What is this? On my 1997 Monster 750

[Mike Qube]

Forgive me if I sound new, but I am.
Today I noticed this little rubber nub held on by a hose clamp on, I believe the intake manifold. The rubber is dry and cracking on the right side and one the one on the left side of the bike, I went to inspect it and the top of the nub came of because it was so dry and cracked.
What is it? What does it do? Is it really bad that the bike was running with them in bad shape. Here's a pic with the arrows pointing at it;

[Mike Qube]

Also, lately it's been idling like crap. It'll go good for a minute and then bog down and stall. Could this have anything to do with it?

[teddy037.2]

:Edit: looks like someone removied the emission can, and used the nub to seal the nipple

if it's cracked, you've got a vacuum leak.

you can replace it, or take that and the nipple off and replace it w/a bolt (sealed somehow, of course)

[Mike Qube]

:Edit: looks like someone removied the emission can

if it's cracked, you've got a vacuum leak.

Thanks for the quick reply. Would that have anything to do with my crappy idle until it warms up?

[Mike Qube]

:Edit: looks like someone removied the emission can, and used the nub to seal the nipple

if it's cracked, you've got a vacuum leak.

you can replace it, or take that and the nipple off and replace it w/a bolt (sealed somehow, of course)

Why would someone remove the can? is there any benefit to that?

[teddy037.2]

i'd reckon so  


removing the can is like giving the finger to the Man 

on some of the newer bikes, the emission can will get in the way of high mount exhaust

[Buckethead]

Why would someone remove the can? is there any benefit to that?

Because it's ugly, and not really, but no harm if its done right, either.

[Mike Qube]

Thanks for the help! I just did a search on the rubber caps on it looks like they're about 20 cents each!

[dlearl476]

Thanks for the quick reply. Would that have anything to do with my crappy idle until it warms up?

Yes, most definitely.

Thanks for the help! I just did a search on the rubber caps on it looks like they're about 20 cents each!

Make sure their some kind of heat resistant rubber, otherwise they'll melt.  It's better just to remove the fittings and replace them with bolts and crush washers.

[Porsche Monkey]

That is a vacuum cap available at any auto parts store.  If it is cracked or missing it will most certainly affect how the bike runs. 

[ducpainter]

They've been using those caps in the auto industry for ever.

A couple of new ones will last a long time.

[hooligan machinist]

 

They've been using those caps in the auto industry for ever.

A couple of new ones will last a long time.

I keep about a half dozen or so in my riding jacket, just in case i lose one during a ride.
They'll blow off if the bike backfires at startup and the heat causes cracking and brittleness. Generally though i change them every other spring. No big deal at all.

[Mike Qube]

I bought a box full of them today at the auto parts store for $5.
I also had to buy a battery charger, I killed my battery this morning because it kept starting for a sec and then stalling, now the battery doesn't have enough juice to turn it. So hopefully, once I get the caps on and the battery charged, it'll come back to life.

[Porsche Monkey]

 

[Mike Qube]

I put the rubber nubs on, charged the battery for about an hour. I don't think it needed much juice. It started right up and stalled, my dumb ass didn't use the choke. Started with choke, ran for a few minutes, took the choke off and it ran perfect. I went for a quick ride and noticed it's running a bit smoother, it doesn't seem to be backfiring like it was before. I'm willing to bet that it needed these things the whole time I had it (10 days now). I cant wait for the sun to come out and go for more of a ride.

Thanks for the help everyone!