NC24 Jetting, apologies in advance !

[Old Painless]

Im sure this has been discussed to death and back again so i apologise in advance.

Having searched about and looked at some microfiches and workshop manuals i am now totally confused.

My 1987 VFR400R-H NC24 is fitted with 112-115 main jets, the workshop manual i have found lists 120-122 main jets, a couple of other sources list different jets besides those.

Where can i find a source of information which is correct ? Do i need to identify my carb model first ?

Everything is going to be stock BTW when i eventually start it. The engine needs the cylinders and outer cases stripping off and cleaning out and de-coking before it runs.

[superlite]

Definitely shouldn't have 120/122, that's UK spec NC30. The workshop manual lists 110/112 for NC24 (probably incorrectly). Check out Neosophist's post below:

viewtopic.php?f=24&t=107&st=0&sk=t&sd=a ... 2&start=10" onclick="window.open(this.href);return false;

[Old Painless]

Thanks, i have found this which is probably what you have.

http://members.multimania.co.uk/stevejb ... anual.html" onclick="window.open(this.href);return false;

It lists 110 F - 112 R which may explain the excessive carbon buildup on the exhaust ports, overly rich jetting.

[superlite]

Yep, that's the NC21/24 supplement from the NC30/35 Haynes manual.

[Old Painless]

The exhaust ports are chocked with carbon, its like the coal burner at the front of a steam train.

[Neosophist]

That haynes book lies.

http://www.jacksons-lair.co.uk/specs.html

Proper specs. (by me)

NC21 is 112 / 110

NC24 is 115 all around. (4 hole emulsion tubes at front, 5 hole at rear)

tbh i've never come across and NC21/24 in the uk with different jetting, occasionally parts in the wrong place as theres buggar all about in terms of aftermarket systems and the standard set-up works really well, even an end can is tuneable off the pilot screws.

Now.. Too much carbon.

Hmm.. worn engine, rings, bad valve clearances, wrong plugs, dirty air filter, carbs set up wrong, wrong fuel.

[Old Painless]

Cheers for that. Mystery as to why i have got what i have.

Valve clearances were large but probably not over spec, plugs were completely wrong type, air filter was missing, carbs were set up diagonally and wrongly.... the list goes on.

Ring condition should be okay as its done very little mileage but if its been running stuipdly lean it could be bad.

[Neosophist]

And if it's done the mileage it says

The engines are bullet proof anyway.. normally only no oil and complete retard will kill one.

That's probaly your problems then.

Make sure the jets are clear (emulsion tubes proper way around) exhausts all sealing, air filter new and selaing properly, correct plugs, carbs set properly, clean it all up and use at least 88 ron (uk minmum is 95) so you'll be fine unless out of uk fuel and you'll probably find it runs much better.

[Old Painless]

Yup, it will be treated to some nice goodies from david silver spares before it runs. Filters and plugs etc.

I was wondering if i would need to run 98/99 RON due to the 11.3:1 compression ratio but the manual says 95. I wonder what it would need if i swapped the base gaskets for gasket sealant to tighten up the squish.

All of the carb internals have been soaked in paraffin and drowned in carb cleaner after that, completely spotless.

[Neosophist]

I brought an old dentist ultrasonic cleaner off ebay for about £50

had some zxr carbs that looked spotless but the bike idled like shit, put em in that and all black stuff came out of the jets etc even tho they looked spotless, runs mint now.

Keep your eye out for a cheap one, there invaluable.

Ignore the book it lies.. 86 or higher, 91 is reccommended if you get pre-detenation with lower grades of fuel.

The heads don't come off. There part of the crank case.