Snatching below 4000rpm.

In the uk, at near enough sea level. Temperatures of around 15-20 celcius.

Current jetting is 168 main, stock 42 pilot, stock NCVU needle (was on fifth clip, worked down to third now as felt rich and rough idle) and 50 leak jet.

Whole top of airbox cut and both sides, baffle fully removed, putoline air filter over stock cage. Stock fuel screw at 1-3/4 out.

Bikes a supermoto.

So, there some basic info above. Bike runs well, ish, well no. I lie.

It feels very 'flat' past 7000rpm.

And anything below 4000rpm I get a lot of chain noise/vibes. The idle is also rough.

I've tried clips 3,4,5 on the needle. And felt third smoothed out the idle, and felt slightly crisper all over, idle still seems rough and it feels flat up top.

Any suggestions?

The snatching is driving me mad, it's not real bad just feels like I'm in a gear too high, I have to keep up over 4k rpm to avoid it!

Any suggestions?

Bad TPS?

Lean on pilot and rich on main?

Is a 168 main too large at sea level? Or am I expecting the bike to rev out more than it does.

Has zero hesitation, the snatching is my main issue!!:thumbsup:

Regret buying it currently, my xr400 is silky smooth in comparison!

Everything looks like you should be ok with the successes everyone else haves. I would spend $20 and change the stock needle to the NCVS needle. It just sounds like something is not quite right with your jetting and this is the only thing I can think of from what you have provided.

It isn't a XR400

There isn't much under 4K for chugging. Mine does the same thing.

The 450X is a race bike and likes to run, not trot.

Just my opnion though.

I was thinking that bond, but I feel I want to try and improve it at least.

And regarding the ncvs, this is very slightly different in the last 1/8 of travel and that is all, so is that going to be richer at 1/8 throttle? If that makes sense?

Check the jetting sticky.

46 Pilot Maybe. I went with a 48 and it help starting and idling.

Cheers

Is "snatching" a British term? Does that mean surging?

I would look at your pilot screw. I'm close to the same elevation and I have a 45 pilot and I'm over 2 turns out on the fuel screw. I've had to replace a pilot screw because I couldn't get it clean.

HAHAHA! I was thinking the same thing....In America snatch is a good thing, no?:worthy::lol::busted:

Anyway, if it's lurching or surging then the problem is jetting related. My 450X would pull like a freight train off idle to the limiter and my 450R will do the likewise....but the right needle is critical.:confused::thumbsup:

Checked the jetting sticky, but not many people are running the same needle so kinda throws it off. JD kits are big money once shipped over to here also, so going to try and work it out myself.

And I use the term snatching, in reference to the chain snatching.

It's sorta like surging, but it just feels like I'm in a gear too high. Which I don't think it should feel like at 3500rpm? Should it not sit quite nicely there?

It isn't a XR400

There isn't much under 4K for chugging. Mine does the same thing.

The 450X is a race bike and likes to run, not trot.

Just my opnion though.

I was thinking that bond, but I feel I want to try and improve it at least.

And regarding the ncvs, this is very slightly different in the last 1/8 of travel and that is all, so is that going to be richer at 1/8 throttle? If that makes sense?

I don't agree. My 2008 has more bottom end than any xr400 I've ever ridden. You should be able to get to smooth linear power from idle to 7k.

In the uk, at near enough sea level. Temperatures of around 15-20 celcius.

Current jetting is 168 main, stock 42 pilot, stock NCVU needle (was on fifth clip, worked down to third now as felt rich and rough idle) and 50 leak jet.

Whole top of airbox cut and both sides, baffle fully removed, putoline air filter over stock cage. Stock fuel screw at 1-3/4 out.

Bikes a supermoto.

So, there some basic info above. Bike runs well, ish, well no. I lie.

It feels very 'flat' past 7000rpm. IT WILL WITH THE STOCK HEADER AND PIPE.

And anything below 4000rpm I get a lot of chain noise/vibes. IT SHOULD RUN CLEAN DOWN TO 2500RPM, BUT ONLY AT VERY SMALL THROTTLE OPENINGS. YOU MIGHT HAVE TO ADD AN R&D FLOAT BOWL IF YOU WANT IT TO RUN SMOOTH DOWN THERE. STOCK PIPE ISSUE AGAIN TOO

The idle is also rough.

