Port Matching, Porting And Trenching Two-Stroke Engine Cases

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hello , if you want to sell your crankcase 5bm ....but i live in france

Never understood trenching. Fuel mixture gets sucked by the piston and goes behind the piston. The piston pushes it trough the ports afterwards. What kind of use is flowing towards the transfers from the reed..... It never goes that way (except for the coanda one through exhaust resonance)

In general, a completely useless operation. No difference in power. Many have said it both in the ass feel and in the dyno.

Thanks for sharing all you have done and know. Have you or have you come across any data that would isolate the effect/gains of this wkrk by itself? Obviously the effect of enlarging the case area as part of the porting and trenching is hard to remove. Thx!

Thanks for sharing

Disposable ear plugs are great for sealing holes for filling, painting and even general penetrations in house floors for speaker wire etc. Especially good for small holes and pretty easy to remove even when painted.

Hi i watched you video on porting What I've done in the past is When you have gone to far strip the coating of 1mm wire and with a sharp knife cut it up 1mm 2mm Lengths Before you put JB on the case stick the wire sleeve in your casing with Super Glue then put JB over the case on the smoothing out you will see the tops that you glued in if you go to far then once finished you can touch each one you see with drill bit and refill over job done ✔ HOPE this helps you 👍 😊 then put heat and oil resistance Spray paint over the work to protect it 👍

Leave a rough finish on areas where fuel / air mix is travelling and polish exhaust till it's shiny. Rough surfaces help with atomization of your mixture and you want the exhaust to have the least amount of friction you can deliver.

When i do matching work i like to make my own gasket/spacer from some 2 or 3mm thick aluminium sheet i tap the holes with the same thread as the studs i the bolt it to the cylinder and match it to the cylinder while theyre together then ill take it off and bolt to the cases that have marking fluid or a bunch of permanent marker on the base area and scribe out my lines using the matched aluminium spacer/gasket its not a quick process but it allows you to get as close to a perfect match as possible it is good for a matched gasket making template ill generally make my bolt holes in my gaskets have zero slop in the holes so my studs thread into them slightly so theres no chance of it moving and encroaching on the transfer area. I know its an old video but someone might get some value out of this information🤷

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Reed valves don't like a lot of crank case volume. I know you can gain movement with the pipe effects, but with tight crank case volume with reed valves, the reeds tend to stay open longer as the larger volume of (elastic air) takes more time to develop a negative pressure to open the reeds. Wiith tighter crank case volume and reeds, the pipe should open the reeds earlier and keep them open longer.

"Porting" is a term for cylinder port modifications, not for the cases. It refers to the "port window" at the cylinder, much like a window on the side of a ship is called a port window.

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Doug Flannery calls it tunnel porting when match porting the case to cylinder. It makes a big difference in low end HP on snowmobile engine.

As far as i know, air from the intake doesn't go directly into the cylinder, but into the crankcase, only after the piston moves downwards, compresses the air and opens the ports will the air enter the cylinder. So that trenching thing is a waste of time and effort. Id rather make a smoother pathway between the crankcase and transfer ports than all of this.

Will what you're doing cause poor lubrication for the crank and Rod. Therefore premature engine failure?

Color the entire gasket surface, with the marker, then use a scribe-all or pick to make a fine, very accurate line to follow.

hello, is there any problem when I cleaned the crankcase of the old silicone, I scratched the crankcase where the silicone comes in, is there a problem

Is it advisable to use red rtv gasket maker instead of the stock gasket because my chainsaw is no longer made and it's impossible to find replacement parts!?