[Sidman]

Originally Posted by ilangop

Dude, which spark plug are u using? Could you look into the number mentioned on it and write it down here?

Its NGK G-Power - BPR5EGP
Gap is 1 mm
Something like "H027" is seen on the plug.

[foby.sebastian]

Spotted this lamby getting restored @ thrissur

[Stanher]

Originally Posted by foby.sebastian

Spotted this lamby getting restored @ thrissur

Wow, a Hyderabadi Lambretta! Interesting rear mask btw!

And foby chetta,
this is NOT a Lamby, but Lambretta!
Can make out from the side-panels.

This is a Lamby:

[ilangop]

Originally Posted by Sidman

Its NGK G-Power - BPR5EGP
Gap is 1 mm
Something like "H027" is seen on the plug.

Sid,
W5DC or W165Z2 are the recommended ones for our scooters, that too with a gap of 0.5 mm. Higher the gap, the plug needs higher voltage. But our system voltage is limited by the capacity of the magneto and point set. So always stick to 0.5mm. In case you get a 1mm plug, still you can tap the gap down to 0.5. Do check the attached pdf as well the following link.
Bosch to NGK cross reference page 2

[Sidman]

Originally Posted by ilangop

Sid,
W5DC or W165Z2 are the recommended ones for our scooters, that too with a gap of 0.5 mm. Higher the gap, the plug needs higher voltage. But our system voltage is limited by the capacity of the magneto and point set. So always stick to 0.5mm. In case you get a 1mm plug, still you can tap the gap down to 0.5. Do check the attached pdf as well the following link.
Bosch to NGK cross reference page 2

Thanks, Ilango! That was informative! What do you use to measure the gap, and how do you adjust the gap without damaging the plug?
I found a useful video on cleaning spark plugs:

YouTube - How to Clean a Spark Plug

I will get a couple of W5DC plugs with 0.5 mm gap. It looks like none of the plugs I have are what is recommended for Lambretta. Thanks again!

[ilangop]

[quote=Sidman;2042898]What do you use to measure the gap, and how do you adjust the gap without damaging the plug?quote]
Sid,
So far, havent used a gauge to measure the gap. It was all by visual judgement only. You can say, 0.5 mm gap is more for 1 nail thickness, while less for 2. Put in your nail and check . Sparkplug feeler guages must be available in most of the autostores. Give a try. Should'nt be costing more. Probably a few tens of Rupees. Previously while you buy an airfilter for a Lambretta, you get the spark plug cleaning & gap setting thing for free. No idea if those are sold the same way, now a days.
-Ilango

[Sidman]

[quote=ilangop;2043000]

Originally Posted by Sidman

What do you use to measure the gap, and how do you adjust the gap without damaging the plug?quote]
Sid,
So far, havent used a gauge to measure the gap. It was all by visual judgement only. You can say, 0.5 mm gap is more for 1 nail thickness, while less for 2. Put in your nail and check . Sparkplug feeler guages must be available in most of the autostores. Give a try. Should'nt be costing more. Probably a few tens of Rupees. Previously while you buy an airfilter for a Lambretta, you get the spark plug cleaning & gap setting thing for free. No idea if those are sold the same way, now a days.
-Ilango

One of my friends is headed to JC Road, so I asked him to get me spark plugs, wire brush, and also to check if that tool you speak about is available. Let's see if he is successful...thanks for the guidance, I will update you when he gets the goods.

[Sidman]

Originally Posted by Sidman

One of my friends is headed to JC Road, so I asked him to get me spark plugs, wire brush, and also to check if that tool you speak about is available. Let's see if he is successful...thanks for the guidance, I will update you when he gets the goods.

