2 annoying NC23 issues

[BillingCBR]

Hi all, my CBR has 2 small problems which don't seem to be particularly damaging, but are annoying all the same.

1- When starting from cold (i.e left overnight) the bike fires up fine, but will die if you don't hold the throttle open a little. This happens no matter what the position of the choke, I know the choke is working because I had to use it a week or so ago. This problem goes away after literally 5 or so seconds, and the bike will idle happily after this point, it also doesn't happen if the bike is slightly warm (i.e left for 15 minutes) What could cause this, and what can I do to fix it please?

2- After I changed my exhaust system last monday (mild steel was changed for stainless) I have noticed that there is a metallic rattling coming from the bike. This happens at 5k to 6k, in any gear or neutral, with the throttle on or off. I have been told that stainless systems can sometimes do this, and not to worry too much, is this true? If not then what should I be looking for? I have been all over the bike making sure things are tight, and so far I haven't found anything loose

[Cammo]

2- After I changed my exhaust system last monday (mild steel was changed for stainless) I have noticed that there is a metallic rattling coming from the bike. This happens at 5k to 6k, in any gear or neutral, with the throttle on or off. I have been told that stainless systems can sometimes do this, and not to worry too much, is this true?

I used to have this noise on a stainless system, never could get rid of it. It's just resonating that causes it.

[Davez29]

Glad Im not the only one with this Stainless zingy? noise issue, its been driving me crazy since i changed from the standard pipes to a new stainless system from ebay.

Things I tried included making sure the headers were centered over the ports and copper washers and not touching the heads, I had noticed vthat one pipe was maybe off centre slightly so pulled it away from the head while tightening. The exhaust header clamps, I noticed depending which way I had them they seemed closer to the pipes, so had to swivel them for better clearance. The underside clamp I put extra rubber washers and made sure there was no metal to metal contact. Finally the exhaust hanger was touching the can so pulled it down a smidge while tightening.

By doing the above I seem to have cured quite a lot of this zingy stainless noise and whats left seems to disappear when heat expansion takes place as the bike gets warmer, I also reads as the pipes get used carbon will coat the pipes stopping this resonance..

Still dissapointed but on the bright side I heard a new R1 the other day and he also appeared to have the same problem. I hope my findings help you out.

BTW I would not worry about your other problem, seems normal to me, just needs to warm up a bit to idle a small amount of throttle is nothing just to start the bike.
dave

[BillingCBR]

Thanks for the replies, I'll be taking the pipes off tomorrow to put my new gaskets on as I didn't change them when I put the s/s on. They sealed up fine, it doesn't blow, but can't hurt to change them anyway.

The other issue might be something stupid like a bit of crap from the 3 years it was stood before I bought it, or the carbs need to be balanced Either way it's just one of those little 'quirks' that you get used to (like how almost nobody can start my old CG first time )

[Cammo]

They sealed up fine, it doesn't blow, but can't hurt to change them anyway.

Famous last words!

[Jon]

on the noise being a stainless sytem thing.

My Ethos sytem is the same, even with all slip joints selaed with sensor safe silicone so that the wide band exhaust gas analyser i was playing with wasnt seeing drawn in air.

A good clean, balance and idle mixture adjustment would be the place to start with your carbies.

[superlite]

on the stainless.

I isolated everything possible on a Yamamoto system to no avail. I don't mind the noise too much though. Just live with it I reckon.

[Adrian89]

This noise could possibly explain the problem I'm having with my bike too, Iv been frustrated by it for a little while now, had thought it might need valve shims doing, but this stainless system thing seems more likely
cheers

[Mrpedro]

on the noise too it does my fricken tits in on my nc23 iv had that noise year now such an annoyance i was thinking of putting some coper slip on the inside of the end can where it joins to the downpipes at the rear or get a new end can but then i could be left with the same problem

[BillingCBR]

I've fixed at least one issue with the bike, the annoying rattling has gone now :D swapped back to my old carbon fibre end can because I had a strap to fit that (the micron is 10mm smaller diameter, so need to mod the strap to fit it.) and the noise is totally gone :) looks like I need to strip the Micron can down and see if theres anything obviously loose, I have a funny feeling that any remaining sound deadening may 'fall' out while this happens