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Upgrading My 315

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I am thinking of doing a few upgrades to my 315 montesa. I've heard of a different barrel and head being put on. Boysen rad valve being put in, flat side carb, has anybody done any such upgrades to their monts and was it worth it / how much did it cost. I've put the jitsie shock plates on, different clutch plates.

I don't want to throw money at it as its always only going to be an old 315, but I don't ride often now and have got money left over from selling my 4RT. Any suggestions?

Best mods to do are;

Porting barrel send it to Haven.

Modify ignition pickups to advance engine.

Boysen reeds only.

Keihin carb.

Jitsie plates.

If above is done it will feel much livelier and steer better. A couple of hundred quid should sort it.

Only additional one that might be worth a try is to change the 'S' shape pipe inside the silencer to a straight pipe.

If you get hold of some punched out sheet, then you can make this up for a couple of quid.

  • Author

Thank you both for your replys, that gives me somewhere to start, cheers

I think motocross type shops stock perforated tube as standard, just need diameter required. Was going to chnage mine before SSDT last year but ran out of time.

DEP Pipes make the silencer cores you require- in 3 different 2stroke diameters

Any decent mx shop should be able to get them or call DEP www.deppipes.com

I have a second hand but only used once kiehin

carb for one of these if interested !

  • Author

I have got a Dellorto flat side carb, but how much do you want for Keihin?

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