Timing without dial gauge

[Farmingstock]

Is it possible to check timing without a dial gauge?

Got a 94 KTM SX 250 and it’s sneezing and popping back when trying to start, my foot is black from trying to kick it over.

It has a HPI ignition on it and as far as I’m aware it should be 2mm before TDC and on the second big line on the stator, only issue I can’t accurately measure TDC (well 2mm before) I have bought 3 different dial gauges and neither fit, so they have all been sent back! I would need to cut some off the stem to make fit or take the engine out completely! Either way, before I order another would there be any other reason for the sneezing and hard not starting/kick back? Carb is definitely clean!!!

[Pete.]

You don't need a dial gauge you just need something to screw into the plug hole to act as a dead stop for the piston. An old spark plug with the guts knocked out and a piece of dowel inserted in the hole would do it. Turn the engine forwards (gently by hand) until the piston hits the stop, mark the flywheel next to the timing mark. Now turn it backwards until it again hits the stop and mark the flywheel again. TDC is right in the middle between the marks. If the marks are too far apart shorten the dowel until they are close enough for you to mark the mid-point accurately. If you get them 4mm apart then one mark is your timing point.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[stinkwheel]

One of these?
https://www.feked.com/tdc-timing-tool.html?srsltid=AfmBOop3ZueUd1auaAB_QbiPJ2sETMWnc_URKxet61vI5rhu6awSVxh8

Or use it to find TDC (or with a dead stop tool as per Pete.s post) then use a degree wheel on the end of the crank and strobe it.

mmBTDC is a bad way to get the timing point anyway. It's just giving you static timing and most electronic ignitions have an advance curve, so the firing point will change according to revs. Some even have an extra retarded timing point at very low revs for easy starting.

I was having real trouble getting my enfield to run properly on an aftermarket electronic ignition. I'd got it set up bang on (it even had a vernier scale on the back plate for setting the degrees BTDC). When it strobed it, the timing was all over the place. I put the points and mechanical ignitin advance back on and the problem went away.

Or go old-school and just try retarding it a bit at a time until it starts easily.

Is the timing even adjustable? Most modern bikes I've worked on have it keyed in making measuring the ignition timing a bit of a moot point.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Farmingstock]

This is how they are, it’s not a woodruff crank with this ignition on, just tighten down, I’ve watched several yt videos but they all use a micrometer!

[Farmingstock]

Just checked the timing again and it looks spot on, the last time the bike started it was almost forcing fuel out of the carb like pressure was coming out of the inlet, I’ve checked the reeds and carb both clean and fine!

Now the bike won’t start my foot is in agony from kicking it over, the bike is kicking back to which is dangerous! I definitely think it’s timing related, however it seems very close to perfect and makes no difference if I adjust slightly.

When kicking over it’ll just cough/sneeze and a cloud of smoke will come out near the barrel, definitely looks like timing is out but I’ve don’t what was suggested and it looks spot on, the flywheel hasn’t moved, it has spark it’s not thick blue, but it’s a racing plug and was the same when it was running fine!

[stinkwheel]

Sounds like the behaviour of an engine that's 180 or 360 degrees out. I presume it's a lost spark?

Has it actually run with this setup?
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Farmingstock]

I’ve taken everything ignition related off the bike, checked everything as good as I can, refitted and the bike has fired up perfectly! I don’t know what I have done, everything has gone back on exactly the same way as it came off and I haven’t changed anything as far as figment, timing back in the same pen marks don’t know what I’ve done, I think I’ll mark the nut on the crank with tip ex just to make sure that doesn’t move[/code]

[stinkwheel]

Tightening down a rotor onto a plain taper can be tricky without something rotating out of position in the process. No easy way to hold the crank stillI'd guess this is what happened. It's why manufacturers use woodroffe keys.

My electrex one was like that (fits to the crank with a tapered collet). You needed to somehow hold the crank and rotor still and in the same position as you tightened down the central bolt. Either could try to turn as the bolt gripped either the rotor face or crank thread. I landed up seating it on the taper with a mallet then jamming up the primary gears with a piece of folded denim to stop the crank rotating, THEN holding the rotor still with a big spanner while I tightened down the central bolt.

You should still strobe it. Dynamic timing is the only way to be sure.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Fizzer Thou]

KTMs are notoriously bad for fitting dodgy spark plug caps that are cheap and not up to the job.Indeed,on the KTM UK Forum quite a few people said that they would carry a pocket full of them to fit as and when they experienced an ignition problem.Taking this into account I fitted an Iridium NGK spark plug and a new plug cap from the same people and not had any problems since.Friends with other versions from KTM have since done the same and appear to have found the right combination and now run a more reliable ignition.
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Just talk bikes.What else is there?

Always have a 'Plan B'

[Farmingstock]

I thought the issue had gone away but it hasn’t!

There has been no change at all to the timing, the marks are in exactly the same place, yet the timing is off again!

It’s mechanically in exactly the same place, I bought the tool to measure tdc and it’s exactly the same as before, timing is exactly the same as before, however the timing is now off, I don’t know if the aftermarket HPI cdi is faulty but the physical timing is in exactly the same place, however the bike is kicking back and the timing is off!

[Farmingstock]

Any other advice guys?

The bike started fine, ran for a little while then turned it off, went to start it again and it nearly broke my foot with the kick back! It just feels wrong kicking over.

The timing is in exactly the same place as when it was running, the stator readings are fine according to manufacturer, the plug is new, the coil is new year the timing just seams off sporadically!

