• 232 GY6 Race bike

  • The GY6 platform will be the first officially supported engine family. Post here if you have a GY6! Let's see some pictures of your machine to determine the best installation methods down the road.
The GY6 platform will be the first officially supported engine family. Post here if you have a GY6! Let's see some pictures of your machine to determine the best installation methods down the road.
 #236  by 3strokeEngine
 Fri Dec 28, 2018 8:36 pm
Hey yall this is my 232cc gy6 race bike. Following the established conventions for making it run like a scalded dog I stuck the biggest possible engine in the smallest possible frame. The result is a 25 horsepower engine in a bike thats under 150 pounds. She'll outrun most cars in the 1/8th mile and give a lot of bikes a run for their money.

I got real short gearing for a 232 (15 x 37) but if you hold it wide and let it eat it'll do 75 mph at a little over 10k RPM, but this bike wasnt made for highway cruising. Longest trip its been on was about 50 miles non stop on 45-55 mph roads. With the oil cooler (which was taken off a Toyota supra's power steering pump) and 108 octane fuel, itll run around all day turning 6-8k RPM cruising with no heat or detonation issues.

Pictures:
https://imgur.com/a/0732Fr8
https://imgur.com/a/GOMSpgn
https://imgur.com/a/dDU8AfH

Here are the engine specs:
(Excuse me for using metric and freedom units here. mm is obviously millimeter and " is inches)

Bore: 67mm
Stroke: 66mm
Total displacement: 232cc
Combustion chamber volume: 18cc
In/Exh valve size: 30.5mm / 26.5mm
Piston dome volume: 1.5cc
Deck clearance: 0.015"
Head gasket thickness: 0.010"
Compression ratio: 13.4 : 1
Camshaft: Taida T300 "high rev"

T300 camshaft specs:
Intake lift: 0.314" 7.98mm
Exhaust lift: 0.254" 6.45mm
Intake duration @0.050: 229*
Exhaust duration @ 0.050: 215*
Intake centerline: 96* ATDC
Exhaust centerline: 94* BTDC
Lobe seperation angle: 95*
Intake open @0.050": 7* BTDC
Intake close @0.050": 42* ABDC
Exhaust open @0.050": 30* BBDC
Exhaust close @0.050": 5* ATDC
Overlap @0.050": 12*

Transmisson: Stock variator with 11 gram slider weights 842 powerlink belt. Stock rear pulley with stock contra spring. Hoca high friction clutch with blue clutch springs approx 5000 RPM Stall. 15 × 37 (2.47) Final drive ratio

Fuel: VP C12 108 octane leaded race gas
(Similar stoichiometric air/fuel ratio as pump gas @ 14.6:1)

Intake: 30mm CVK flatslide 125 main / 38 pilot jets, stock vacuum spring, needle clip in 2nd from richest position

Exhaust: 1-1/8 inch ID header pipe with straight through "glasspack" style muffler

Ignition: stock GY6 DC CDI box, timming is set around 28-29* BTDC which is 3-4 degress more than stock because I slotted the crank trigger to get some more timming in it. Assuming i go forward with the EFI setup i would put the crank trigger back to the stock 25* BTDC and control timing via software so i could have timming be advanced to maybe 30* BTDC@ 5k-8k RPM over X amount of throttle position then back the timming off to 25*BTDC or maybe even less @ 10k RPM to reduce pumping losses in the highend and still keep all the torque down low

Charging system: 11 pole stator with 3 phase regulator (AC magneto coil not used).


I'd love to run E85 instead of C12 so i could spend 2$ per gallon instead of 11$ per gallon but E85 from the pump is just too inconsistent with ethanol content to work with a carburetor with out rejetting everytime you fill up at a different station. Hopefully this is where EFI can come in :D

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