RS125 wont run withought choke on???

[TangoRS]

Just rebuilt my rs125 bottom end after oil pump decided to retire early and engine seized at about 70mph scary!!

Engine has been fully rebuilt but now will only run with the choke on :/ ?????????????

Please any ideas would be soo much help!!!!!

[chrism15]

big air leak, inlet manifold sealed up level and tight? bit of instant gasket along the joints on reed cage to inlet manifold ect?

do the spray test:

take off side panels

start it up and get it to run with the choke off as much as it will let you

get a areosol of flammable contents - be sensible about it so dont use "deicer" haha (use WD40/ CARB CLEANER ECT THAT BURNS EASILY BUT WONT HARM THE ENGINE)

Whilst engine is running spray closly over areas you suspect the engine is drawing unwanted air in

look in areas like inlet manifold and reed cage, air box rubber (make sure the airbox rubber is tight too!) basically any joints bewteen airbox and crankcase

if you spray on a area and the revs go up even slightly, or drop slightly then thats what needs sealing up

for example if you spray on the inlet manifold and the revs go up slightly or down slightly then remove the inlet manifold, clean it slightly with sand paper and apply instant gasket or copper grease and bolt it back on tight and level to make a aior tight seal

[TangoRS]

Il give it ago fingers crossed thanx for the help

[chrism15]

carb cleaner is best

im asssuming you are using stock airbox and have the correct jet for the set up yerr?

because running a open/k&n/cone/foam air filters and using too small of a jet can create same symtoms as it will draw in LOADS of air