Jetting

[anakin40]

hi i have recently bought an l4 model. it has desnorkeled k&n, full micron, it was bogging around 8k. had 95 main jets and i was advised to put 105 jets in and thats made no difference.
if i put choke on then it pulls again... should i give up on the k&n or is it possibly a needle problem?
its been many years since i messed about like this, so my heads a bit rusty lol

[captain orange]

105's are correct. middle pos'n on the needles. You have prob a blocked filter or breather problem. Make sure you have the 2 rubber plugs back in the airbox.

[anakin40]

there is no adjustment on the needles, guessing they must be the standard ones? it is a brand new k&n. i put the snorkel top panel back on minus the snorkel itself and it seems to go a lot better, need a dry day now to know for sure!

[captain orange]

Ah you need the dynojet kit really, missed that. The DJ kit has adjustable needles. Micron's are difficult to set up on the little 400 as the pipe diameter is so big 2.5"! Mine ran OK with only a fluff at 3500rpm which apparently you can never get rid of. Although I have heard that some folk cut the primary baffle out of the system, but never seen it proven yet.

[zimm]

shim the needles

the L4's have N770 needles which are V lean compared to others including the dynojet ones.. lifting them up with shims will richen the midrange

if you cant get it to pull through cleanly try

stock filter, snorkel back in and #100 mains

hth

[banner001]

also, the shims you want are M3 washers...cost £2 for a hundred on ebay

http://www.ebay.co.uk/itm/FORM-A-M3-M4- ... 33759dff07

[anakin40]

thanks Zimm, will try 100's with the standard filter, have airscrews on 2, is that a reasonable starting point? and do i need to shim the needles as i'm reverting back? doing the cam chain and valve shims tomorrow, so will put it back to standard and see what happens... might save some fuel too! many thanks

[anakin40]

hi, i put the 100 jets in, standard filter... its stil bogging at 10,000. choke cures it... not sure what to try next, i guess put the 105's in? or a washer under the needle?

[anakin40]

forgot to add it starts without choke, so it tells me its rich til the main jet cuts in then weak mid range, smells 'hot' when i give it some... am really struggling with what to do...

[ross46]

Try this website, I think it explains quite well
http://www.factorypro.com/tech/carbtune ... gines.html

[banner001]

@anakin, here's what im using as a guide.

K&N air filter, sandy bike spares downpipes and a straight through can with a de-snorkled airbox still with the top silencer cover (i think it helps to stop rain getting in the airbox.

pilot air screws set to 2 and 3/4 turns out from fully in - any less and i need a touch of choke to fire up, any more and i can smell unburnt petrol on tickover.

pilot jets - K35 as standard

needles, N77S (standard) but with 3 shims underneath to raise the needle by ~1.5mm - this means that the needle doesnt block the fuel path quite so much throughout the midrange, you can test this by seeing how the bike pulls from 3k - 6k rpm in ~3rd gear and see if you need more/fewer shims, i wouldnt go for more than 5 as a guess judging by the look of the DJ needles.

float height - all set to 11mm (standard)

mains, running 100's i still needed choke so i went for 105's and it flies! you test this as you were doing by opening the choke at wide open throttle and >8k rpm in mid range gears (3rd) and checking to see if your bike picks up (still to lean), boggs down (ok to slightly rich), or does nothing (slightly lean to ok).

im gonna dyno mine soon, might still need to go for 107.5's, or possibly a mix, 105's on the outside cylinders, 107.5's on the inside ones.

a lot of it is feel, you can feel its not right, so play with the settings one at a time and see what effect it has, and getting it running how you want it.

[banner001]

also, if you have not done your valve clearances, do them! bike will be so much better afterwards!

[6K1RKYJ9]

How are you getting on with this? im having the exact same problem. please let me know what youve done and if it worked etc, it would help me a lot. cheers.

[anakin40]

hi kirky have at long last sorted it... am now running 105 mains with one shim under each needle, k&n with top plate but no snorkel, 2.25 turns on the fuel mix, floats set to 11mm, cr9ek iridium plugs... hope this helps

[anakin40]

had already checked valves and balanced the carbs, will rebalance them tomorrow as i have had them apart a few times, goes like the clappers now, pulls so cleanly