HELP! Slow after new kit

[infuser599]

Long story short bike got stolen but got my racing carb and 36 tooth sprocket back. I got a new kit put it on another 26 inch cruiser but it's super slow I did everything the same as I did on my old bike I used to be able to do 35 cruising and top out at about 40+ now maybe 25? It runs good for the first 5-10 seconds of a cold start but then rpms drop and it kinda boggs at full throttle I've removed the baffle like on my old bike like I said everything the same but running kinda bad.. Maybe running a little rich? I put a little more oil just for the break in but cmon. Also it doesn't sound like it's firing every rotation at higher rpm I tried my friends spark plug and his runs good and made almost no difference. I'm running out of ideas I've tried almost everything I can think of.

 

[Agreen]

Extra oil in the mix makes it more lean.

Not firing every revolution is the sound of 4 stroking, and that's too rich.

Bogging down at WOT is too lean.

Does is make a sharp bra-ap-ap-ap-ap when you nail the throttle, or does it just kind of die off?

 

[infuser599]

It's making the sharp brap and won't get past a certain rpm like it has a rev limiter

 

[infuser599]

Just watched a video in 4 stroking definitely the sound it's making

 

[crassius]

I used to get motors many years ago that ran really rich until they ran in for 50 to 70 miles - if you lean it out, be sure to keep an eye on it so it doesn't get too lean later when rings seat better.

 

[infuser599]

Whats going to be the best way to lean it out?

 

[infuser599]

also why would my idle screw not be working? has no effect on the idle at all

 

[crassius]

idle screw all the way in usually means too rich also - drop the needle down to get it leaner

 

[infuser599]

I have a racing carb, does it have a needle? the throttle line connects to a slide. I've never taken the racing carb fully apart before. I was using the stock carb until the float got stuck and flooded and wouldn't even run

 

[crassius]

bummer, you'll have to look up your carb and see if it can be adjusted easily

 

[Agreen]

"Racing carb" means absolutely nothing. I can sell racing cockroaches and not be lying.

I'd need to know what kind of carb it is before giving a correct answer.

Generally, there's a metering rod, or needle, that is for part throttle tuning. For wide open throttle, the main jet either needs to be soldered and re drilled, or replaced with a smaller one.

 

[infuser599]

Took both stock and racing carb completely apart tried both jets on both carbs. The racing carb still 4 stroked and the stock carb ran like crap and when WOT it would stop running. Then I tried an extra Cdi I had didnt make a difference. Any other ideas?

 

[infuser599]

And when I had the stock carb on i moved the clip on the needle up and down on every knoch and no difference. What jet would you recommend for the racing carb?

 

[Agreen]

You have to know which jet is in there first. Usually it's a 72 (I think ). You can buy a jet kit, or if you have a propane torch and some solder, you can buy some micro drill bits and change the jet size yourself.

 

[Agreen]

Tuning the NT carb:
https://youtu.be/l0s-aCPJf4c

Re-jetting the NT carb
https://youtu.be/PerfQbB45O0

The application should be similar for others.

 

[infuser599]

I dont think its a the carb anymore because both of mine made it 4 stroke. is it possible its a spark issue not the carb? even just motor break in

 

[crassius]

part of it could be break-in, but I suspect you've somehow gotten your standard carb out of tune - the 'racing' carb is hard to tune on a modified motor, and rarely works well on a standard motor - the standard carb should show a difference when the needle is changed

if you could borrow a good working carb from someone near you, it would tell a lot about what's going on

 

[infuser599]

ill see if my friend would trade carbs for testing purposes and ill get back to you.

 

[Agreen]

Take a look at your spark plug. If it's wet, black, or has a gummy residue on it, it's too rich. If it's just a dry brown color, it's right on target. If it's white, chalky, or getting metallic flakes on it, too lean. Careful though, because the white color can just mean it hasn't gotten a color *yet*.

Another question... how many miles are on this engine? It's probably needing to be broken in first if it's still fresh out of the box. Remember, lean is mean! If you try to re jet the carb too soon (i.e. before it's broken in) you can risk damaging the engine. As the rings seat, it gains compression. That means it will result in a more complete burn of the fuel mix. So leaving it a little rich during break in is ok. You should not be riding it WOT for more than a few seconds at a time. Once you've ran a few tanks of gas through it, then you can consider re-jetting.

 

[infuser599]

ITS FIXED!! it was the carb i tried my friends and it worked perfectly grabbed my stock carb and took it apart put it back together (no idea what i did) put my carb on my bike and Bam works perfect going 40+mph again Thank you Everyone Who helped.