LCGB Forums

Hi All,
I have just bought a 175 conversion kit for my GP, do i need any special top end gaskets for the kit.
Cheers
Stag

Ummm surely if you bought a kit then it's come with the appropriate base, head, inlet and exhaust gaskets?

not the answer I was looking for. No it does not come with gaskets.

Donnie is right but if you haven't got them you will need a std 150 base gasket a 175 convertion head gasket a std 150 inlet manifold gasket and all exhaust gaskets are the same fitting it depends on the bore of your exhaust

Well if it's not the answer you are looking for then you need to be more accurate in your opening volley.

You say you have bought a kit, that implies a complete 175 kit including gaskets, studs nuts and washers.

Any dealer worth their salt will sell a kit like this as without the proper head gasket and the studs it's essentially incomplete.

But to give you the specific answer you are looking for?

Yes is the answer

Thanks for the answers. Now I need to track down the gaskets.
Stag

Make sure you thoroughly wash it out before fitting - you wouldn't believe the crap that comes out of them.

Thanks for that tip Jetex, I will certainly keep that in mind.
Cheers
Stag
From sunny Isle of Skye

Hi All,
After striping the top end of the engine sil gp 150, there are spacer shims on the con rod to piston. As mentioned I am fitting a 175 kit, will I use the shims on the new piston to con rod. Looking for positive reply's so I can get started.
Cheers
Stag

I never fit the spacers and have no issue through not using them

Whether the shims should be there at the small end is dependant on the type of big end is in crank you have.

If there is side float built into the big end you should fit the piston shims.

If the crank has very little side float and is shimmed then you should not fit them.

The shims are designed to ensure that the conrod is centralised either at one end or the other - never both.

You might get away with not fitting them to a crank with side float, and indeed that was the received wisdom when good quality piston shims were hard to come by.

Isn't it irelative what size piston you have? I thought the shims were needed to remove extreme lateral movement from the con rod small end, as you can't shim the big end. That's how I've read certain bits.

Maybe I'm wrong.

In other words you always need to shim it if there is lots movement.

Kristof Lammy pie wrote:
In other words you always need to shim it if there is lots movement at the big end.

FTFY

The shims fit either side of the small end bearing. They are designed to prevent any side float in the small end when used with a crank which has side float built in. If you omit them the conrod is free to move laterally. This can lead to uneven wear in the piston bosses or in the small end bearing. This is not such an issue if you use one of the wider small end bearings.

When the crank is shimmed at the big end, use of shims in the small end would mean that any degree of misalignment between the conrod and the piston would lead to pressure on the rod possibly leading to rod failure or uneven barrel wear.

Hi All,
I have gaped the rings at 0.25, any thoughts in this.
Cheers
Stag

have a read of this by MB Scooters it should be helpful
http://www.lambrettaspares.com/info/setting-up-*-engine-carbs-3/setting-up-*-cylinders+163.html

kennystag wrote:Hi All,
I have gaped the rings at 0.25, any thoughts in this.
Cheers
Stag

Fine if you mean mm

Bit wide if you're in inches

I came across this article a while ago.

It's very interesting as it's based upon practical research. However, as the tests were conducted using four stroke engines, we have to be cautious bearing in mind that we have ports that rings must traverse. So 'ring spring' & flutter are something the author of the article was not concerned about, although there is some acknowledgement of two strokes.


http://www.diagnosticengineers.org/jour ... 20Gaps.php

Thanks for the replies now sorted.
Stag

Hi Warkton Tornado no1,
Thanks I sent you a PM, they sometimes take a long time to get were they are going.
Cheers
Stag

Hi All ,
An update on the 175 kit, engine is in my lammy, she started second kick, sounding really sweet, very happy so far. I do not foresee any problem, I got a good deal with this kit. I got it from a UK eBay seller, he has sold many 175 kits with all good feedback, that is why I took the chance to buy from him. Now the long trawl off running her it lol.
Cheers
Stag