www.zxrworld.co.uk

Hey,

I wonder if the wise people would be able to tell me the differences in the above bikes e.g. with the engine and electrics?

I know that the L5 engine was slightly different and have noticed a few things already with the physical look of the engine and also speed wise as well. With the L5 I was able to get 150mph out of it and it was relatively quick off the mark! However the L4 I now have only will push up to 130mph and is seems to take a longer time to get there as well.

Both of my bike had standard gearing one Renthal and the other is Kawka standard (should not make a difference)

Should I be looking at the carbs on each bike? i.e. Would a richer running bike make it go quicker?

Thanks Ciaran

I'll check the data sheets again but fairly sure the L5a is the seriously restricted bike with less aggressive cams - it may also have the smaller 30mm carbs.

I am sure I have posted these data sheets up so check using the search function.

MM!

EDIT: It was the L5a with the less aggressive cams not L4a I had typed - if you have a L5a in the UK it will be a JDM import.

Cheers MM. Had a quick look at you data sheets could't see any for the L4 Uk model but read through the thread and some good info.

Is there any way to check the types of cams from the different models as I'm sure I have a couple spare like distinguishing marks?

I have an L4 and it's not restricted. The stated power output from the engine is the full 65bhp, the gearing is the same as the other bikes, so just by working through the physics of the thing you can tell what the theoretical top speed is. IIRC the L model was tested by MCN in the 90s at 141mph top. It's difficult to see why a UK L4 would be restricted in any way from a dealer as at that date there was none of this silly restricted licence shenanigans. Once you passed your test on a 125 in those days you could ride anything, so there was no market for restricted 400s. That came later. Of course, an L4 could have been retrospectively restricted, but that wouldn't have involved cam changes.

This is not to say that MM is wrong, there could be a 4a restricted version but would this have been a UK model? Certainly it is wrong to assume that the L4 per se is a lower power version of the L5. No way! I've had 135mph on the clocks on mine over the mountain at the Isle of Man. No doubt Cargo will p*ss himself laughing at that speed but it was fast for me on open roads and I almost filled my pants when someone came past me on an RC30 (returning to the paddock having retired in the race earlier) as if I was stood still, Brought me down to earth like

On what basis are you claiming 150mph? Are you going on the clocks? They are not accurate at those sorts of speeds and with a 10% error (which even plod will allow you) you could be looking at 135mph in reality. I know when I trigger those roadside speed signs that my clocks over read by about 5mph at 30. If your L4's clocks are more accurate then you could really be looking at the same speed as you were getting on your L5.

Personally I don't believe it is physically possible for the L in standard trim to do more than a shade over 140mph (actual spped, rather than indicated). Cargo posted a link one time to some fancy calculator that would give you a theoretical top speed with a given power, gearing, wheel diameter blah blah.

Presume you've done all the usual crap like balance carbs? And check you haven't got any kinks in the fuel line which could be restricting flow. Maybe try a fresh fuel filter. And bung a dose of carb cleaner in your next tank of gas.

I can see how the clocks may be out slightly and obviously will not read the correctly. However on the same straight bit of road I go on everyday I try and push the L4 it just does not seem to be as good as the L5 I have. It feels slower on pick up where the power from the L5 would be straight there the L4 seems a bit sluggish.
I am normally 130mph+ well before the bend in the road on the straight road I use and the L4 it just about gets to 130mph by the corner!

Might be worth looking into whether your L4 has a problem then. It's not something inherent with the model. Sluggish suggests poor carburation, maybe even poor combustion (how long since a plug change?). I'd be looking at giving it a thorough service with a carb balance and carb clean (try the cleaner and maybe putting a few tankfulls of Shell V-Power) and see where you're at then. If the valve clearances are out you're not going to be getting good power either. Once you know the engine is tuned up nice then you've got a better benchmark to work forward from.

Mine was a little sluggish when I got it back on the road. Poor on pickup. I had done everything except a carb balance (mainly as it had only been done 1000miles before it went into store). I did that a few days ago. Numbers 1 & 2 were in balance with each other, ditto 3 & 4, and the difference between the two pairs was very slight. I balanced this out and it has transformed the bike. This bike really does not like out of balance carbs, slight mismatches do make a noticeable difference to performance. I'd suggest a carb balance if you haven't done it for a while.

150mph on a 400?

Did you drive it off a cliff or down a ski slope?

The ZXR speedo's read over by quite a bit, my GPS'd bike is doing 114mph when the speedo is reading just shy of 130mph.

Regardless of top-speed.

A lot of it comes down to if the bike was originally from the UK or Japan as there seem to be differences with carb-sizes and cam's, and possibly ignitors too.

Most of the JDM bikes i've seen have CVK-D30's on them but the UK L1 manual I have says the UK model (stated 65ps) had the CVK-D32's. From MM's data too the cam-shafts seem to have differences too, the UK L1 cams are more agressive than the JDM L1 cams.

The Jap bikes were restricted by law to 59ps. (60hp), it makes theoretical sense at least to me that the UK bike was able to produce another 5hp with slightly bigger carbs (coupled with larger jets (95s vs 90's) and more agressive cams, which is something Honda wern't doing with the VFR400, so the extra 5hp would really be a selling point in the UK over the other 400 dometic model (NC30).

The UK L ignitor (M) doesn't have a speed restriction built into it. I have both the (L)-JDM and (M)-UK igntion boxes and keep meaning to have the bike dyno'd back to back to see if the ignition boxes do make any difference to over-all power, when I get aroud to this i'll post up the results.