GP 200 Vibration and noise.

[rog60]

My thoughts only:
Vibration - My Indian GP had exactly the same problem from about 150 - 450 miles but gradually mostly disappeared as the barrel, piston and rings ran in further. My engine took about 1100 miles to run in fully.

Expansion Exhaust System - If you are still using the Jetex carb you will certainly have to upjet to about 125-128 main jet or more (better to go too rich) or risk seizing the engine.

I would concentrate on running the scoot in first otherwise with the expansion pipe you may try to push the engine too quickly and seize...............

[emo5c]

Thanks for the advice, it's very helpful. I was intending to run in until at least 1000 miles anyway and i'm not too heavy on the throttle (my younger days of thrashing a bike have gone) so shouldn't be too impatient to get it going too soon.
The carb that's fitted is a Jetex but with a number SOI-100 stamped on it. It doesn't mention this one in Sticky's manual so will your suggested main jet settings still be relevant? if so i'll order a few different sized jets from 123 to 128 and fit the largest while running in to avoid any overheating and seizing etc.
I do appreciate your help on this matter.
Cheers.

[rog60]

Just to clarify..............

You probably have a 118 main jet in the carb, which is the Jetex that everyone seems to knock,
if you have the 42mm clubman fitted. This should be more than adequate for running in on that set up. I only intended that you upgrade the jetting if you CHANGE the exhaust system to a performance type as you mentioned.
I did fiddle with main jets, as 'Sticky's' book suggested you should, and fitted a 123 main jet. It was too rich and I reverted to the 118. It is also beneficial to change the Indian supplied jets atomiser and slide to the Italian made equivalents to give marginally smoother carburation, they are the parts thet are inter-changeable.

Hope that helps a little...........

[emo5c]

I've fitted the sports exhaust but as I can't rev it over half throttle yet anyway i'll have to wait to do the plug chop. Thanks for the advice about the jets, i'll buy a 120 and see what happens when i've fitted that after running in.
Could you tell me where you bought the Italian made atomiser and slide please then i'll get one of each to fit as well.
Thanks.
D.

[rog60]

Just re-read the posts on here and the 120 jet will probably not be large enough. Mate of mine bought the same exhaust accelerated down the road and seized after about 3 miles. Obviously he hadn't changed the jetting

Bought jets from Cambridge Lambretta and slide from Scooter Restorations. I called them to confirm that they were Dellorto Jets/Atomiser and the slide is much better than the Jetex one.

http://www.scooterrestorations.com/lamb ... de-7895-1/

[emo5c]

Just fitted a 128 jet so when we get some decent weather i'll take it for a spin to see how it feels....

[rog60]

[quote="emo5c"]Just fitted a 128 jet so when we get some decent weather i'll take it for a spin to see how it feels.... [/quot

Sounds about right..........

[emo5c]

Tried the 128 jet, much too rich, 4 stroking and sounding like a tractor at anything over one third/ one half throttle so fitted the 123 (thought the 125 might be a bit rich too) and it runs much better. I still think it's a little on the rich side as it's a bit heavy on the throttle but safer than running weak. I'll leave it at that until i've done a few more running in miles then do a plug chop.....watch this space....

[emo5c]

Hi All.
Sorry not been on for a while. Further to my new exhaust fitting I started with a 128 jet, wouldn't run smoothly over tickover speed (four-stroking), fitted a 125 and was still obviously too rich so fitted a 123 and it's much better but still suspect a bit too rich as it stutters a bit and feels a little heavy on the throttle. I'll try a 120 and that should be ok. I don't think i'll need to go back to the standard 118 but will let you know how I get on.
Took it for an mot today and it went straight through. I was a little concerned it might fail on something bearing in mind the problems I had after buying it and the dealer not doing a very good job of the engine rebuild.
:biggrin: