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Showing posts from April, 2011

Aprilia Rs250

Spent a day on servicing an Aprilia Rs250 for Hari(GR). Quite a nice bike and very well designed.  I really like the bigger workspace in the engine over a Suzuki Rgv250. Handling is very promising for a dead stock bike though power delivery is quite linear for my taste.  Carbs are way rich for stock bikes at 270 (powerjet +55) for LH cylinder & 280 (powerjet +35) for RH cylinder. Ignition curve is a little bit retarded as well, it seems like even stock bikes would benefit from a couple degrees ignition advance. The expansion chamber dimensions would be fine with a few modifications & smaller lengths here and there plus lighter end cans. Speaking of weight, I also don't like the steel subframe on first models but I believe this can be changed easily. Overall, it still is one of the best 250cc street bikes out there. I think I must put it in my wishlist of 2stroke project bikes...

Woodruff key mod for Tzr250 1KT

This is a quick & dirty way of altering the base ignition advance on magneto type ignitions. By milling the woodruff key, you will be able to reposition the flywheel to an advanced or retarded position, hence altering the base ignition advance. The proper way of cutting the flywheel key is with a milling machine, though a coping saw and/ or a jewellers precision file will do the job as well. In the below photo, there is an example of a modified woodruff key for a Tzr250 1KT motorcycle near a stock one.  Remove as much material you need from the side of the woodruff key to advance the timing, Start with 0.1mm increments until you reach the desired ignition advance. Also, cut to a depth of 2.2mm (this measurements counts for most Yamaha 2stroke bikes) so you will ensure that the bottom face of the cutout is slightly below flush with the flywheel taper.  Reassemble the flywheel key and advance the flywheel anticlockwise until the slot sits against the cutout face of the woodruff key. 

Crm250 AR PGM unit

Currently trying to find a solution on accessing the main board of the Crm250 AR PGM unit ...without having to spent a week with removing black goo. The RC Valve circuit is positioned vertically on the main board, looks more similar to a pc motherboard rather than an old motorcycle ecu...  It seems like I'm getting close but replacing the malfunctioning parts is still major pita.  The AR unit in the photo, belongs to David (UK).  Thanks to all 2strokers that trust my services.  Cheers!

Tripoli circuit, racing 125-250cc category

Κατηγορία Racing στη Τρίπολη, στις 10 Απριλίου 2011.  Οι συμμετοχές λίγες αλλά αρκετό πάθος ακόμη στην κατηγορία. Αποτελέσματα:  1) #1 ΚΙΤΣΟΣ ΓΙΩΡΓΟΣ, 24:05.836 2) #42 ΛΕΦΕΒΡ ΑΝ∆ΡΕΑΣ, 24:12.508 3) #19 ΚΟΛΛΙΑΣ ΙΩΑΝΝΗΣ, 24:58.310 4) #9 ΑΥΛΩΝΙΤΗΣ ΙΑΣΩΝΑΣ, 24:36.502 5) #36 ΣΕΦΕΡΟΓΛΟΥ ΚΩΝΣΤΑΝΤΙΝΟΣ, 24:57.672 6) #5 ΧΡΟΝΟΠΟΥΛΟΣ ΣΤΡΑΤΟΣ, 24:12.625 Best Lap:  #1 ΚΙΤΣΟΣ ΓΙΩΡΓΟΣ, 00:59.051 at 128.024 Km/H. 

2strokes, going for a walk... Vol.II

Some friends were gathered to go for a walk and watch the Greek motorcycle racing champion (10/04/11). There is a 2 stroke scene in Greece, indeed! Rg500 x2 Rd350 x2 Ns400  Rgv250 vj21 Rgv250 vj22 Rs250  Tzr250 

Back on the road...

Finally managed to finish the fabrication of the exhausts and my Tzr250 is back on the road again.  The making of the exhausts was a long journey with many problems and disappointments though quite interesting and educational as well, not to mention that the first impressions riding the bike are kicking ass! More on that later...  I own many thanks to all my friends that helped through this construction, each on his own way. So many to mention but you know who you are! Thanks to all! 

Big thanks to CCSpecialty Porting Tools for supporting this blog.

CCSpecialty is the biggest supplier of 2stroke porting & polishing equipment.  They have everything related to engine porting, from hang-up motors and handpieces to carbide cutters and abrasives. If they don't have the proper porting tool for you, chances are you don't need it! Especially the #1MC right angle handpiece is the most recognizable porting tool among two stroke tuners.  Don't forget to check their links for quite a few interesting 2stroke related stuff . 

Safety lock wire

Lockwire is essential for securing parts on racing and track day conditions. It prevents parts from unintentionally falling off the bike due to vibration or other forces. On motorcycles, the most common safety lock wire is 0.8mm stainless steel but lighter-heavier gauges can be used as well depending on application (lighter gauge for grips, heavier gauge for bolts, springs etc). 

Jim Lomas factory tour

Handmade exhausts for Tzr250 1KT

Just finished the expansion chambers for my 1KT bike. My goal was performance, ground clearance and weight that order. It seems like they will do the job well.  For the construction I used 0.7mm mild steel and autogenous Tig welding. For the end cans, I'm going to try stainless steel, mostly for testing my skills rather than appearance...  The design is based on TSI spec exhausts for Rd500 (lower cylinders).  

The sexiest ECU unit...

These days I'm repairing a couple Nsr250 Mc28 PgmIV units for Peter(DE).  This is bar far the sexiest cdi ever been put on a two stroke bike...  Contrary to common belief, the memory card does not include the ignition advance but only part of it and some alterations here and there. If you trigger the PgmIV unit, you can run the bike even without the memory card slotted in! Though, I believe this is static advance you will be using... quite aggressive for most applications.