Review of Mikuni VM and performance exhaust on Shineray XY250GY-6B

ricardoguitars · 07-03-2017, 11:59 AM

The carb was a plug and play swap, no modifications needed, I get better throttle response and easier cold starts, I no longer need the choke to start it in the mornings, it starts right away! The stock pilot jet is too small (20), it backfires a bit when decelerating, typical lean condition, I will get a 25 and a 30 to check which one works better; right now I'm trying with a 125 main jet, it seems to work fine but the bike is smoking a bit, its probably running rich at high RPMs, I will go down to 120 and see what happens.

The exhaust is the same you guys are using on your Hawks, I had to do the same little mods you do on your Hawks to make it fit, the frame is probably the same, the engine is the same Honda CG clone, aside from the head, this engine head is an OHC, additionally I had to cut one side of the rear mudguard to avoid the muffler touching plastic, I also heat wrapped the header, it got really hot without wrapping, the header got yellow because of the heat

after wrapping it runs cooler than the stock exhaust

It is on the loud side, car alarms go off on parking lots

but it won't hurt your ears, deep low note. I got a noticeable gain of power, it climbs RPMs faster, nothing crazy but appreciated, specially hill climbing and escaping from stupid cagers on their phones turning their cars on you

Megadan · 07-03-2017, 02:45 PM

I would say start with the 30 pilot. It's always safer to start on the richer side of things and work your way back. Obviously altitude and other conditions means what I run is apples to oranges, but I have a 30 on my OHV engine with a stock exhaust, and it is actually just a hair lean. I am installing a 32.5 this weekend to try it out.

The 120 main should be close. Don't forget about the half-step mains either like a 117.5 or 122.5 if you find yourself still needing to do a little fine tuning.

The exhaust should turn a nice golden/straw color. That's color shift from heat at work, and it's what stainless steel does.

Glad to hear that you like it so far. Once you get that carb dialed in, it should definitely be a bit more responsive and perky than it is now.

07-03-2017, 11:59 AM	#1
ricardoguitars Join Date: Jun 2016 Location: Costa Rica Posts: 82	Review of Mikuni VM and performance exhaust on Shineray XY250GY-6B The carb was a plug and play swap, no modifications needed, I get better throttle response and easier cold starts, I no longer need the choke to start it in the mornings, it starts right away! The stock pilot jet is too small (20), it backfires a bit when decelerating, typical lean condition, I will get a 25 and a 30 to check which one works better; right now I'm trying with a 125 main jet, it seems to work fine but the bike is smoking a bit, its probably running rich at high RPMs, I will go down to 120 and see what happens. The exhaust is the same you guys are using on your Hawks, I had to do the same little mods you do on your Hawks to make it fit, the frame is probably the same, the engine is the same Honda CG clone, aside from the head, this engine head is an OHC, additionally I had to cut one side of the rear mudguard to avoid the muffler touching plastic, I also heat wrapped the header, it got really hot without wrapping, the header got yellow because of the heat after wrapping it runs cooler than the stock exhaust It is on the loud side, car alarms go off on parking lots but it won't hurt your ears, deep low note. I got a noticeable gain of power, it climbs RPMs faster, nothing crazy but appreciated, specially hill climbing and escaping from stupid cagers on their phones turning their cars on you
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07-03-2017, 02:45 PM	#2
Megadan Join Date: Apr 2017 Location: Omaha, NE Posts: 7,986	I would say start with the 30 pilot. It's always safer to start on the richer side of things and work your way back. Obviously altitude and other conditions means what I run is apples to oranges, but I have a 30 on my OHV engine with a stock exhaust, and it is actually just a hair lean. I am installing a 32.5 this weekend to try it out. The 120 main should be close. Don't forget about the half-step mains either like a 117.5 or 122.5 if you find yourself still needing to do a little fine tuning. The exhaust should turn a nice golden/straw color. That's color shift from heat at work, and it's what stainless steel does. Glad to hear that you like it so far. Once you get that carb dialed in, it should definitely be a bit more responsive and perky than it is now. __________________ Hawk Information and Resource guide: http://www.chinariders.net/showthread.php?t=20331 2018 Hawk 250 - Full Mod list here. http://www.chinariders.net/showpost....62&postcount=1 2024 Royal Enfield Shotgun 650 https://chinariders.net/showthread.php?t=34124
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