Paolo M

Actually where i go a little bit lean, it's kind on the edge this setup. 0.50 is good for me

Paolo

Paolo M

Killa,

beside DJ advise, i will add that you need to do several laps before tuning the engine on the track. The ZX12 have this particular thing with the tuning. If the very first laps the engine feel ok, it will be for sure lean a few laps later. The engine need some time to reach the operational temp. My advise, start a little bit rich on the top end, heat up the engine properly in the track (around 6 to 7 laps and then depending on the situation, lean it or rich it. Temp wise i cannot give it to you cause i don't meausre on sedan. The rule is: as long as the engine is fast, smoking and consistant performance, it does not matter the temp.

Paolo

quietstorm76

iTrader: (12)

Done! went up to .5mm didn't have the shims for .45mm. Performance seems better specifically bottom and mid-range but I'll see how it works on the track weekend. Thanks again

Gael L

iTrader: (3)

So the clutch should be ok then right? If it was the clutch then the problem would happen right from the start and not when the engine heats up?

Thanks
Gael

captian

gael
after all the help from paolo and dj you still need help i will be at the next test and tune and i will help you out . so you can keep running those nice lines

captian

oh
did not forget about the pics

Gael L

iTrader: (3)

Thanks Cap

My car felt pretty good on the track I just need to get the engine dialed and I think I will be good.I lost a lot of time on each lap due to the engine bogging the way it was.

Oh also one more thing to add is that if I come out of the corner and go half throttle it will not really bog. It is when I go wide open throttle that I have the problem.

Gael L

iTrader: (3)

Is it possible that my change in driving style can be contributing to the problem. I used to blip the throttle a lot but didn't like the way it unsettled the chassis. Now I let off a little earlier and just go half throttle through corners. Could this be causing the engine to load up?

Gael

captian

its hard to say with out seeing the car run . but with a good clutch set up and a better tune on you engine. you will be back in the fight.
i gotch ya

dj apolaro

I think that you just need to tune the motor properly. Also make sure that the carb is only being pulled to the needed opening and not past that. Oh and since when do we only go half throttle. j/k I know what you meant

Gael L

iTrader: (3)

What do you find works better blipping the throttle a lot through the track or being smooth on the trigger? I think I may be faster blipping the throttle but more consisntant being smooth on the throttle.

C Mike Hunt

A starting point for zx12 on 16% nitro would be -
0.4mm head shims
LSN 6 turns out- HSN 5 turns out- idle to suit
Clutch gap 0.6 to 0.7 - heavy spring- 1,2 to 1,4 mm preload
Do not over-gear first gear, let it rev.

As stated previously- be patient and let the motor warm up and the temp stabilise before tuning.

Hope this helps.

C Mike Hunt

This is with ambient about 25-30 deg celsius and a #6 plug.

Gael L

iTrader: (3)

Last year the motor ran great for me. It is this year that I am having slight problems. Trying to narrow down the source. Only changes I made were the conrod and bearings.

C Mike Hunt

One area to look for tuning problems is the low speed needle o-rings. They tend to be split easily by the sleeve. If a problem - fit the new ones with lots of rubber grease or teflon grease. (seal the whole end of the slide if necessary once you get the LSN set)
Also the possibility of air leaks on the back plate etc after the repairs.

New rod can increase compression - what is the shim stack dimension. Did you replace the head shims? They get distorted and hardened after fitting.

These motors are great once you get all the bits in place- but they are not too tolerant if the clutch, gearing or tuning is out of range. They are also thirsty when running strong. But when you get them right they run like a bat out of hell. Well worth the effort.