engine changes to the L5 & L9 zxr 400's

[Tadpole]

Been on ZXRworld and it advises that the L9 model from 1999 had some big engine improvements, but doesn't advise on whether these made any power or torque gains. I know the earlier l1 models had 65 hp... Does the L9 or even the the L5 come to that give better performace & if so how? Can't seem to find out

[zimm]

ok, zxr engine changes are a bit of a grey area, but this is how things stack up afaik..


early bikes (pre L3?) have cams with more duration and lift
some L imports have smaller carburettors, they look identical but the throat diameter is ~30.5mm compared to 32mm
inlet stubs (from head to carb) got a few mm longer from L3 onwards.. the later items being necessary if fitting ramair as they space the carbs away from a head a bit more and give more clearance for the box.
L9's have stronger conrods and crank, but this isnt really advantagious, as these were never a weakspot in the first place, and L9 version's are heavier, possibly a better base if you intend to lighten/balance them

and of course, only L's have the KBATL slipper clutch


H and L have different gear ratio's too, the H being more evenly spaced.

basically, if you are going to run the engine "as it comes" and on the road, i'd get an H (because of the gear ratio's), on track, an early L (with 32mm carbs) and if you are going to tune it... then it doesnt really matter what you start with.. as long as you have the 32mm carbs

[Mr.Mash]

and of course, only L's have the KBATL slipper clutch

I was under the impression the sp's were the ones with it?

I got a h (m?) sp after the L lump dropped a valve and i know the baskets and the pressure plate is different but im not sure if thats just because of the difference in models but the sp came with thiner steel plates and i rember reading something about swaping the thiner plates to adjust the amout of 'slip' you got from it,

Ill try and find the site and post a link.

ash

[Vard66]

Just following this thread through from another thread about Carbs.

Now I'm reading about the cam differences.

Can anyone expand on the differences between the pre L3 cams and later items?
And if I were to get it into my head that picking up a pair of pre-L3 cams would be a good idea with a mind to putting them into mine in the future, would that be a good idea, or a heroically bad one, and furthermore what else would need changing or adjusting if I were to pop a set of the earlier, more aggressive cams in my L4?

[bendog66]

the cam chain tensioner blade was made of a different material L5+

The difference in cams is barely noticeable, lets be honest.

[zimm]

The difference in cams is barely noticeable, lets be honest.

depends... every H model or ZX-4 ive had pissed on my L4 import at the topend irrespective of what i bolted on to it (fresh topend, micron exhaust, KnN filter, DJ kit in 32mm uk spec carbs, uk spec ignition, etc etc )


the cams all drop straight in Vard666, just re-set each valve clearance and off you go..

you may need a minor carb tweak, but it depends how your bike's setup, and how its running
'
the cams do wear though, so check the lobe heights against the specs in the manual on any cams you do get hold of

[bendog66]

The difference in cams is barely noticeable, lets be honest.

depends... every H model or ZX-4 ive had pissed on my L4 import at the topend irrespective of what i bolted on to it (fresh topend, micron exhaust, KnN filter, DJ kit in 32mm uk spec carbs, uk spec ignition, etc etc )

I was assuming he meant pre L3 cams i.e. L1/2.

[Vard66]

The difference in cams is barely noticeable, lets be honest.

depends... every H model or ZX-4 ive had pissed on my L4 import at the topend irrespective of what i bolted on to it (fresh topend, micron exhaust, KnN filter, DJ kit in 32mm uk spec carbs, uk spec ignition, etc etc )


the cams all drop straight in Vard666, just re-set each valve clearance and off you go..

you may need a minor carb tweak, but it depends how your bike's setup, and how its running
'
the cams do wear though, so check the lobe heights against the specs in the manual on any cams you do get hold of

Well, being that I may well be having to do my HG next month anyway, I might have that set of CAMS, (I meant to say CAMS the first time, ffs) you had on the bench on Tues off you and just drop them in.
Did you check them? I seem to remember you saying they were the same as the SP cams, but I don't remember if you said you checked them for wear.