petcock/vacum

[cnicko23]

help ! i am new to the forum and looking for some answers 1975 t500
replaced the petcock for an after market on /off type just 2 outlets
but what do i do with the vacum pipe that went from the carbs to the old 3outlet petcock can i just bung the hole up?
chris

[GTandcbr]

Yes just needs to be sealed to prevent any foreign matter getting in and of course unwanted excess air!

[dgoodsy]

Yep. It needs to be capped off and sealed or else it changes from a vacuum tube to a massive vacuum leak.

[cnicko23]

thanks
next question i have replaced gasket jets airbleed screws in fact i bought a carb kit and replaced every thing the bike now runs as though the choke is on permanantly / not getting enough air. ?

[Alan H]

That's because you bough after market and not genuine.
Read some posts on after market carb kits.

[dgoodsy]

I'm trying to learn about carbs at the moment so i'm not the expert!

However one doesn't need to be an expert to say this: The carbs need to be cleaned extremely thoroughly for the bike to run right. All the little orifices need to be cleaned (spray carb cleaner and watch and make sure that where it comes out is a nice clean spray, not spurting, bubbling and uneven, and consistent across all carbs.

Have you checked float levels?

Are your symptoms at idle only or do they clear up with some load/throttle?

Which kit(s) did you buy? Did the bike run prior to putting in the new kits? Are the new jets the same size compared to stock (or previous)? What is the air screw setting compared to previous?

[GTandcbr]

Air filter dirty and clogged ?

[cnicko23]

after a restoration the bike was running but over revving air leak due to not blocking off the vacum to the petcock so i decided to remove the carbs and block the vacum whilst i was at it decided to refurb the carbs with the after market carb kit now it seems choked all the way through the rev range and wont idle ive tinkered with the air bleed screws but it makes no difference
JETS ?

[dgoodsy]

You think it's running rich? What exactly are the symptoms? Is it just very lazy to rev? if you turn the choke on does it make it run worse or stall even easier, or does it make no difference?

Which carb kits did you buy? As Alan touched on, many people have had poor luck with aftermarket/non-genuine carb parts.

Float level?

I would be tempted to put the original jets back in and try that since you don't know that they are bad, and you have now blocked off the open vacuum tube.

[cnicko23]

it was bought on ebay from rustyiders
it does make a slight difference with the choke on but not much
thankyou for your assistance it is much appreciated and i will take your advice and start at the weekend and replace the original parts and see what happens
ill letyou know what happens
thanks again
regards chris

[dgoodsy]

Not a problem, hopefully I'm more help than hindrance! Update us after you get a chance to work on it, let us know how things went.

It would be worth noting the sizes of the old jets and compare them to the new jet sizes. Also before taking the carbs apart please make sure the old jets are as clean as you can get them, and inspect their orifices with a magnifying glass and light.

Good luck.

[rngdng]

Don't forget that on these carbs, the "choke" is really an enrichning circuit. It supplies more fuel, not less air. The aftermarket carb kits all suck. The only parts that can be used are the float valves, and bowl gaskets. All of the jets are ALWAYS wrong. I can't explain why, but they are simply always wrong. If you haven't thrown away the old jets, and needles, clean them well with carb cleaner and compressed air, put them back in. If you got rid of the old parts.....



Lane

[cnicko23]

thanks for the info
i have now put all the original parts back and it starts well sound good then after a 45 - 50 seconds it cuts out like its fuel starvation
any ideas
ta !

[dgoodsy]

That sounds like symptoms that could be caused by fuel flowing too slowly from the tank to the carbs and the float level slowly getting lower until the engine runs lean. Make sure the fuels path from the tank to the float bowls is not blocked, clogged, kinked etc. Make sure the try the petcock in the reserve or prime position (if it has either) to see if that makes any difference.

[GTandcbr]

Are you closing the choke before it cuts out? You should as soon as its started or it may flood . pull the plugs straight away are they wet? Is the float level set too high causing cylinder to flood?