TS 185 ignition in the twin pipe head f--k!

[090]

So we have a TS185 ignition on the twin pipe. Put a tdc mark on flywheel and case. Found 3mm btdc for firing mark.  Roughly put backing plate where I thought it should be. Started it up and put the timing light on it...shit! thats very close. Take it for a run and its either detonating or pinging, mainly around the pilot area. Played with the timing and have found that I can turn the backing plate up to 50mm and it will still run (maybe more). Usually 20mm or so means the difference between running and not.Would the ts ignition spark more than once during a revolution? She starts rattling when at operating temperature. It has a different piston and rod so the compression could be up to shit . I have put one extra head gasket on so far and am going to put another on to see if that helps. Jets are big and I tried a bigger pilot and it blubbered. Any ideas with any of this??? The bike seems to run well even with major differences in position of backing plate.

[DR]

Brad not knowing diddly squat about ignitions I can tell you the '78 and later TS185 fires at about 16° BTDC at 1000rpm advancing to 20-21° BTDC at 6000rpm and the earlier models fire at 16° BTDC at 1000rpm advancing to around 24° at 6000rpm.

3° sounds rather detonating it's not running backwards is it? kiddin'

[090]

I have set it so that it is basically 3mm btdc at full advance, seeing that they dont have advance with the original points.

[Bamford#69]

Hi
Just a thought , Is the flywheel running in the right direction , to allow for the advance/retard mechanism to operate as it would on a TS 185? , do you put the flywheel on backwards with the trigger /source coils in the ignition  cover or are they mounted in the crankcase?

[090]

The ignition is running the same way as its on the other side(RH) and is inside out so windings are in the outer cover.

[Bamford#69]

Hi
Be careful not to  chase your ignition problem through your Carb, in particular changing/leaning off your main jet, if you have a 32mm carb, keep a 260 main in it til get rid of the pinging, if its pinging in the pilot jet range, (30/35 is a safe start,), check,check,check your ignition, oh yes TWENTY to ONE (20:1)  fuel/oil ratio.

[JohnnyO]

So that means the flywheel is now spinning in the opposite direction to a TS185. Does that matter?

[090]

I have put a 34 with big jets in it. 45 and 260main. Making sure of that. Had the 32 on with a 35 and 200 which i thought was too small. I am trying to do one thing at a time. I just put another head gasket on this arvo and seemed to be better. Ran out of light so I will try again.

So that means the flywheel is now spinning in the opposite direction to a TS185. Does that matter?

No its running the same way. If you imagine pushing the flywheel through the motor to the other side , then putting the stator inside of the flywheel from the outside. That is how its mounted.

[Bamford#69]

Hi,
I don't know about the TS185, does the TS  motor (not the flywheel) run in the same direction as the CZ ?
IE; backward or forward?

[090]

Both go in the same direction. It is advancing the right way as I had a timing light on it to watch the advance .

[brent j]

I chased jets on my XT500 and found a similar thing, ie detonation just off idle, at very low throttle openings.

A bigger pilot caused it to run rich at idle but still had a detonation problem. I increased the needle jet size and kept a small pilot. The pilot has most effect at idle and this effect reduces up to about 1/4 throttle (or a bit less I can't quite remember). This is where the needle jet is taking over.
Cured my problem.

I think you may need to change things a fair bit as the new ignition is going to give the engine different characteristics to the old one.
With the XT I needed to jet differently for points or CDI or drastically different when I ran an ATOM ignition module.
My two cents worth anyway

Brent

PS just realised, are you running a Mikuni?

[090]

Yes Mikuni. I will put that on the list thanks. I will give it a go.

[Nathan S]

Interesting way of dealing with the 'flywheel spinning in the wrong direction' problem, Brad - I wish I'd thought of that!

Are you sure that the flywheel is exactly the same depth inside the stator coils? I don't know that it could be the source of your problem, but it seems possible that if the flywheel isn't properly engaged, you could end up with a 'fuzzy' timing point. Although, I guess that would be easy to see if you've had the timing light on it.

Also, your compression ratio theory sounds like it might have some merit. I put the wrong head on my AT1 once. Went great for about a lap, then pinged its head off once everything was up to temp. I didn't bother trying different jets in it, but richening it up on the mixture screw and needle made absolutely zero difference.

[brent j]

To add a bit to Nathan's post.
When the other Brent up here built his YZ250G he had similar problems to you. It turns out someone had shaved the head and it was only when he picked up a NOS head we noticed the difference, correct comp and it ran like a charm.

Another two cents worth.....................................

[Lozza]

The 3mm BTDC maybe very different timing from the CZ to the TS. I can tell if I had the stroke and rod length.Using the TS figures Doc quotes your looking at 1.38mm BTDC(16deg) at 6000 and 2.59mm(22deg) @ 6000. Which is a long way shy of your 3mm figure.
What's the head volume?
Doing a plug chop at the det zone and posting a pic of the plug and the piston crown will speak volumes.
Oh yes I do like the novel inside out solution for RH stators. 2 thumbs up from me