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'80 Bajaj chetak, '05 LML
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'80 Bajaj chetak, '05 LML
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Hi all, hoping that someone can help out.

I'm running a vespa super 150 but have swapped out the points and flywheel for electronic ignition. Everything else about the motor is stock.

I have timing set at 22 degrees, the original setting for a super 150. It runs ok but pings at high revs, especially under load.

My question is, should the timing still be 22 degrees with the CDI, or does it need to be retarded a few degrees?

Later p engines that came in either points and electronic versions seem to have different timing settings depending on the system used. So this got me thinking......

Cheers
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Molto Verboso
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Re: stock points timing vs timing with CDI
Warhorse wrote:
Hi all, hoping that someone can help out.

I'm running a vespa super 150 but have swapped out the points and flywheel for electronic ignition. Everything else about the motor is stock.

I have timing set at 22 degrees, the original setting for a super 150. It runs ok but pings at high revs, especially under load.

My question is, should the timing still be 22 degrees with the CDI, or does it need to be retarded a few degrees?

Later p engines that came in either points and electronic versions seem to have different timing settings depending on the system used. So this got me thinking......

Cheers
Hi,
First, I thought the CDI's function was to replace the stock points only. It that's the case, then, pre-ignition is caused by something else. Unless, the instructions suggest a different timing setting. In any event, re-check the timing, or retard one degree and re-check. Another thought, check the head for excessive carbon build-up?
Good Luck!
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The timing spec of 22 degrees was from a day when leaded fuel was the norm. Try 19-20 degrees and see how it does.
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"worlds 2nd fastest"74'super 150 . 79'p177x ,1983 lml 150, 2007aprilia sxv 450.
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"worlds 2nd fastest"74'super 150 . 79'p177x ,1983 lml 150, 2007aprilia sxv 450.
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points of interest
i have the "worlds fastest 1974 vespa super 150"....i have the original 6 volt points system... i have my spark advance set for 18degrees btdc...as i understand it... if your motor is tuned ...that is to say... bigger transfers...bigger intake port... less squish...higher compression...bigger carb ...all together resulting in more air fuel mixture to be ignited in the combustion chamber....then, you would need to retard the ignition timming... OR, the big load of air fuel mixture ,igniting too early, would hinder the piston,too much, in its travel to tdc,so much so,that it might blow a hole in the piston top,...or some similar type of event...(or at least cause pinging)?
now this does not answer your question... sorry for that,
i dont have an electronic ignition...but, dont electronic ignitions change advance spark timming as rpms increase?...or is it points, that lengthen timming opening? because as rpm increases ,the higher rpms, defeat the springs ability to follow its flywheel's cam lobe accurately, ?....okay now i am confused...
let this be a lesson to you!...the internet is full of idiots...
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There are some CDI systems that change the advance based on RPM but most don't. most the time the advantage of CDI is only a faster voltage rise (allowing a folded plug to still work) and eliminating point bounce at high RPM.

So on a stock engine points or CDI set to the same timing will perform about the same.
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1974 Rally 200, 1974 Rally 200 with sidecar, Vespacross bike
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Points ignition systems take longer to deliver full spark energy. When you switch to electronic you can't run the same timing because the energy will be delivered faster and cause pinging. We are only talking fractions of seconds but it's true. P150X points 21 BTDC and same engine with electronic 18 BTDC. Same difference for yours 22 points and 19 electronic. This also applies to the people who install performance cylinders to points bikes. A Sprint V with points ignition and a Malossi 166. Malossi calls for 18 BTDC but that is based on electronic ignition, if you run points run 21. I know people will want to dispute this but I have set up alot of bikes and this info comes from an old school tuner who used to race dirt bikes in the late 70's and when they made changes like that they had to adapt timing numbers between points and electronic ignitions. The gas we have also plays a roll but those milliseconds make a bigger difference. This is also why an unmodified DR177 when bolted to a P150X points bike runs stock timing and when it's bolted to a P150E electronic ignition bike also runs stock timing even thou the stock timing numbers are different. I have experimented a great bit with this including running points on a stock P200 engine and we ended up at 26 BTDC to get the feel and the temperature it had with electronic ignition.
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Molto Verboso
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Mattgyver wrote:
Points ignition systems take longer to deliver full spark energy. When you switch to electronic you can't run the same timing because the energy will be delivered faster and cause pinging. We are only talking fractions of seconds but it's true. P150X points 21 BTDC and same engine with electronic 18 BTDC. Same difference for yours 22 points and 19 electronic. This also applies to the people who install performance cylinders to points bikes. A Sprint V with points ignition and a Malossi 166. Malossi calls for 18 BTDC but that is based on electronic ignition, if you run points run 21. I know people will want to dispute this but I have set up alot of bikes and this info comes from an old school tuner who used to race dirt bikes in the late 70's and when they made changes like that they had to adapt timing numbers between points and electronic ignitions. The gas we have also plays a roll but those milliseconds make a bigger difference. This is also why an unmodified DR177 when bolted to a P150X points bike runs stock timing and when it's bolted to a P150E electronic ignition bike also runs stock timing even thou the stock timing numbers are different. I have experimented a great bit with this including running points on a stock P200 engine and we ended up at 26 BTDC to get the feel and the temperature it had with electronic ignition.
Hi,
Being new to the whole two stroke theme (I'm more performance SBF V8 oriented), I find your reasoning interesting as learned through experience. Of particular interest, is the whole temperature scenario, as timing and fuel AFR can have a big affect on head temperatures. In advancing the timing, as you are suggesting when going to "CDI"from "points", would not the head temps have to monitored closely? If so, where is the line drawn on head temps?
I'm not judging nor being critical, so much, as "picking your brain".
Happy Trails!
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I have a Super 150 with Scoot_RS's 12v CDI upgrade kit. I run it at 18 degrees BTDC with no problems whatsoever. I also just picked it up from a tuner who was port matching my DR177 kit and he agreed it should be set at 18.

