NC29 Jetting guide needed

[Davez29]

I notice in the V4 section there is an excellent jetting guide by Dataracer, http://www.400greybike.info/newforum/vi ... 24&t=14524 . While I realise most would be similar for the NC29 there are lots that need to be more specific to the NC29 I would have thought. For instance if I have 105s fitted how high would I need to go, 107.5 or higher perhaps 112.5, see I just dont know so a guide would be handy.

So is there any one upto the challenge of producing a similar guide for us CBR owners? please!!

BTW the reason I ask is that I fancy mucking about my self as Im sure my bike is still running lean and I noticed this on ebay and thought surely you dont need to spend that much to rejet etc..: http://cgi.ebay.com/ebaymotors/91-93-CB ... ccessories" onclick="window.open(this.href);return false;

[scratchin]

get in touch with greame france he will advise you on what jets to use and can supply them

cheers tony

[Wozza]

Within about a month I should have upjetted and dyno'ed my NC23 so will post the results in here.

[GF Racing]

Be a little careful - there are varying carb models on the NC29 - some love full dynojet kits - some hate them - some just need an up jet - some like the slide hole lift mod - some dont.

We keep a database of what works with each type of carb. versus what air box / what air filter / what headers and what end can is fitted.

Carb. ID is stamped on the body ie AA AB - don't simply use the trumpet type fitted as many carb. sets have been modded by now.

To write this all up would take me ages ....I have about 20 stickers on my jet box with all the data - about 15 years worth of set up work.

By all means ask for a quote - a simple up jet starts at £20 up to £180 for a full early carb. ram air set up. Ram air set up on the later B spec carbs is way cheaper.

[Cammo]

BTW the reason I ask is that I fancy mucking about my self as Im sure my bike is still running lean and I noticed this on ebay and thought surely you dont need to spend that much to rejet etc..: http://cgi.ebay.com/ebaymotors/91-93-CB ... ccessories" onclick="window.open(this.href);return false;

From ebay ad: Includes: Main Jet, Shims, Spacers, Drill Bits, Slide Hole mod, Idle Mixture mod, and step by step instructions with photos.

So what you get is 4 jets, 4 normal washers and a drill bit.... 90 quid is very steep. If you got all this new from honda (or a keihin distributor) it will cost about 20 quid.

Contact Graeme France and go for the jet sizes he recommends for your bike setup, along with pilot screw setting information (write it down!) and needle height (height of washers if any). That's all you need.

Jetting the nc29 is very similar to the nc30 once you have the carbs off the bike, the basics are all the same. Obviously jet size and pilot screw settings will be different. Give it a go yourself when you have all the parts. if you get stuck just post a query on the forum.

[Davez29]

Hi, I have a standard bike apart from that stainless exhaust and can changed last year, to be honest Ive never been happy since putting it on, never seemed right since then, starting and low running seemed to have changed for the worse. I tried everything from carb cleaning (twice), pilot screw settings, no change at any setting but I have left them at 2 1/2 turns, 1/4 turn out from standard, although it does seem to work at first after a short time, back to normal. Tried raising needles, was worse than ever. new standard air filter no help, really the only thing i have not tried are the jets, so thought why not give this a go as i've run out of ideas. I may go up two from the 105 to 107.5 to see if that helps, although a mate with an RC30 says he would only go up one size at a time, not two and a half. Dunno? If no worky I will contact Mr France for advise.

Still I would like to see a specific guide to help us newbies, thanks for your input appreciated.

[LUCAS]

Hi, I have a standard bike apart from that stainless exhaust and can changed last year, to be honest Ive never been happy since putting it on, never seemed right since then, starting and low running seemed to have changed for the worse. I tried everything from carb cleaning (twice), pilot screw settings, no change at any setting but I have left them at 2 1/2 turns, 1/4 turn out from standard, although it does seem to work at first after a short time, back to normal. Tried raising needles, was worse than ever. new standard air filter no help, really the only thing i have not tried are the jets, so thought why not give this a go as i've run out of ideas. I may go up two from the 105 to 107.5 to see if that helps, although a mate with an RC30 says he would only go up one size at a time, not two and a half. Dunno? If no worky I will contact Mr France for advise.

Still I would like to see a specific guide to help us newbies, thanks for your input appreciated.

did you buy one of the 4-2-1 systems that are on eBay - DK ones are common? They are renowned for being difficult to jet properly. I have a set and im not happy with the jetting. Like you said its starting and the low to mid range. Fortunately they are coming off at the weekend and being replaced by a decent system

[Davez29]

did you buy one of the 4-2-1 systems that are on eBay - DK ones are common?

Well it was from ebay, they are always advertised, Sandy bike spares. seems ok but as you say there may be problems with them as I tried two end different cans but had the same problem so it more than likely the pipes. I notice reading around various common jetting guides they do say you go up two on the main jet if you install an aftermarket set of pipes, but what always confused me, not being very techie is that it runs fine at most throttle openings where I would expect the main jets to work apart from low down, which in theory and from what I gather is the pilot screw setting but no amount of twiddling those made any real difference for me. I tried all other options such as float heights, needles etc, nothing changed..

[royster81]

. I may go up two from the 105 to 107.5 to see if that helps, although a mate with an RC30 says he would only go up one size at a time, not two and a half. .

i might be wrong in saying this but i thought some jet sizes go up in 2.5 increments (110-12.5-115-117.5 ) others in 2 then 3 increments ( ie 110-112-115-118-120).

[Davez29]

. I may go up two from the 105 to 107.5 to see if that helps, although a mate with an RC30 says he would only go up one size at a time, not two and a half. .

i might be wrong in saying this but i thought some jet sizes go up in 2.5 increments (110-12.5-115-117.5 ) others in 2 then 3 increments ( ie 110-112-115-118-120).

Yes, I have also seen this mentioned elsware but not sure if this is the case with Keihin jets, chances are it is right, maybe someone can tell me for sure? BTW I only mentioned to my mate I was going up 2 1/2 maybe if I had specified the sizes he could have told me, will have to see him again later.