vfr missing still

[kiwi cowboy]

hi people
my vfr400k is still missing.
it starts fine and idles fine the trouble is when riding it at about half throttle at 7000 reves [a little over 100 kms] the thing starts missing and the temp goes up to about 2/3.
if i chop it down a gear get it up to around 8000k it seams to be ok but if i ease off the throttle abit it starts missing again but if i give it more throttle it takes off.
i have had the carbs off and cleaned the main jet and the one beside it but cant work out were the needle jet is and how to get it out. will it be the needle jet? or somthing else.i dont think it is electricle as it runs fine at lo revs and if i give it a handfull.has anyone got a carb diagrame for the nc21 carbs or no were thr needle jet is? any help appreceated

[geoffm]

Look in the manual links - there is a VFR400 manual out there. http://blackbears.ru/index_en.php?get=manual might have it.
G

[kiwi cowboy]

took the carbs off again and still cant get the needle jets out so just blew fuck out of thr holes with compresed air.
i took one of the boots off between the carbs and the engine and it was perished and had a crack in it were the clamp went round it. if this was leaking air would this make it miss at mid throttle?

[sAsLEX]

Check the plugs.

Mine were a little rounded and ran like a bitch and was hard to trace the problem to anything as it would sometimes run fine then others not.


And go to repco to price them, you will have to order them but they will be half the price of the likes of Cyclespot etc

[NighthawkNZ]

it could be electrical... I would change the plugs, and check the leads. It you have a faulty lead or dieing plug can give those symptoms as well...

[sAsLEX]

Ah yes leads. The HT leads in my 4x4 were the original ones and was running like you describe kinda and swapping them out was I think $20 from Supercheap and fixed it good as new.

[vifferman]

i took one of the boots off between the carbs and the engine and it was perished and had a crack in it were the clamp went round it. if this was leaking air would this make it miss at mid throttle?
Fer sure. (plus some crap so it's more'n 10 chars.)

[koba]

If it has an air leak in those boots it will run lean, not fire properly and generate excess heat, as vifferman says: fer sure!

When you have the carbs and tank off to fix that, check the fuel filter, fuel tap/regulator and unto the float bowls (bottom) of carbs and pull the jets out and clean the again making sure you take careful note of where they go back, one out at a time is a good idea.
A miss around 7000 on a VFR may also mean the little emusion hole thingys are blocked up, these are in the bottom near the main jets. the needle jet is the one that the needle seats into that you can get to once the main jet is off. Use a bristle off a nylon brush or somthing else not as hard as the jets to clean out the holes so you dont make them bigger than they should be.

I got my VFR after it had been sitting in a garage for ages, and of the 28 or so tiny holes in the emusion tubes (I think thats wat they are called) 4 were not blocke up with crap. missed like crazy at around 7 thou, ran luvley after a clean, just check you filter if you want it to last more than 2 hours, unlike me!

[more_fasterer]

The needles are attached to the slides / pistons, make sure they can move up & down OK and that the little hole in the end isn't blocked up.

This webpage should help you get a better understanding of what I mean:
http://www.akhara.com/nc30/nc30hrccarb/index.html

[kiwi cowboy]

cheers everyone it seems getting the inlet boots are going to be hard to get [[three months from japan they tell me] have puled the jets out and the little holes in the jets seem clear but cant work out how to get the needle jet out. the shop in alex is trying to get an exploded veiw of carbs in english to see if that tells how.has eny one here got a manual for the latter nc30 and 35 made by clymer ithink aperently they have a section on specs for the nc21 i would like to get my hands on if pos cheers

[sAsLEX]

cheers everyone it seems getting the inlet boots are going to be hard to get [[three months from japan they tell me] have puled the jets out and the little holes in the jets seem clear but cant work out how to get the needle jet out. the shop in alex is trying to get an exploded veiw of carbs in english to see if that tells how.has eny one here got a manual for the latter nc30 and 35 made by clymer ithink aperently they have a section on specs for the nc21 i would like to get my hands on if pos cheers

the Haynes manual. My copy is with a mate in Cromwell you could borrow that when he gets back from racing at Phillip ISland this weekend?

[kiwi cowboy]

the Haynes manual. My copy is with a mate in Cromwell you could borrow that when he gets back from racing at Phillip ISland this weekend?

well got a good second hand boot today put it back together and it seems to be running good now but i did notice it still heated up a bit [2/3 way up the guage] but stoped up the road and taped the radiator cap and dont know if that did anything but the temp went back while ideling and stayed on 1/2 way up the guage all yhe way home so thinking a new thermostate or cap may be in order anybody agree?
saslex i would like to borrow the manual if posabile cheers:niceone:

[roadracingoldfart]

If you ever suspect an inlet manifold to be leaking then a good way to check it is to spray a product like brakleen around the manifold joints while idling. If a leak is there the engine will change revs a bit and put a vapor/misty smoke out the pipe.
Just a small tip, but im sure many of you have tried it before.
Paul.

[kiwi cowboy]

If you ever suspect an inlet manifold to be leaking then a good way to check it is to spray a product like brakleen around the manifold joints while idling. If a leak is there the engine will change revs a bit and put a vapor/misty smoke out the pipe.
Just a small tip, but im sure many of you have tried it before.
Paul.

good tip and one of many i diddnt know about will keep in mind cheers