Flash 5 Rises Like a Phoenix from the Ashes of F3

[Wheelman-111]

Greetings:

The spark plug wasn't chopped. It was sliced, diced and Tenderized.
Sinceriously, the reading was intended to reflect how close to correct the Pilot is, and it looks like it's where it needs to be. MMmmmm... Chocolate.

I guess I should rephrase my concern: Why should this engine NEED a Pilot as big as a 50 when the Corsa was running 45-48 in a bigger carb? I also found the Air Screw seems to like being around 1 turn out only, suggesting I could go even bigger to a 52. Am I sucking air someplace and tuning to that imperfection, or is 50 a "Typical" size for this cylinder, pipe and carb setup?

Baka I believe I understand about narrowing the powerband, but if the entire cylinder is raised, how does the Intake/Exhaust relationship change? It seems to me if both go up equally, their timing with respect to each other stays the same. What am I not getting?

[bakaracer]

Timing comes from the crank turn. With the port heigh the way it is now, malossi set it to be even port time equal to the rpm where it makes peak power. Raising the ports you add duration . More so to the intake since it sits lower to where the crank turns more due to rod angle snd location. Pistion movement is slower 20 deg before and after bottom dead center. It doesn't effect the exhaust port as much. So that .3mm base might move that intake duration another 3-4deg. The exhaust will move 1 up.

[Wheelman-111]

Greetings:

What an eloquent description; even Wheelman can understand. Funny how we see piston movement as linear in speed when it's anything but. Thanks, Bak.

I have inspected the engine up one side and down the other. (Without disassembly.) I see no trace of leaks, but I'm sick of wrenching for a while and haven't pulled the flywheel or even the shrouds to have a peek. The engine runs pretty well, 0-40 at 1/2 throttle or less with the expected first-run tuning glitches at 1/4 throttle - needs needle moved I suspect. But do I need to worry that a 50 Pilot completely A-Typical for this block?

[bakaracer]

yes its really easy to get the port timings out of sync and takes less than 1/2mm to do so. Did you retorque everything after your heat cycles and ride breakin? If air is being sucked in you won't see signs of leak. In some if not all cases, it happens under load when rpms are up. Double check those exhaust nuts.

[Wheelman-111]

Greetings:

Yes I know it's good practice to retorque. I won't be able to get to it until Thursday however. I may yank that stator off to see the right crank seal. The pipe joint looks real clean so far.

[kingkamehameha]

50 is big for a 26mm especially with your ported block. You live in a different spot than me so idk what works out there. So your saying it reaches peak rpm at iddle after only one turn out?

[Wheelman-111]

Greetings:

My OKO is a 24, not 26. I'm not sure if free-breathing porting increases or decreases demand from to Pilot, but yes, if I try to turn past 1-1/8 or so it starts to stumble badly. This suggests my 50 is small, if anything, and that's my worry.
I have a free evening Thursday, and I plan to pull the bucket, shrouds and retorque the head. Maybe pull the flywheel and peek at the R crank seal, along with careful search for signs of leakage somewhere. It's not running bad at all at part throttle, and the temps and (#9) plug are reassuring. Still, even running AVGas, I worry about roadside stranding.

[fastplastic]

What is ur compression at? Have u lowered it yet I haven't seen if added gaskets and retested tested yet

[Wheelman-111]

Greetings:

Compression is 175 PSI, or a hearty 11.9:1. I haven't added gaskets or hogged out the piston/head, and I'm not gonna. Lower compression generally means lower performance. Instead I opted for all the performance the Insane Aslylum Escapee Engineers hired by Malossi envisioned. We're running 50:50 AVGas with the requisite 32:1 Motul Synthetic instead.

[kingkamehameha]

d*** wheelman let me know when you go broke buyin that av gas haha

[Wheelman-111]

Greetings:

AVGas is $6.25 mixed 50:50 with Premium which in Deepinnaharta sells for ~$3.90. Add a liter Liter of Motul is $18/for 8 gallons of fuel. It works out to about $7.32 a gallon total. Plus the gas for the car for the 10-mile ride to Deepinnaharta Airport once a month or so.

[fastplastic]

As for jetting I belive ur compression even with 50/50 mix is still going to give u issues when lowered I belive u will find ur self close to where the coras was..... I'm sure others on here will tell me im wrong but I'm used to it

[bakaracer]

Greetings:

Compression is 175 PSI, or a hearty 11.9:1. I haven't added gaskets or hogged out the piston/head, and I'm not gonna. Lower compression generally means lower performance. Instead I opted for all the performance the Insane Aslylum Escapee Engineers hired by Malossi envisioned. We're running 50:50 AVGas with the requisite 32:1 Motul Synthetic instead.

Just to let you know, you cant use cylinder compression to get compression ratio. There is no formula to use cylinder compression to get compression ratio. To many variables that can change the numbers. If using your way of finding the CR that means a corsa or mhr is a 10.2to1 CR kit which its not. They are 13.5to1 kits

[kingkamehameha]

13.5 is insanely high most cars run 7:1 or 8:1. Performance engines sit right above 10:1

[eliteguy50]

13.5 is insanely high most cars run 7:1 or 8:1. Performance engines sit right above 10:1

Performance street engines designed for pump gas are 10:1ish. Race engines running race fuel are higher, 12-13 cr is not uncommon.

CR is simply a volume ratio, TDC volume and BDC volume.