I managed to find Mico W5DC spark plugs, after visiting 7-8 shops. Most of them tried to sell me W8DC, which has 0.8 mm gap. Most of these guys don't seem to understand that the recommended gap is 0.5 mm, and anything above 0.6 mm is going to require too much current. After looking at the links suggested by Ilango, and doing some research on the net, the following are the recommended spark plugs for Lambretta/Vijai:
Mico W5DC
NGK BP7ES
Champion N4C

Lambretta/Vijai need long thread spark plugs with plug gap not exceeding 0.6 mm.

Here is a good link to help you understand the types of NGK plugs available: Scooter Help - Spark Plugs

I will put in the new spark plug and let you know how it goes after that.

[manishalive]

0.8 mm gap can be readjusted easily to any value by taping the "j" grounding electrode in a sparkplug. The tool for gap adjustment might not be available these days, but feeler gauges are readily available and are of good use for checking the gaps.

What one needs to do is insert a 0.5mm feller gauge in the plug gap and slightly tap with the head of a screw driver or rubber mallet. this would do the job for you.

[Sidman]

Originally Posted by manishalive

0.8 mm gap can be readjusted easily to any value by taping the "j" grounding electrode in a sparkplug. The tool for gap adjustment might not be available these days, but feeler gauges are readily available and are of good use for checking the gaps.

What one needs to do is insert a 0.5mm feller gauge in the plug gap and slightly tap with the head of a screw driver or rubber mallet. this would do the job for you.

I read that this is not recommended for some plugs, as the electrode could get damaged. But I don't mind giving it a try now. Where can I get good feeler gauges in B'lore?

[manishalive]

Originally Posted by Sidman

I read that this is not recommended for some plugs, as the electrode could get damaged. But I don't mind giving it a try now. Where can I get good feeler gauges in B'lore?

Sid,

The will be no damage to the electrode, infact it is sacrificial in nature and wears down from use. That is the reason while tuning we clean and adjust the plug gap. So a 0.5 mm gap after use may become 0.7mm and then you have to tap slightly to get back 0.5 mm (all this is for the single "J" type plugs).

Any Tools shop will have the feeler gauge, SP road is the place.

[TuffRyder]

Look what I managed to find. Can someone help me with a good dial around here? The one in this is beyond repair unfortunately.

[Sidman]

Originally Posted by manishalive

Sid,

The will be no damage to the electrode, infact it is sacrificial in nature and wears down from use.

Thanks for the advice, Manish! I plan to go to SP Road tomorrow. Update on my Lambretta's running problem: I fitted the Mico W5DC plug. Rode a total of 6-7 km in 2 days without any problems. Today, when I started the scooter, it was misfiring, so I decided not to ride it. So now, the spark plug has been ruled out as a cause of the problem. I'm guessing I need to check the points next?

[ilangop]

Originally Posted by Sidman

Thanks for the advice, Manish! I plan to go to SP Road tomorrow. Update on my Lambretta's running problem: I fitted the Mico W5DC plug. Rode a total of 6-7 km in 2 days without any problems. Today, when I started the scooter, it was misfiring, so I decided not to ride it. So now, the spark plug has been ruled out as a cause of the problem. I'm guessing I need to check the points next?

Sid, while the scooter has been running fine once it gets started, give a check to the ignition coil too. Since the firing is proper while running there cant be any problem with timing. Which ignition coil are you using? How does the spark in the spark plug look like. Is it just a single arc or multiple strong arcs.

[insaneinsaan]

Hi guys.
Have been having to deal with the following problem on my lambretta:
My silencer keeps developing a leakage every month. I figured the cause, it is due to the copper foil-coated packing between the cylinder and the u-bendpipe. This part gets overheated and burns up inside with time (under the copper foil is some kind of cardboard or cotton), leading to a leakage between the cylinder and the bendpipe (the worst place to have a leakage, I believe).

The question is, why is this happening so regularly (every 3 to 4 weeks). The sound keeps getting louder and louder over this time, as the leakage gets bigger. Eventually the bike is so loud that I feel apologetic to the public to even start it!

Is it possible to get a better quality of that particular packing? Or some way to prevent it from burning out?