VW Vortex - Volkswagen Forum banner

2.0 16v 9a Cbr900rr carbs

2K views 1 reply 2 participants last post by  lonchovalle 
#1 ·
What jetting should I use for main and pilots? also what size shims should I use for needle jets?

-Thanks
 
#2 ·
Hi, that´s what i did.

Engine 1.8 8V, CBR 900RR carbs, stock ignition, centrifugal dizzy with vacuum advance unpluged, mechanical fuel pump with fuel restrictor to carbs.
Number of testslow jet sizeidle screws turns outmain jet sizeNeedle jet heightResults
1403155standardGood idle, no throttle response and low power with bad revving, running hot and too lean
2403165standardGood idle, no throttle response and low power with bad revving, running hot and too lean
3403180standardGood idle, no throttle response and super bad revving and no power at all, really bad MPG, super black spark plugs with carbon fouling, running super rich
4501.5165standardBad idle, better throttle response and better revving, feels a bit of power, bad MPG, black spark plugs with carbon fouling, running rich
5501.5155standardBad idle, better throttle response and better revving, feels a bit of power, bad MPG, black spark plugs with carbon fouling, running rich
6501155standardBetter idle, better throttle response and revving, feels more power, better MPG, spark plugs with light carbon build up, running rich
750 3/4150standardgood idle, good throttle response and revving, feels more power, better MPG, spark plugs with light carbon build up, running rich yet
850 1/2150standardgood idle, good throttle response and revving, can feel the power, nice MPG, spark plugs with very light carbon build up almost unperceptible, running almost normal
At this point i get an AFR narrow band gauge, the numbers at idle was oscilating between 14.3-14.6, at WOT oscilating between 12.3-13, maybe use a 140 mains play with needle heights and see what happens
950 1/2140standardgood idle, good throttle response and revving, +-25 MPG, spark plugs with no carbon build up, running normal, 14.3-14.6 at idle, 13-14 at WOT
After around 200 miles of driving the spark plugs shows very little carbon build up may be caused by the combination of slow and main jets at middle range throttle so the slow jet was replaced with a 45 size
10452 1/2140standardNot yet, check pending
After driving around 100 miles take out the plugs and it seems OK no carbon build up at all, wet or oil. I think i get the correct AFR mixture, got a decent MPG (~4.5 gal in 100 miles) so i decide use this setup permanently.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top