Please see the below for information regarding fitting a TSP Head or Insert to your bike. It includes squish clearances, deck heights and additional information. This is to suit our own TSP designed heads, and should not be assumed that it is the same for your stock head.

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Disclaimer/Liability notes:

• TSP does not accept any liability for any damage, injury or loss resulting from the use of these products. If you do not agree to the terms of sale or if you are unhappy with this product in any way, please return it before installation for a full refund.
• These products are intended for competition closed-course use only.
• It is the owner’s responsibility to ensure jetting/fueling are suitable for their local weather and conditions to avoid engine damage.

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KTM/Husky Models:

KTM/Husky 85cc 18-on – HIGH COMP/Raised:

Installation instructions:

• Remove existing head
• Check deck height (distance from the top of the cylinder to the top of the piston edge at Top Dead Centre). Adjust by installing different base gaskets if necessary. Your new head insert is designed to work with a thicker base gasket than stock. The new base gasket thickness is 1.05-1.10mm
• Install new head O rings
• Make sure dowel pins are in place and properly seated
• Install your Billet Head making sure that the 2 inner O rings that seal between the 2 parts are properly in place and do not get pinched. If necessary coat them in oil to help avoid pinching.
• Tighten head nuts/bolts in a criss-cross pattern to the required torque spec in your owners manual.

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KTM/Husky 125cc 16-23 (CARBY) – HIGH COMP:

Installation instructions:

• Remove existing head
• Check deck height (distance from the top of the cylinder to the top of the piston edge at Top Dead Centre). Adjust by installing different base gaskets if necessary. Your new Billet head is designed to work with the factory installed base gasket thickness.
• Install new head O rings
• Make sure dowel pins are in place and properly seated
• Install your Billet Head making sure that the 2 inner O rings that seal between the 2 parts are properly in place and do not get pinched. If necessary coat them in oil to help avoid pinching.
• Tighten head nuts/bolts in a criss-cross pattern to the required torque spec in your owners manual.

 

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KTM/Husky 125cc 23-on (TBI models) – HIGH COMP:

1. Intended Squish Clearance: 0.95mm-1.05mm
2. Deck Height required for intended SQ: -0.30 to -0.40mm
3. Base gasket normally required for this deck height: 0.90-1.00mm Base gasket stack
4. Recommended Fuel for intended squish: 98RON

Installation instructions:

• Remove existing head
• Check deck height (distance from the top of the cylinder to the top of the piston edge at Top Dead Centre). Adjust by installing different base gaskets if necessary. Your new Billet head is designed to work with the TSP supplied base gaskets. You must use both gaskets together.
• Install new head O rings
• Install your Billet Head making sure that the 2 inner O rings that seal between the 2 parts are properly in place and do not get pinched. If necessary coat them in oil to help avoid pinching.
• Tighten head nuts/bolts in a criss-cross pattern to the required torque spec in your owners manual.

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KTM/Husky 150cc 16-on – MID/HIGH COMP:

Installation instructions:

• Remove existing head
• Check deck height (distance from the top of the cylinder to the top of the piston edge at Top Dead Centre). Adjust by installing different base gaskets if necessary. Your new Billet head is designed to work with the factory installed base gasket thickness.
• Install new head O rings
• Make sure dowel pins are in place and properly seated
• Install your Billet Head making sure that the 2 inner O rings that seal between the 2 parts are properly in place and do not get pinched. If necessary coat them in oil to help avoid pinching.
• Tighten head nuts/bolts in a criss-cross pattern to the required torque spec in your owners manual.

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KTM/Husky 250cc Carby & TPI Billet Head 2008-2016 & 2017-23 – LOW/MID/HIGH/V-HIGH COMP:

Installation instructions (New one piece style head + changeable insert):

• Drain coolant and remove existing head
• Set deck height using different base gaskets as necessary. Deck height is the distance between the top of the cylinder and the top of the outer piston edge at Top Dead Centre (TDC).
• Install new head O rings on top of the cylinder and make sure dowel pins are in place and properly seated.
• Place the supplied 23×2.5mm o-ring into the groove on top of the combustion chamber insert. Place the outer ‘Cap’ section of the head over the insert, taking care not to dislodge the o-ring. Screw the spark plug finger tight into the top of the insert. Holding the spark plug, lift the head assembly onto the cylinder as one unit. Position the head carefully, making sure dowel pins align and o-rings remain seated.
• Tighten nuts/bolts in a criss-cross pattern to the required torque spec in your owners manual. Refit the head to chassis mount brackets.
• For Carby models install the optional Coolant Plug into the 10mm threaded hole at the rear of the head. For TPI models install the temperature sensor into the 10mm threaded hole.

