Originally Posted by
losi_racer
thanks, im going to give horizion a call tommrow.
Anyone have any tips on tuning this beast? i heard its hard and different to tune??
i idle thru 6 tanks of fuel today but ran out of light so i couldnt drive it so im going to drive it more tommrow. ill prob do like 3 tanks and slowly leaning it out then go ahead and start tuning.
most of the tuning comes in from the lsn ...its kinda reversed from most engines ...from what i understand ...i have not ran mine at race tune ...but have seen plenty of them at the track ...all temping at 180-210 and running good ....i will go out on a limb and say your not gonna touch the top end alot ....mostly the bottom ....will know more as i get more fuel on it
Originally Posted by
tristyn
I have had some major tuning issues with the GRP.21. I am no pro tuner so I could use some help. I have had some experience with the jammin jpx.21 &.28, os vspec & a few others with good results, but I am currently running the GRP.21 in buggy & GRP.28 in truggy (JAMMIN X1X CR & X2 TRUGGY) The GRP.28 tuned very easily but the .21 has been frustrating. The problem I have is that it seems like it is always running very fat off the bottom until it hits the mid. My current needle settings are aprox. 3 3/4 on HSN and 5 on LSN. If I lean out the top much more it continues to flame out. If I fatten the hsn back and lean out the lsn then it sounds lean and has little bottom end. I have tried to keep temps arround 190 -205. I run a fioroni turbo slider clutch, 13 tooth cb and a jammin jp3 or jp4 pipe(most the time the jp4 as it seems to help the bottom a little more. I have tried the c6 ,c5 ,c4 GRP plugs. I run BYRONS GEN2 30% and have tried running it with 1 extra shim and also stock shim set up. I have researched this thread and a lot of guys are running totally different needle settings. some say 3 1/2 hsn & 5 1/2 LSN & some are 6 hsn & 2 1/2 lsn. 2 1/2 lsn just seems way to lean and 6 to fat to even fire. Although when I called horizon hobbies for stock settings they gave me 6hsn & 2 1/2 lsn. HAVING 1 HECK OF A TIME WITH THIS ENGINE any thoughts or input would be appreciated. THANKS
you have your settings very close to stock ...someone said horizon=retards ...in an effort to dispell any rumor about stock needle settings ...i measured mine brand new out of the box ....never touched
hsn=3-1/2 turns out from bottom
lsn= 6 to 6-1/2 turns out from bottom
the lsn looks like another turn and it will fall out ....this being said when braking in ...i had to lean the lsn 1/2-3/4 of a turn and the hsn i left alone ...and could idle it for like hours ..again im not broke in yet so i wont know fully till i am ....also consider the fioroni clutch(which i ran my first full year of nitro ...they work ok and are low m/a ...but i had them cause some problems on the low end when i was running gotechs ....do you have all standard springs on it ? if so ...you may wanna try 1 standard in the front and 1 standard and 1 hard in the rear ...possibly even 1 hard up front and 1 standard and 1 hard in the rear ..also if youve been running them for longer than 3-5 races becuase you thought they never wear out ..trust me they do wear out allthough the shoes dont ...was just a thought ...also you may try an 053 pipe none efra as many have said it wakes the bottom up ...im breaking in with the grp 2053 then going directly to the 053 as it has less restriction ....hope that helped anyways ...later
