GT186 revs Question

[Warkton Tornado No.1]

It is a long time since I had a quick blast on a GT186 but I remember being impressed by it's torque & thinking to myself "Short shift"

However, I don't think that is the issue here.

The carburation is probably not far off, but you may need a needle change or it lifting. (Do be aware that changing the atomiser effectively changes the jetting throughout the range, though I am not trying to dispute that suggestion in any way ) I can't recall whether you mentioned having an air filter fitted......

I think the ignition needs adjusting as other's have said. The fact that fuel quality etc has changed, does mean that we need to be aware & compensate, but we can get paranoid to the extent. I was reminded of the fact when WT No2 built a scooter up from scratch after an absence of 30 odd years. Because he had been in a time warp, he set his points ignition @ 21 DBTDC & it runs absolutely beautifully! Mind you, he does use Super Unleaded. The power pick up is smooth & the plug colour text book brown. We only had to dial in the PWK carb a little which was yet another revelation.....

I would suggest you strobe your engine to be about 17 - 19 DBTDC when the engine is @ the kind of revs when you are in the power band but with more to come, if that makes sense?

[Muppet]

you cant strobe a variatronic to high revs the strobe will max 2 sparks every 360 instead of 1; id strobe it at 2000 and set it 23-24 it be around 16 degrees on power

[Hughieboy]

Thanks guys.... mine is currently set at 21 btdc and I could try advancing it. But just one question from someone who doesn’t fully understand... (!).... does advancing it further so it retards back to a ‘normal’ range not kind of negate the so called advantage of having a retarding ignition in the first place, ie so that it runs cooler? I am probably missing something here through ignorance, and to be honest am starting to wish I had bought something other than the Varitronic. The current crank, albeit rebuilt by Harry Barlow and with a 116mm rod and quality bearings is an Li taper, half of me thinks I should bite the bullet and change the crank for a GP type and put a more regular/versatile stator/flywheel/ignition system on.... I’m sure I could flog the existing crank/Varitronic/old Suzuki pistoned kit that was on their previously. Strikes me the Varitronic is maybe not helping my cause?

[Muppet]

theres a few mates of mine that use the variatronic on tuned ts1 gt200 and other fast road scoots with ignition @ 23-24; using 23 degrees it will retard to 15 degrees or less at revs

[EddieStone]

Check the alignment of the pick up coil to the flywheel tangs. If they are out of alignment it won't rev higher than about 6000 rpm. By alignment I mean along the crank axis - in towards the engine, or out towards the flywheel.

It's useful to mark the pickup and tangs with tippex so you can see if they align when the flywheel's on.

[Muppet]

Check the alignment of the pick up coil to the flywheel tangs. If they are out of alignment it won't rev higher than about 6000 rpm. By alignment I mean along the crank axis - in towards the engine, or out towards the flywheel.

It's useful to mark the pickup and tangs with tippex so you can see if they align when the flywheel's on.

if its variatronic no pickup to align it has 4 pole flywheel 4 coils 3 for lighting 1 for ignition

[Warkton Tornado No.1]

Regardless of any variable ignition, I would aim to guesstimate the best advance setting required @ working rev ranges, set it @ that, then anything else just ends up where it will. So, strobing when the engine is coming into it's powerband & again as it's revving out. I doubt whether many road going Lambrettas using pump fuel require any more retard than to 15 DBTDC, but to know this for certain takes a good tuner by the 'seat of their pants' or using a dyno.

One Motoplat ignition that I still have advanced rapidly from zero revs then retarded something like 10 degrees over a Lambretta working rev range.

Better still are the type that do initially advance, then retard & finally start to advance @ the upper rev range to allow over-run.

[Hughieboy]

Thanks fellas.... I think a trip to a Dyno could be in order..... Feeling a little out of my depth to be honest and I don’t want to balls it up......!

[Rich_T]

GT kits should rev much further than that. First try running up the road with out the air filter and see if this improves thing. If it does you need to down jet because of a restriction in the filter (this is common). If not strobe the timing, as several have mentioned, I'm not a fan of variable timing that has no fixed trigger point. If you don't get to the bottom of it get in touch directly.

[Leo]

We have just fitted a AF 52 big bore with he 30mm stinger to his GT186. Its transformed it. Cheap pipe too.

The rest of it is set as below with an Indian Electronic ignition at 18º BTDC

No head gasket Squish set using base gaskets.


Jetting
Main 135
Pilot 53
Float needle 400
Atom AS266
Slide 40
Needle X2

1.25 squish