Understanding your motorcycle, Kawasaki Vulcan air suction valve, spark plugs, Valve Lash/Clearance

This is part 1 of a two part video showing a detailed description of how to check and adjust valve lash in a Kawasaki VN800 motorcycle. This bike uses replaceable shims to adjust valve clearance. Along the way we examine the Kawasaki Air Suction Emission Control system, some fundamental details of the cooling system, and we do a spark plug change.
If all you're interested in is seeing the valve lash adjustment, you may want to go to part 2 directly, it's here. • How to adjust Kawasaki...
For a pdf guide to doing valve lash, the following file is helpful, though their exhaust valve target is similar to the oldest version of the dealers repair manual. drive.google.c...
For a free pdf copy of a more recent dealers repair manual, try this www.werder.ee/Manual/VN800.pdf. Or for the most recent version of the manual you can purchase this electronically from Kawasaki directly.
This is an amateur presentation offered in good faith, for free, but with no guarantees as to safety or accuracy. Never rely on one source for critical information, and if in doubt go back to the dealers repair manual for important guidelines.

[@mperhaps]

You guys are lucky, you get to adjust lash. I have hydraulic lash adjusters on my VN-2000 which means I'm fucked. The HLA's are like 20000 mile parts. If you change your oil religiously maybe 30000 but there are no VN-2000 that don't have clogged or inoperable HLA's. Worst part of owning a VN-2000 and those rockers are not accessible with that one ton engine in the frame. Heavy sigh.

[@TheSteelBlinds]

I’m a simple guy. I see a new spelunkerd video, I hit like 👍

[@SVImpavidus]

I was just getting in to that when part II flashed up. My Blackbird's were a pig to change the plugs. The later one (second one I had) had fuel injection no more carb balancing!!!!!! Looking forward to your next vid. Sail Safe mate. Ant, Cid & the pooch crew.

[@spelunkerd]

Thanks!

[@slobodanstupar3662]

Hello. I am following your channel for a while now and I was wondering could you maybe do a video on how to adjust the suspension (rear shock) on your VN800. Thanks and keep on doing a great work

[@shawnmrfixitlee6478]

ENJOYED, Great share ! Will be back for part 2 ..

[@spelunkerd]

Thanks Shawn, I put part 2 up today.

[@mxdaddy1]

Hi there I was hoping you could help. i've watched a ton of your video's and you're super detailed and great at explaining. I just did a valve shim on my vulcan 800. I cannot for the life of me find out where the crankcase breather hose goes. I know it's the middle hose on the airbox but I have no idea where it goes from the airbox. It looks like there was a clamp on there I can't tell where it goes to??? I've scoured the manual and the internet. Please help :)

[@spelunkerd]

There is a drain on the airbox that simply drips onto the ground, mounted on a downward pointing nipple that is located in the airstream between the air filter and the carb. Mine is routed forward so it hangs down on the front, overlapping the starter motor. There is a second larger short tube that connects the airbox to the crankcase. There is a third tube that connects the air suction system to the airbox, which some people tinker with and eventually remove. If yours is removed, you may be looking at that nipple. I did a detailed video explaining how that air suction system works, and I show some of those hose connections in a handful of other videos. These bikes don't have a PCV valve, they have an old school design that equalizes air pressure with an open tube. With all those connections, oil from blow-by gas can build up in the air box so Kawasaki added a drain. My tube lasted a year or so, and then the oil degraded the factory vacuum line tubing into mush. I replaced it with more durable fuel line that plays nice with oil.

[@mxdaddy1]

@@spelunkerd hey thank you for taking the time to respond. Very much appreciated. I have watched all of your vn800 videos. great info. The one I was talking about was the crankcase breather hose. I did find it on the crankcase. I was having trouble finding the location. I needed to remove the carb in order to get a better view of it. I found it, but super grateful for the reply.

[@spelunkerd]

@@mxdaddy1 Thanks for the feedback. I was looking back at my old videos and found a brief glimpse of the end that goes into the air filter housing (in the video of how to remove the fuel petcock). I've never had to chase down the other end, I'm glad you found where it goes. As you say, the dealer repair manual shows a small diagram in 2-12 but not much detail of where the other end lands.

[@skipper3069]

love watching all of your video, i have the same ride and i wondering if you can help me. I have a problem with the carburetor fuel coming out on a cold start. thank you sir for your hard work.

[@spelunkerd]

I'm not sure what you mean. Are you saying it won't start because fuel isn't getting to the cylinders, or are you saying fuel is leaking out of the carburetor onto the ground?

[@AndreiStabell-f2i]

I do have 1 Vn classic 99 And wanna find out which size retainer is needed , A huge problem happened oil running on spark , muffler too . I dunno if wud finding Retainers of valve similar to replace . Z900 have hurd is alike to Vulcans 1500 Vn 😮

[@gcanaday1]

I've got a request, if you're still seeing these comments. Can you show in a video the bracket for the choke mount? I didn't receive a complete bike and I'm rebuilding, but I did not get this bracket. The manuals do not show it and the parts lists do not give a part number! Most assume the bracket is there, but in my case it isn't and I need to know what it looks like before I go dropping money on random bracket pulls on eBay. Thanks, if you see this.

[@spelunkerd]

I can send you a couple of snapshots if you like. Leave your email address here, and I'll get back to you in a couple of days. Delete your post after that so your email is not embedded in the thread permanently.

