when this floptest yields a leakdown of about 15 seconds , the engine is perfect .


do not oil the cylinder before leakdown test , it will change the results dramatically .

LOL! Yes, adding oil will make a "dead" engine appear to be much better than it is.

its a new engine

Hi All,

you are right M7H.
I set the HSN 1/8 rich because it was to lean (now it has 10 to 15 sec the higher idle) and than I lowered the idle and it was really perfect.

And I know what you meant "Only, it might be possible that the idle will be to low when your engine is not fully on operating temps"
After a cold start the idle is to low, but it is only a couple of rounds and than it is perfect.

Thanks a lot to all of you - my issue is now fixed and I have understood how it really works.

But I have as well seen that it is different from engine to engine. Some of them have these high - low idle fall down after 15sec others like the RBs not.

racer_hh

Your welcome!

The other engines your talking about also might have other small problems, like leakages, on which they will get some false air, maybe a bad front engine bearing, who knows....
Just focus on your own stuff, and get it running the best you can!...

Hi Racer_hh.

Nice work

You have set the HSN and LSN perfectly now. That means that you close to never, will have to tune the LSN ever again. All it takes is to adjust the HSN a little in or out if something isn't right during a race day or the next time, you are at a track.

If you want, you can make a temperature measurement now. That is when you engine is completely warm. Make the measurement with a ½ full tank. This is the right temperature for your engine/car/setup/track/driving style this specific day. Eg. on a colder day, other track, other gearing etc. etc. it may change a little.
You will find out that the temperature will change 8-15 degrees Celsius depending on how much fuel, you have in the tank. Full tank = richer setting = cooler temp - and visa versa.

You are up for a long happy racing career, now you took your time, and got to learn how those wonderfull engines work.

Cheers

Thanks much definitely a worthwhile read for a Newbie like myself; thanks for for the Thread

I have taken Rob's bible and converted it to Word format - easier to read, print, and carry in my opinion!

Hope this helps.

Bob

thats pretty cool


its Ron Paris r.i.p.

Not in any way shape or form to discount or defame Ronnie, I think I have found an error in the tuning bible. Has this been pointed out before?

"One tell tale sign of this is if after revving up the completely warmed up engine it tends to idle fast for a few seconds then drops to lower idle speed. If you start leaning the bottom end a little at a time [then repeat the revving up and idle test] and it takes longer before the idle drops your going in the right direction.""

I find that the longer the time until high idle drops it's too rich. If idle never comes down it's too lean or needing idle adjustment.. ?


Monty?? Help with this one.

if high idle takes a longer time to drop, it's not as rich as one which the high idle takes a lesser time to drop.

that is what he is saying , when the idle stays up in rpm then you are getting it close to proper tune with a leaner low speed , once it stays up at idle then you lower the idle rpm's until desired .


tuning is not easy , trust me . takes a while to figure it out and even then there are some mind boggling situations that you have to really use your kanoggen to figure out

the newer style cavity barrel with long needle nova carbs are even more fun

gday there houston,sorry to bother you bud,im running in a fms at the moment in my 808.everything is going sweet as,im only on my 5th tank and at the moment im sitting at 202degrees,i was just curious about my idle,when im running it idles sweet , if i come to a complete stop the idle is pretty high,then it drops back down when i take off,i know its still very early,any tips would be appreciated,cheers,burty.

dont eben worry about the idle at this point , you probably need to richen the low speed about 1/4 turn . big port engines love fuel and make power with it

thanks houston,i cant wait too open this baby up,long way to go yet,whats the ideal carb setting for the fms? im running super strong 9901,41029 mugen tight short header, sorry for all the questions,
cheers burty.