450 petcock vacuum

[Guest]

So as some may know I'm working out the kinks in a rebuild of a 450t and have a wicked hanging idle.

I've got all the boots on order but was thinking about other possible air leaks and a thought occurred.

The vacuum attachment on the carb to the petcock was very loose, so I used some blue Locktite to keep it from falling out.

My question is, if that isn't sealed would it play a substantial role in my air leak situation? If so how would you recommend I seal it more effectively?

[pete]

Not sure if you ruled it out already, but I'd suspect it would be more likely to be something like the airbox not sealing or missing an air filter or something if the boots etc. don't resolve it.

Essentially, anything from the air filter to the inlet side of the head can be susceptible to air leaks...

As to your vacuum attachment, I guess it's possible as it's only an interference fit onto the carb, but mine is such a snug fit I couldn't imagine it being too much of an issue...

[jeffasaurus2]

Oh I haven't ruled out the airbox or the boots, I've got all that on order to replace and plan to seal the airbox.

Thats the thing though, mine isnt that snug of a fit, one could pull it out with bare hands and *very* little effort, if I had turned the carb to the side it would have fallen out.

[pete]

Wow really? Maybe it's not even the right airbox? Noone's reported an airbox that easy to get out before

Glad to hear you've got it under control though.

[jeffasaurus2]

Haha, no not the airbox, that is a PITA to get out. I was refering to the barb in the carb to which the vacuum to the petcock attaches, the barb is super easy to pull out.

i was wondering if it would be a substantial air leak, i guess ill find out when i get these boots in.

[pete]

Haha ok that makes sense

Probably your locktite idea would be best for that...

[Bobber]

When you say hanging, what do you mean? If the idle is staying high, then it is more likely a vacuum leak. If the the bike idles high and then drops to normal or low, then more than likely its the pilot circuit in the carbs. Maybe a good cleaning is in order.

[jeffasaurus2]

When its revv'd it sticks then drops to idle or a little less. Its also a tad sporadic while warming up at idle.

pilot circuit, what exactly would be included on that? Im actually just reassembling from a carb cleaning and plenty of shotty maintenance from a po.

[pete]

Pilot circuit for us 450 owners as far as I'm aware is the pilot jets, pilot air screws/mixture screws, and the associated passages. Should cover from closed throttle to something like 1/4 throttle.

[jeffasaurus2]

honestly that all looked fine and dandy. The only thing I was really concerned with in the carbs was the main jet. The PO had scarred up the slot on it for the screwdriver but it didnt look like anything terrible. Should that be more of a concern for me?

[pete]

I would imagine as long as he didn't damage the threads on the hole itself then it should be fine, and that certainly shouldn't affect idle either, main jet doesn't come in until nearly WOT from what I understand...

[jeffasaurus2]

The only other thing i can imagine would affect the pilot system is part #20 on our carb fiche, the 'jet needle'.

everytime ive taken the bowl off ive had to pry it loose, carefully of course, and the 'jet needle' always remains stuck in the bowl. When i rebuilt them i used pliers to pull it out which did marr it so i used some sandpaper to remove the burrs. It still a tight fit with the oring on there so i know it is sealing, should i look into replacing it?

[chuckycheese]

Lean

It sounds like it's running lean. I'd suggest you back out your air screws about a half a turn and see if that takes care of it. Also, take a look at your plugs. It sounds like you're looking for a big problem when you've probably got a little problem......which is really common!

[jeffasaurus2]

It wouldnt surprise me if it was something silly, im still waiting for my boots to come before i tinker anymore.

i have checked the plugs though, one has a whitish tip and ther other is black and dry, in another thread i understood it to be whitish is lean to ok and black would be rich, correct?

[chuckycheese]

Lean

Yeah, you've got the hang of it. Try backing out the air screw on the carb with the 'white' plug and see if that helps get your idle down faster. If not, wait for your new boots. It is important that they're in good shape, no matter what else.