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how does it run when hot? can you get 8,500 rpm in 4Th?the standard air cleaner is dry,not oiled.how is the timing?is it retarded ??just a few ideas to check
Hi,As with most 4 to 1 in my day ran as rich as hell.You are going to start from basics float height,every air way clear,smaller jets etc.Go find a nice stretch off road give it full bore hit the kill switch with the clutch in coast to a stop pull the plugs and see what colour they are and adjust as necessary smaller, bigger jets etc.Frackin pain in the arse remember it well also cant remember with the 500 have you got anything blocking the air intake like the 400 vent under the seat?CheersBitsaps Dont know if its me but just once I wish my 750 plugs would look a bit black but they dont with fuels in the 70s lead etc they should look slightly brown impossible today confuses the crap out of me but they are the same colour as my modern xjr1300.
Has it just started doing this? was there any changes that are relevant? just rebuilt? not been used etc.An easy statement would be that it has too little oxygen to burn the fuel......if the jets are normal then you would first look at the air supply.......is the choke completely clear when not used? remove the whole airbox and try it, should run a bit lean in that spec.As John says, have you verified the timing is normal.
Can you physically see that any choke influence has been removed when you feel it's off?
Looking back at your original post, I don't understand "main jet set at 100" what is that referring to?Also, what position are the main needles set to, i.e. the circlip postion on the needle grooves. Usually five grooves with factory setting ordinarily the centre one.