Two Stroke Racelab

Ετοιμάστε τις διχρονίλες και ελάτε να κόψουμε τη πίτα μας για το καλό του νέου έτους. Μπόλικες εκπλήξεις - δώρα, διχρονοκουβέντα και μπυροποσία θα μας περιμένουν στο Pit Stop, τη Κυριακή 26 Ιανουαρίου. Περισσότερες λεπτομέρειες στο παρακάτω  ...θέμα.

Sakis and his Yamaha TZ350, last weekend at Homestead Miami.

Frits Overmars is a well known tuner and very knowledgeable on Aprilia 2T racing bikes. The below schematic with calculations, offers his point of view with a simplified exhaust concept that will give some basic exhaust dimensions to start working on.

The SPJ carb from a later RS125 bike can be fitted on an earlier NF4 bike without much issues. The carb collar is a tight fit though removing the carb from the frame looks to be much easier than the stock PJ due to the shorter body. The throttle cable fitment clears the frame nicely as well. Most probably just the fitment of the carb without a proper electronic conversion from later bikes doesn't worth the hassle and the cost but it can still be used nonetheless. 

Pickit is a family of programers for PIC microcontrollers, made by Microchip Technology. The latest version called PICkit3 features a 16-bit PIC24F processor and offers a useful & convenient way for either programming or debugging PIC and dsPIC microcontrollers. Accompanying the pickit3 and available for free download is a powerful graphical user interface called MPLAB Integrated Development Enviroment (IDE).  For the connection to the PC you only need a free USB port and the pickit can be connected to the target via a header and instantly used as an in circuit serial programming (ICSP) device.  Making a simple Google search for motorcycle projects using PIC microcontrollers, you will find lots of stuff like CDI units, Quick Shifters, Shift Lights etc. and sometimes these projects include the HEX files so you're ready to program and experiment with some PICs with the help of Pickit3. 

I have a lot of backordered expansion chambers and a lot of R&D left on a electronic gizmo that I'm working on. I'm trying my best, yet still, can't organize my schedule and keep up with the deadlines and I've left quite a few people disappointed. I'm currently fabricating some Battery Eliminators, modifying and repairing PGM and YPVS units for Marti(CY), Jason(MT), Yuri(IT), Antonio(SP) & Eddi(ZA).

Next in line in the  "Low Budget" cylinder repair articles, is measuring the piston to cylinder bore clearance. There are few tools out there but keeping the budget in mind, not all of them will suit our purposes.  Hence, a quick and easy way is to use piston fit fillers, something everyone should have in his toolbox. Piston fit fillers are cheap and very useful.  You will need 0.002, 0.0025 & 0.003 inch fillers as these will cover most of your needs.  You will have to measure the clearance on a 90 degree position in relation to the piston pin. Along the "boost" port is what I usually prefer. A 0.002 inch clearance is suggested for most engines (0.05mm) but consider going up to 0.003 inch (almost 0.08mm) as this will most probably save the race!  Also check :  a)   Muriatic acid for removing piston deposits from nikasil cylinder.   b)  Cylinder honing and a few more notes on piston fit fillers in the link below Piston fit fill...

Following the topic on using muriatic acid for removing piston deposits  from nikasil cylinders, next step is cylinder honing.  Cylinder honing can easily be done at our workshop and that's very useful, especially when there is no access to industrial tools and/ or machine shops. A honing tool can be sourced quite easily and there are two types of them, with hone balls or honing stones. For our two stroke engines only the pictured one with honing stones is suggested. This type of honing tool uses flat stones that are spring loaded from the tool shank. It is suggested to use 100mm honing stones or bigger as they come in a variety of lengths for various uses.  The honing tool should be used in conjunction with an electric drill. The tool shank is flexible so there is no need to precise position the electric drill with the cylinder. Compress the honing stones to insert them in the cylinder but first...  ...ensure that both the tool and cylinder are very we...

I like how Don from the  North American Two Stroke  forum refers to this acid, "Two Stroke Hone = Muriatic Acid". Muriatic acid can be used to remove aluminum deposits left on the nikasil plating after a piston seizure or any other engine damage. The process is very easy and straight forward and it only takes a few minutes.  You will need the following  a) Muriatic acid (obviously),  b) chemical resistant disposable gloves  c) and a couple cotton swabs.  Let's start with the cylinder. This one is from a Cagiva Mito 125cc bike that had a piston seizure in the past. There are a lot of piston deposits on the left hand side of the exhaust port that we need to remove.   Carefully dip the swab in the muriatic acid and gently rub the nikasil plating all over the damaged area of the cylinder. In a few seconds the piston deposits will react with the muriatic acid and start removing easily from the cylinder surface in a liquid...

It's been a while since I last took a photo of a PGM unit so here's a rare view, Walter's(IT) NXA unit. There were some issues with the unit that are now repaired... still checking the wiring loom though.