Check out Scooterhelp's page about the A and IT marks on a flywheel for electronic ignition:
http://scooterhelp.com/tips/timing/electric.timing.html
Quote:
PX200, PX150 & PX125: The image on the left is a flywheel shared by the all these models. It has a mark on the flywheel casing labelled 'A' (23 BTDC for the 200cc model) and 'IT' (18 BTDC for the 125 and 150cc models) which should align with a casting on the flywheel (blue arrow) at the correct degrees BTDC. These flywheels are easily identifiable as they do not have an inspection hole with a rubber grommet.
The P150s and a PX150 which were both contact breaker have a BTDC of 21, while the PX150E switched to electronic ignition and had 18 BTDC, again according to Scooterhelp. Your barrel will be a little different than theirs with a bit less displacement, but -- especially if you have a very late model Super from '78 or '79 -- you may actually share some common parts with a very early P150 series.

My '78 Super, for instance, had a 3 port case and a P150s cylinder head.
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Thanks all, Your replies are much appreciated. I'll retard a couple of degrees and see how that goes.

The more I work on my scooter, the more I realise it is not an exact science. It seems that a lot of the more detailed set up comes down to 'feel' and experience.

Phaetn - I've been following your posts while rebuilding mine as our rides seem to have a bit in common,. I'm running the same cdi system, and I'm also running a 150 super trying to push 10" wheels. Mines only a stock 2 port with original gearing, so it struggles a bit in 4th. Do you have the original gearing for 8" or did you swap it out to suit 10"? I may have to kit mine to make 4th more useful and get a better top speed. 80kph is the best I can get so far, but maybe the timing change will help.

Cheers
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'78 Super 150 Mk II ported DR177, banded clutch, ASC Big Bore
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Personally I'm *much* happier with the 10" wheels for handling and got tubeless rims with Michelin S1s installed. Day and night compared to the 8" Michelin S83s that I had a few years ago. Even though it's not original and some purists don't like it, I'd never go back to 8" as I use the scoot as a daily commuter during riding season. I like the bigger brakes, too.

To answer your question: I kept the original gearing. Supers with 10" wheels end up having very similar (if not identical) gear ratios as early 200s but don't have the displacement and grunt to use it to best effect. It means they cruise well at a lower RPM for a given speed compared to 8" wheels but definitely give up acceleration and don't have the power when in top gear to get up to top speed.

Definitely 4th is an issue. That's why I've gone in search of torque rather than horsepower. I stayed away from high-revving kits as I wanted something that would work down low in 4th and hit a sweet-spot cruising in 3rd rather than struggling.

As of last year, with my DR177, ASC big bore exhaust, Si20/20 carb with heart mod and de-blued I could cruise all day at 80-85km/h. I could go higher if I needed to but never go on a freeway so there isn't the opportunity on my commute to go faster.

Two or so years ago -- before the DR177 kit (i.e. with a 145cc setup but three ports rather than your two) I once had it up to 90+km/h for an extended period but then soft seized it when backing off for a red light. I don't think that would happen with the DR177 now and it could easily do that speed, I'm sure. I'll report back later when I've got the engine back in and running after the port-matching and inlet-enlarging that I just had done.

Do you know if you have a 3 port or 2 port case? That would affect what kit to get...

Scooterhelp's gearing calculator shows a max speed of 103km/h at 6,000 RPM using:

A 22/67 primary drive gear combination
A 150 Super standard gearbox
A 3.50 x 10 rear tire size

That's assuming you've got the power to get there and compares to a max of 88km/h at 6,000 RPM with 8" wheels...
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'80 Bajaj chetak, '05 LML
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UTC quote
Just for the record....I changed the timing from 22 back to 19 degrees and it runs MUCH better than before.

oopsclunkthud, Mattgyver - Your expert advice is much appreciated.
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