Help me get more power...

Well, this is essentially a brand new NT carb and I've had it apart several times. It's quite clean everywhere I can see.

If I could just solve this dying while idling with the engine hot, this bike would be much more rideable. I've warmed it up and used a spray bottle (water) on fog/mist and sprayed all over. No changes. It dies like I'm describing after it's really been worked hard.

Any thoughts would be greatly appreciated.

Tyler6357 said:

Hey, glad you figured out your jetting. It's unusual to need a jet that big for one of these little china girl engines but it really depends on things like the altitude and barometric pressure of where you live as well as the porting done to the engine. If the #80 works better use it!! The richest jet you can use and still get good performance the better it will be for the longevity of your engine. As far as the idle is concerned, usually idle problems are fixed by messing with the carb. Quite honestly, I haven't spent much time messing with NT carbs, I've been using an HT/ Dellorto Clone carb. The best advice I can give is to check your twist throttle cable and make sure it's springing back when you release it. Also, make sure that the slide is set low so that just a sliver of light shines through when it's at bottom throttle. Perhaps others here could better advise you on that.

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I'm essentially right at sea level. I did notice, with stock jet, when I was riding and pulling a heavy trailer a few weeks ago up a 2000' vertical climb on a logging road that as I got closer to the top of the road (4600' elevation), I started to be able to use full throttle. That makes sense, right? Because as you go up in elevation you have less barometric pressure so you need to jet down or you'll be too rich, right? For me, I must've just been getting into the elevation/baro pressure range where the stock jet (.065 from what I can see) was getting closer to the correct size. Hmm...

Is there a possibility that this engine just needs a 'bigger' carb? I probably have the throttle 1/3 open just to get it to idle. I have the idle screw all the way in and with the air filter off can see the slide adjusting up and down and see where it ends up. Seems quite high to me--then it even dies at idle when hot after being worked hard in spite of getting this much throttle at idle. Any thoughts?

Tyler6357 said:

It sounds like you need to adjust the throttle cable so that the slide will sit up higher at bottom throttle, The higher it sits the more gas will get in at bottom throttle and keep it going. Also, you should try running it with the air filter off just to test it. If the air filter is dirty it could block the proper amount of air flow. See if it will idle without the air filter.

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I've tried both of those things in the past. Neither made any difference. Just tried without the air filter a coupele of days ago and made zero difference.

waynesdata said:

First I did not have time to read every post. Wife having baby in two days. Someone may have posted most of what I am about to. Sorry guys you are going about this all wrong.

(1) How is your spark plug looking? This will tell give you a good idea of how your engine is running.

(2)
Vacuum and exhaust leaks make a massive difference in bottom end power. Many people on here have gone to bigger jets than gone back or smaller after finding a vacuum leak.

(3)
Make sure your engine is well attached to your bike. If you can grab the engine and get it to move that is a fail. Even a small move is a fail. Engine movement will limit power and cause engine mount bolts to snap or fall out over time.

(4)
Is the engine broken in? Get 500 miles on the engine before doing mods. First mod should be moving from break in mix to 32:1 You engine will be more smooth and make more power after break in and oil ratio change.

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1) It's one of those three prong plugs and it's looking a little black, but I've only been running 40:1 for a short time. I need to kill the engine when it running hard and pull the plug then instead of letting it idle first.

2) That makes sense. I've been very careful to make sure mating surface are flat before joining with a gasket and have sprayed misted water all over the engine trying to find a vacuum leak to no avail...arrghh.

3) Using a SBP jackshaft shift kit and that make the engine attachment to bike rock solid.

4) I might have 80-100 miles on it, so not broken in to that. I hear so many diffenent things on this. Guys that know also start at 24:1 for one tank then right to 40:1 too. I've probalby got 60+ miles at 16:1 and maybe 20 miles at 24:1 and just a few short miles at 40:1 now.