Carb setup

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chownsy
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Carb setup

Post by chownsy » Wed Oct 06, 2010 6:26 pm

Rightio,

While cleaning my carbs i deceided to follow the guide i was linked to in another post.

Here is how the bike is currently set up

Front carbs

#35 pilot
Jets 112
5 holes on emulsion tube

Rear carbs

#35 Pilot
Jets 110
5 Holes on emulsion tube

The carb/Engine are off a NC21.

I have standard NC24 exhaust system and dont intend on changing for a while.

Currently struggles to start on cold (choke dont work but operates fully) but once running sounds sweet (aint been rode on the road yet)

Is this set up fine?

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thunderace
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Re: Carb setup

Post by thunderace » Wed Oct 06, 2010 6:46 pm

Should have 4 holes in the front emulsion tubes, not 5 ;)

chownsy
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Re: Carb setup

Post by chownsy » Wed Oct 06, 2010 7:04 pm

thunderace wrote:Should have 4 holes in the front emulsion tubes, not 5 ;)
there is 5 all round (this is a 21 so maybe it was different as it was the earlier bike)

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Cammo
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Re: Carb setup

Post by Cammo » Wed Oct 06, 2010 10:33 pm

chownsy wrote: Currently struggles to start on cold (choke dont work but operates fully) but once running sounds sweet (aint been rode on the road yet)
It sounds like the choke circuit is blocked up, common on older carbs that might have been sitting around for periods with fuel in them. The only way to rectify this is to take them fully apart and get them ultrasonically cleaned.

Setup sounds fine, make sure to check your float heights (spec is 6.8mm).
"It's just a ride" Bill Hicks

chownsy
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Re: Carb setup

Post by chownsy » Wed Oct 06, 2010 10:40 pm

Cammo wrote:
chownsy wrote: Currently struggles to start on cold (choke dont work but operates fully) but once running sounds sweet (aint been rode on the road yet)
It sounds like the choke circuit is blocked up, common on older carbs that might have been sitting around for periods with fuel in them. The only way to rectify this is to take them fully apart and get them ultrasonically cleaned.

Setup sounds fine, make sure to check your float heights (spec is 6.8mm).
How do i check the float height

I have these stripped out and will clean and then blow the choke all through as i cannot afford £400+ i seen quoted for carb cleaning services.

Thanks for the reply

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Re: Carb setup

Post by Neosophist » Thu Oct 07, 2010 1:04 am

I'm pretty sure the NC21 has 30mm carbs and the NC24 has 32mm carbs... What happened to your NC24 carbs? There the best ones and easiest to tune to use with the engine.

The NC21 carbs should have 112's in the front and 110's in the rear. The NC21 carbs have the same emulsion tubes front and rear so that sounds ok. (I have the parts book infront of me.)

http://www.factorypro.com/tech_tuning_p ... edure.html

You should try the search function more, I wrote this up about NC21 carbs a couple of weeks ago.

As for the choke not starting it's probably blocked up. If you remove the caps, be careful not to get the diaphram wet or broken you'll see the passage the carb opens, make sure everything is clean.
xivlia wrote:i dont go fast on this bike so really do not need a rear brake.. /
vic-vtrvfr wrote:Ask xivlia for help, he's tackled just about every problem u could think of...

chownsy
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Re: Carb setup

Post by chownsy » Thu Oct 07, 2010 9:16 am

Neosophist wrote:I'm pretty sure the NC21 has 30mm carbs and the NC24 has 32mm carbs... What happened to your NC24 carbs? There the best ones and easiest to tune to use with the engine.
Here is a quote from you regarding running a NC21 on a NC24 ignition loom and also putting the 24 carbs on a 21 engine
Neosophist wrote:in a nut shell, it probably wont run, or wont run right.

carbs are differnt, air jets and main jets are different, along with different mounting rubbers.

the nc21 has different cams / valves and internals.

Never tried mixing them, dont know if it'd work with the NC24 igntiion box.. it Might run but I can't imagine it being right.

I Dont' have the ignition advance curves and the other data to hand but there are differences, so with the NC24 box on there its going to be firing slightly differently.

If it's an NC21 engine stick with the NC21 carbs, NC21 loom and NC21 ignition box otherwise your setting yourself up for more problems.

The NC21 carbs are going to fuel slightly different too, as the NC21 has a slightly lower compression ratio compared to the 24

BOTH the NC21 and NC24 make 59PS (60bhp) from the factory so your not going to be getting anymore power intermixing parts, just causing problems.
so that is why i was using my 21 carbs (they also run smoother than the 24 carbs did)

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Re: Carb setup

Post by Neosophist » Thu Oct 07, 2010 10:42 am

You have an NC21 engine in the bike?

I forget what you've done with it... I was thinking you were retrofitting 21 carbs to an NC24 engine.. :)
xivlia wrote:i dont go fast on this bike so really do not need a rear brake.. /
vic-vtrvfr wrote:Ask xivlia for help, he's tackled just about every problem u could think of...

chownsy
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Re: Carb setup

Post by chownsy » Thu Oct 07, 2010 11:16 am

Neosophist wrote:You have an NC21 engine in the bike?

I forget what you've done with it... I was thinking you were retrofitting 21 carbs to an NC24 engine.. :)
Haha yea i know its confusing :P

NC24 engine headgasket blew and was swallowing water faster than you could put it in basically so i put in the NC21 engine :P

So i will clean it all out and then put it all back in as its set up? No need to rejet on standard exhaust?

ALso why does the NC24 have trumpets, does this help the carbs be more efficient or something?

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Re: Carb setup

Post by Neosophist » Thu Oct 07, 2010 3:17 pm

They shold both have velocity stacks. (trumpets)

http://cgi.ebay.co.uk/HONDA-VFR-400-NC- ... 2eac9799ee

Set of 21 carbs there without the plate.

Sounds like your missing bits...
xivlia wrote:i dont go fast on this bike so really do not need a rear brake.. /
vic-vtrvfr wrote:Ask xivlia for help, he's tackled just about every problem u could think of...


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