Pete.L wrote:Have you checked the exhaust gasket at the rear pipe about 40 cm away from the head. Because it's hidden by the swinging arm it often gets missed and it is the most common seal to go. It will give you lovely back fires on the decel when it's on the way out
Good luck on the Dyno
Pete.l
BINGO! Doing a fuel screw adjustment and balance on Friday and heard a slight exhaust leak, and I reckon its the join in the swingarm. Guess I need to get exhaust seals in next Partzilla order!
Also, dyno today, and here is the result (100% throttle);
Keihin 178 front and 182 rear mains. FP needles are middle clip plus 1x 0.6mm shim front & rear, 48 pilots, screws 1 7/8 front and 2 1/8 rear, TPS 499 ohms, idle around 1300rpm.
On the horsepower graph, the green line is the previous run hp figure - 102.68, and the red line just below it is todays hp figure - 100.23.
The AFR graph - the upper red line is todays run, probe in right hand can, the blue line is probe in right hand can, previous run. The lower red line is the left exhaust can, todays run.
So... I still have a sweet curve (more good luck than good management!). The dyno operator is suggesting the exhaust pulses may or may not blend in the joined section of exhaust, so take an average of the left and right AFR reading, but it is possible the front is still a tad lean and/or the rear a tad rich (as shown on the AFR graph the right hand can is quite a bit leaner than the left can). 5500 to 7500 maybe a bit rich on the left can, not sure whether to touch it though, and below 5500rpm quite lean.
Paul (the dyno operator) suggests the 3500-5000 lean bit could be the slides opening slowly - probably too much tension on the spring (which are OEM Honda) and he also suggests going down to a 45 pilot and tweaking with the screws. He is telling me it has a slight surge at cruise (which I felt but it was barely noticeable), and he is saying the hangup when blipping the throttle could also be a rich thing not necessarily a lean issue.
*BUT* - he also said it rides beautifully, has a beautiful curve, even watching the tacho go up during the dyno pull, no hesitant spots, just a smooth rise to the limiter. So I can leave it the hell alone, or speed up the slides, go a smaller pilot and retune the screws. Mmmmm, carbs off 1 more time..... or buy something non carby like a rear hugger. Tough call!!!