predator 420 jet with VC kit

[raydhd]

Originally Posted by rammunition361

how is it adjustable? and slo, i can tell when an engine is lean. it would run on choke but not off. no air leaks. runs ok on 45 so far but not perfect. i will get the adjustable kit.

It is a larger jet with a needle valve in it. Like other vehicles with carb adjustments. Wow 27" tires. That is a little more load on the cvt. Also what is your secondary set on. I am using B1 for a quick shift over.

[raydhd]

I bumped Shepard's thread of my fixed by him VC 3 circuit. It has an adjustable main jet. Prior to this I used the VC supplied 2 circuit unit that I also added an adjustable main jet. Both carbs run great from idle to 5600 rpm red line. The 3 circuit is somewhat smoother in the 2000-2500 rpm range. For tuning I keep going richer by a quarter of at a time until the engine starts to stumble and the throttle response goes away. back it off an eighth of a turn and it will run great and have super throttle response. The plug will read slightly on the rich side. For whatever reason this is what the clone likes to run with a modded stock type carb.

[slonomo]

If your clutches are not fully shifting, look to your secondary spring setting. Less preload will net you a quicker upshift. More preload will delay upshift. Also, using a stock spring is recommended, the aftermarket "torque spring" is not needed with a clone engine and will not work well. Some aftermarket torque springs are way too stiff and can actually shatter clutches.

Are you using a stock secondary spring?

[slonomo]

It could be the big tires holding you back. Do you have some smaller tires to put on there for a test? If not see if you can borrow a buddies set. Run the smaller tires with no other changes, do the black sharpie test, see what happens.

The 27" tires are quite a bit heavier and change the final drive ratio quite a bit. The engine may not have enough power to overcome that. Or....if the engine isn't running 100%, meaning the air/fuel ratio is off, you could be underpowered at the moment.

I would at the very least upgrade the clone carb to an adjustable one if you can get one. Me personally, I would upgrade to a 30mm Mikuni VM style carb. There are some decent ones available in the aftermarket, Mikuni copies, that seem to work quite well. The trick with the swap is the intake. You can find the correct rubber carb mount quite easily, but the intake side/air filter side is tricky with some carts. Requires some creativity to avoid clearance issues. The throttle cable also is a roadblock for many, but can be overcome with some research and some trial and error. I ended up using a bell crank setup on my engines which worked out fantastic. The hookups were actually quite easy once I figured out what works and what doesn't. Let me know if you need any help with that.

If you swap to a Mikuni, you'll be pleasantly surprised with the response and power. It's not going to add lots of HP, but the throttle response and crispness thoughout the rpm range is incredible.

[rammunition361]

I'm going to try tires first. I need to get the 27" mudlites off anyway. It's a road cart now. It shifts fine in neutral so I'm assuming that's the issue