Bizzy13
XS400 Addict
That's what I said. Into the vacuum tube on the right intake boot.
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The mystery HOLE!
- Thread starter Inflict
- Start date
Bizzy13
XS400 Addict
My plug didn't work on the tach hole. It's still spewing oil around the plug I put in.
Edward
1978 XS400E
I think he means on the other side of the carbs, the filter/intake side. If you connect the breather to the vacuum, it'll start pulling stuff (air/oil) from the crankcase straight into the combustion chamber. On the other side, with no pressure/vacuum, the breather is free to vent out as necessary.
There is a seal in there that you will have to replace to stop the leaking. Or remove the tach drive all together. To do that you will have to remove the rocker box then plug it. There was a guy on here that made plugs for the tach drives his handle was milliniumfalcon I think. I got one of them on my spare engine it's nice.
Attachments
Bizzy13
XS400 Addict
Yes, that's what I mean!
Do not vent the crankcase into the intake boots between the carb and the head. Bad idea.
Bizzy13
XS400 Addict
Okay cool. I was just wondering. I just out a small cone filter on mine.
peebuck
XS400 Enthusiast
Hough why do you say its a bad idea to vent back in to intake, if thats what the Factory did?
The factory vented into the "H" pipe before the carbs. That's fine. He was talking about venting into the ports in the intake boots after the carbs. That's bad. It introduces additional air after the carbs have metered the fuel meaning you would be leaning out the mixture.
Recreateme
XS400 Addict
On a bump here - does anyone currently use the Reed crankcase vent? I was looking at buying one but someone said its difficult to fit without elaboration. I just thought it would be as easy as just pushing it into the hole and your done. Anyone know?
Charles
XS400 Addict
Why would it be any different if the PCV vent was where ours are located compared to the XS650 rocker cover vent??
Recreateme
XS400 Addict
Thanks Chris, I will just pick up the 9$ chrome/Rubber filter from xsdirect then.
The 650's benefit from having a reed valve on the crankcase vent because they can develop a vacuum when both pistons rise at the same time (depending on the crank installed). The 400's have a 180 degree crank (1 piston up, the other down) and won't create a vacuum.
I used to have my crankcase vented to atmosphere through a filter. It would mist oil on occasion, and at every stop sign and traffic light I could smell oil fumes. Made me think I'd developed an oil leak and generally pissed me off. I made some velocity stacks for my pod filters and vented the crankcase into them. Similar to the SOHC H-pipe intake boots. No more oil slobbering or fumes. I was also able to slightly lean out the idle mixture as well. Much better!
Don't try to undo all the factory engineering, try to make it better!
I used to have my crankcase vented to atmosphere through a filter. It would mist oil on occasion, and at every stop sign and traffic light I could smell oil fumes. Made me think I'd developed an oil leak and generally pissed me off. I made some velocity stacks for my pod filters and vented the crankcase into them. Similar to the SOHC H-pipe intake boots. No more oil slobbering or fumes. I was also able to slightly lean out the idle mixture as well. Much better!
Don't try to undo all the factory engineering, try to make it better!
Charles
XS400 Addict
Interesting. I've heard talk about the engine in my car developing vacuum and it's not arranged like the XS650.
Do you have actual documentation or can you be more specific as to why the 180 degree crank set up would not benefit from creating a slight vacuum?
Not trying to be argumentative, just trying to understand better.
Do you have actual documentation or can you be more specific as to why the 180 degree crank set up would not benefit from creating a slight vacuum?
Not trying to be argumentative, just trying to understand better.
A 180 degree twin CAN'T develop a vacuum in the crankcase. The internal volume of the crankcase doesn't change. The 650 twin will develop a vacuum in the crankcase as both pistons rise and fall at the same time.
All piston engines will benefit from a vacuum in the crankcase as it will help seat the piston rings and make them seal tighter. But very few designs can do it, and most of them shake like they are trying to come apart...
All piston engines will benefit from a vacuum in the crankcase as it will help seat the piston rings and make them seal tighter. But very few designs can do it, and most of them shake like they are trying to come apart...
Charles
XS400 Addict
That makes sense. Thanks!