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KTM/Husky 300cc Carby & TPI Billet Head 2008-2016 & 2017-23 – LOW/MID/HIGH/V-HIGH COMP:

Installation instructions (New one piece style head + changeable insert):

• Drain coolant and remove existing head
• Set deck height using different base gaskets as necessary. Deck height is the distance between the top of the cylinder and the top of the outer piston edge at Top Dead Centre (TDC).
• Install new head O rings on top of the cylinder and make sure dowel pins are in place and properly seated.
• Place the supplied 23×2.5mm o-ring into the groove on top of the combustion chamber insert. Place the outer ‘Cap’ section of the head over the insert, taking care not to dislodge the o-ring. Screw the spark plug finger tight into the top of the insert. Holding the spark plug, lift the head assembly onto the cylinder as one unit. Position the head carefully, making sure dowel pins align and o-rings remain seated.
• Tighten nuts/bolts in a criss-cross pattern to the required torque spec in your owners manual. Refit the head to chassis mount brackets.
• For Carby models install the optional Coolant Plug into the 10mm threaded hole at the rear of the head. For TPI models install the temperature sensor into the 10mm threaded hole.

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Sherco Models:

Sherco 300 18-on Models:

 

IMPORTANT:

• Deck height is measured at the center flat spot of the piston as per diagram, not at the edge where it is normally measured
• When fitting the TSP Sherco 300 Head, you must ensure that you have a 0.00mm to -0.10mm deck height. This may be achieved by using either a 0.50mm or the supplied 1.00mm base gasket, but it may vary between some bikes. The best way to check this is to put a metal ruler for reference flat across the top of the cylinder, and when rotating the engine to top dead centre, the middle flat part of the piston crown should just touch the ruler or come within -0.10mm below. You should not have a positive deck height. 

 

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Yamaha YZ Models:

Yamaha YZ125 2005-2021 – MID/HIGH COMP:

Installation instructions:

• Remove existing head
• Check deck height (distance from the top of the cylinder to the top of the piston edge at Top Dead Centre). Adjust by installing different base gaskets if necessary. Your new Billet head is designed to work with the factory installed base gasket thickness. Be aware that some aftermarket YZ125 base gaskets are thinner than the stock gasket. If you install one of these gaskets your squish clearance may become too tight and engine damage may result. Always double check that squish clearance is correct after a rebuild.
• Install new head O rings
• Install your Billet Head making sure that the 2 inner O rings that seal between the 2 parts are properly in place and do not get pinched. If necessary coat them in oil to help avoid pinching.
• Tighten nuts/bolts in a criss-cross pattern to the required torque spec in your owners manual.
• Be careful to centre the head on the cylinder accurately. Part of the YZ125 detonation problem is caused by heads that are installed off-centre. Use the studs as a reference and make sure the head is aligned so that the studs are perfectly centred in each hole. If necessary use a couple of nuts machined to a 45 degree angle to centre the head against the studs… tighten the 45 degree nuts by hand on 2 opposing studs, and then install 3 of the stock nuts to hold the head in place.

 

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Yamaha YZ125 2022 – HIGH COMP:

Installation instructions:

• Remove existing head
• Check deck height (distance from the top of the cylinder to the top of the piston edge at Top Dead Centre). Adjust by installing different base gaskets if necessary. Your new Billet head is designed to work with the factory installed base gasket thickness. Be aware that some aftermarket YZ125 base gaskets are thinner than the stock gasket. If you install one of these gaskets your squish clearance may become too tight and engine damage may result. Always double check that squish clearance is correct after a rebuild.
• Install new head O rings
• Install your Billet Head making sure that the 2 inner O rings that seal between the 2 parts are properly in place and do not get pinched. If necessary coat them in oil to help avoid pinching.
• When locating the head onto the cylinder, gently rotate the head counter-clockwise to ensure the dowel pins are correctly located. The first initial design of TSP heads has the dowel location in the water jacket, but there is no issue with this.
• Tighten nuts/bolts in a criss-cross pattern to the required torque spec in your owners manual.

 

 

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Yamaha YZ250 & YZ250X 1999-on – MID/HIGH COMP:

Installation instructions:

• Remove existing head
• Check deck height (distance from the top of the cylinder to the top of the piston edge at Top Dead Centre). Adjust by installing different base gaskets if necessary. Your new Billet head is designed to work with the factory installed base gasket thickness.
• Install new head O rings
• Make sure dowel pins are in place and properly seated
• Install your Billet Head making sure that the 2 inner O rings that seal between the 2 parts are properly in place and do not get pinched. If necessary coat them in oil to help avoid pinching.
• Tighten head nuts/bolts in a criss-cross pattern to the required torque spec in your owners manual.
• Tighten the allen head bolt under the rear mount LAST (marked by BLUE arrow in pic), after the head bolts have been tightened.

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Honda CR Models:

Honda CR500 1989-2001 LOW/MID/HIGH COMP:

Installation instructions:

• Drain coolant and remove existing head
• Set deck height using different base gaskets as necessary. Deck height is the distance between the top of the cylinder and the top of the outer piston edge at Top Dead Centre (TDC).
• Install a new head gasket on top of cylinder.
• Install your Billet Head making sure that the 2 inner O rings that seal between the 2 parts are properly in place and do not get pinched. If necessary coat them in oil to help avoid pinching. Take care with this step to avoid engine damage!
• Tighten nuts/bolts in a criss-cross pattern to the required torque spec in your owners manual. Refit the head to chassis mount brackets.

 

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How to measure your squish clearance: