PHBH pilot circuit / tickover troubles, boring i know!
Posted: Wed May 20, 2015 3:51 pm
As the title suggests, im having a mare setting up my tickover.
Its a 28mm phbh on a home tuned, peaky suzuki conversion, 60x117 plus jl3 plus advance / retard, worth noting as on tickover set at 16, then advances to 24 or so (cant remember exact figure) and retards back.
When I first built it a few weeks back, I had no trouble, found I needed up to a 60 pilot jet to stop having to wind out mixture past 2 turns, but on slide height i had plenty of movement to create a fast tickover. However, I then noticed after one long run I had developed an air leak, could have been present since the build, but there was a noticeable change on tickover, ie racing. Rest of rev range seemed okay, no lean symptoms, but knowing it would only get worse i stripped it and found the base gasket dry and brittle and blown.
Since rebuilding everything is tight and fine, although I can no longer achieve a tickover. the slide height adjuster is all the way in and nothing. So. I did the obvious and checked the choke. Decided to strip carb down and give it a clean, and replaced choke plunger and spring, and im 99.5% sure its sealing properly. float height set correctly, although using 9.5 g float, which i hear can richen things up low down. however, ive tried pilot jets ranging from 60 back to 53, with absolutely no difference between them. The rest of the jetting is as follows, not that it has any impact really: 40 slide, 300 float jet, av266 with x7 currently on 2nd clip down (far better than next clip down but a tad worried its too lean when in power) and 130 main jet.
So I think ive covered everything really. It really points to the choke being open but Ive checked and rechecked. Slide isnt too worn where the adjuster sits also, so not lower than standard.
any help appreciated.
ta!
Its a 28mm phbh on a home tuned, peaky suzuki conversion, 60x117 plus jl3 plus advance / retard, worth noting as on tickover set at 16, then advances to 24 or so (cant remember exact figure) and retards back.
When I first built it a few weeks back, I had no trouble, found I needed up to a 60 pilot jet to stop having to wind out mixture past 2 turns, but on slide height i had plenty of movement to create a fast tickover. However, I then noticed after one long run I had developed an air leak, could have been present since the build, but there was a noticeable change on tickover, ie racing. Rest of rev range seemed okay, no lean symptoms, but knowing it would only get worse i stripped it and found the base gasket dry and brittle and blown.
Since rebuilding everything is tight and fine, although I can no longer achieve a tickover. the slide height adjuster is all the way in and nothing. So. I did the obvious and checked the choke. Decided to strip carb down and give it a clean, and replaced choke plunger and spring, and im 99.5% sure its sealing properly. float height set correctly, although using 9.5 g float, which i hear can richen things up low down. however, ive tried pilot jets ranging from 60 back to 53, with absolutely no difference between them. The rest of the jetting is as follows, not that it has any impact really: 40 slide, 300 float jet, av266 with x7 currently on 2nd clip down (far better than next clip down but a tad worried its too lean when in power) and 130 main jet.
So I think ive covered everything really. It really points to the choke being open but Ive checked and rechecked. Slide isnt too worn where the adjuster sits also, so not lower than standard.
any help appreciated.
ta!