GX200 carb choice

B

Blue bandit

New member
Hi Guys maybe going to race my GX200 again
I have theese differents carbs to choose between

Tillotson 304wx
Genuine Honda GX390
Genuine Honda GX270
Genuine Mikuni 24mm flatslide

engine has following mods
runs gas octane 95
stock 196cc
flat top piston
gx160 thick headgasket
14cc cylinderhead milled 0,070/1,7mm, ported and installed 28,5mm/25mm SS valves with 26lb springs
shafted raceseng non-rollerrocker 1-1.3ratio
agk/isky 276lift 246duration camshaft
GX160 aluflywheel with 8 advance timing means= 28total
arc rod also of course.

I want the engine to rev high
Please tell what jettings you like to this differents carb
 
304 would be my choice. What stands out the most to me with your build is the 14cc head cut .070, that's a lot of compression for methanol much less 95 octane pump gas. You've got to be running into compression block unless your piston is way in the hole. How thick is the 160 head gasket? Either way I'd swap to methanol and put a 304 on it. Jmhop
 
IT will be 95 or 99V-power, so should I change piston to the stock dished and cut it flat to sit lower instead, or run double headgakset?
 
The 160 and 200 iron flywheels are not the same, the Aluminum flywheel from the GXV I do not know where it measures.
 
winnerscircle said:
I run 13.1:1 with methanol. Using .010 head gasket. .015 in hole. My new build is 13.3:1 and just about max out a GX200 build without resleve to 3" or lenght the bore.
Click to expand...

Exactly your on methanol not 95 pump gas, he's on pump gas. I'm running 15:1 2.90 bore stroker, with a oringed head on alcohol which is fine, I've actually successfully ran 17:1 it was just scetchy to me as hard as I run my motors I knew it was just a matter of time before something came out of it.
 
Unless you are given different information. We always put GX160 flywheels onto our GX200 to gain some advance.

GX160 31100-ZE1-000 Superseded to 31100- ZE1-010 25*
GX200 31100-ZE7-000 Superseded to 31100-ZE7-010
-------- 31100-ZL0-010 ----------------------------------- 20*
or he could have 31110-Z4M-000 GX160 UT2 @ 20*

The original poster states GX160 Aluminum Flywheel this came on the mower with blade brake right. GXV160
 
I don't know what you are getting at, The Gx160 has always had different ignition timing than the GX200 or do you disagree with that.

The after market manufacturers don't make specific flywheels for the GX160 that I know of, but many in the past were using the Alu flywheel from the GXV so that is my assumption.
 
If you find a GX160 that is not 25* usually a white plastic surround on the magnet, I will be surprised. As I have measured many 160 and 200's over the years.
 
@winnerscircle
It runs stock length Arc rod, I do also have an Arc flywheel but sits on another engine. but it is the GXV160 I have on it
 
winnerscircle said:
Stock lenght rod with t2 flat top piston puts it .035 in the hole 13101-z4m. A .020 over rod is .015 in the hole with the same piston but this rod gives 13.1:1 with 14cc head and .010 gasket. Oops that's on a GX 200, bore size the same but stroke is less on 160 so compression ratio would be less on 160
Click to expand...

on the GX 200, with your numbers, the compression ratio is 13.0-1.
On the GX 160, with your numbers, the compression ratio is 11.0-1.
 
Kart43 said:
Unless you are given different information. We always put GX160 flywheels onto our GX200 to gain some advance.

GX160 31100-ZE1-000 Superseded to 31100- ZE1-010 25*
GX200 31100-ZE7-000 Superseded to 31100-ZE7-010
-------- 31100-ZL0-010 ----------------------------------- 20*
or he could have 31110-Z4M-000 GX160 UT2 @ 20*




The original poster states GX160 Aluminum Flywheel this came on the mower with blade brake right. GXV160
Click to expand...


See above the latest models have 20* but alll previous models are as I stated.
 
winnerscircle said:
GX160 @ .015 in the hole +.020 rod yes, @std rod .035 in the hole 10.05:1
Click to expand...
the standard Rod would change it. I come up with a slightly different number than you, .05, hardly enough to worry about, but just for a way to critique my spreadsheet, what numbers are you using? I have 1.772 stroke, 2.677 bore and the hole in the head gasket at 2.70. With these numbers my spreadsheet calculates a compression ratio of 9.99. Are our numbers different or is my spreadsheet wrong?

From the desk of Al Nunley
Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory. (Al Nunley)
 
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