First valve clearance adjustment on my cb200t. Little help please.

[sixsixtie]

Ok, fellas. I know this is easy for you OG gear heads. This is my first bike and I'm doing my best to get this thing running as nice as possible and learn as much as I can in the process.

When I got the bike it was idling extremely high. Like 5k. It was ugly. I rode it home anyways and tore apart the carbs and cleaned the living shit out of them and replaced all gaskets and needles that came with my rebuild kit.

Fired it up and it no longer idled extremely high. (could have been a product of reseating all the adjustment screws) However it wouldn't idle for long. I could get it to fire up and run nicely at 2k (high still I know) however not for very long, eventually the idle would drop and it would stall out. You had to keep on the throttle to keep it from stalling. But while it was running it sounded like it was running pretty strong. I even took it for a rip around the parking garage. It seemed to be ok, yet it would still want to stall while idling.

I started to do some searching and it sounded like it was the valve clearance was off. So I went down today and gave it the old college try after reading through a couple different manuals. (the honda one and a Clymer one). I got everything off and was a little confused as to what I was supposed to be measuring with my newly purchased feeler gauge. I did some more reading and studied the pictures for seemingly way too long and I think I figured it out. Though once I put it back together I'm not sure if I was right.

I'll attatch a picture with what I was measuring.

This picture was taken pre-adjustment. Now at first I figured I was measuring the gap between the rocker and the valve but I quickly realised that was wrong. It's between the valve stem and the adjusting screw.

So what I want to do is lower the screw until the screw is .05mm away from touching the bottom of the valve stem? Is that correct?
If that is correct can someone explain it to me like I'm five what a bigger gap does and what a smaller gap does? Should I also make sure to adjust my cam chain tension before doing this?

Also another quick question. How I can be certain which valve to adjust when I get the generator rotor line the T up to the index mark. Whichever one is lower? It says closed but how can I tell if it's closed? In the picture was the one I figured was closed. Can you tell from the pic or no? What should I be looking for?

Sorry. That was a lot of words and questions. But I'm a newb with a willingness to learn and asking questions to people that know more than me helps.
Thanks.

 

[Sonreir]

Yup. Cam chain adjustment before tappet gap adjustment.
.05mm sounds right for the intake valves. Exhaust are .08mm.

The adjustment needs to be made when the cam lobes are down. This can be checked by turning the engine to TDC and watching the rocker arms. The arms will depress the valves every other rotation. The valve gap should be set on the rotation when the rocker arms are NOT depressing the valves.


Having these properly gapped is important for several reasons:
1.) Too much of a gap will cause increased wear on the tappets and valve stems because this piece acts a little like a hammer every time it's actuated. A smaller gap means less wear because the difference in speed between the tappets and stems is less. Bigger distance means the tappets are moving faster prior to coming in contact with the valve stems and more wear occurs.
2.) Too little gap and the rocker arms will be holding the valves open even when they're meant to be closed. Metal, like most things, expands as is heats up and when you're setting the gap on a cold engine, there's less of a gap when it gets hot. This scenario is extremely bad because you're likely losing a lot of power and, also, the exhaust valves can overheat and burn up.
3.) The valve gap adjustment, to an extent, also controls the valve timing. If the gap is out of adjustment then you will be modifying the power curve, slightly. Go too tight on the adjustment and the valves are opening sooner and closing sooner than desired. This causes a loss of high RPM power. Too loose on the adjustment and the valves are opening later and closing later. This causes a loss in low RPM power.

 

[sixsixtie]

Thank you very much for writing that up. I'll give it a shot tomorrow.

 

[crazypj]

It may be easier to buy a cheap set of feeler gauges from Wal-Mart then bend/curve the end so it slides under adjuster screw
One other serious effect of tight tappet that no one seems to mention (probably because I haven't told them yet )
When valves get too tight, it's extremely likely that rocker will be touching cam all the time and the oil film will break down.
This causes a lot of wear on the nose of cam, often until it wears down.
I find it much easier to use a go/no-go method.
Use a 0.002" and a 0.003" on intakes and a 0.003"/0.004" on exhaust.
the smaller size should slide under adjuster, the bigger shouldn't

 

[sixsixtie]

Is there a reason for the difference between exhaust and intake? Because the manual says .05mm all around. It never mentions differences.

