Honda NC29 with running issues

[kingarthur83rd]

Hi everyone!

new member here having a browse and I am happy to report i am back on 2 wheels after a short break!

my recent weapon of choice is a Honda CBR400 RRL Gullarm - which has been derestricted

however, it has a couple of issues which im fully aware of, and Im just scouting for some advice!

1st (sadly, there is more than one! :) ) is a running problem at low throttle. it feels like 2 of the barrels arent getting fuel or a weak/no spark. course, give it a fistful and it rockets off like a cat with its bottom on fire, as it should! having a browse and from personal experience, its either dodgy plugs, a coil going down or the CDI unit on its way out. (i say that after a bad experience on a bike which will not be named (cough-maha) or a simple fuelling problem. hopefully the latter . any ideas or help would be appreciated. (floats/jets/lines etc)

the second (and final) problem is a money burner.. gearbox fault... when riding the bike it goes up the box perfect, neutral to first is clean, but coming down is a bit tempramental. when rolling to a stop 6th>5th>4th>3rd>2nd>N>1st. however, under braking, its a bit hit and miss if you fettle the clutch aswell.

Im not going to deceive anyone, i bought it like that, thinking that it would be a cheap fix (selector spring not putting enough tension on the drum)? (bit of a gamble i know). would this be a problem with the selecting mechanism or the selector forks? as one of the engineers the seller spoke to thinks its an issue with the selector forks?

any help is greatly appreciated, and theres no rush (as its not my sole means of transport. Well... until my car goes in for a major service an MoT work (boo! hiss! :D )

[leopard_pagan]

selector fork can get bent easily from what i am told. no idea how much or what it takes to sort.
running issue.
start with the plugs>HT leads
take it to a dyno and get it set up as maybe wrong fuelling

PS welcome to the site.

[Petetheengineer]

I had the running issue on my cbr a few years ago

check the plug caps and then move onto the leads.

The cbr carbs are sensative as well so give them a clean.

If your stripping it down to do the gearbox then it the perfect time to check everything.

[k33py]

I just had the same prob with my nc29. (running crap up to about 4 thousand revs then a spit and a splutter and then it would run ok at top end)
No 1 cyclinder wasn't running right.(leave it idle and quickly touch the exahust to see which ones are colder)
I changed the plugs and it was excatly the same so I whipped the carbs out and cleaned all the slow idle jets and now she's running like a dream again.

I did notice that No 1 inlet was holding fuel.

Whilst I was taking the cabs off I noticed I have got a metal insert in the rubber housing between my carbs and my inlet,
Does anyone know if this is a restriction ?

[kingarthur83rd]

HI everyone,

Just giving an update. Ive had the carbs off and with the more knowledgeable hands of my dad, checked the jets. it turned out number 4 was blocked. we also found number 2 to be partially blocked (which is why it felt like a twin some times)

Unfortunately, the clean jets come at a price... sadly, anti-sieze compound wasnt used on the screws (assuming as its said the carbs can be prone to blockages), which, when applying "justifyable force" in cracking a screw, has cracked one of the float bowls, due to seizing/corrosion on the thread.....

We motored on to prove the point that as the bike was getting a good spark, the jets were blocked

so, new carbs, please! which I hope to take delivery of sometime next week thanks to the on hand service of E-Bay!




PS k33py: quite possibly a restriction. alls ive got is the carbs, the rubber manifold and then the inlet to the barrel/valves. (and i know mine is unrestricted )

[leopard_pagan]

does it look like a silver washer with the hole off centre?
if so and there is one in each inlet.. yes they are 33bhp restrictor washers.