Trying to get an understanding on ignition systems for GT186...

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Burnside
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Mon Oct 14, 2019 2:10 pm

Hughieboy wrote:
Thu Oct 10, 2019 7:29 pm
Burnside wrote:
Thu Oct 10, 2019 1:24 pm
Hughieboy wrote:
Wed Oct 09, 2019 8:56 pm


I was hoping to get it to pull right through the rev range. Unless I’m mistaken, the preferred timing set up is a static 19 degrees btdc to prevent it hitting its ceiling and sort of ‘four stroking’ at high revs. So by using the Hermes CDI it can be set at static timing (or there are two variable settings) that can be used without the need to set the timing high in the first place. I’m guessing that to get 19 degrees at above 5000 revs, say, I would need to be setting the initial timing at about 27 degrees btdc which seems very high. With the Hermes I could set it at 19 static, or switch it to 5 or 7 degrees advanced before 5000 rpm or 2 degrees below (17 static) if needed for any reason.

It seems like a good compromise to retain the Varitronic system but hopefully make it more suitable for the kit.

Or at least that’s how I read it....
Static timing for the GT kits is 17 degrees BTDC
Is it?

I got this from the Lambretta-images GT set up page...

"All ignition systems must be reliable and timed accurately to 19 degrees BTDC (2mm BTDC with 58mm stroke and 107mm rod), electronic ignition is preferable. Barrel studs & threads must be in good condition. Gear selectors, clutch and chain must also be in good condition. Series 1 & 2 cranks with plain bush small-end bearings must not be used..."

Is there something else I should be looking at?
According to the manual on Eden's website https://lambretta-images.com/granturismo-manual/ it states "Timing set at 17 degrees BTDC". As Richard says above 19 degrees with a box exhaust but you are running with an expansion.

Hughieboy
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Mon Oct 14, 2019 10:02 pm

Yes, I saw that bit in the end.... I’ve set it at 17.... and after all that after reading a few horror or stories I’m thinking I really ought to upgrade the crank... but which one! Never ending.... ;)

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Burnside
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Tue Oct 15, 2019 10:24 am

Richard's GT cranks are pretty good ;)

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coaster
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Wed Oct 16, 2019 10:31 pm

You might be better contacting Richard Taylor via the Grand Tourisimo Face book page. Posting questions on there will illicit answers from Richard or Eden who does most of his product development.

Davidsquaredson
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Tue Oct 22, 2019 1:02 pm

About AC/DC. I'm pleased enough with the following set up I have out it on all 3 of my lambrettas. AC for head and tail light. Scootronics regulator which trickle charges a sealed battery. Off the battery I run LED turn signals, a 120 dB horn, and usb port. You can hide the horn under the floor boards and a solenoid switch in the horn cast so you can still use the standard horn button.

Good luck
DD.

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1974 Rally 200
1965 Li150
1963 TV175
1974 Eibar Jet200

Hughieboy
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Tue Oct 22, 2019 1:40 pm

Thank you. Sounds like a good compromise.

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