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Showing posts from November, 2013

Trying to get my messy desk under control.

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).

Piston to Cylinder Clearance.

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 fillers.

Bye bye till the next time. :)

Cylinder Honing

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 well oiled. Any type of thick …

Muriatic Acid for removing piston deposits from Nikasil Cylinders

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 form. Be careful that muriatic acid does not drip to the…