Scooterotica

After 2-3000 miles, following original dyno, two of my tuned scooters are running very rich, probably crept up on me. Is this normal?

One of the carbs is open, so I guess dust etc. could wear down needle/atomizer.

It’s not engine related because I have just changed all oil seal and piston rings on TS1,

Many Thanks

Paul

paulnobodyimportant wrote:After 2-3000 miles, following original dyno, two of my tuned scooters are running very rich, probably crept up on me. Is this normal?

One of the carbs is open, so I guess dust etc. could wear down needle/atomizer.

It’s not engine related because I have just changed all oil seal and piston rings on TS1,

Many Thanks

Paul

maybe the settings have changed with all that lambretta rattling

the fuel passing through over time will cause errosion but 2 or 3k is nowt,

i just usually tinker wi the settings and fook it up or change the jets :bigsm: :bigsm: :bigsm: so i wouldnt have a clue how long they are good for

Paul, I've had an atomiser weaR IN A FEW THOUSAND MILES runnin open brass and grime don't work well. Out in a fresh atomiser and what a difference . If you taper a small piece of steel you can use it to measure the bore of an old atomiser against a new one.

Eden, my Monza started suddenly and I have gone through all the checks that you have mentioned and still an issue. (see old thread on LCGB http://www.forums.ilambretta.com/viewto ... 15&t=34929)

So for now it’s parked up in the garage until I can get round to it.

With the TS1, which is what this thread is about, it wasn’t running as rich before I re-built the engine, but really bogs down when I wind it up to full throttle. Funny though, because as well as re-building both engines, the only thing that I have changed is to do the DC conversion using the Wassel box. But I’ve also done the same on a Jet200 and no issues.

Eibar, good answer, for the sake of a few pounds, I think I will try a new needle and atomizer.

But like Boothy_the_makem, I have a feeling that in my haste I may

just tinker wi the settings/jets and fook it up

Let us all know how you get on with that Eden, becuase I'm going to be busy today sat in a chair on Skipton High street, getting wet. So nothing much different than a wet day on a long scooter run.

Good Luck

To wrap this thread up, as I've now cracked the issue and give feed back for others to take in and ponder in pursuit of carb heaven.

When I originally built the engine I had it dynod at Chiselspeed, after around 500 miles of running in and it ran perfect, with the first set of carb settings shown below.


Now, 2500 miles later, thought smoke coming out was oil seal failure, although the engine ran really well through out the rev range. However, took engine out and changed oil seals and put new rings on.

Once I put engine back in, it ran like a pig up to half throttle (really rich) then ran like a dream above half throttle. Setting for PHBH 30 carb below. And this is the setup that I ran all the way down to Dorset Modraphenics rally in March, doing around 5-7 miles per litre and an unpleasant ride.
Main jet 130
Atomiser AV266
Needle X2 P2.5
Pilot 53
Power jet 30
Slide 50

Whilst in Dorset, changed above needle clip to point 1, and played around with air screw, but not much difference.

Anyway, in between maintaining the rest of the fleet, I've snatched time to play with these carb settings and changed to a much leaner atomiser and needle, far more than I would have anticipated, that being:

AV264 and X7 needle on top clip (P1).
Still to do some more confidence checks on plug chops and may change to P1.5. But the moral of the story is the big jump in needle atomiser settings.

Just to finalise this thread and flag up other issues that cloud the problem. Whilst doing plug chops, it would cut out at just over half revs. Turned out to be faulty Ducati CDI unit, that never caused a problem on the way back from Dorset where I ran at almost full throttle all the way up the M1.

Top position on an x7 needle seems very lean Paul..imo..get the plug chops done.

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Paul.....wonderful that you now seem to have the scooter set up and running nicely, however.......do you not have any concerns about the fact that your scooter ran spot on for 2500 miles with the richer AV266 and X2, but now you are suddenly running a much leaner AV264 and X7......?

If no mechanical components have been changed, and you've only done 2500 miles, what the hell could account for the need to make such drastic changes? THAT would be my main concern and main question, and until I found a reasonable explanation I would not be comfortable.

In fact the point you make about it running even worse after you rebuilt it sounds alarming....?

What are the exact specs of this engine?

List your cylinder, piston, reeds, head, any tuning/porting work, packer plates, comp ratio, squish, ign timing, flywheel, crank, stroke, rod, exh pipe, carb and gearing so that we know a bit more about your engine, and that will put your jetting into perspective.

The two PHBF's on my guzzi are very sensitive to float height. Could be idle/progression is a bit of a kludge and any variation is more marked.
Should imagine a 2T would be worse.

Andy -Top position on an x7 needle seems very lean Paul..imo..get the plug chops done

Yes, the big jump worries me. That's why I feel that I need to go out again and do some more plug chops to give me the confidence. Initially tried it on P2, but ran really boggy up to half throttle.

And Dan - .......do you not have any concerns about the fact that your scooter ran spot on for 2500 miles with the richer AV266 and X2, but now you are suddenly running a much leaner AV264 and X7......?

Yes, it does concern me, but I can't figure out why the big jump. Also, massive apologies, it was you who dynod this scooter and results shown below.
As for the engine, it was a standard Monza kit that I bought directly from CamLam, with an already jetted 30PHBH with power jet and ram air filter, the kit crank was a "GP Road/race with 116mm rod and a CamLam piston to suit the rod and kit. This standard kit came with reed valve, don’t know what make.

I built the engine, with no alterations to the boxed kit. I put on the cylinder with a thin metal base gasket and a gasket seal at the head to give a 1.3mm squish, as specified on the cylinder head. The exhaust is a JL3. Gearing is standard Indian GP200, timing is strobed at 18 degrees and the flywheel is a standard Indian.

After 500 miles of running slightly rich, you then fine-tuned it on your dyno, with results shown below.


All I did on the re-build was change the oil seals, new clutch plates and piston rings. In addition, did Wassel conversion to stator to give me full DC output, but that’s all about the lighting circuit really.
But as you have all suggested, the big change does worry me. In the last couple of weeks I have changed the stator, (DC Conversion) because i am paranoid about stators and re-checked TDC and the timing, all spot on.
I will also check out float height, as Warts has suggested, if only to eliminate that.

Many Thanks for all your input so far.