33bhp restrictor kit

Looking for 33 bhp restrictor kit for 98 Cat, bit of bug bear but i need it till feb next year then free!

Some time ago I removed a set of restrictor washers from a Diversion 600 (the older air cooled model), and sketched them up so anyone could make a set for themselves:

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The ones I sketched have a 15mm diameter hole, whereas the ones on eBay have a rounded triangle shape.  But for a sharp-edged orifice the peak air flow, which is what restricts the power, will be proportional to the area irrespective of the shape, to a first approximation anyway.

If you were making up a set for a Thundercat, apart from the obvious need to change the outline to suit the mounting details (these fitted next to the cylinder head, btw), the hole size would need to be changed.  I'd guess the Thundercat's valve timing will have a bit more overlap than a Divvy's, so to keep the total mass of air per cycle, and hence the power, down to the same level the holes would need to be a bit, but not a lot, smaller - I'd guess 13-14mm diameter should do.

As far as I'm aware, a certificate is not mandatory, nor is a dyno run print-out.

Ive got a set coming, so when i get em il measure up and post :-D

I know im posting this a year later but, ive just bought a tcat for my first bike and im wondering how to go about it with the restrictor and so on, how do i prove it has one and do insurers to the power from back wheel or crank shaft? Thanks quick reply would be brill

Using advanced search and the "google search" rather than just "search" gives you these results

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Have a trawl through them as the answer might be in there.

I think Ellie might know but from my often unreliable memory I think your word that it has been fitted is good enough and you only get into trouble if after an 'issue' the bike is inspected and found not to have them.

HTH

Cheers
Rosco