Dyno chart - MEGA rich!!!

[VFR400+]

Well the bike passed its MOT yesterday but its smoking a hell of a lot, not riden a bike since my test 2 months ago so didnt want to ride it hard. Sure some of the smoke is condensation where its been stood for ages. Although its too dense to be just condensation so took it to a dyno today. The results are off the scale literally!!

Its currently go 115 & 118 jets in set to air screws set to 2.25 turns. The dyno guy reckoned I want to drop the jets towards the 100 area. Its got a JHA full twin stack exhaust is the only proformance mod.

After your suggestions really :)

[CMSMJ1]

Airfilter?? You got one that works? Take it out and see what it goes like!

Are you 33bhp restricted?

[VFR400+]

Airfilter?? You got one that works? Take it out and see what it goes like!

Are you 33bhp restricted?

Put a brand new filter in from RO, Ive got restrictors although they are fitted in my tool box

Just to add Ive added the 0.5 washers and drilled out the slider to 2.5mm also.

[CMSMJ1]

Anything else at all non std about the airbox and so on? not been chopping bits off it have you? All flaps in place?

Are your choke linkages all clean and are they definitely closed??


If you can get anywhere near a decent A/F it should be a nice power output! Smoking like a trooper as it is not able to burn the fuel.

[VFR400+]

No it seems standard, still got the rubber flap that fits inside the frame. Notice some funnels have foam bits on the inside, mine hasnt although it doesnt look like it ever did.

Checked the choke over when I cleaned the carbs third time round and im pretty sure they are closing. Although will look again when I take the carbs off. Got the fitting of the carbs to an art form now!

Yer I was quite happy with the power as considering its being flooded! I told Tim it was smoking (abit) before he shut himself in the room and tested it. He came out coughing saying ...smoking abit?!! Properly smoked out his workshop!

[Neosophist]

Do not drop the jets to 100's.

This is compensating for a fault.

Your bike is running way to rich.

The NC30's came stock with 115/118's on the later JDM bikes and they don't run rich.. even the early 89 bike had 110s.

So even a stock system has bigger jets and doesn't run lean.

In comparission the stock UK bike had 120/122s in it.

You need to find out why your getting too much fuel.

It goes mega-rich from 4000 onwards which is when the main-jets are starting to kick in.

Are they 115/118 jets? Are your emulsion tubes ok?

Are the needles in the right carbs? Are they the right needles? Try ditching the washers.

Are your float heights ok? Are the float needlevalves sealing or are the carbs flooding?

Is the choke circuit staying open?

Rough guess but it looks like either your jets are wrong, needles are wrong or there is way too much fuel in the carbs.. or possible a combination of all 3.

Don't drop the jets.. fix the problem and you'll be closer to 60hp.

[kevprojex]

do not drop the jet size

Are your float heights ok? Are the float needlevalves sealing or are the carbs flooding?

Is the choke circuit staying open

Don't drop the jets.. fix the problem and you'll be closer to 60hp.

ill second that one its a fault not a jetting problem take the carbs off and give them a clean making shure the float valves are closing properly .

[VFR400+]

I have check the carbs over a few times now but maybe I've been missing something. Did think it strange of the spec to have to change the jets.

Anyone fancy looking over the carbs for beer tokens?

[spud]

might be a stab in the dark , but you checked your fuel tap to see if its allowing to much petrol though , as mine was running very rich when running stock jeting and rick o said to check my fuel tap , just a thought

spud

[VFR400+]

might be a stab in the dark , but you checked your fuel tap to see if its allowing to much petrol though , as mine was running very rich when running stock jeting and rick o said to check my fuel tap , just a thought

spud

Its a possibility I guess, I have just fitted a new diaphram in the fuel tap to stop it leaking in to the carbs.