Hi, The GX range are designed as off-road motors. An on-road motor is a completely different kettle of fish all together. I really don't think you will find this motor at all suitable for on-road - not in a Serpent 1/8.
If any of the GX range were going to work in this application it would be the 7 Port with it's strong top end, which is what on-road motors are all about with the different gearing of the on-road cars.
Give it a try, but I think you will be dissapointed, and would be better off with a purpose built on-road motor from someone like Novarossi, RB or Mega IMO. On-road motors have completely different porting and power bands than off-road motors.
I know the GX is a much more economical option, but on road motors are in the higher price bracket because of the revs they pull, and the technology that is involved in making a motor that revs that hard even remotely reliable.
The Mega engines would most likely be the cheapest option for a club style on-road motor that will do the job.

try the nova header & see if it works, or go to your next on-road meet & ask around if anyone has a spare header that you could try to see if it will work !

& with the carb just set the idle gap at .7mm & tune to that as you don't need to touch the idle on the GX range once it's set, if your idle goes off there is usually a cause for this & adjusting the idle wont fix the problem, just check the idle gap each time you have the motor out. JMO
keep us informed on how u go

Hiya...thanks will set carb as mentioned. Will try a nova header with the pipe. I do normally run a sirio AAC onroad but since running on a smaller technical track over winter as nationals finished. Hence decided a gx 5r as read alot about it

no harm in givin it a go, they said the MG66 would be no good in a drag car but people here are have a ball at the rc drags

It will be an interesting experiment - let us know how it goes. The punch of the 5 Port might be a little hard on the drive chain, but it won't be slow off the mark !! If it's a really tight track with no long straights it might be cool.
I was picturing you running it on a full size track, where I think it would lack the top end to be competitive.
I guess my main concern was people bagging the motor on here later, when it was being used for something it wasn't designed for or intended for. Just me being paranoid, but you know how it goes on these forums sometimes

the GX-7R with long LSN, FEMCA 0801 pipe and an onroad header would be the best bet for onroad. even with all the above except using a 2072 pipe, you're going to have too much torque.

Just thought I'd let you guys know- as of this point I'm ordering all GX engines with long LSNs. We still have a fair amount of carbs and GX engines with the short LSN, so both will be available. When we exhaust GX engines w/ the short LSN, we will still have that LSN available separately.


MORE TO COME!!!

i best keep my shorties then. i dislike the longs cant find a good tune on em. but i can tune the shorts with ease.

Sounds good Trey!...Ive been running the LONG LSN for about a couple weeks now and it is DEFFINENTLY SMOOTHER!....Nice move on the changing the needles for the USA motors......

they are tricky!...BUT they WILL improve run times! and run great once you master the tune!...it sounds stupid but TRY them again and FOLLOW the tune guide that Grizz1 and Massive Modds and Flanno1 have posted!...it is easy once you figure it out!....THE WATER HOSE TUNING is PERFECT!

trey, sent you a pm.

Good call Trey. They do run better on the long needle. Just a matter of educating the masses now on the slight difference in tuning. I enclose a run-in / tuning guide with every motor that goes out the door, and find 99% of customers have no problems.

Good idea Grizz

Going to run it tomorrow if it not raining !!!!
Dont think torque would be a problem as we got two speed and alot of different gears ratio to play with....

thats kind of what i was thinking!...just make sure its PROPERLY run in!....and not a FRESH motor cause it will pop under all that RPMS, if not run in correctly!