Series 2 Jota

S

STEPHEN

New member
I am just finishing off a my top end engine rebuild on my series 2 180 Jota and have set the ignition timing up as the book i.e. notch at 'PM' mark

When I start the engine and strobe the rotor, the little notch is at the 'A' mark even at low revs and doesn't appear to advance

It has the correct rotor.

I've haven't checked the centre cylinder yet as I have to mark the rotor

Is it possible the ignition boxes have failed and gone to full advance at low rpm, is this common with the BTZ ignition?

I appreciate the ignition is fundamentally rubbish, but I'd like to start off with the BTZ

Thanks
 
Hi Stephen

So just to clarify - you set TDC how? In other words, how did you know the engine was at TDC ? The marks embossed on the ignition base plate rotate with the plate, so you can't rely on PM being punto massimo (TDC) without using a positive stop/degree wheel or similar. You need to make your own TDC markings as explained in this thread
https://laverdaforum.com/xf/threads/41270/

What revs did you take the motor to? - advance will occur around 2,800rpm or so
 
maybe the pick up coil wires are reversed, common enough and can show what you are describing = certain engine melt down, maybe that is why your top end is/was apart?
you must check the two systems individually, and not just at tickover but to prove that they both advance to the max as well.

tell us why you took the top end off and more details about your ignition set up.

none of this applies to non BTZ systems really.
CLEM
 
Thanks all.
The top end was taken apart because I was setting up the cam timing with degree wheel and dti, then thought I thought there was a bit of oil seepage so put a new head gasket and o rings in.
Then went back on to the valve timing, which took ages (drilled and tapped new holes and filed slots). I set TDC with the degree wheel and positive stop through the plug hole.
I then marked the engine case where the rotor notch was, so I knew true TDC was.
I did rewire the pick ups as the wiring had degraded and I may have reversed the wiring in the plug, which sounds like the problem. I didn't rev the bike as I had too much advance and I had just put it back together.
So, I think I'll flip the wiring over and see what happens
Thanks again
 
Might well be the issue. However, as already suggested: bin the BTZ and get either a Sachse or a DMC. Mine are running on DMC's since 1992 (the Jota, DMC 1.1 with original pickups) and 2000 (1000 SFC, DMC2 with optical sensor). They never missed a beat and I will only exchange the DMC1.1 on the Jota by a DMC 3 now as some issues with the pickup-setup ruined my starter clutch... (not the DMC's fault necessarely, but a coinsidence of it trying to ease out the idle while the pickups seem to have been miss-alligned).

The advantage (aside of the service free ignition timing) is that the advance is a curve and not a switch as on the BTZ, wich springs from late to early all of a sudden around 2.700 or so.
 
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