We are a Uk ltd company est 1972  we aim for next day delivery when poss 

       All the items we list are in stock ready for immediate despatch 

This kit has a specially modified OE YAM CYLINDER lined and bored , machined TKR piston cnc machined to ensure correct valve clearance is maintained 

With you using your 125 cc cylinder head  piston will not catch on head or crank due to oversize 

YOU MUST BORE YOUR CRANKCASES OUT IF FITTING TO 125

The Big bore kit is made specialy for the tt125  to be 180cc 

65.50mm 

bore size 65.50mm 

big increase ,Please check the photo the kit you see in the photo is the kit you get  ,

gives you a hell of a difference makes hill climbs easy pulls 1 gear higher everywhere ,

55 more cc so worth doing transforms the little bike

Comes with full fitting instructions if you want we can post or email them

This is a OE spec cylinder relined and bored to 65.50mm patterned modified in the uk 180 cc piston kit and oversize gaskets 

The actual parts in the photo you will get 

1 x alloy oe Yamaha cylinder bored to 65.50mm 180cc 

1 x 65.50mm piston TKR HIGH COMP

1 X 65.50mm  piston rings

1 x gudgeon pin

2 x clips

1 x Oe Yamaha gasket set fit all gaskets for best results

(both thick and thin base gaskets ) gives correct compression

1 x performance cam 

You can buy with confidence from a UK company big bore kits in the UK 

MADE TO BE GOOD FIT WITHOUT HASLE ,ALLWAYS AT THE END OF A PHONE FOR ADVICE ETC. AND FOR FURTURE  SINGLE ITEMS GASKETS OVERSIZE PISTONS ETC  

delivering from the UK 

CARRYING STOCK IN UK 

UNLIKE MANY OTHERS ON HERE

Delivering to your door within 2 days 

AVT AUTOPARTS ltd 

82/84shields road 

Byker 

Newcastle upon Tyne 

Ne61ds 

Tel   07773070793   Colin lee 

We support many race teams thoughout the world and our teams win 🥇Portugal ttr race series winners use our parts see photos of 

Joao piers 1st place 🥇 

No76 Skye Adams flat track racer seen in last two photos who runs our kit on her bike Part of berlt racing team Showing the boy's the way with some girl power 😂😂😂👍👍🏁🏁 Go on syke you show them

IMPORTANT BERLT BIGBORE KITS ARE FOR COMPETITION USE ONLY

TRACK DAYS / DIRT RACING/ CLOSED CIRCUIT RACING ONLY

NOT SUITABLE FOR ROAD USE

IMPORTANT GOODS SENT TO WORLD WIDE DESTINATIONS CAN NOW BE SUBJECT TO EXTRA GOVERNMENT TAXES/DUTY ON ARIVAL TO YOUR COUNTRY THIS HAS NOTHING TO DO WITH US AND IS BEYOND OUR CONTROL PLEASE CONTACT YOUR GOVERNMENT /POST OFFICE