I've tried clips 3,4,5 on the needle. And felt third smoothed out the idle, and felt slightly crisper all over, idle still seems rough and it feels flat up top.

THE NEEDLE WILL ONLY HAVE A 'CURSORY' AFFECT ON THE IDLE. IDLE IS ALL ABOUT PILOT JET, HOT START WORKING, CHOKE WORKING, VACUUM SLIDE PLATE SEAL, AND FUEL SCREW ADJUSTMENT.

Any suggestions?

The snatching is driving me mad, it's not real bad just feels like I'm in a gear too high, I have to keep up over 4k rpm to avoid it!

Any suggestions?

Bad TPS?

Lean on pilot and rich on main?

Is a 168 main too large at sea level? Or am I expecting the bike to rev out more than it does.

Has zero hesitation, the snatching is my main issue!!:thumbsup:

Regret buying it currently, my xr400 is silky smooth in comparison!

You are going to have to be more specific with your term 'snatching'. You describe that raising rpms makes it go away. What about reducing throttle, reducing load, or anything else? Have you set your accelerator pump tuning?

Jetting only does so much. You cannot change the power band with jetting.

You can change WOT conditions for more power, partial throttle conditions for less hesitation, etc.

If you want a wider power band, you need to create one: cam, header, muffler, etc.

If you want cleaner running, you have to create it: R&D power bowl, better fuel screw, replace worn needle jet (not the needle, the jet it drops into, they wear out), get rid of the NCVU needle and go to S, adjust apump volume, squirt, duration etc.

People are saying the right needle, but an ncvs is VERY similair to an NCVU?

And snatching at constant throttle is undesirable when cruising at steady speed through town. .

Let me try to clarify the issue,

If I'm going into a town, say 30mph limit, top gear it wants to sit around 3500 rpm. At this speed it will not stay smooth revving. I suppose surging is the word, feels like a gear too high but I think it's due to poor set up.

Where as at constant throttle at higher revs (say 50mph I same gear) it will be smooth.

Never adjusted AP in any way, but that has no effect at constant throttle.

It is no way clean down to 2500rpm! Suring and snatching at the chain lots by this RPM.

Load appears to make no difference, although it seems worst going up hill (the wrong gear feeling this is)

Gotcha, jakescool1234. Worth a try for a different needle. Try it and if it helps you know you're on the right track.

Il order an ncvu needle tomorrow then! :thumbsup:

Like you say, worth a try.

And okay krannie, if it's an ECU Mapping/timing what are you saying?

I feel it's jetting causing the problem, just trying to explain it.

At same throttle and higher rpm it doesn't snatch.

Mine's supermoto as well with a slightly similar jetting setup, except I have a JD needle and I think a 45 pilot - at sea level. Mine runs smooth from idle to redline, but I won't even bother cruising under 4k. I don't get any surging, but the chain does make a lot more noise down there - just feels like too much load on the motor for cruising. I usually cruise around 5.5k if I can help it.

Have you tried unplugging your TPS for a test ride? I ride with mine unplugged because I was getting some bucking/snatching/surging at certain RPMs during steady throttle.

JD needles are known for seamless smoothness.....Good idea to try it with the TPS disco'd too.

What Elan said is bang on and the point I tried to make. Keep it over 5k

Yeah, I was paying attention to my revs this morning and I can't even imagine lugging my motor around 3k! I upshifted just to lower the revs, and the whole bike sounded like a wet fart :thumbsup:

Looks like I'm usually cruising around 6k - everything just sounds better at that engine speed, and there's power if I need it.

And when I say cruise, I'm talking like 40-45MPH roads where I'm usually in 3rd gear I think. If I jump on a highway, 60+MPH, I'll shift into 5th. I run 15/44 gearing.

Elan

In your original post you state, "baffle completely removed" Is that true? Gotta think this thing is stupid loud with the baffle out and that may be lowering the back pressure too much.

Just a thought, I'm no expert. Hell I'm the guy that put the throttle plate in upside down and rode it that way for years!

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