starting question
 

Hi guys,

After hours of cleaning and searching for parts, Iv finally re-assembled my bike... to an extent anyway.

I tried to start it today with no joy. Iv put a brand new battery in it and its turning over no problem bt not firring. The spark is ok and compression os OK (although not properly tested, only by hand).

I think the problem is with the inlet rubbers as they are very worn and I cn see them flapping as the engine turns over. would this cause it not to fire at all or would yo expect it to still fire badly?

thanks guys,

Rob

if your getting good spark and no signs of it firing then your probably not getting fuel, those inlet rubbers are probably allowing way too much air into the motor.
you will need to get them rubbers sorted out before you run it anyway as its going to run too lean and you risk burning valves and damaging the piston.
oe rubbers are expensive try somewhere like wemoto.com

cheers mate, iv ordered some new ones...watch this space!

am I right in thinking that I wont be doing any harm by starting it without that 2nd rubber from the air box as the 2nd carb doesnt open till it gets to higher revs, so if im just starting it and letting it idle it wont open anyway.

havent managed to find the air box rubbers on the net and I expect yamha will charge something silly so I was hoping to wait until something comes up on ebay.

Rob

it should be fine starting it without the rubber hose on.
you could always stick some duct tape over it if you're worried about any dirt getting in till you get a hose, stick some over the hose hole in the air box too as any dirt getting in through there will be the engine side of the filter and could be drawn in through the hose thats fitted.

the hose wasn't that expensive it was £13.69+vat a couple of years ago part no i have is 3tb144540000 joint.

new inlet rubbers worked a treat! with a little persuasion from easy start she fired up nicely. havent got it to idle properly yet but didnt have chance to spend too much time with it.

cheers for the advice,

Rob

once its breathing properly through the air box it will be a lot easier to set the idle up correctly.
even tho the std yam carb setup is supposed to only open up fully with the throttle wide open at upper end of the rev range it will still have some small effect at idle if all the hoses are not in place on that secondary throttle.