[hondapaneuro]

As you may know I've replaced the original silencers on my 2000 NX650 with the end cans off a Triumph Street Triple (see original post).
Now the winter nights are here I'd like to 'up' the main jet a bit as per comments on other people's posts about changing exhausts & air filters.
So, I've started stripping but already hit a stumbling block - all pipes / cables etc disconnected from the carb, but how do I get it out ? Does the rubber connector to the head have to be undone ? (looks like 3 allen head bolts), please don't tell me the airbox has to come out first....
If I ever get the carb off and see what main jet is in there I'll probably be looking more advice!
cheers

 

[RedRocket]

Loosen and slide away hose clamps on both sides of the carb.
On the airbox side, pull the inlet hose off the carb. (It's rubber and should be pliable)
Then pull the carb back the half inch it needs to clear the intake boot on the cylinder head.

You can now pull the carb forward and sideways (left side of the bike) to clear the intake boot. It is fiddly, but be patient and be careful of scratching the frame and bashing the carb body.

Come back and tell us how it went

 

[650 Fred]

Unfortunately the book says to loosen the airbox and push it back enough to allow the carb to come out but its much easier to undo the 3 bolts you speak of and pull the carb out with the inlet manifold on. I rotate the manifold on the carb so the widest part is vertical instead of horizontal to help it come out easier its a right bitch to do, and watch you don't damage the O ring on the inlet manifold especially when replacing the carb

 

[hondapaneuro]

Thanks, so far guys. Just had another look at it and I don't think in this cold weather the inlet rubber will be pliable enough and I really don't want to break anything, so I think I'll resign myself to removing the airbox and all else that goes before it. It'll be a good opportunity to do a bit of cleaning in there anyhow! I'm back in the house now and the fire is lit.... so just to put a movie on - the bike can wait.

 

[650 Fred]

The Inlet rubber don't move much in the hot weather either or when its new. I had to buy a new one after i replaced the O ring with one slightly thicker i thought it would squash down when i tightened it up but it didn't instead i cracked the hard part where the screws are

 

[650 Fred]

I must apologize In the manual for the RD02 model (which is the only one i got) it says to remove by undoing the insulator bolts (what i call the inlet manifold rubber) so don't know where i got the airbox bit from although the RD08 has a shorter inlet rubber than the RD02 for some reason

 

[Bounder]

I always undo the three bolts on the engine side of the manifold. Undo the choke fitting carefully and throttle cables and front hose clamp
You can then pull the carb out the left side, once you have the carb turned pull the insulator off and manoeuvre the carb out.

 

[hondapaneuro]

Got the brute off the bike after removing the battery, air filter internals and loosening up the airbox enough to shove it over to the side (couldn't get airbox out through the frame, I suspect it has to go out the back - mudguard and silencers off for that). Got the carb off by going up through the frame - it wouldn't go out the left because it hits the idle screw bracket welded to the frame and I didn't want to take off the inlet rubber either.
So, eventually I've go to the main jet - it says 145 on it.
What is the consensus of opinion on the size I should be changing to please ? (my only change to the breathing is the silencers - Street Triple - much more free flow than standard )
Where do I source the main jet ?
All answers greatly appreciated - I've never meddled with carbs before.
cheers - James

 

[Bobn]

What a nightmare, it sounds like the BMW Funduro I used to own, to remove the (twin) carbs required removal of the exhaust silencer and airbox. That's why I like the FX and SLR, the carb comes out at an angle and can be pulled in under 5 minutes. I realise this doesn't help.

On the jets, any traditional bike shop should have boxes of them in stock. I use Manhattan Motorcycles in Sheffield and I just go in an match up what I want. In general a free flow exhaust should put you up two sizes, they go in 5s so look at a 155 to start. When fitted find a stretch of open road, preferably up hill and get the bike flat out in top. Rolling on and off the throttle should produce a difference in pull across the entire range. So if you find that the last 1/4 or 1/8 don't make the bike go any faster you're probably still lean. However, if you find that the last 1/4 or 1/8 throttle don't make the bike go faster AND when you snap the throttle shut you can feel a little surge in power before it shuts off then you are too rich.
You'll also want to turn your pilot fuel screw out 1 or 1.5 turns more.

 

[hondapaneuro]

Thanks Bobn
Is this the Pilot Screw ?

 

[Bobn]

Yes that's the little fellow.

 

[iansoady]

And it's not all chewed up!

 

[aboynamedsue]

What it's not chewed up !! Let me at it!

 

[hondapaneuro]

Yesterday was the first opportunity I've had to give the bike a real test with the new jet. Crap / Worse / Awful - choose any or all of those words to describe how it went! It does pull well when giving it the beans, but as soon as I back off the throttle to try and maintain a steady speed (in any gear) it just surges and bucks about. It was better with the standard jet. What does the pilot screw do ? (I backed it out as instructed in previous posts).
I'm not looking forward to another 3 hours knuckle skinning carb removal....
Cheers

 

[Bobn]

Sounds too rich.
So all you've changed is the main jet and the pilot screw setting?
Maybe the exhaust isn't as free flowing as expected? If that's the case then the main jet that went in could be too large.

 

[iansoady]

Main jet wouldn't be affecting it after he backed off though.

 

[Mototed]

Carb removal is easy. I can do it in about a minute now. But i've had a lot of practice

Remove the the three screws out of the airbox. 10mm heads.

Pull the rear rubbers back off the carb and tilt them down. Pull the carb backward out on the inlet manifold.

Tip the carb forward and wiggle it up and back through the gap in the frame. It takes a fair bit of wiggling. It's easier if you take the throttle cable bracket off the carb first if the screws aren't chewed up.

What size jets are you using ?? Are you modding the airbox or filter ?? Standard headers ?

 

[hondapaneuro]

Yep, that's mighty much the same method I use now - I have got quicker now I've done it twice.
Standard jet was 145. I changed it to 155 and things got worse.
No mods to airbox or header, just the change to the silencers.
I put it back to standard last night !!

 

[Mototed]

If the silencers are road legal then standard jetting will be okay. If they're free flowing then you need to put a free flowing filter in and cut some holes in the airbox snorkel. Even then only go to a 148.

Increasing airflow and jetting will give the bike more top end power but they tend to loose a bit of low end grunt.

The pilot jet should be increased by one size whatever you do. Even with a stock set up its too lean and causes the famous Dommie cut out.

 

[hondapaneuro]

Bike still going like crap even though I've now put things back to standard. I had some pictures of the pipes etc before I started but must have deleted them - I'd just like to confirm what pipe and where it goes to, should be connected to the tube marked in red...
I had it connected to a breather that has a y piece in it down the back of the engine, the other pipe from the y connects to the tank.
Help please....