Tight spot in chain?

[Wilson]

Howdy peoples,
I recently picked myself up an NC30, and I've had a few opportunities to take her out for a ride (and I'm loving it!). When I'm cruising, though, I feel a regular pulse of power, every second or so at a rough guess.

At first I put it down to engine characteristics, not having ridden an NC before, and reading about its big bang firing.

But realistically, it's too slow to be from an engine that's turning over a few thousand times a minute. Is it a chain tight spot, then? Any ideas on how that can be rectified?

Cheers.

[MexicanGringo]

Most chains wear unevenly eventually, you can tell by rolling the bike forward a bit at a time, then pushing the chain up midway on the underside and compare its slack. You need to adjust the slack for the tightest spot, and this means having it too loose for the loose spots which means the chains slaps a bit.. When you say pulse, you mean a vibration or a surge of power? Not sure about the whole big bang thing tho, its a v4 firing 1-4-3-2 a cylinder at a time

[Cammo]

Not sure about the whole big bang thing tho, its a v4 firing 1-4-3-2 a cylinder at a time

That firing order is not quite correct.

2 cylinders fire together at a time.

[Wilson]

Most chains wear unevenly eventually, you can tell by rolling the bike forward a bit at a time, then pushing the chain up midway on the underside and compare its slack. You need to adjust the slack for the tightest spot, and this means having it too loose for the loose spots which means the chains slaps a bit.. When you say pulse, you mean a vibration or a surge of power? Not sure about the whole big bang thing tho, its a v4 firing 1-4-3-2 a cylinder at a time

Cheers. I'll roll it about and feel the tension to see if that gives any clues.

It doesn't feel like vibration at all. Just like an extra little boot of power every second (a mild boot, obviously, but noticable). I've not had this problem on my CBR250, even when the chain was worn enough to replace.

I was under the impression that the NC30 has an odd firing pattern of 90-180-90-270 that matched the RCs, and was different to what the VFR-Fs ran.

[CMSMJ1]

Not sure about the whole big bang thing tho, its a v4 firing 1-4-3-2 a cylinder at a time

That firing order is not quite correct.

2 cylinders fire together at a time.

It actually goes
bang bang bang bang bang bang

[MexicanGringo]

That firing order is not quite correct.

2 cylinders fire together at a time.

Looking at that diagram, it shows cyls 1 and 4 on the power stroke 90' apart, then 3 & 2 90' apart.. Thats still 2 separate power strokes for each 360 revolution.. Big bang is 2 power strokes at the same time?

[CMSMJ1]

big bang is anything other than a regular bang miss bang miss bang miss bang miss on a 4 cyl bike IMO.

the NC is effectively a 4 cyl firing as a twin - as per the above. bang bang miss miss bang bang miss miss

[Neosophist]

big bang is anything other than a regular bang miss bang miss bang miss bang miss on a 4 cyl bike IMO.

the NC is effectively a 4 cyl firing as a twin - as per the above. bang bang miss miss bang bang miss miss

I'd be inclined to agree.

Honda unveiled a revolutionary idea with a 1992 V4 that was timed to fire all four cylinders within 65-70 degrees of crankshaft rotation — the so-called "Big-Bang" engine. Along with a balance shaft that neutralized the single crankshaft engine's gyroscopic effects, the 1992 NSR500 was a breakthrough.

Current performance 4 stroke engines utilize the big bang firing order to create a recovery gap during which the rear tire regains traction.

A regular interval 4 cylinder engine fires every 180 degrees which can overwhelm the rear tire, and generally makes a slide harder to catch as well.

A standard big bang firing order places 2 cylinders firing simultaneously, similarly to a v-twin. The 2009 Yamaha R1 has instead an uneven bang firing order, where the crankshaft will fire thrice with 90 degrees of separation between the firings, will fire again after 270 degrees, and will start the process again after an additional 270 degrees rotation. The uneven bang is the same as a V4, where the VFR and 2009 R1 share the same firing orders.

[Cammo]

The uneven bang is the same as a V4, where the VFR and 2009 R1 share the same firing orders.

I don't think that's a similar comparison. An uneven firing order (Yamaha call it a 'crossplane' crank) is not the same as the nc30 firing order.

The nc30 firing order would be typically referred as a big bang firing order these days. The 2009 R1 has a 'long bang' uneven firing order. Many would remember the big bang 500cc gp bikes, I imagine they had 2 sets (of the 4 pistons) firing at even intervals (but they may not have as many incorporated a balance shaft - something you would want/need with an uneven firing engine!).

Big bang and uneven firing order engines will sacrifice some hp to a regular firing order engine. Period.

As CMSMJ1 says the best analogy to an nc30 firing order is as a v-twin but 2 cylinders firing together (instead of 1 in a v-twin).

Regardless, it's one of the traits (and the noise!) that I love about the nc30. I wouldn't have it any other way (unless g-force design a crossplane crank )

Gotta admit that I applaud yamaha for a bringing such a different engine to the market. If the bike wasn't so ugly I'd have one...

[rich1988]

if you have a bad tight spot take my advice and just replace it and the sprocket, I put it off and it caused me BIGG problems, Ill be lucky if I get 600 from what was a £1600 bike because of not paying enough attention to the chain