4L0/4L1/AC cylinder spacers

[4l04ever]

I made a prototype today.

Will be getting some laser cut in different thicknesses.

Any interest?

[rigga]

For what reason Rob, to change port timing or to be able to reuse barrels that have had the base machined ?

[4l04ever]

These spacers are mainly for when the cylinders and/or head have been skimmed more than can be adjusted for with one gasket. Using a 0.5mm spacer between two gaskets, you can get from 0.8mm up to 2.1mm of range.

I have some cylinders where the base has had about 0.9mm and the top has had about 0.1mm off, so I need to get to 1.6mm to get back close to standard.

If the head and/or the top of the cylinders have been skimmed at the top, then the porting does get messed with (Equivalent of slightly raising all the ports), but better than being unusable.

My tuned 4L0 runs a 1mm spacer as it has an o-ringed head, so these spacers can also be used towards correcting for no head gaskets etc.

[red998]

I have a skimmed head that was from when my bike was tuned for production racing. I don't know how much was taken off without measuring it, but it would be good to have something that could make it usable again. What sort of thicknesses did you have in mind to get cut?

[4l04ever]

I am looking at some around 0.5mm and some around 1mm.

[red998]

My barrels were "jacked" up by using a single metal spacer originally and somehow "glued" to the bottom of the barrels, looks like Araldite or something as one barrel now has the spacer peeling off. The head was skimmed quite flat with only a small edge to the combustion chamber.

I assume I am looking at something like a 1mm spacer in that case. No doubt measuring the spacer will give me that (some) information. I don't know how much was skimmed off the head though. Is there a general thickness of a standard head that can be measured, possibly using a caliper gauge to either measure the edge of the combustion chamber depth on a stock head or is there another way to determine thickness?

[4l04ever]

You could get the head re-profiled.

[red998]

Are you in a position to do that or to suggest someone who can? I assume I would then not need any spacers?

[stusco]

www.muttsnuts2strokes.co.uk/

[red998]

Aug 26, 2023 10:00:14 GMT 1 stusco said:

www.muttsnuts2strokes.co.uk/

Thanks.

[rbridd]

Aug 25, 2023 18:31:31 GMT 1 4l04ever said:

I made a prototype today.

Will be getting some laser cut in different thicknesses.

Any interest?

Yes. 0.5mm would be of interest to me.

[damiensk]

I will also be interested after having head/barrels skimmed by k motors. Will be in touch.

[4l04ever]

Just got some 0.5mm and 0.8mm aluminium sheet. Dropped off for laser cutting. Hopefully ready by Friday.

[4l04ever]

Got spacers now! 0.5mm and 0.8mm versions.

[4l04ever]

Additional information relating to using these spacers :-

If you have over approx 0.8mm thick gaskets, they can keep squashing down over time, so if you need thicker gaskets, you need to use a spacer and 2 thinner gaskets to get to the thickness required to reduce this effect.

[4l04ever]

Lets start doing some measuring and calculating...

Standard 4L0 cylinder height 102.6mm

Standard base gasket 0.6mm

My test cylinder height 101.4mm

My test cylinder needs 102.6-101.4 = 1.2mm extra plus the 0.6mm for the standard base gasket means I need a total of 1.8mm.

So I will uses a 0.5mm base gasket then a 0.8mm spacer then a 0.5mm base gasket. :-)

[Tobyjugs]

Hi Rob these spacers you are making are a good thing, once you start building up the thickness of the gasket material it starts to compress more, so you need to add extra to compensate for the compression.

With a harder aluminium spacer in between this makes it so much easier if you don't have any experiance with the compression rate of the gasket material. 

[4l04ever]

Just getting some 1.2mm spacers made too.

[4l04ever]

I now have 0.5mm, 0.8mm and 1.2mm spacers in stock.

I can supply a gasket stack kit (2 x gaskets and a spacer) to get to most thicknesses between 0.8mm and 2.8mm