JB COMP

me, I just did what the thread said. AB mods gets into port timing, and I don't know any of that. so I can't help you there.
but what I do is bevel the ports, and put guide ports and flow channles. just look at post #251, and you'll see what I do.

proptop

My Feedback: (8)

Basically, everything you need to know is right here in this thread already...

Jim...actually, the pressed in crank-pin is harder so it won't wear as fast. I personally don't care for pressed in crank-pins...they can and have pulled out under extreme circumstances with obvious disasterous results![X(]
I much prefer a 1 pc. crankshaft.

muggy breaker

how much porting is to much? i want to go as big as i can without making the ports to large.

JB COMP

Have you read all 14 pages of this thread?

proptop

My Feedback: (8)

Well...when we (or at least I am ) are talking about "porting" here (for the most part ) we are not actually enlarging the port openings, but smoothing out the flow path of the fuel/air mixture...that's what the talk of "flow channels:, "fangs" etc. is about.


Actual porting of the sleeve, when the port openings are changed, requires special tools and knowlege of how to use them...
Did you read all the way through this thread? (there should be all the pertinent information that you need to know in here...)

muggy breaker

ya i just read all of them so i get it. my flow channels are gonna get bigger.

colintrax

hey, I wanted to know what the stuff cut off said. I'am going to do it to my DTX.18, I've already polished the crank and did some practice on an old sleeve but noticed some stuff is cut off.
Thanks.

duckedup

Been a while since I checked this thread out....

Here's a NX76 I just did...

Before...


After... (horrible background color, I know..)


Crank before...

After

Before

After (nothing extreme..)



This is the cab I'll be using with the motor, it's from a stock MGT. I opened up both ends....
bottom, before..

after.. (not polished)

top, before..

after.. (polished, obviously..)




and check out the NX76 crank vs. OS12CV crank - slight size difference! LOL..



..and now I just need to throw this thing back together for a test run

ST-R

nice job

[markymark]

Theres a very similar article to this by Xrc cars a few years ago...Both tell you to do the same thing pretty much.

I'm wicked nervous to try it...

SAVAGEJIM

I highly suggest you practice on junk parts and engines you dont want anymore before you actually try to mod one you want to use. That way, when you are comfortable and confident enough, you can be assured you wont mess up (to badly).

j_blaze

what can be used to do a mirror polish like that? i always just used the brush but that looks much better.

SAVAGEJIM

I personally use the red dremel polishing compound, but there are better stuff out there. I also use Dremel's polishing kit, PN 684-01 (I think the red polishing compound comes with that kit). You can buy all this at Home Depot, Lowes, Walmat, and even Target, anywhere where Dremel rotary tools and Dremel accessories are sold.

The Winner

hi i am a noob on the mod of the engine! it will be my first time!but i know a lot about engines!i have a lrp z28r spec 3 and i want to make a little mod not to sculpt the shaft or the cylinder!a good polishing on the sleeve and the crankshaft will do any effections?

j_blaze

thanks, i got a new 27 to work on now and i want to polish the others i've done already. i saw on tnt mods they explain the importance of the mirror finish.

duckedup

I use Mothers polish, w/ a few different polishing bits (Dremel), not sure of the part #'s though...

SAVAGEJIM

Unfortunately, no. It is actually up for debate by many if the polishing will actually help fluidd flow; I personnnally think it will because it promotes laminar flow. However, to really get some power gains, altering the timing profiles is a must. The polishing will provide very little, if any, performance gains.

j_blaze

that will be my next project.

The Winner

yes but the lrp is a factory mod engine!and if i mod much more will be at his limit!but first i will try at my old engine(gx-21) and then at the lrp!

duckedup

I haven't messed with timing yet, I will eventually, just not comfortable with it yet... I did however notice quite a power difference after P/P my SH P6 (mostly low end) and I didn't mess with timing on that one... So, you can get noticeable results without changing timing, just not as drastic.

j_blaze

ok, had the ported 25 out today and the front bearing went bad (after making some crazy long jumps). it was making a loud "chirping" sound once in a while, then all the time. i've ported 3 engines and this is the first time this happened, engine just completed its 2nd gallon. oh, its a rtr taiwan engine CY25. questions:

does the scallop on the counter weight affect the balance internally?
should i take some off the piston or con rod as well for balance?
would this slight loss of balance damage the front bearing?
how do i get that bearing off, is it heat from stove then it drops out?

heres what i got

SAVAGEJIM

No, it should not, not where you cut it and ho small your turbo scallops are. I dont think you affected your harmonics much at all.

j_blaze

it may have been the clutchbell bearing, still investigating...

j_blaze

nope, it was the clutch bearing. never had one make that noise before, usually they just stick and make the wheels turn.

i modded the .27 (power racing made by toki) with long fangs that go all the way to the bottom of the sleeve. i rounded the bottom of the sleeve again but only directly below the ports. also i cut the fang at the back of the combustion chamber. took about 15 minutes plus 15 minutes of disassembly and reassembly. the 1/2 hour was totally worth it. i had the 27 in my buggy last weekend and was clearing a 30ft jump with about a 20ft run-up. previously i could only make it about 3 feet short and land on the rise. i say i added about 6 feet to the jump distance after the mod. i ran the engine for a full gallon before the mod and even slightly lean could only jump about 27 feet. this is the same engine i did the "drake" break-in on that is in the november xrc mag, pg 36. i plan to get an sts d21b and try this mod on it and see how it goes. today i had the 27 in my truggy and it too was clearing a 30ft jump at another track, this is all too cool.

JB COMP

Ok need alittle help.

I have a STS 21B that I want to mod (somtime don't know when) but I don't know how to mod the 2 little ports (see pictures below, there the ones the aeros are pointing to)