Could this happen with a faulty ecu? It’s an aftermarket HPI ignition CDI, I have contacted them and they said they can only test CDI in the workshop.

Any other ideas? I build the bike up, think it’s fine then it does it again!

[stinkwheel]

Try retarding it a touch? Could be trying to start backwards?

I had a look at the kit. It has a built-in advance curve. It's very retarded up to about 500rpm, then it advances sharply by 10 degrees, then climbs andother 5 degrees then gradually drops as revs increase.
https://www.hpi.be/curves/068_curve_1c_068_full.png

The initial retarding is to assist starting and prevent kick-backs. If you're passing into the advance as you're starting, it probably would kick back violently. Might be an issue with the CDI programming which, as they say, can only really be checked at the factory. Could be if you're really giving it some welly, you push it over into the advance (if it gets two pulses, 0.12 seconds apart, it'll advance)?

Maybe try kicking it over more sedately? Or a gentle "priming" kick first so it's powered up and all functioning before it's being asked to start the bike?
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Pete.]

It's obviously triggering inthe wrong place. Going off Stinky's post above i wonder if it's picking up random trigger events that makes the cdi think it's spinning faster and thus applying full advance when kicking over.

Check the wiring and if there's a facility open the gap on the trigger a little.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Farmingstock]

Tried adjusting the timing both ways but still the same, tried kicking over as explained but still the same, was looking at a timing light? Is there a way to check timing using one?

[stinkwheel]

It looks like you have built-in degree marks for setting up the rotor so that makes things easier.

The timing light will make the mark on the rotor appear to stop at the point when it produces a spark. What I'd do is put some white paint/tip-ex on the timing mark on the rotor and a dab where that lines up with the 15, 25 and 30 degree points. If the workshop is fairly dark, it'll be easier to see.

At idle, it should be sat somewhere between the 25 and 30 degree marks and should appear to rotate towards the 30 degree mark as you increase revs.

What it wont show you is the fully retarded setting with the motor running (unless you can get it idling below 500rpm). The way I'd approach that is to take the plug out and have it connected to the HT lead and grounded to the head so it can still spark but you have no compression. Then set up the timing light and use an electric drill with a socket attached to spin the crank with the ignition on.

That should show up on the 15 degree mark. If it's showing higher or wandering to a more advanced position, that's your problem.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Farmingstock]

Thank you for the reply’s, can I check the timing with a light if it’s not starting or does it need to be running?

Currently the bike will not start, it has a thick blue spark every revolution, which looks to be at the top of the stroke.

I’ve checked the wiring with the multimeter on beep test and all the same as the spare stator I have, don’t have another CDI to check.

[stinkwheel]

The strobe will flash every time it makes a spark, doesn't have to be running. Although most strobes are powered off the battery these days so if it doesn't have one, you'll need a 12v supply to hook it up to.

I'd imagine there's a minimum revolution speed necessary to create the optical illusion a timing light gives you but I'd guess it's not all that fast, probaly in the hundreds rather than thousands of RPM. Faster than you'd manage to turn it by hand or with the kick start though, electric drill would probably be the way forwards.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Easy-X]

I hear these new fangled "moving pictures" need to show 20 images or more per second for the illusion to work. I'd imaging the strobe needs to run at least that fast
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Farmingstock]

If I take it to bits again, get it started again and use a timing light it shouldn’t move from that point should it? Ie the marking on the flywheel still lines up perfectly with the line on the stator?

This is how it was I marked the stator and flywheel to make sure it hadn’t skipped as there is no woodruff key! Literally started the bike fine. No hard reving etc! Turned off, left to cool, went back and timing is off again! All marks still line up fine, I test tdc and everything exactly how it was! When it’s kicking back and backfiring through on each kick, if I take the plug out it’s soaking wet, like it’s not firing at the right time!

I’m thinking either the crank has snapped and it’s skipping timing but the flywheel is staying in the same place (far fetched as it starts again after being taken apart! OR the CDI is bad and it’s not giving the correct map sporadically!

I’ve not got a dial gauge to check timing just the pen one! Can’t find a dial gauge that’ll fit without taking the engine out completely

[stinkwheel]

Your last post confused me a bit.

So to be clear, your static timing isn't moving? You set it up, it starts and runs fine. Then when you go back to it it's kicking back and refusing to start? But when you check the position of the rotor relative to TDC, it is correct?

If it was being caused by a snapped crank (I've seen it happen on a mates turbo Z650) the rotor would be out of position compared to TDC. Likewise if the rotor had spun on the crank taper.

So if that's all ok, you come down to electronic advance curve or a sensor/signal issue.

The plunger TDC gauge will put you in the right ballpark. A dial guage would be more for fine tuning but you wont be more than a couple of degrees out using the plunger type. Even if you just use it to find TDC and put a mark on the rotor then check to see if it lines up in the same place afterwards.

I think strobing it is a good idea. It's about the only other thing you can do in the home workshop. I had an issue with the electronic ignition on my bullet and when I strobed it, the firing point was wandering all over the place. I put the points back on it.

[Farmingstock]

Stinkwheel yes sounds wrong but everything was set up and the bike started fine, turned off everything is marked the same, same place, same everything but won’t start and just back fires and kicks back, loads of fuel in cylinder!

Taken everything off ignition related again now, however everytime I put it all back together it starts fine, then the next time I go to start it it’s not right!

It’s very strange!

[Farmingstock]

Rewired it, re-timed it everything is tight and it starts and runs perfectly! Will have to try again tomorrow! As it has done this before then just stops working!

Checked it with strobe as the picture shows.