Two Stroke Racelab

James(UK) asked for a Battery Eliminator for his Crm250 bike and even though I've stopped making them a couple years back, I thought of making another bunch.  If you need one please message me for orders.  P.S The BEs will come with ring terminals for M6 screws. If you need another type of connectors please send me details and I'll do it for you. Thanks. Nick 

I've been working on some YPVS controllers for Pete(GB), Gavin(GB) and LES(CA) and I just found out a new exhaust valve curve that I want to share. Pete owns a Tz250H converted to an L (electronic power valve). I have a few TZ250 (mostly reverse twins) exhaust valve curves on the blog but the below one is new to me.

I repaired a TZ250 YPVS controller today that belongs to Dale(UK). It's from a 1987 TZ250T model and I came across another one unknown YPVS setting that I'm sharing below. This setting doesn't seem to do a lot and it's more like an "on-off" switch for the exhaust valves, as it starts opening the valves at 7.500rpm and it completes movement at about 8.000rpm. And here are a few photos from Dale's bike. Cheers.

Handmade main jet wrenches can now be purchased via my online store.   This tool can be used with all Keihin carburetors for Honda Rs125 - Rs250 bikes and Mikuni carburetors for Yamaha Tz125 - Tz250 bikes.  It will also fit almost all Keihin - Mikuni carbs with 6mm hex main jets. Main body of the tool is made of aluminum, it's longer than common jet wrenches as to better clear the carb bowl and features a knurled grip. 

ENEOS TZ250 Parginos(GR) and Lefevr Jr(GR) in the pics.

An ignition curve that I decrypted a few months back and I had completely forgot it's existence. It is out of a TZ250 5KE project that SEEL Racetec had prepared for Kurz GP racing team. Bike features were, one-off ramair box, one-off crank, one-off cylinders, featuring Rs250 NXA porting layout one-off titanium exhausts etc It's interesting to observe the similarities-differences  of the two selectable ignition maps and how they compare to stock RS-TZ250 ignition curves. Nevermind the notes written in Greek language... LOL.

Quick layout out of a Tz250 5KE kit cylinder ('01 model). Layout is for general view purposes only,  actual dimensions do not include port chamfering, cylinder radius etc., so they are quite accurate.  Main and auxiliary transfer ports are staggered as per the layout.  Height of the auxiliary exhaust ports is 10mm and width is 13.5mm. Main & auxiliary transfer ports have a width of 22mm & 21.2mm respectively. Boost port has a height of 13.4mm and a width of 16.7mm. Exhaust diameter at the flange is oval shaped at 37x39mm and distance from the piston is 53mm. Total height of the cylinder is 79mm, front and rear stud hole centres at about 96mm. 

Sakis Basilopoulos aka "Sakis, The Greek Guy". Just found and wanted to share this interesting commentary from   motopressnews.blogspot.com  (in greek language).

A nice looking Tz250U 3AK '88 model. Thinking of buying it though the asking price is a little bit on the high side but still is a nice and rare find. Sounds ready for a race as well... The reverse TZ250 models are the ones that really attracted some attention on Yamaha racing bikes. The engine is similar to previous TZ models but with the cylinders now reversed 180 degrees with the carbs in front and the exhausts exiting straight to the rear. Three models were released prior Yamaha started developing V2 engines. The '88 model is the first reverse TZ250U (3AK) '88. Then came the '89 Tz250W (3LC) '89, quite similar but with a few differences, like a newer design on the bodywork, more strengthened engine components, better brakes and powerjets on the carbs. Last reverse is the TZ250A (3TC) '90, with the major differences from the previous model being a smaller crankcase and 5'' rear wheel. This model win the Isle of Mann at an average of 185 Km/H...