I went out and adjusted today but it didn't do much. The thing is running far too rich. I'll attatch the video. I ran it for about 10 minutes and when I checked the plugs they were BLACK, BLACK. I'm starting to get discouraged here. I've done seemingly everything I've read multiple times. I just haven't adjust the timing yet because I haven't found a timing light.

Here's a video of it today post adjustment.

http://www.youtube.com/watch?v=xVh2shA2fqM&feature=youtu.be

 

[sixsixtie]

Doing some more reading. It seems I was adjusting the wrong cylinder at the wrong time. I was doing it when the was aligned and the spring and valve stem were in the down position. It seems like I need to do it to when the t is aligned on the cylinder with the spring and valve stem are in the UP position. Is this correct and could this be the root of my problem? I'm going to have to give it another adjustment that's for sure.

 

[Sonreir]

Difference in intake and exhaust gaps are due to heat. Exhaust valves run much hotter and so they expand more.

Black plugs could be anything from low compression, to retarded timing, to just idling the bike too much without running it.

As for valve adjustment, it sounds like you were doing it wrong, yeah.

 

[crazypj]

I knew there was something bugging me about your first picture, where is the lock-nut off adjuster screw?

 

[OJ]

My advise would be to keep working on the bike and you will get better adjusting the tappets, timing etc. I wouldn't try to run the bike too much until you get your timing light and can adjust/set everything, but maybe that's just me. As PJ said, bending the feeler gauges, if you have not done that yet, will help.

And yeah....where's the lock nut? Do not run the bike without the lock nuts tightened! I had the lock nut and adjusting screw come loose on my bike and got extremely lucky that both got lodged in in the cam chamber and didn't f&%* things up big time. I probably left the lock nut loose and my engine was lucky to live another day.

 

[teazer]

When you get it, it seems so simple and up to that point it all seems like voodoo magic. Let's back up a step.

Too much valve clearance really hurts performance and damages the valves and cam and rocker arm. Too little clearance can cause a valve to stay slightly open and burn out. There are other issues, but that's enough to go on with. The exhaust is often set with a larger clearance because it gets hotter and expands more than the intake valve.

Setting clearances is quite simple. First set the motor to teh T mark for top dead center. On that engine, both pistons rise and fall together and at TDC (Top Dead Center) one is firing and one has both valves slightly open. Rotate it another 360 degrees and the one that was closed is now open.

So, at TDC one set is slightly open and one is completely closed. How to tell? As you rotate the engine forwards (never back) watch teh inlet valves. One will close way before TDC and the other will start to open just before TDC. as you go past the T mark, on one cylinder the exhaust valve will start to open at about 90 degrees past TDC and the other inlet will be closing.

So at TDC, if you rotate the engine back and forward a few degrees you should see one set of valves rocking open/closed and the other pair is sitting still. The still pair are on the FIRING stroke and that's the pair you set.

If both pairs are way too far open. Go to the T mark and close up both sets until there is zero clearance. Now rock the motor a few degrees back and forth and see which pair moves. Set the OTHER pair to .05mm and repeat for the other side.

And do not forget to fit a lock nut on that adjuster screw. They are a fine thread and are hardened, so get the right one. If you can't find any PM me and I'll send you one or however many you need.

Once you have done it, it will start to become obvious and simple. Good luck

 

[sixsixtie]

And yeah....where's the lock nut? Do not run the bike without the lock nuts tightened! I had the lock nut and adjusting screw come loose on my bike and got extremely lucky that both got lodged in in the cam chamber and didn't f&%* things up big time. I probably left the lock nut loose and my engine was lucky to live another day.

Don't worry I just snapped a picture with the nut off. I never started the bike with it off!