based on nova engines

oOo.. i like jp now lol

I'd love to race 1/8s, always thought they look more purposeful, but no clubs near me race 8th scale nitros so theres little point for me

he daniz,i have a G4 to with a jp fx t03 full option on it .
its verry fast.

If you're still using the old G4 clutch, upgrade now! It will be faster and more consistent on the final. Have a good race with JP Racing Engines.

Guys, just some findings at the track yesterday...

Tried to retune engine according to your recommendations. Managed to get better low end out of corners into straights by richening HSN and leaning LSN slightly. But engine stalls when getting into corner/off throttle. Tried to increase idle considerably and restart engine but engine has difficulty in firing up. When fired up eventually, the engine sounds too lean and starters when apply throttle. When cool again, tried richening the low end again and increase idle until engine idles properly and out to track. Temp reading around 105-110 C. Bottom end suffers again with quite abit of smoke until a few laps when its already warmed up then delivery of low end is better. But engine stalls again when off throttle.

As some of you have mentioned - its really hard to get perfect tuning. Too lean and engine overheats. Too rich and engine bogs down until a few laps that it gets too hot and stalls. Has this got to do with the Head Clearance of 0.4mm shims, and plug no. 7 i'm running? I've ran a grand total of 25 tanks till now. Should i just remove 0.1 Head shim and run with the original 0.3 mm shim and start from there again? And if doesn't work try changing to plug 6? I just want my new JP to deliver good bottom end, without overheating and to idle properly.


Thanks.

I think try to seal your carburetor and check for any leak is the best move. Do you ever change your front bearing?

Daniz, this is a new engine. Just ran 25tanks! Do you mean that the carb is already leaking or do i have to change the front bearing so fast?? I hope not - if not this will be my first and last JP.

A sure tell tale sign of carb leaking and front bearing worn out is when you find lots of oil stain on the carb neck and on your chassis respectively.

Sometimes this can happen. Have you taken out and unscrew carb from the crankcase before? The process of putting it back in can somehow not be correct.

But there are no oil stains on the carb neck and chasis. the usual grime here and there but that's about it. I suspect the tuning is still not right? Any ideas?

It could be many things that have gone wrong. I assume the clutch is set correct? If it's not, you could also overheat the engine when the clutch overheats causing the carb to overheat as well.

I also think that the head clearance may be too much with 0.4 mm shims. Check the total head clearance with shims. You should typically aim at about 0.5 to 0.6 mm at most for ideal performance. This may end up using the stock 0.3 mm aluminum shim or you may end up with even less at 0.1 mm or 0.2 mm to get you at those head clearance measurements.

Anyway, when you start to tune to race, always start with a small carb opening when the engine is idling at neutral position. Take out the carb insert and check the carb opening. It should be about 0.7 mm if I recall. A rough guide would be that the thickness of the flat tuning screw end should be the same as the carb opening.

Reset the needles to stock setting. Warm the car up about a tank or so around the track. Then start to race tune the engine. This is assuming your engine is broken in.

If you find difficulty in keeping the engine idling, try leaning the LSN bit by bit. You will come to a point where the engine idle will rise a bit. Stop and then richen the LSN by a 15 minutes.

Tune your HSN till you get crisp top end on the starter box first to get you in the ballpark. Slowly lean it bit by bit and try to listen to the engine revving. Put it on the track and try to run on the straightest part of the track. A few rounds and come in to check the engine idle and temp. Lean the HSN bit by bit and 5 minutes movements at a time. The engine should come in and idle should be steady and not idling erratically. If it is idling erratically, then richen the LSN. Test the engine out on the track till you're satisfied. Hope this helps.

I think maybe you needle setting are way out after all that messing, reset. The LSN is key here! do as InitialD says and you should have a good low speed setting, know your ready to start dialling in the high end again.
Also check out your clutch! a badly setup clutch will commonly give you the impression that you engine is running out of tune, to much slip could lead to over heating as InitialD mention, to tight + to early engagement your engine will bog down making you think it has no bottom end.

Thanks guys for more info.

Err...do you know where i can get the standard/factory needle settings for my JPfx12T05? I think its all over now

Here you go;

http://www.jpracing.com/ang/catalogu...ages_carbu.php

What do you mean all over now?

Thanks D for the URL!! That's gonna help me save this engine!!

'All over'? - what i meant was the needle settings have been messed up!