Hi, Can someone tell me the difference between the R-01 and the R-03 .21 engines. Are they close in H.P. and rpm.

R-01 is a 7 port engine, and the R-03 has 1 additional port which makes it an 8 port engine. Also you can install the R-03 piston/sleeve assy to an R-01 crankcase they are the same.

The two engines are identical except for the sleeve material. The R-01 is an aluminum sleeve (AAC) just like the old 421P from Novarossi. For some reason or another(longevity maybe) they discontinued the R-01. The R-02 is the 7 port version. Get an R-03 if you have a choice.

*I just checked the website and it says differently. BUT, going on my past experience and watching the JP motors that others around me have used I stand by my statement.

It is the R-02 which had the AAC set originally, but it's not available any more.
The biggiest difference between the R-01 and the R-03 is the underhead.
Go for the R-03 /w ceramic rear ball bearing if you can.

That is what I know too

Thanks for the info. I did look on the JP website and it looks like the top of the sleeve is different. Other than that they look the same.

Anybody know what the USD "best pricing" is on the JP engines listed below?

FX . 12 T-03
FX . 12 T-03M
FX . 12 T-03S
FX . 12 T-03T

Also, is there a noticeable difference in bottom end to mid range performance between the stock engine and the modified engines? How about between the 3 modified engines?

Thanks in advance,
Rainer

contact Howard Cho at http://www.teamtitan-ca.com he may help

The FX 12 T03 and T03M are the same, both are 3ports modified with EFRA legal spec.
The FX 12 T03T is the 3ports modified with IFMAR legal spec (tear drop on the crank)
The FX 12 T03S is the 3ports stock, which comes in hardcoated crank but none modified sleeve/piston

You should notice a big difference only at big/high traction track. For a small track the T03S is more than enough.

Hope it helps!

Thanks for the info Howard - and yes, it helps.

Correction there is no JPFXT03T it is JPFXT03MT

Then what's this??
http://www.jpracing.com/en/products/...s/fx12t03t.php

A TYPO ERROR
Where does it say JPFX 12T03M ?

Funny Sam.