Flash IV

[bigluelok]

here is another problem that is going on with jiangwayne. http://totalruckus.com/phpBB3/viewtopic ... 10&t=43671

[Wheelman-111]

Greetings:

I daresay that JW's customer "Service" attitude is not the best. I had already read that thread about the Kymco 125 mis-match for some reason. I had an exhaust gasket shipped to me rattling around the V8 muffler box, and predictably that ceramic item fractured and failed in use. Instead of sending me another for the nominal cost incurred, they:

1: Tried to blame the user.
2: Took it back.
3: Specified the reason why no instructions accompany items they sell is for "liability" reasons.
4: Hid behind the "Special Price - No Warranty".

The Dio exhaust I purchased also had some fitment issues to the Elite. It bumped the turn signal until I cut/rotated it. Once again, they state they "never said it fits the Elite" despite emailed query responses to the contrary.

That said, JW has some good prices, if not screaming bargains. The best thing to do in my experience is to matter-of-factly state the issue and request redress. Once you start name-calling, your hope for a painless/quick resolution is vaporized.

[devenex]

90cc's!!! You're really going over the deep end now wheelman!

You don't think 8.4 gears are too short for that much displacement?

[Dakine]

You should try running 6.8 or 7.4 gears... I don't think you'd top out both of those gears. But yet again you are wheelman

[bakaracer]

You should try running 6.8 or 7.4 gears... I don't think you'd top out both of those gears. But yet again you are wheelman

Those gears are way to much for his setup.alot of guys in hawaii run those gears because its like the saying"when in rome do as the romans do" so everyone runs that same thing because the next guys runs that setup.with 8.4to1 gears you can get about a 70mph topspeed which is pretty good and plus you will get there fast and not take 2 miles to get to that speed.If anything 8to1 gears would be the most I would go.

[Wheelman-111]

Greetings:

Thanks, Bakaracer. That was my thinking as well, but it's good to know I'm not the only one.

Flash II ran with 7.8s, and while it was nice to boast speeds near 60 on fully kitted 65ccs, the compromise was not ideal in everyday street riding. Take-off performance was fair at best, and the runup to 55 took half a mile. Maybe a ZX pulley would improve the former, but top-end power, not gearing, was the limiting factor.

8.4s to 70MPH? Maybe, but it's going to take some RPM - not sure my JW 26 chamber is up to the task. It tops at 9600 with the very modestly ported Nikasil 78. I'll go for 90ccs worth of low-end torque and save my pennies for a PG Long someday. Meanwhile, quick-to-60 will be just fine. (Assuming I can even get it to start... )

[Ed: Ran the numbers. If the engine can be coaxed to 9600 RPM, I obtained theoretical top speeds between 71 and 82 MPH, plugging in different hypotheses for variator overdrive and either 90/90 or 3.50 rear tires. It seems Baka was right as usual. ]

Back to F4, tonight I traced and measured the Ruima ports:



From my huge Pile O' Base Gaskets and temporary All-Thread studs, I mocked up the bore. 2 0.85 base gaskets (= 1.7mm) left the piston just knocking the head. Adding a thinner 0.55 (total = 2.25) left me with clearance and the piston just clearing the bottom of the exhaust port without disengaging the top ring. Good enough?

I tried to measure squish with 1mm flux-core solder but failed to get a crush, maybe because it strayed from the piston rim. I'll try again before final assembly. How does one position the solder strand?

The shroud seems to fit this 51mm bore with the usual plug hole relocation issue. BTW Lynn at JiangWayne recognized the absence of cylinder studs and nuts was unfair and promised to "make arrangements" to ship me those ASAP. We'll see...

[Wheelman-111]

Greetings:

I paid more attention to the combustion chamber after I sorted out the Ruima/Ministroker base gasket question. With 2.25m of base gasket - the minimum from the combination of gasket thicknesses I had - the piston no longer kissed the head.

Measuring squish was a challenge: The piston has a very shallow dome. The head of this Ruima bore kit is cut with a very deep Hemispherical shape - evidently to provide sufficient chamber volume to compensate for the longer stroke and/or much larger-than-stock 51mm bore diameter.

