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TTP 904s Sports Big Bore Kit

  • Description
  • Reviews

There are very few modifications you can perform on an engine that will improve power and torque right through the rev range, but TTP's 904s big bore kit is one of those modifications. Increasing cubic capacity and compression ratio give improved performance from idle to the rev limit, with no downside.

In use the extra top end horsepower is excellent for acceleration and top speed, but the revelation is the extra torque through out the rev range. It makes riding a Triumph twin far more exiting as when you open the throttle, the engine just pulls and pulls to the red line.

Designed by TTP, the 904s kit includes excellent quality high compression race pistons with exceptional quench properties for powerful combustion, a custom 904 MLS steel head gasket together with OEM cylinders which are bored, Nikasil plated and then powder coated externally to give a virtually new set of barrels.

Available for the air cooled Bonneville, Thruxton, Scrambler, America and Speedmaster from 2001-2016.

Kit Features:
  • 12:1 compression ratio.
  • Tight quench to improve turbulence, combustion burn & eliminate pinking.
  • Anti-friction coating on the piston skirts.
  • Pistons hand balanced to within 0.1gms of each other.
  • Nikasil plated barrels give tighter cylinder/piston clearance.
  • Hand gapped piston rings.
  • Custom 904 MLS steel head gasket.
  • Optional OEM gasket kit.

Core must have no broken fins and no scratches on the bore or mating surfaces.
Shipping details will be on your emailed order receipt.

7 Product Reviews - Average rating 5 / 5 (Show All)

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904S Kit

- 10th May 2021

I now have all the power I need. The bike is so different now. Raised gearing and greater millage, engine is more reactive now, and the feel is right.

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 If you select this option, there is no need to send us your cylinders for exchange.

We supply a set of cylinders that are ready for the 904s pistons. They have been bored out and the bores have been Nikosil coated.

The external surfaces of the cylinders have been re-finished like new.
The Stage 2 Power Induction Kit comes complete with
fitting kit, DNA Performance pod filters, installation
instructions and the required jetting or EFI tune for
the 904s kit.

Carb Stage 2 Kit            EFI Stage 2 Kit
Carb Stage 2 Kit          EFI Stage 2 Kit
This gasket kit includes all of the OEM gaskets
required when installing the big bore kit.
(except head gasket which comes with 904s kit)

904s Gasket Set
904s Gasket Set
The Safe Start is a good preventative measure for
a standard engine, with the 904s Big Bore Kit
installed giving an increased compression ratio,
the Safe Start will give protection from the only
engine structural weakness of the air cooled
Triumph twins.

NB: If you're upgrading to the green clutch springs,
why not install the Safe Start while the clutch cover
is off, for complete peace of mind.

TTP Safe Start
TTP Safe Start
Price: £922.00 (£1,106.40 Inc. VAT)
€1,088.33 EUR    $1,119.34 USD    $1,577.60 AUD