How to sort tune out on this engine

[DaveG28]

Ok had my first nitro run in nearly a year on Sunday and struggling to get the tune right on my OS speed.

Basically after playing I am now at the point where it:

1. Doesn't cut out at all, can idle and run etc no issues

2. At high speed is slightly rich (still some smoke on a long straight) but close to right, not far off at all

3. It has no low end pickup, it smokes and takes a long time to clear...the track basically had a slow half and fast half and was fine once it got uptisnpeed in the fast half, even at picking backup, but once well into the slow half lost all power and got eaten on the first fast straight before getting up to speed.

4. If I lean the hsn any more it no longer has any smoke at all on the straights

5. If I lean Lsn much more it holds on the throttle when I lift and idles high.

6. I am getting under 8 mins per tank!!


I am thinking I need to lean the lsn then reduce the idle...but always nervous about going lean!!

Anyone any suggestions!?

[reg]

If you have run the engine in with the same plug,i would change that first,
I always tuned the top end first,if you run the car flat out,it will clear all the lowend fuel so you are left with only the top end needle setting,forget if it boggs dowm to start with,it will because the low end,or iddle is rich,slowly tune the top end untill its nice and crisp,
then start to tune the bottom end,
everyone has there own way,but this always worked for me,
it could even be a clutch spring sticking making the clutch drag slightly so the engine isnt free to get reved up before the clutch kicks in.

[Ross]

Does this help.

I also wouldn't have any more than 1mm idle gap. You want to richen the LSN drop idle, but make sure first the idle gap is correct.

[Chris-S]

I'd change the plug to start with. Also go round and check for any leaks, so split fuel line, tank not sealing properly, exhuast gaskets leaking.

What engine is it ?

Sounds like the low speed needle is very rich and the idle gap is wide to stop it cutting.

[mark christopher]

Originally Posted by Chris-S

I'd change the plug to start with. Also go round and check for any leaks, so split fuel line, tank not sealing properly, exhuast gaskets leaking.

What engine is it ?

Sounds like the low speed needle is very rich and the idle gap is wide to stop it cutting.

Clue...reread his 1st sentence

[mark christopher]

Sounds like hsn is about right but I'd richen 5 mins , lean bottom and drop idle, rich bottom needs high idle to prevent cuts. You won't knackers it going too lean on bottom, it will just baulk, if if does go rich, idle should drop down near instant off throttle

[DaveG28]

Cheers all, will try that, as I say happy to keep the top end a little rich, just want to recover the punch!

There is a chance there's a tank issue actually, the lid needs an extra push to seal and although its not leaking it's hard to guarantee air can't get in whilst that's the case!

[Chris-S]

Originally Posted by DaveG28

Cheers all, will try that, as I say happy to keep the top end a little rich, just want to recover the punch!

There is a chance there's a tank issue actually, the lid needs an extra push to seal and although its not leaking it's hard to guarantee air can't get in whilst that's the case!

I'd sort out the tank closing issue, mis-adjusted o-ring or some sort of flashing left behind in the lid/tank? Then pressure test it with a syringe in a bowl of water to see if there are any leaks.

[Kurtje]

The last thing you write is very important Only 8 minutes on a tank is not long enough. I had the same problem with the OS Speed XZB. Only got 7.30 on a tank, after getting the OS back to the standard idle gap and setting HSN and LSN I got runtimes of 10min + on the same track!

You have to make sure that the idle gap is between 0.5mm an 0.8mm, then tune op your HSN Needle and then the LSN needle.