Unlike every other head I've seen, here is no squish band in the head - at all - just a smooth continuous curve until it reaches the rim of the head gasket. This means the rim of the piston meets the head like this: /____\, rather than <___>. I was able to get the solder to crush only by spreading it clear across the bore - parallel to the wrist pin - but measurement was over such a short crush at the tip that it was not repeatable. I was getting everything from 0.7 to 0.9mm, smaller numbers nearer the solder tip obviously.

Added to that was the need to center carefully the head gasket. There was enough slop between its holes and the studs to permit considerable lop-sidedness. I dabbed some grease to keep it as close to centered as my eyeballs and fingers could produce.

[bakaracer]

push the solder to the wall of the cylinder to get the squish measurement. If its between 1mm to .6mm your good.don't run to high of a compression if using pump gas.engine knock is going to be hard to hear with the carb noise and exhaust noise.you will hear it better around 1/4 throttle if there is engine knock going on.for the mini stroke 135psi is about max for 92 octane pump gas.

[Wheelman-111]

Greetings:

Thanks Bak! For some reason my Snap-On compression tester (the only "quality' tool I own...) has taken a dump in bed. I may have to make yet another trip to Harbor Freight. *Sigh*.

I have a Keihin PWK 28 carb to try out. Funny thing is that the main jet with which it came is UN-Marked! It indexed at about a #54 - pretty tight - so perhaps a 140. Anyone with PWK experience can suggest a starting point for 90ccs of Ruima Power? (small pipe for now...)

[Trafficjamz]

Greetings:

Thanks Bak! For some reason my Snap-On compression tester (the only "quality' tool I own...) has taken a dump in bed. I may have to make yet another trip to Harbor Freight. *Sigh*.

Wheelman, you own a snap-on compression tester?

I Always thought your toolbox consisted of a rock, adjustable wrench, a stick, and maybe a screwdriver.

This totally changes what I imagine your toolbox to look like.

[Fishman43]

T-jamz is funny!

[bakaracer]

Greetings:

Thanks Bak! For some reason my Snap-On compression tester (the only "quality' tool I own...) has taken a dump in bed. I may have to make yet another trip to Harbor Freight. *Sigh*.

I have a Keihin PWK 28 carb to try out. Funny thing is that the main jet with which it came is UN-Marked! It indexed at about a #54 - pretty tight - so perhaps a 140. Anyone with PWK experience can suggest a starting point for 90ccs of Ruima Power? (small pipe for now...)

52 pilot and 135 main to start from

[Wheelman-111]

Greetings:

Jamz, thanks for the laugh, but you forgot the Rock. I'm now the proud owner of the Fabulous Harbor Freight $10 Special Compression Tester. Reads the same as Snap-On... when it used to work.

Bak, I'll try the unmarked 145 for breakin and see what CHT and Plug have to say. I'll keep the 135 at the ready. Forgot to check the Pilot - good idea!

[bakaracer]

keihin pwk 28 carbs come with 135 main 38 pilot jet from the factory with a jjh needle.

[Wheelman-111]

Greetings:

Predictably, the Pilot tube is also unmarked.

I used All-Thread studs temporarily to mock up the bore, perform clearance and squish measurements, and check compression with Mighty HF $10 tester last night.

A Bakaracer-prescribed 137 indicated but cranking was done with a battery that had sat on a shelf for a bit too long. It was showing 12.25V and only feebly turned the engine over for 8-10 slow spins. Suitably recharged for 12H on the HF Battery Maintainer, it provided lustier and sustained cranking to a cylinder with a few drops of oil sloshed around for good measure:

Hmmm, 150 dead-even. My only option is to thicken the base gasket stack by about 0.3mm, swapping one .55 for a .85. I believe that'll be too much loss of compression, and the piston port clearance is perfect at the moment. Flash II was a bit over-compressed but ran strong with an initial static reading of 175. I'm thinkin' I'll keep running Premium fuel. What say Ye?