[@gcanaday1]

Actually I was just on my way back here. This morning I went through all of my parts looking for every bracket in my parts bins to see what others I might need to replace. What do you know, there was an old choke cable in there with the bracket already on it! I'd gone through the parts before, looking for the cables to see what I got with the bike and what I didn't and I did not see a choke cable in there at all, so I ordered a new one, which did not come with the bracket. Lol and behold, got it! It just goes to show that another look is always worth it. Thanks muchly for the offer!

[@billk5727]

Thanks for sharing! Bill

[@JamesBrownlip]

Hey I just got my Vulcan and when I let throttle down at 50 or 60 mph I get popping from exhaust. I was told you can get rid of the air suction system valve. They make plates you put where the plastic box is. There is a thing called marbling but the plates are more permanent. What do you recommend?

[@spelunkerd]

I'm probably not the best guy to ask about that since I take effort to leave a vehicle the way it was designed. Popping exhaust is characteristic of many V twins, and it happens in many vehicles that don't have the air suction system. If it were my vehicle and I wasn't sure about prior maintenance I'd probably have a look at the lifter shim thickness since that is a critical maintenance procedure. While at it I'd clean the air intake system at the same time and inspect those reed valves and the vacuum actuated valve. During that exam I'd pay special attention to any evidence of leaking intake gaskets which are very common on old bikes. The air intake system relies on manifold vacuum to open and close that pathway so if there is a leaking hose you might get abnormal function. If your bike has a modified exhaust, popping could be caused by pressure imbalance as a result of the modifications, and I know that some pros will adjust carb settings to try to compensate for that. I'd run through a couple of tanks of fuel in case water in your fuel is complicating the situation. You'll never get popping or backfiring as a result of a normally functioning air suction system.

[@JamesBrownlip]

@@spelunkerd ok thank you man. I will look into it

[@MrBraffZachlin]

omg i was clueless and couldnt find for sure what what hose off the suction valve was or was doing. i have carburetor issue i thought but that hose was damaged and i had no way to know if it effected performence or what it was doing attached to the carb on my vulcan 500

[@spelunkerd]

Glad it helped. If the vacuum hose leaks air, you'll have a vacuum leak that will cause fast, irregular idle that improves under load. Also since the fuel petcock requires vacuum you could have a fuel delivery problem causing all kinds of issues.

[@williamhebert4047]

Hello I am unsure if you will see my comment but I’ll give it a try aha I have a 98 Kawasaki VN800 I am wondering on the Air Tube Intake Duct Housing Cover what is the three hoses on the back for and I think the bottom is just a drain.. I bought this bike a couple months ago and I hope to bring it back to life for summer time it did not have any lines connected therefore why I am trying to figure out where it comes from and what nipple to connect it to thanks I hope to hear back 🙏😬

[@spelunkerd]

Yes, there is a drain hose that dangles from the air filter housing down to the ground, open to the air at the bottom. Old engines like this drip straight to ground. I bought my bike new and within a couple of years the oil had degraded that vent hose to mush, so I swapped in a more robust fuel hose. There is no PCV valve on this bike but one of the hoses connects from intake to crankcase so it makes sense that you'll get oil showing up there, especially if you overfill engine oil. You've got a great bike. I still ride mine and aside from routine maintenance it hasn't needed anything. I put an inline fuel filter into mine, and I left the air suction valve assembly completely stock. The critical maintenance item is measurement of valve clearance and replacement of shims, which if ignored could kill your engine. I did a two part video showing how this is done, every 8,000 km as I recall. Every single bike video I've done has been on an almost identical bike to yours, so I hope you find my playlist useful. Cheers! Dave

[@MotorcycleMenace]

What is the difference between an air suction valve and an EGR? I have bypassed the EGR on my diesel bakkie (what we call a small pick-up in South Africa) I have just bought a Honda Deputy moped (semi-automatic) and it has an air suction valve. I am having idling issues and the engine almost bogs when driving or fully opening the throttle too quick on occasion and stalls. The carburettor is clean and in good shape. I am also experiencing exhaust backfire especially on deceleration and alot of heat, seems very much like the symptoms of faulty EGR. Would bypassing the ASV cause any issues? And could it be the cause of my problems???

[@spelunkerd]

Great question! The simple answer when comparing EGR to Air Suction is the air goes in opposite directions. With EGR the air goes backwards from exhaust to intake, only during conditions of reduced vacuum. With air suction, air is drawn from the intake manifold into the exhaust, and like EGR it happens only during reduced vacuum, such as when accelerating, not when coasting. The air suction has two valves in the air stream, the vacuum switch and the one-way reed suction valve, see in the diagram at 6:40. The vacuum switch closes during states of high vacuum, such as idle, or when coasting to a stop. So, if the air suction system were causing problems during those states, the only way it could do so would be if that vacuum valve is bad, or if the manifold vacuum needed to close the valve is reduced, or if there is some kind of additional leak in the air stream. People monkey with these connections all the time, so look for something simple. If you're concerned that you've got a problem with the air suction system, I'd start there. A common cause of strange idle is a vacuum leak, which is really common in bikes. Have a close look at all the connections, looking for cracked hoses, disconnected hoses, gaps in the fitment of the carburetor where it attaches to the intake manifold, etc. One of the most helpful tests to find a vacuum leak is a smoke test, where smoke is blown into the intake to see where the smoke comes out. Alternatively, while the bike is idling, you can spray either water or something flammable at areas of concern, listening for a change in rpm as the liquid is sucked into the system. Obviously the risk of fire needs to be carefully considered if you use something flammable. When examining the air suction system, closely examine both reed valves to be sure they aren't mucked up with carbon or blown out. Of course the other issue is the fact that your system may be very different. I'd get a Honda OEM repair manual to get details regarding your bike. Good luck!

[@eng0605]

good video Thank you