iv noticed a few times my lights dim down or brighten up (whichever way you look at it) while riding and the 1st thought was the reg/rec

they a cheap part so not a major problem

my question is could the reg/rec issue (assuming it is the reason the light change brightness) also cause my splutter when quickly opening the throttle below 7k ish

no..but get it sorted.

do the checks and be sure that your battery is not fucked.

I am often surprised why people reckona 21 yrs old bike is going to take full throttle at low revs and like it... be nice and tickle that throttle in, wind it on...the bike likes it.

Twist of the wrist 2 - worth reading. makes sense.

CMSMJ1 wrote:no..but get it sorted.

do the checks and be sure that your battery is not fucked.

I am often surprised why people reckona 21 yrs old bike is going to take full throttle at low revs and like it... be nice and tickle that throttle in, wind it on...the bike likes it.

Twist of the wrist 2 - worth reading. makes sense.

Mines ok

Since it's got CV carbs it can't over fuel or over air itself like if you crack some FCR type carbs wide open.

It doesn't bog or stutter it just goes, not as fast as a new FI bike picks up but theres no problem from crackign the throttle wide open from off the lights (obv when warm).

Lights will dim slightly when running at idle.. most cars do the same, brightening up with rev's shows that your generator is doing at least something.

As been said though it's 20+ years old

Test the battery and electrical system fully, clean and rebuild the carbs, valve clearances, plugs / air filter etc.

Engines are fairly simple but do require service and maintainance to keep them running properly... after 21 years there can be quite a bit of neglect from people, dirt in the system you name it.

Most common is down the to electrical system and carbs.. people have tinkered, modded and generally broken them, or they've done nothing... dirts got in the system, carb rubbers are leaking air along with vaccum tap pipe, valve seats are worn so valves arn't sealing 100%, maybe plugs and filter are past their best.

If everythings as it should be the bike should be fine.

lol..you are the second coming of Soichiro aren't you mate? Your NC works and has had the attention that it needs.

My point is that they don't actually leap forwards with low revs and full throttle...they have a wee think and then kind of get going. It is normal.

CMSMJ1 wrote:lol..you are the second coming of Soichiro aren't you mate? Your NC works and has had the attention that it needs.

My point is that they don't actually leap forwards with low revs and full throttle...they have a wee think and then kind of get going. It is normal.

haha sorry and I wish!

And oh yep.. they are slow to pick up compared to any modern bike.. FI and super ECU's do wonderful things, not to mention lighter flywheels and fancy wizardary.

My old man had an 03 954 blade with a QA throttle and that was the most evil engine ever, it went from 0 - 10k quicker than you could think, if you could keep the front down.

I got the impression from the OP's post that it was bogging down when giving it some gas, the stumble stumble cough cough you get when cold / bad float heigts and general neglect! (which ties in with a 20 year old grey import!)

Difficult to say without riding it and going by text only! If it's just 'slow' thats beucase it's an old 400, if it's stumbling, coughing, bogging, spluttering then good service and carb check / reset are first port of call and some time at a good dyno tuners.

surely it cant be normal to splutter

ive had alot of 2 strokes from the same era and my father has had several 4 stroke super sports (fzr 750 cbr 600 etc) from the same era and not one spluttered they just got up and went

leerc wrote:surely it cant be normal to splutter

ive had alot of 2 strokes from the same era and my father has had several 4 stroke super sports (fzr 750 cbr 600 etc) from the same era and not one spluttered they just got up and went

Neosophist wrote: It doesn't bog or stutter it just goes, not as fast as a new FI bike picks up but theres no problem from crackign the throttle wide open from off the lights (obv when warm).

Read the thread.. the concensus is that it won't pick up super fast like a new FI bike but you shouldn't be having problems.

As said above, test your electrical system, service the bike and reset the carbs. 20+ years is along time for neglect and while quite simple compared to a new bike, all the components need to work properly for optimum results