will engage. The green button once over 1000RPM enriches the mixture. The 5mm screw adjusts the mixture. When pressed the revs should stay the same or rise very slightly.
Regards Martin.

RicK G wrote:

MartinW wrote:For the test to work the idle has to be set at 1000RPM or over or the starter motor will engage. The green button once over 1000RPM enriches the mixture. The 5mm screw adjusts the mixture. When pressed the revs should stay the same or rise very slightly.
Regards Martin.

To make things quite clear here it is actually 711RPM when the ICU prevents the starter motor turning by removing the earth from the start relay.
The enrichment is controlled by the ECU and will enrich the mixture for ease of starting while the button is pressed.

MartinW wrote:First thing you should buy or download is a manual. These are available on this site on the download page. The idle adjustment screw is approximately in the middle of the throttle body linkages near the throttle cable. But if you check the available and downloadable manual on site it will clarify your situation. Warning unless you like headaches don't mess with the screws with the blue paint on them.
Regards Martin.

DBRMN wrote:

You won't have much luck with the wool. Putting a washer in the end of the pipe would be much better and you can tune it by rotating the angle. IMHO your bike will run better with more torque if you have back pressure

https://www.tabperformance.com/Reduce-Back-Pressure-Exhaust-s/203.htm

Glenn

That sounds like it's going to get a lot more complicated. If it is a question of simply a lack of back pressure I've heard that some wire wool shoved in the silencer would create a bit of back pressure, so I'm going to try it when I get round to starting it. 

Your talking bout a side by side comparison aren't you, yeah I think thats a good idea. It would never hurt to try the old exhaust as a control variable.

I'm currently waiting till I finish my coolant overflow tank, cause the bike doesn't have coolant in at the moment. But straight after that is this, so I thought I'd get my research in early.

glennpm wrote:

DBRMN wrote:

You won't have much luck with the wool. Putting a washer in the end of the pipe would be much better and you can tune it by rotating the angle. IMHO your bike will run better with more torque if you have back pressure

https://www.tabperformance.com/Reduce-Back-Pressure-Exhaust-s/203.htm

Glenn

That sounds like it's going to get a lot more complicated. If it is a question of simply a lack of back pressure I've heard that some wire wool shoved in the silencer would create a bit of back pressure, so I'm going to try it when I get round to starting it. 

Your talking bout a side by side comparison aren't you, yeah I think thats a good idea. It would never hurt to try the old exhaust as a control variable.

I'm currently waiting till I finish my coolant overflow tank, cause the bike doesn't have coolant in at the moment. But straight after that is this, so I thought I'd get my research in early.

Point-Seven-five wrote:My experience with steel wool is that it gets blown out in the first 2-3 miles.

DBRMN wrote:

Point-Seven-five wrote:My experience with steel wool is that it gets blown out in the first 2-3 miles.

really? how much did you put in? how dense etc.

DBRMN wrote:

Point-Seven-five wrote:My experience with steel wool is that it gets blown out in the first 2-3 miles.

really? how much did you put in? how dense etc.

glennpm wrote:Hi,

I had another idea this morning for a temporary baffle for testing that wouldn't require drilling a hole.

Take a piece of sheet metal and cut a strip about equal to half the exhaust pipe outlet diameter. The strip should perhaps be about 75 to 100mm long. Bend this in the middle of the 75mm to make a V shape. The open part of the V should be greater than the exhaust outlet and the gauge of the sheet metal stiff enough so the V bend will not bend with finger force. The legs of the V should be inserted into the pipe and if your angle of the V is not too large or too small, pushing into the ID of the pipe will hold it in place. Push it in so the V is close to the end or sticking out a little bit.

I was going to add about silencer packing and how it works but Chris846 just did it well.

Glenn

glennpm wrote:
Sure, quick pattern made out of cardboard. Make the open end of the V large enough so when you slip it in the pipe, it has some grip on the inside.

glennpm wrote:Good!

I think the 1mm would work. If it bends too easy when you go to insert it, you'll know that you'll have to go with 1.5mm instead and certainly no thicker than that.