What are these things

[Russ]

I noticed a very small what appears to be oil spot on the concrete under the bike on inspection, it appears to have seeped out of one of these tubes. So first, what are these and should I be concerned? Second, when looking at the tubes, I found this plastic thingamabob is cracked. What is it and should I be concerned? As always, thanks in advance. 

[Russ]

And on re-reading, I realize I neglected to say location. This is kickstand side, towards rear tire, behind exhaust, almost directly below passenger floorboard. 

[M61A1MECH]

I cannot help with what the plastic thing-a-bob is, but I can shed some light on the tubes.

Those are drain/vent tubes, one of them goes to the airbox, it is part of the Positive Crankcase Ventilation (PVC) system. As the engine creates vacuum to pull air into the carbs,  there is a line from the airbox to the crankcase, oil vapors and in some circumstances liquid oil is pulled from the crank case into the air box, the vapors are supposed to go into the carbs and out the exhaust. If there is to much vapor it can condense back to a liquid and settle in the bottom of the airbox where it collects at the end of the tube which then gravity drains onto the road way or your drive way. It is very common to have this happen and is part of the design. The situation can be made worse if you over fill the crankcase with oil or at sustained high speed riding as the oil tends to slosh around more than normal and is more prone to get sucked up into the PVC tube and then the liquid oil ends up in the air box. Next time you have the tank off, open the air box and inspect for oil residue, wipe it dry that should solve the dripping for a good little bit.

The other two tubes may be carb vent hose in the case a float sticks the excess fuel will drain out those hoses, if that is not correct , someone will be along shortly to set me right.

[Russ]

Thank you! That eases my mind quite a bit! Now to figure out that plastic thing! 

[djh3]

Well I looked in the parts diagram and couldn't run across where the plastic thing goes to. But it also appears to be a vent box. If you look the tube starts low and goes higher before it can exit. Indicating it is capturing a liquid possibly and if it gets to high it can then drain out. But its idea is if there is some liquid it can evaporate before it would drip. Would make sense if it was some sort of crankcase vent, or possibly fuel?

[WIZ]

I think it is part of the AIS system. Part number 22.

22

CASE, AIR CLEANER 4XY-14857-00-00   In Stock

$65.99 $49.64

Edited September 14, 2023 by WIZ

[BratmanXj]

I do believe that 2nd picture is the air intake for the Air Injection System (emissions) 

[Russ]

#22 looks like it! How urgent is this to replace or can it wait until I put her up for the winter? 

[BratmanXj]

On 9/27/2023 at 5:42 AM, Russ said:

#22 looks like it! How urgent is this to replace or can it wait until I put her up for the winter? 

I gutted the AIS system from my bike all together... I capped the ports on the cylinders with 1/2" copper plumbing caps.

 

I may have that part in my bin O spares, I'll take a look this weekend.

[Russ]

20 hours ago, BratmanXj said:

I gutted the AIS system from my bike all together... I capped the ports on the cylinders with 1/2" copper plumbing caps.

 

I may have that part in my bin O spares, I'll take a look this weekend.

That'd be awesome! What exactly does that system do? It sounds like it's not really needed. 

[BratmanXj]

On 9/29/2023 at 4:10 PM, Russ said:

That'd be awesome! What exactly does that system do? It sounds like it's not really needed. 

I guess that was some of the few parts I didn't keep.  Its an emissions control unit that injects a small puff of air into the exhaust pipe to cause a secondary burn of any unused fuel coming out of the engine.  I've disabled it on a few bikes during tuning with no adverse mechanical results, but obviously slightly higher emission out the tailpipe .

[Russ]

1 hour ago, BratmanXj said:

I guess that was some of the few parts I didn't keep.  Its an emissions control unit that injects a small puff of air into the exhaust pipe to cause a secondary burn of any unused fuel coming out of the engine.  I've disabled it on a few bikes during tuning with no adverse mechanical results, but obviously slightly higher emission out the tailpipe .

Thanks for checking. I'll probably leave it as is for now and then look into either replacing or repairing it this winter. Thanks again! 

[BratmanXj]

Yamaha Air Injection System AIS Removal or Disable XVS 650

This is for the 650, but its basically 1/2 of our engine and the concepts still work.  I was able to use 1/2 copper plumbing caps right at the port on the heads by re-using the stainless wadding from the original piping and lightly tapping it on.