Porting cyls w/ racelogic template and 4mil short rod

[lms1977]

its a shame you don't have regular pistons to throw in so you can degree and port prior to boring in case you slip with the porting tools

[registered user]

I always grind the exh floor in a way to aid the ring in coming back in cyl , there is more to it than measurements I gave the op some measurements as a guidline

but what transpires in the tunnels and behind the sleeves is what matters, just remember when starting out less is more

you can put a small arc on the window floor to help the rings. but it sounds like the piston at bdc will be well below the exh floor. i see no reason to hog out the bottom portion of the exh to match the piston. what happens at the window is as important as the tunell imo

Edited January 24, 2014 by registered user

[registered user]

its a shame you don't have regular pistons to throw in so you can degree and port prior to boring in case you slip with the porting tools

thats not really a issue with sleeved cylinders. alittle slip wont hurt anything. even with plated cylinders its not a huge deal unless your slipping alot in the same area and put a big gouge in the plating. once you get a feel for the tool its pretty rare to slip

[lms1977]

I would still port before boring it just makes more sense IMO.

I have done it both ways but prefer to bore after I port it

 

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[registered user]

to you maybe it makes more sense. but not to me. do it how ever you feel comnfortable is what it boils down to

[sheerider11]

to you maybe it makes more sense. but not to me. do it how ever you feel comnfortable is what it boils down to

[sprinklerman]

 

to you maybe it makes more sense. but not to me. do it how ever you feel comnfortable is what it boils down to

I'm still waiting for "registered user" to post pictures of his work or dyno numbers substantiating some of his claims in other posts. ..no proof he has even done any porting or building of any sort.

 

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[camatv]

degree with your full setup on the motor.  base gaskets your going to use, you should probably order a few sets .,actual pistons your going to run,  dont forget to compensate for the pop up..  with the engine in mockup it will be very easy to use a degree wheel to get to where you need to be on the actual port timings.  now the rest..  that takes time and some real work.    try 192/ 128 timings first.  set width at 70-72% of bore. use nice gradual radius on the top of the exhaust port..  that will get you started.  leave the intake bridge stock width, you can add a lot to the intake roof height. DONT hog out the actual intake tunnel where the reeds sit.  you can go to high and break into water jacket easily.  open the exhaust port up a lot and match to the pipes flange size. 

 

back when i did a lot with the degree wheel i made a custom one with 0-190+ markings on it. to make things much easier and much less confusing than atdc and btdc..  now i have a program that i can input the rod length, stroke, deck height etc to give me really precise measurements.  makes things go easy as far as numbers are concerned   practice using the 90* tool before you drop it into the cylinders you want to use.

 

just some quick tips..

[Atomic Monkey]

Tonight I got 1 intake done. I used the template, but mostly left the center section width alone. I knife edged the center, and opened the rest of the intake to both compliment the reed flow, and the draft of the crank. Not sure if this is the right approach.

I have two seperate concerns with dropping the exhaust floor. 1- if I do, the overlap of the skirt @ TDC is very small (around 3.25mm). If I don't, maybe it could cause unwanted turbulance???

Will post a pic of the progress later

Edited January 25, 2014 by Atomic Monkey

[Young Guns Racing]

I applaude you taking the plunge, even more so doing this with pencil grinders, it aill take forever. But perhaps it is a good thing, slow and steady is best. Keep up the research and attempts, you don't have to chase big dyno numbers if what you get is what you wanted out of it. Plus u will have some self satisfaction in the work. Trust me there will be many errors before you get your tecniques where you want them.

 

I have 2 sets of stock jugs that are completely un usable, so I have been using them for triple exhaust port designs and playing with overly large boost ports. Not really leading anywhere at the moment but giving off a good basis at the potential of these cylinders.

 

Good luck with your work

[registered user]

i wouldnt drop the exh floor. you will gain nothing from it. but you might open a escape route from the pipe to crankcase, but you may already have that problem. put cylinders on and see if theres a hole under the skirt. if its small hole you should be ok, if its large hole you might want to reconsider what height you set the cylinders. but having no escape hole is the best

 

having a paper thin bridge is not a good idea but on the other hand i dont see a reason to keep a mile wide bridge either.

[Atomic Monkey]

I skipped the pencil grinders for the intake, and used a 1/4" with extended bits, only used the small flame and a straight. I probably won't drop the exhaust because what "Registered User" was talking about.

[Atomic Monkey]

Here's a couple pics. I still have a little work to do, going to flatten the floor, and blend the area around the boost a little better. Also need to raise the roof a little to clear the top reed stop.

[Atomic Monkey]

And unported for a reference

[trickedcarbine]

Coming along