Bike no low end?

[trademe900]

4. Stick a bit of cardboard in front of the airbox to recreate that flat section in the front of the headstock?

Thanks.

I dont think that there is and piece of plastic there anyway. I think the 35 only has the rubber flap.

Check it out on here the only thing there is the rubber flap that you have Number 2 on this diagram
http://www.cmsnl.com/honda-rvf400rr-nc3 ... t/F28.html

Nice one but I'm pretty sure it's not on that diagram because it is attached to the front of the airbox, I don't think it actually mounts onto the frame.

[Cammo]

I dont think that there is and piece of plastic there anyway. I think the 35 only has the rubber flap.

Check it out on here the only thing there is the rubber flap that you have Number 2 on this diagram
http://www.cmsnl.com/honda-rvf400rr-nc3 ... t/F28.html

Ah yes harvd is correct, the airbox lower only extends on the nc30, nc35 setup is different.

[trademe900]

My apologies and thank you for that info Harvd.

Awesome, looks like I have an unmodified setup then. Didn't know the 35's come without that plastic flap. Looks like the carbs are a lot more forgiving than NC30 and don't mind 'ram air' from the front.

Does anyone know if it is important that the rubber flap that I pictured creates a good seal around the headstock to prevent wind getting in? My one has gaps around the edges. Is this more or less positioned correctly? http://img858.imageshack.us/i/sdc13026.jpg/ http://img706.imageshack.us/i/sdc13027.jpg/ http://img203.imageshack.us/i/sdc13028.jpg/ http://img822.imageshack.us/i/sdc13030.jpg/


Speaking of airboxes and airflow... I saw some Japanese press material that had a diagram of the NC35 ram air system but is this for real or pretty much just a marketing gimmick? Here it is http://www.hondarvf.com/workshop/differences/diff9.gif

[Cammo]

Speaking of airboxes and airflow... I saw some Japanese press material that had a diagram of the NC35 ram air system but is this for real or pretty much just a marketing gimmick?

The latter!

[trademe900]

Just found the float heights too big. Measurements were scattered around 15mm instead of stock 12.5. Hard as to measure accurately though.

[hardnutdvd]

i just wanted to ask about the pilot screw settings of the RVF
Looking here
http://www.vsource.org/VFR-RVF_files/Brvf400r-mi.htm

it says
Pilot screw initial opening 1 5/8 turns out
Pilot screw final opening [1/4 turn out]

whats the 'final opening'?

[Cammo]

Just found the float heights too big. Measurements were scattered around 15mm instead of stock 12.5. Hard as to measure accurately though.

Good job you opened the carbs up and checked everything for yourself!

They are difficult to measure precisely, but gettng them right is important or it will throw all your jetting off if they're out.

[trademe900]

Ok update:

Glad I didn't give up on getting needles out of diaphragm...

Got the destroyed screws off the carb bowls and checked stuff.

Thanks to Cammos guide, putting the carbs back on was easy.

Bike now needs full choke to run from cold. It didn't need any choke before. I had to turn the idle wayyy up. It doesn't idle as well as before but it's ok. It hangs a bit from idle if you blip the throttle. Looks like these settings are a lot leaner than before but what I don't get is that for the RVF pilot screw it's turn in for rich, out for lean. I have gone from 3 turns out or so to the stock 1 5/8 but the symptoms are leaner than before. Doesn't make sense to me.

After getting the idle turned up enough I had it warm up. threw the seat on and went for a spin:

- 6k- top end is awesome, I think somehow it's even better than before. It used to only be 7.5 to top end. Mid to top is damn good if you count 6k as mid range?
- Low end is not so good, different but still suffering, I would say better though. It's still got a flatspot at 3k and stutters at 5k but feels now lean instead of rich. The sound when going through this is like a raspy thin sound instead of a fat gurgling like before.
- It now sounds lean and not rich. When you give it full throttle from the low end it emits a leanish sound. It feels better than before which was probably an overly rich setting.

Is it the float height or the pilot screw which is causing these changes? There is no way I can guarantee the float heights are exact but I'd say I can get it within 1mm. Are you supposed to tune the float height or does it stay the same regardless of setup?

What I also don't understand is that if I adjusted float height from 14/15mm or so to 12.5mm... doesn't that mean it should be more rich? This is really confusing.

I'm not sure if I am even measuring the float height properly... do you just tilt it until it flops over?

What do you guys think? Go another full turn out on the pilot screw will do it? I really have no idea how much the pilot screw actually does apart from the idle. Not sure if this low end change is the smaller float height or pilot screw.

Will a dirty air filter be any part of this?

Sorry about all the questions but it takes me bloody ages to do all this stuff so I want to have a good idea before I go in.

[Cammo]

Did you try an extra washer under the needles? Your midrange sounds lean, this should fix it up.

The pilot screws affect mixture at idle and very low revs (e.g. pulling away), not much else. Personally I would leave them at the stock setting. Stock is 1 & 5/8, ±1/4 turn. Anything different to this will just be covering up other issues IMO.

At 3-7k rpm the needle will be the main factor in fuelling (along with pilot jet which doesn't need to be changed from #35).

With all of these changes to the carbs it's pretty normal for them to need balancing/synching, typical sign is a not so smooth idle. You can synch the carb butterflys physically while the carbs are off which works well (much easier than balancing with vacuum gauges!), try a search on here for info.

There should never be a need to deviate from the standard float height setting. Just set them to this as best you can, your frustrations in getting them right will pay off.

A dirty air filter may affect the fuelling, but I doubt it in this case if your stock jetting is fine at high revs. Use compressed air and blow it out from underneath to clean it up a little for peace of mind if unsure.

Full choke from cold is normal, so it sounds as though you're getting there!

[trademe900]

Hey man, yeah thanks I seem to be doing something at least.

Ok so just took carbs off again, changed pilot screws and put them back on. Did it all in 30 mins the second time!

I turned the pilot screws out nearly half a turn from stock to 2 turns. Started the bike and it idles very nicely! Really smooth and even. Revs don't hang but they don't plummet too fast either.

Observations:

Ok even though it's just pilot screws there are definitely changes.

It sounds pretty good down low, the 3k spot is there but it's slightly better and sounds normal. The 5k spot is better as well and it didn't sound ill going through but it is flat. Can't be totally sure though as the bike wasn't fully warmed up.

Everything from 6k upwards is great still. It just isn't even though... you pull out and it goes flat on the 3k and then another slight hesitation at 5k.

I haven't tried a washer under the needle yet. Maybe that's what I need to do now. Just put another 0.5mm one on eh? Is it possible to do it without taking the carbs off?

My goal is really just to get a smooth running low end that will give me the best fuel economy. It's wicked up top already.