Flash IV

[Wheelman-111]

Greetings:

Stacking gaskets. I have heard of custom spacers but don't know of a source to buy one @ 50mm. If you have such a source, let me know?

[Wheelman-111]

Greetings:

Used a single Dio base gasket and the piston just clears the bottom of the exhaust port. Timing and duration seem close enough. Two 1mm copper gaskets put compression back at 114. I may. Try 1.5 after break-in.

F4VTHeadGasket.jpg (141.87 KiB) Viewed 3225 times

Low-rev Kymco clutch, Polini Natural triplet, ZX rear pulley and 654 belt, and 35g in the big Vario to keep the revs low during break-in.

F4.2LBReady.jpg (38.86 KiB) Viewed 3224 times

Using 28:1 premix, and 60/158 jets. Oh and that Taz pipe that likes to make low end torque, for now.

F4.2_RReady.jpg (36.02 KiB) Viewed 3222 times

[Wheelman-111]

Greetings:

Home by 17:15. Ready to fire up F4.2 by 6PM. I'm getting quicker. Started in precisely 2 kicks, carb primed by unchecked oiltank. Full of oil from assembly lube, it smoked and smelled fantastic. But why was it continuing to smoke like Lindsey Lohan in Crack rehab? And why won't the carb respond to idle mixture adjustment?! Oops, forgot to shut down the choke...

I diid 3 heat cycles then an easy lap around the apartment complex, then a 10-minute cruise around the block. So far so good. Temps stayed surprisingly low - 200=250. The probe for the VDO gauge had come loose, and I JB welded it, so I do not trust the gauge readings completely. I may have to dig out an old spark plug probe...

[Wheelman-111]

Greetings:

Up to a whopping 30 minutes' run time - about 12 starts and cool-downs. Not much time since the Rebirth to play and tune. This one has an easy-going personality as currently set up - very much like the Nikasil, perhaps a bit stronger. My Q for today:

Running a pair of copper 1.12mm head gaskets. Copper is known for heat-conductivity. Anyone anticipate issues with a 2mm-thick band of the stuff encircling the combustion chamber.

I have yet to pull the spark plug to assess color. My VDO gauge reads ~250 but with its JB-Welded probe on a head nut it inspires little confidence in its accuracy. I may have to knuckle under and get a TrailTech or Vapor unit.

[Wheelman-111]

Greetings:

Popped the spark plug off tonight. It's coal-black, and kind of oily. Actually for now that's what I wanted. Considering how rich it looks, the temps are more believable, and I'm impressed it runs as clean and strong as it does. 158 main and 60 (!) pilot. I might start with lowering the needle a click... After a tankful or two.

[Wheelman-111]

Greetings:

Setup below. Still running 60/158 Pilot/Main in the OKO 28/30 carb. Spark plug is a BR9HIX Iridium. The Spark plug was very black, oily when pulled off after heat cycles, about 10-12 so far. Idles at ~200 F. After the first timid ride to do an errand, less than a mile away the plug was still pretty dark, but at least no longer oily. Temps stuck around 225-250 . Run time ~ 50 minutes total, about a half-tank of 25:1 HP-2 Synthetic premix burned.

So a bit longer ride tonight. All is well, throttle barely cracked open goes, 30 MPH at 6250 RPM. Temps still ~250. Run along like this for maybe 3 miles, varying throttle position 1/8 to 3/4, perhaps 1-2 seconds maximum time at the larger opening, thus gaining speed to maybe 35 at most, on and off-throttle.

However after an extended drone up the road at about 35mph, once again a stumble and reluctant to take throttle. Suddenly my suspect VDO has jumped to indicated 350, and it stalls. Smells hot, too.
What the phoque, sez I. Surely a 60 Pilot is big enough! Is the hot engine opening up a vacuum leak someplace? Can this be explained simply by insufficient run time for the challenge imposed??

Anyway, it started right back up and got me back home, albeit with little throttle applied. Some say a 2-stroke never runs right until it soft-seizes, but a stall in any circumstance sure doesn't inspire confidence for the next ride. Sheesh, the Italian bores were never this fussy!

