Powerland 420cc GAB 2.0

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bob58o

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I think the goal should be 0.011". Work on that.

I'll look into that. LOL (the ultimate blow-off response at work)

I've got bigger fish to fry. Like how do I plumb the nitrous to the manifold fitting and a separate fuel system to the power jet on the carb.

I've got to measure the size of this power jet.

I'm thinking a $20 aluminum puke tank/ catch can for a secondary fuel tank gravity feeding the power jet (air box side of throttle). I will cap off the the original source of fuel for the power jet (which is separate fitting into the bowl).

Thinking a solenoid in the line from the puke tank/ fuel tank will prevent me from running rich when not on the bottle. A button on the steering wheel will be convenient for the solenoid.

Thinking the shot will be small enough where I don't need a fuel pump. I have researched and maybe posted jet sizes and fuel psi for various size nitrous shots. I'll have to dig that up.

Then I'll just run the whip cream charger nitrous system to the pulse fitting on the manifold. Also mounted to the steering wheel so I can push both buttons while holding on to the wheel.

Simple wet system. Open the throttle, press and hold the left button to allow extra fuel, then press and hold the right button for the nitrous.

 

bob58o

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My favorite part!!!

I peeled the rest of the stickers off but wanted to post the name of the manufacturer on the sticker.

Chongqing Sanding General Power Machinery Co. Ltd
 

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bob58o

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I have installed a 35 pilot and 145 main. The installed jets it came with were 32 pilot and 122 main. The thread pitch for the power jet is M5 x 0.8 and appears to have a smaller oriffice than the 32 pilot jet (<0.0126”).

I guess I don’t have any jets between 122 and 145 of this style.
If the main was 1.22 mm and the pilot was 0.32mm (which it isn’t) the the total oriffice area would be 1.25 sq mm. Something like a 1.26 mm jet would do the same as the combined two if not using the power jet. The 145 jet has oriffice area of 1.65 sq mm.
More than 30% increase in oriffice area.

The 145 should be richer than the 122 main plus the power jet.
I might have to drill a few of the smaller jets to get some in the 125 - 140 range.
 

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bob58o

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Well I ordered the NR Flat-top Piston.
The info I had said 9cc for the dish on a stock 420cc piston (maybe 460cc?).

I milled 0.085" to take the chamber from 41cc to 29cc.
1cc reduction in volume for every 0.007" milled.

I have a 0.032" Thick x 90mm head gasket.

Piston "In the Hole" ~0.004".
90mm Bore
66mm Stroke
With 9cc dished piston 0.004" in the hole... 10.6 :1 SCR
With flat-top piston 0.004" in the hole... 13.1 :1 SCR

With a 0.063" Gasket I could get that 13 :1 down to around 11.5 :1.
A pair of 1cc (each) valve reliefs cut into the piston would get it to 11 :1 SCR.

I am still not 100% sure about the rod length. I think stock length should be 4.41", but I'll try to measure once I take this head back off. If this rod is longer, I'll be happy so use a shorter 4.41" to keep SCR down.

I'm scared to take the head off. I had some scares when torquing the head stud nuts. I used anti seize instead of ARP lube and thought I stripped every hole in the block. Wonder if I can remove the rod from without taking the piston out of the cylinder.
 

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I think I have some jets and I also still have my timing key from Vegas karts if you need them.
 

bob58o

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I think I have some jets and I also still have my timing key from Vegas karts if you need them.

I have already advanced my ignition timing to 31 degrees BTDC, but thank you so much!!!
A #6 key (not 6 degree key) took me from 25 to 31. An 8 degree key ( about same as #6 key) would do about the same.

Are your jets for the OKO carb? The hex jets? I bought a kit, but it skipped all the sizes from between 122 and 145. I might have already ordered some more jets. I need to check my recent purchases.

Yep from Rocky Mountain ATV / MC..
I ordered larger than 145, but need some in the 120 / 130 range.
They are like $2 each.

I’ve got lots of jets. Pilot jets, round jets, hex jets,... Still need more.
I can make a custom kit, picking out the ones I want. But I'm dumb and paid more for less.
https://www.amazon.com/gp/product/B071VZZSR9/ref=pe_2816780_288119290_em_1p_0_ti
 

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bob58o

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Oh man, I wasn't planning on 13:1 CR.
It has me thinking about E-85, Methanol, Nitromethane, or not using the flat-top piston at all.

Are those fuels worth the maintenance? For me, probably not.
But could probably be done easily.

145 jet on gas with 31 BTDC timing becomes ~215 jet on methanol with 36 BTDC timing.
145 jet on gas with 31 BTDC timing becomes ~260 jet on 20% nitro with 41? BTDC timing?

I figured you need 2.2 times methanol vs gas. So area of gas jet orifice x 2.2 = area of methanol jet orifice. Then I've read 20% nitro jetting needs a JET SIZE 20% bigger than methanol. So a 215 methanol jet becomes 215 x 1.2 = 258 Jet Size for 20% nitro???
Read it on the internet, so it must be true. LOL

A shorter rod (if one even exists), a Thicker gasket, or unneeded valve reliefs aren't sounding great right now. I need my head unmilled a few dozen thousandths. LOL

Maybe this flattop piston will become a paperweight.
 

bob58o

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Alright. I think I can use the 0.063" Gasket with Flat-top piston 0.004" in the hole.

