NC50 bogs at 25mph

So, my '80 NC50 runs fine until I hit 25. I've gotten 28 out of it before. Now, at 25, it bogs and seems like the engine loses power and drops down to 20. I'm running 40:1 mix with one of those clone carbs you get for $20 on eBay. I haven't noticed any smoke or anything out of the ordinary apart from the above description. Any ideas?

Re: NC50 bogs at 25mph

Jack Rutherford /

four strokin'?

Re: NC50 bogs at 25mph

You'll have to forgive me, but I believe so. I don't actually know what four stroking sounds like. New to this stuff.

Re: NC50 bogs at 25mph

Jack Rutherford /

check this out at 2:50.

Right at 2:56 is starts four stroking.

at 4:38 as well(edited)

Re: NC50 bogs at 25mph

Get rid of the clone carb, it is not designed for or tuned for your bike. The fact that it fits is where the similarities end.

Re: NC50 bogs at 25mph

That's a 10/4 on the four stroking, sir.

Re: NC50 bogs at 25mph

Mr. Rutherford seems to not have trouble with the carb, as it was per his recommendation, but what would you recommend?

Re: NC50 bogs at 25mph

Jack Rutherford /

Stock carb four strokes as well so what are you going to do.

Give it more air if you want.

If it only four strokes at full throttle going down hill then that's how it is supposed to work.

Think of when you go uphill and need more gas. If you eliminate all four stroking then that is not good. And don't think that by eliminating four stroking that it is going to gain any significant amount of speed. Maybe you'll go to 26 instead of 25.(edited)

Re: NC50 bogs at 25mph

Well nothing you buy that wasn't designed for the bike will be a "bolt on" regardless of whether it physically does bolt on. The jetting is off. You may be need to find new jets or play with jetting via soldering and precision drilling, air restriction by way of the air filter assembly, or both. Some clones operate fine enough because they don't all have absolute trash castings but whether the jets match your original carb is always questionable.

Re: NC50 bogs at 25mph

Ah. Getting more air. Fuel air mixture screw? Filter? Jet size? Again, forgive me for my naivety.

Re: NC50 bogs at 25mph

> DPC Ryan Wrote:

> -------------------------------------------------------

> Well nothing you buy that wasn't designed for the bike will be a "bolt

> on" regardless of whether it physically does bolt on. The jetting is

> off. You may be need to find new jets or play with jetting via soldering

> and precision drilling, air restriction by way of the air filter

> assembly, or both. Some clones operate fine enough because they don't

> all have absolute trash castings but whether the jets match your

> original carb is always questionable.

I apologize, you posted that right as I was posting my previous post.

Re: NC50 bogs at 25mph

Jack Rutherford /

I revised my previous post but they were meant to four stroke some in certain situations. See above.

You can change your air filter but remember too much air is bad. Your screw settings aren't going to do much and you need those right to start it so if you change them, you may be screwed on starting it.

Try a more free flowing air filter. Or maybe panty hose and a rubber band for now just to see.

or do as Ryan says and drip some solder into the main jet hole and re-drill it slightly smaller.(edited)

Re: NC50 bogs at 25mph

Alrighty. I'll do some playing around with it. It does four stroke downhill, which makes sense, but it definitely four strokes at full throttle on flat ground. Are you saying it's designed to four stroke at that point?

Didn't you mention to me (on YouTube) it runs a 75 main jet? I can replace it.(edited)

Re: NC50 bogs at 25mph

Jack Rutherford /

I think the stock jet on an nc50 is a 75. I'd have to double check. The stock jet on the clone carb may vary. You'll want to check its size with some micro drill bits.

There are other limiting factors as well. The stock exhaust is very restrictive. Even more restrictive if it is lined with a layer of carbon.(edited)

Re: NC50 bogs at 25mph

Oddly enough, just barbecued and repainted the exhausts of my two nc50s this weekend, so they should be clean.

I do have some other air filters around. Admittedly they are cheap, but I'm sure some of them are more restrictive tham others. I've replaced the jet on my other NC50 with an 80, and it didn't get above 15mph, so I went back to the one that came with the carb.

I'd like to get the top end I used to have, but not seize anything trying to do so.

Re: NC50 bogs at 25mph

I think I've got it figured out. Switched air filters. Back to running sweet and not four stroking at high revs. This is the air filter I switched to. You're right, I guess it wasn't getting enough air. Didn't want it to be the seals or something.

Re: NC50 bogs at 25mph

Careful with getting that saturated with oil residue. It doesn't have a paper element but it can still get coated with droplets of 2t and cause more restriction.

Re: NC50 bogs at 25mph

Jack Rutherford /

> Mac Patten Wrote:

> -------------------------------------------------------

> I think I've got it figured out. Switched air filters. Back to running

> sweet and not four stroking at high revs. This is the air filter I

> switched to. You're right, I guess it wasn't getting enough air. Didn't

> want it to be the seals or something.

If you have original seals, they probably are in need of changing.

Re: NC50 bogs at 25mph

Ryan, thanks for the tip. I haven't checked the air filter I took off to see if that could be an issue.

Mr. Rutherford, I actually have the seals as I thought they could be a contributing factor. I'm sure I'll be reverting to your videos for tips.

Re: NC50 bogs at 25mph

Most of my expresses have four stroked in the 25-27 mph range with stock carbs (i've had maybe 4 or 5 of them).

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