1980 Series 1 Jota - BTZ ignition (weak or no spark at all)

S

steve.bennett

New member
Location
burbage village .leicestershire
Original BTZ ignition Nippon- Denso Coils, pick ups,BOSCH -Amplifiers NGK plugs all original system still fitted.
virtually will not start the odd miss fire and eventually wets all 3 plugs. i have removed all 3 plugs connected to the NGK plug caps and earthed to the cylinder head, with no compression resistance and engine turning over faster than normal, sometimes all three spark though it seems weak at times.i have checked the Amplifier connections very good condition no corrosion ,fuse box original all in good condition ,Handel.LL bar kill switch operates no short!Laverda multi-terminal block nose of seat just under the tank all connections firm and no corrosion no bare wires,a good earth strap from the battery,the two ballast resistors nr coils have good firm AMP spade connection.
some advice to point me in the right direction to a fault that may cause this condition via the forum would be appreciated .Mr,steve.Bennett Rejioned member 4269J.
Thankyou.
steve.
 
step number one, lift the seat and look for two wires (very short) coming out of the loom, by only about 40mm and bolting to the frame tag using a a single ring terminal, this is on the right frame rail, tucked away on the underside, the wires can sometime fret on the steel plate holding the majority of the electrics and give a false earth (badly) when the wires have seperated from the terminal, this would give the syptoms you describe.

That single terminal was always a bad idea, because the two wires don't fit in it very well, and if it parts company, you get problems on both the ignition boxes, my cure was to properly extend the wires so that they never get placed under stress, and fit an individual terminal to both wires and then bolt onto the stock frame tag, so.....if one breaks you might have two cylinders still running, or if unlucky only just one.! plenty of ignition system have been replaced with aftermarket ones due only to this very quickly rectified defect.

But then again there are dozens of defects that will cause your difficulties, give it a go its quick and easy

ONE WARNING THOUGH, always be sure the plugs are very carefully earthed when checking things out, one loose plug could spoil the box(s) I use a strip of aluminium drilled and tapped with three 14mm holes and bent at one end for a 6mm bolt to fix it onto an engine case.
CLEM
 
Bad earthing as Clem suggests, but also the wrong combination of Spark plugs with resistance and spark plug connectors with resistance can cause that. else measure what voltage the coils get, check the battery, especially under load (when cranking the engine with the spark plugs in the engine...)

Wett spark plugs can be caused through several causes. the most likely ones are:
-wrong starting procedure (to much choke, non synchronized choke sliders)
-overfloating carbs (float hight to high or non-closing float valves
-way to rich idle setting
-to much resistance on the spark plugs/connectors (only one should have a resistance, plug or connector...)
-Weak spark due to bad earthing
-dito by bad coils.
-dito by bad battery that almost dies once you crank the engine

HTH
 
Check the pickup wiring. It goes brittle with age and can short out intermittently. You can measure the individual pickup resistance and insulation from earth, also voltage, but a careful visual inspection may suffice.

The ballast resistors can be dispensed with too.
 
steve.bennett said:
virtually will not start
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Virtual non starting is OK and shouldn't affect the running of the bike
Actual non starting is a whole other issue. ;)

PS: If you're getting weak spark on all three plugs, then the cause is something common to both ignition channels. That pretty much narrows it down to power supply or earth wiring. There's a dodgy connection somewhere. If you have no clue as to where it is, your only option is to start from one end and work your way through the system. Check and clean every connection from battery through to BTZ boxes and coils (including ignition switch and fuses) then all connections from BTZ boxes to earth.
 
First things first, NEW plugs NGK B8ES. It doesn't matter i.f they look ok, put new ones. It is very common for the btz to be very sensitive to plugs. New plugs usually make it ok for a short while. Plan to upgrade the ignition sooner rather than later.
 
I have the same problem as Steve, contemplating getting rid of the old original coils etc. and replacing the ignition system. with an up to date modern set up. Any ideas for a recomended make and where to get it. I have an 82, 120 Jota if that helps.
 
Ignitech with a Redax Hall effect trigger plate. Since you are UK, Keith Nairn at Laverda Scozia is an agent for Redax kit. He should be able to supply you with the necessary wiring loom too.
Your existing HT coils should be OK - your issue is the original Bosch ignition amplifiers that provide a marginal spark at cranking speed. The coils work fine (assuming they are the original Nippon Denso items) when properly driven by a decent ignition black box.
 
Rob said:
Ignitech with a Redax Hall effect trigger plate. Since you are UK, Keith Nairn at Laverda Scozia is an agent for Redax kit. He should be able to supply you with the necessary wiring loom too.
Your existing HT coils should be OK - your issue is the original Bosch ignition amplifiers that provide a marginal spark at cranking speed. The coils work fine (assuming they are the original Nippon Denso items) when properly driven by a decent ignition black box.
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Thanks Rob, the coils are NDenso sort of a pinky colour ? it also has Bosch ign. Ill ring him tomoz, best to get it done before I ride to Belgium. 🤘 🏴󠁧󠁢󠁷󠁬󠁳󠁿
 
I think they ARE ND coils and are bullit proof, not even Steve McQueen could trash them. The HT lead is replaceable, just a little different to the norm, get back if you need to do that.
CLEM
 
It started on three ish, then dropped to two, now its down to one with the occasional back fire. 42 year old electrics me thinks. cheers GB.
 
Those ND coils are common on many 70's Suzuki, fitted to my bought new in September 1973 ( happy birthday bike ) GT750K, as Clem indicates are robust in construction and service life, the HTH lead needs careful removal process, spike termination at the end of the recess.

Carefully remove the epoxy and outer sleeve, then the inner 7m/m HT lead and replace with plain copper 7m/m HT lead. Ohmic value is 3.3 Ohms primary and around 15K from memory secondary, auto transformer internal connection, ie one secondary end is terminated to one end of the primary, no HT return path via the silicon steel center pole or mounting frame. j
 
"Those ND coils are common on many 70's Suzuki,"

GT380, GT550 and GT750 gives you all three coils for a 120, or the single coil (x3) for the 180 with the twin oulet coil coming from GS1000 and other fours and you get two. From breakers be wary that this far down the line the coils may not be the bomb proof ND type but aftermarket and the breaker might not even know!

CLEM
 
gabow said:
It started on three ish, then dropped to two, now its down to one with the occasional back fire.
Click to expand...
This is nowt to do with the ND coils and everything to do with crumbling old trigger wiring, and/or less than efficient BTZ boxes further hamstrung by the coil supply resistors if still in place. A weak battery/poor connections will further hinder things.
Always worth slinging a new set of plugs at it. If they work, ride it away immediately - don't sit 'warming it up' to avoid cold fouling.
 
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