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232 GY6 Race bike

PostPosted:Fri Dec 28, 2018 3:36 pm
by 3strokeEngine
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.


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

Re: 232 GY6 Race bike

PostPosted:Wed Jan 09, 2019 9:48 am
by Travis Nano
Awesome build! GY6 232's are wild. And I should mention that is a great example of how to post a build/compatibility thread. (y)