Beta Evo Factory Power and Compression

[NoTraction]

I wonder if any Beta experts can help with this one? Long post I’m afraid…

I recently bought a 2023 Factory 250, unwittingly a supposed ‘Euro Spec’ (or at least non-UK) version, the seller didn’t actually enlighten me to that detail. Usually this means no flywheel weight and a higher compression cylinder head insert, I believe. I bought it because I wanted a Factory for the better brakes, forks, yokes and rear shock and was of the belief that power wise, for UK spec models anyway, they were the same as the standard Evo. So, when I found out it was non-UK spec I took the flywheel off and the weight is present, and I fitted a standard head cover and low compression insert. I had to change the head cover as well as the insert as the head and insert fitted had been shaved down by 0.5mm, there was ‘-0.5’ etched on the head cover. And hence, the low comp insert wouldn’t fit on without also changing the head cover. I thought this would calm it all down and make it soft like a Beta Evo usually is. However …

The bike is still quite feisty and has a hell of a lot of compression when kick starting. It’s not the soft kick I associate with Betas. I rode it back to back today with a standard Evo 250 which suited me much better power wise, I am only a ‘wobbler’.

I rang Beta UK and they weren’t sure what to suggest themselves surprisingly but said they would look into it. Hopefully they’ll get back to me.

I don’t understand why (a) the original head and cover had been shaved and marked ‘-0.5’ but more importantly, (b), now I have fitted a low comp head, why does it it have such high compression still? - it really is a different animal to the standard Evo and is a bit of a pig to start sometimes as a result, you really have to boot it.

Assuming the basic engines are the same, I don’t understand how this can be, or what to do about it to make it a more rounded ride for me. If you want to fire up rock steps it’s the bike for you but I bought a Beta for the smoothness and ease of starting. This ain’t it! The guy at Beta said it might have a more performance oriented cdi on it but he wasn’t sure. I can’t see how this would change the compression when kick starting the bike though.

If you’ve managed to read this far and can shed any light on this issue I would be very grateful as I’m at a bit of a loss what to do next. Thanks!

 

[robido]

Try a thicker cylinder base gasket

[NoTraction]

I was just thinking that maybe it is fitted with a thinner than standard one. Just checked the squish, it is 1.35mm. Anyone know what it should be for a standard setting?

Edited Thursday at 07:09 PM by NoTraction

[lemur]

Have you done an actual compression test or only based on the kickstart?  Ki

Is the throttle tube white or black? White is the fast tube, the black throttle tube retards the response slightly.  Good chance your bike came with black tube originally like a friends evo factory bikes did.

Edited Thursday at 09:56 PM by lemur
spellk check

[lemur]

more performance oriented cdi  implies more ignition timing advance.   You can adjust timing at the stator to some extent or even the plug gap to a lesser extent.

[NoTraction]

It has a slow throttle. I’ve bought some thicker base gaskets (0.5mm, 1mm) based on the assumption the one fitted is a thinner one. I’ll get it apart tomorrow and see what’s on there.