Here is a proper 2002 powervalve on the left and early type diamond powervalve on the right, if they were all diamond shape wouldn't have a rectangle in powervalve pully. Yamaha didn't make a 2003 they are 2002 models just registered later.

Only the older DT and TZR TDR had a diamond shaped end on the powervalve, all the later 3RM models all have a rectangle end that is an exact fit in the powervalve pully. If it is a 2003 with a diamond shaped end then it is not the original powervalve and probably not the original barrel either.

@d3cme I have a 2002 dtr imported from the isle of man, has the 3rm-20 cdi. Moved the reed switch about 6 inches just cut the insulation so could pull the 2 wires really out of the way. Mine didn't rev past 7-8000 max till moved the reed switch now revs past 11000 and goes off the clock. If you rev it stood still in neutral does it got to 11000.

Added this tilt sensor to my alarm as can set it up easily with bike on the side stand so goes off if the bike moves less than 1mm.
https://www.ebay.co.uk/itm/Tilt-Switch-module-sensor-for-security-applications-motorbike-caravan-alarm/283171094902?hash=item41ee500176:g:bq4AAOSwawBbYKty

This is the alarm I have fitted, excellent alarm for the money and very loud.
https://www.ebay.co.uk/itm/EASY-FIT-Motorcycle-Motorbike-bike-Scooter-Trike-Quad-Alarm-2-wire-connection/191021841479?hash=item2c79c9fc47:g:SdcAAOSwk4RcNMLs

I keep my DT outside till building a new garage, this is the ground anchor I use with a 16mm chain and never had any problems with bike outside for over a year. I use a cheap alarm with an additonal motion sensor that was an extra £5, will find the link for you. Very sensative tilt sensor but doesn't go off in the wind, tilt sensor fully adjustable.
https://www.ebay.co.uk/itm/Oxford-Brute-Force-Motorcycle-Scooter-Ground-Wall-Anchor-Bike-Sold-Secure-LK397/253702132696?epid=1205376285&hash=item3b11d353d8:g:OmgAAOSw6AlbNLUD

Previously fitted a PWK 32 carb to a 2003 dt and the carb is quite small pictured next to a Mikuni TM 30. Fitted it to a modified 2003 dt inlet manifold, throttle cable outer needs shortening by 30mm carb end and with a warm air filter rubber fits over.

Hi, was bored and honed by Mick Abbey to 137cc but still has rebores left.

I've got my latest DT project outside till get round to starting on it but have no worries about being stolen, have 3 chains on it with largest chain on rear wheel through ground anchor.

@Calum yes got the head but knackered and yes the porting is not much better than standard 3mb barrel. Got a 4FU barrel with powervalve and better porting but snapped ring ruined the nikasil plating so needs a sleeve or repair and replate.

HI, ALL SOLD NOW..

Hi, Have a ported Athena 170 kit for sale if anyone is interested with a brand new 34mm carb and full Athena 170 exhaust with it. The cylinder has widened exhaust port along with modified transfer ports, comes with an alloy base spacer as cylinder has had 1.3mm machined off the top of it to alter the port timings for more power. The base spacer must be fitted along with a standard base gasket as if the spacer is not fitted the piston will hit the head due to the narrow squish band. The cylinder has done 3,000 miles mainly green laning and plenty of wheelies which it does very easily, the chrome bore is mint and has a brand new pair of piston rings with it that cost £80. Has a brand new 34mm PWK carb with it jetted to suit and spare jets with it, has an Athena 170 steel expansion chamber and Athena 170 silencer. Exhaust has a small dent in it and could do with a coat of paint on it to tidy it up. Very quick as it has the extra 170cc torque as well as revving to 11,000.
Message me if interested. cheers Terry.

Hi, if you send me your postcode can get you a price for tracked delivery, think the price is about the same as posting in the uk. cheers Terry

I've got my latest DT project outside till get round to starting on it but have no worries about being stolen, have 3 chains on it with largest chain on rear wheel through ground anchor.

@Oisin cost me more than £125 so looking for £175 & postage.

Open to offers, cheers Terry

Hi, was bored and honed by Mick Abbey to 137cc but still has rebores left.

I have a mint condition cylinder from a 2003 that has been rebored and honed by Mick Abbey and with a new Mitaka Piston Kit, will post some photos if your interested. Has a full gasket kit with it.

Team BARacing. https://www.facebook.com/groups/1491149367841270/

@valtteri Within a band of 2000 RPM centered around their resonant RPM they serve to absorb and give back pressure. When the intake port or reed valve closes there is a pressure created by the sudden stopping of the fuel/air flow from the carb. Some of that pressure enters the boost bottle and then exits back in perfect harmony with the intake opening at the YEIS systems resonant RPM. At all other RPM it does so with less force the farther away the RPM is from the systems resonance.

The YEIS is one of the ideal mechanisms that permit improvements of performance and fuel economy in the low and medium speed, part throttle operation of the two-stroke engine."
Pressure variation in the intake tract is more at low RPM than it is at high RPM, therefore the effect of the YEIS is much less at high RPM. Also it has more effect at partial throttle than at full throttle because the pressure variations in the intake manifold are more at partial throttle.

So running both bottles actualy gain in Hp at the bottom end, on race Tzrs etc they are blocked off as do nothing for top end power but disrupt the fuel flow through the inlet tract. You can actualy gain about 1hp drilling the hole larger on the bottle on top of the inlet manifold, drill the hole in the bottle 2mm larger than the diameter of the hole then swill out the bottle with petrol.