[bakaracer]

check to see if those exhaust bolts are loose. same with the head bolts and intake bolts.spray carb clean on that oil plug to check for leak there.

[sanjuro]

Time for a Polini or Malossi jug.

[Wheelman-111]

Greetings:

Thanks, Bakaracer. I will indeed check to see that my nuts are tight. But assuming they are, could Steve of VT Cycles be correct that my 25:1 oil ratio makes the mixture too lean even for 60/158 jets?

He does have a point; the overheat occurred as soon as I cracked the throttle past 50%.
He went on to describe how some Hawai'ian brothers are running 50:1 and even less oil, albeit using Motul.

My plan, after checking my nuts, is to raise my needle (this is getting bawdier all the time...) so the main comes online sooner.

Also I'm converting to Motulism; drained the tank of its Blue HP-2 in favor of the crimson 800 stuff mixed at the conservative 33:1. I was sure I had a 160 but can't find it. Ya think the richer fuel and raised needle will be enough? Stay tuned!

[wiguy05]

What the phoque, sez I.

Time for a 4-stroke!

Best of luck, scooter brethren

[Bear45-70]

What the phoque, sez I.

Time for a 4-stroke!

Lazy mans way out!

Those great big carbs are a PIA at mid-range because the venturi and throttle bore are so big and a small air flow thru them makes them lazy in supplying enough fuel. IMHO, for the added 1/2 mph it is giving you, it just is just not worth the hassle. If you were doing land speed record runs then fine, but on a street machine, not in my world.

Yes, the 25 to 1 could have been leaning you out. Is raising the needle and dropping the oil ratio gonna cure it? Can't tell you. An EGT would probably prevent the seizing, a CHT is just to slow to show the temp raise. The carbs I ran were not slide carbs mainly because slide carbs are not truly performance carbs. They are mileage and low and mid-range performance enhancers. True performance carbs have a throttle valve and at most a mid-range fuel circuit, but a needle is at best a pain for mid-range tuning.

[losthope]

get a new thermocouple http://www.westach.com/

Also PM me your address and ill send you a 160 main if you like.

[Wheelman-111]

Greetings:

I couldn't find the thermocouple/wire on the Westach site. Thanks for the kind offer. PM sent.

[Wheelman-111]

Greetings:

All was tight, not a telltale trace of leakage anywhere. While I had the head off I checked the bore: smooth as ice. It didn't seize, just stalled.

Still disconcerted by heat spike, I raised the needle all the way. Spring and white retainer made a run for it, but I tracked them down. Re-oiled the UNI for good measure. Now running purple Motul. ( The blue HP-2 remaining in the fuel line mixed with the red in the tanks.)

Now it blubbers like Lindsay Lohan at a sentencing hearing, but temp never exceeded 275 on a 6-mile ride. Slows noticeably when throttle opened to 3/4, but that's the over-rich intention.

When the throttle is opened gradually, it's got decent power. I didn't exceed 40, but it got there pretty quick. RPM no more that 6700 to date. No further stalling.

Right at 1 hour's run time, about 15 miles. I'll get a few more miles before I lower the needle to #4 position. LostHope has generously offered me a 160, so there'll be more tinkering before I re-install the PG Long and really test.

[Bear45-70]

........................... Slows noticeably when throttle opened to 3/4, but that's the over-rich intention.

When the throttle is opened gradually, it's got decent power. I didn't exceed 40, but it got there pretty quick. RPM no more that 6700 to date. No further stalling.................................

That slow to accelerate with throttle thrown wide open is a sign of "TOO MUCH" carburetor. To much carb hurts low end and midrange will slightly boosting top end. The only cures are, slow application of throttle, smaller carb, or the best choice is a couple of smaller carbs. As a Holley tech told me many, many years at the Tulsa Nationals; "When it comes to carburetion, a lot of little holes is way better than a couple of big holes." He was impressed with my tri-power on my 428 CobraJet.