Pls help diagnose RPM/power issue on RVF400

[Cammo]

You should fit a washers under the needles, it will richen the midrange revs as honda intended.

It's a common size of washer, you can get them at any decent hardware store.

[SimonCNZ]

Would the acceleration lagging between 5-6k be more likely from being too rich or lean? I would guess too rich? I'm baffled, running too rich but with no washer and the pilot jet already set lean at two turns. What would happen if I put in the washes and set the pilot jet leaner? Back fire, but could it damage engine?

[CMSMJ1]

Would the acceleration lagging between 5-6k be more likely from being too rich or lean? I would guess too rich? I'm baffled, running too rich but with no washer and the pilot jet already set lean at two turns. What would happen if I put in the washes and set the pilot jet leaner? Back fire, but could it damage engine?

RVF is 1 and 5/8 as std and it is reverse to the NC30 - so you need to adjust that too.

It "should" not backfire - you just need to set it to std and go from there..so washers in.

[Drunkn Munky]

Before you go adding washers check that there not stuck to the bottom of the slide

[SimonCNZ]

So got around to pulling off the carbs again. Can't find any number but 35S. Does this indicate size or just that they are factory standard?

[Cammo]

35S is the original standard sized pilot jet.

You need to check for a number stamped on the main jet (very left in pic).

[SimonCNZ]

Looks like they are all 108's

[SimonCNZ]

Hi Cammo. So with standard size main jet, and the bike running rich at 2 turns out, the only changes from a factory state being the washers under the piston needles (which I have purchased to put back on), and a carbon fibre exhaust, should I try turning the pilot screw back to factory state (making it richer), or try turning it out further? Is there any other thing to check as to why it might be running rich? Thanks

[Cammo]

Did you fit a new genuine honda air filter? I think the change in induction to your new filter from your old disintegrated filter is the key here.

My guess is the bike is running lean in the midrange (particularly without the washers under the needles) which the new (more restrictive) air filter has exacerbated. This is a pretty common running problem on these bikes.

Also, it will be idling very rich at 2 turns out on the pilot screws. Turning them in is leaner on the rvf carbs (opposite to vfr carbs).

Fit the washers under the needles, set the pilot screws to 1+5/8 turns out (standard), and I'd also change the jets to 112's to suit your freer flowing muffler. I'm pretty sure this will solve your issues. Yell out if you're unsure where to get new jets from (also update your profile with your location!).

[SimonCNZ]

Hi Cammo. That looks like a reasonable scenario. Updated profile, Auckland NZ here.
Would you use 112 on all four, or 110/112 front/rear?
Cheers - and thanks for the help.
Simon