29cc Chamber
90mm Bore
66mm Stroke
90mm x 0.063" Head Gasket
0cc Dish/Dome
0.004" Piston - Deck Clearance

11.54 :1 Static Compression Ratio

I wish I could find my dial gauge and stand!
The cam specs I found (which may be for lift at the valve with 1.1 :1 Rockers) say 215 degrees after top dead center for the 0.050" closing of the intake valve. Extrapolating to the seat, I added 39 degrees. So 254 degrees ATDC Intake seat closing, which is 74 degrees ABDC.

If I use 11.54 :1 SCR and a 4.41" Rod length with 73 - 74 ABDC Intake Valve Seat Closing....

I get around 8.5 :1 DCR, which from previous research leads me to believe I can run 93 octane. I may have to back off the timing a bit.



This is how you undo milling by spending more money on a gasket than you did on the milling.
http://www.bullfrogperformanceproducts.com/product-p/100.2062.htm
 

bob58o

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This slope is slippery and I'm not sure how far out I want to go.
A rod means I can get a cam. A cam and I'll probably want to remove the balance shaft. A Removing the balance shaft means I need to get it balanced. Cam will most likely require dual springs. Dual Springs will require SS valves. SS valves need new keepers and retainers. I'll most likely need stronger rocker arms. If I'm getting rocker arms, why not 1.2s or 1.3s. If getting ratio rockers, I need shorter cr-mo pushrods.

Next thing you know I've spent $150 on a rod, $150 to balance the rotating assembly, $150 on a cam, $200 on a flywheel, $200 on rocker arms, $30 on pushrods, $20 on valve springs, $75 on SS valves with retainers and keepers.

Maybe I'll just stick with the original plan laid out by Geoff @ VegasCargts on BuggiesGoneWild???

...I ran a stock rod and valves for ALONG time and ALOT of abuse. I didnt have 1 problem until the day I put a cam in it....
With regards to bang for buck, a 420 clone with the following mods will make 20-22hp and doesnt need a billet rod:

-Timing Key
-Ported & Milled Head
-28-32mm ATV/Motocycle Carb
-Header & Free Flowing Exhaust
-HD ValveSprings

Can be done for $400 including the engine.

-Geoff

-Geoff Warner
702-335-4002


-Advanced Timing Key Check
-35lb HD springs Check
-32mm Carb Check
-Milled and Ported Head Check
-Header Check


Do I build it? At the moment, I don't want to even use the Flattop Piston that is in the mail. I don't want to get a billet rod. I just want to wait for my crankshaft shims and put it back together.
 

bob58o

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Wait for your crankshaft shims and put it back together.

So we are in agreement then?

By the way... 0.010" is the minimum.
0.011" is still on the tight side.
0.012"-0.015" is ideal.
0.015"-0.020" is OK.

Over 0.025" is my like ex-girlfriend. LOL
Abusive, yeah lets say abusive. LOL :thumbsup:
 

bob58o

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I installed the 0.012" crankshaft shim. I put it on the PTO side of the crank. It sits between the balancer shaft gear (on the crank) and the side cover.

I measured endplay using my digital calipers. I measured in 4 places and my measurements ranged from 0.0125" to 0.0150".

This is proof. Subtraction is real! Subtraction by addition. You get less with more.

Going to call that within spec.
 

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bob58o

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Alrighty then...

Endplay fixed!

I found my lifters and pushrods, so I was able to set the lash.
I set it tight. How tight? I don't know, around zero, (less than preloaded, but close?) I really don't like these rocker arms for setting lash. I'm used to the 212 Hemi style rocker arms. These are just like the gx200 / 196cc Clone / Non-Hemi Predator Rockers. After learning how to set to zero lash by twisting the pushrod and checking compression, as done in the ARC video, I opened up the lash to about 0.006" on each.

I measured the pushrods. NR's site says Predator 420's take 7.00" Pushrods. Mine were about 6-33/64". Even after Milling 0.085" and using a head gasket about 0.010 - 0.015" thinner than stock, the pushrods are still short enough.

I was just basing that off of Jody's (slight downward angle on the pushrod side) rule of thumb. If I ever get Cr-Mo Pushrods, I will get the 6.54" ones. If I get the roller rockers, I might try the 6.44" ones.
 

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bob58o

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"Back lash in counter balance gears"???
http://www.pwctoday.com/showthread.php?t=127933

"However, when you turn the motor by hand with the Mag or PTO flywheel you can hear a distinct metal against metal knock sound coming from the crank area. It's most pronounced if you put either one of the pistons at the top of the cylinder then just rotate the flywheel back and forth just a little bit. Sounds to me like the rods are slopping around on the crank. The engine does turns freely and makes no grinding noise when turned by hand."

Piston slap?
Counter balance gear play?
 
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