Can't diagnose the problem so don't know what to try and fix

[derbystu]

Hi All - Not sure if this is going in the right section but I've Got a SIL GP200 problem I'm struggling to resolve. It starts and runs ok for 3 or 4 miles then suddenly starts to splutter and won't rev but continues to tickover. I Limp home on slightly more than tickover (max speed about 10 to 15mph) - leave it for about an hour - starts ok and all seems normal again - but after the 3 or 4 mile run the cycle starts all over again.

I have very little mechanical knowledge/skills but on local suppliers advice have so far tried - a new spark plug, a new air filter, a new coil and finally a new carb (replaced the standard Jetex with a similar Scootopia one, which is about the limit of my skill set!) all without success. Not sure what to try next - grateful for any thoughts/suggestions.
Thanks

[MickYork]

check your breather hole in petrol cap is clear...........

[HxPaul]

If you have 12v ignition,the LT coil may be suspected.These coils seem to run ok when their cold,but start to fail as they get hotter.Changing the stator plate is the way to go.
But as in the post above,check your fuel tank cap first.

[derbystu]

Thanks for replies - have tested the fuel tank cap and it seems to be clear, blows through ok. Local supplier suggested stator plate may be the next thing to try - no idea what's involved in changing that, will get Stickys book out again!

[HxPaul]

If you change the stator plate,stamp the mag housing opposite to the pick-ups.Either that or when its fitted use a strobe to get your timing right.

[bsso78]

If it’s not misfiring it’s not electrical.
It sounds like the fuel supply, check the flow rate of the petrol tap.

[Fast n Furious]

Hi All - Not sure if this is going in the right section but I've Got a SIL GP200 problem I'm struggling to resolve. It starts and runs ok for 3 or 4 miles then suddenly starts to splutter and won't rev but continues to tickover. I Limp home on slightly more than tickover (max speed about 10 to 15mph) - leave it for about an hour - starts ok and all seems normal again - but after the 3 or 4 mile run the cycle starts all over again.

I have very little mechanical knowledge/skills but on local suppliers advice have so far tried - a new spark plug, a new air filter, a new coil and finally a new carb (replaced the standard Jetex with a similar Scootopia one, which is about the limit of my skill set!) all without success. Not sure what to try next - grateful for any thoughts/suggestions.
Thanks

One of the classic signs of CDI LT coil failure is that the engine will develop an almost perfect rev limiting feature when it warms up. Your symptoms fit the bill perfectly here.
Suggest that you research LT coil failure posts within the forum to gleam more information on this matter and how to prove / eliminate/ repair it.
The Lukas Cdi conversion route is also worth consideration if you don't wanna take the stator out. This is also well documented on this forum.
Good luck.

[CHRIS in MARGATE]

My first thought would be stator plate failure.
Most likely LT coil.
Ask any roadside recovery teams !

[drivera]

Simplest way to rule out petrol cap is run is without one , if problem still there then not the cap

[Paul_from_Thornbury]

If the stator plate change is beyond your mechanical capability, then replace your CDI with either a LUKAS from Reedspeed or the universal CDI from Anthony Tambs (see Scootronics on FB)
Your CDI will then gain its power from the lighting coils in preference to the LT coil which is a known weak spot.
A by product is it also runs much smoother at lower revs.

It comes with all the necessary instructions, a simple job to do.

[derbystu]

Thanks for the advice.

Took a look at Stickys book on replacing the stator and pretty quickly decided that's beyond me!

Re the CDI - I replaced the old blue CDI unit (which was on the scoot when I bought it) at the back end of last year but that made no difference to the problem (its marked as a MITSUBHI the 4 terminals, one white, one red and two green). I'll now check over my work on the replacement again. I've also just looked at the 12v Junction box and it looks like it needs a tighten up (and a check of the connections), I'll also check the Regulator connections while I'm at it.

I also wondered if it could be the fuel tap - I did replace that about 5 years ago but guess it might be worth trying that again if the above makes no difference.

Will now search the forum for history of similar faults.

Thanks again

[Paul_from_Thornbury]

Regarding your last post on the CDI, changing it will make no difference if the fault is the LT coil on the stator.
The CDI is powered by the Low Tension Coil on the Stator, these are notoriously famed for failing due to the very thin copper wire used on the windings.
The types of CDI you have been recommended to change it to are different in design in that they get their power from the lighting coils on the stator.
Changing your existing CDI from one to another of the same type will not change your fault.
You must use on of the types recommended.

[Paul_from_Thornbury]

https://www.readspeedscooters.com/produ ... o-cdi.html
https://www.ebay.co.uk/itm/Lambretta-El ... 2601470567

[derbystu]

Many thanks for your last reply Paul - Checking out the Readspeed offering it certainly looks very different to the current CDI (with more wires to ponder) and on first reading it seems to suggest it will also do away with need for the Regulator as well? I will get into the info on previous forum postings tonight, send for a new one as recommended and then keep my fingers crossed that the instructions you mention are the "for Dummies" version and really do make it a simple job - I've never been accused of being over confident when it comes to mechanical/electrical problems!


Thanks again

[HxPaul]

You will still need a regulator.

[Paul_from_Thornbury]

yes I must admit I don't understand their comment on the website that 'no additional regulator required'.
yet on the supplied instructions it shows a regulator.

I had the previous LUKAS CDI which developed a fault, and they sent me a Pro version as a replacement. Its still sat on my shelf as that scooter is laid up at the moment so I haven't tried to wire it in yet.

[HxPaul]

I have a readspeed Lukas CDI that I bought in Dec. of 2017.I use an Anthony Tambs external pick-up and I run the CDI from the lighting coils on the regulator,thus cutting out the need for an LT coil on the stator plate.It works ok and if for any reason the external pick-up packs up working I can switch to the LT coil on the stator plate.

[rossclark]

I have a readspeed Lukas CDI that I bought in Dec. of 2017.I use an Anthony Tambs external pick-up and I run the CDI from the lighting coils on the regulator,thus cutting out the need for an LT coil on the stator plate.It works ok and if for any reason the external pick-up packs up working I can switch to the LT coil on the stator plate.

Assuming it hasn't packed up while you weren't looking ...