Fun Afternoon Learning With a Newbie (Valve adjustments)

[Uhlaf]

Little back story;

I've recently acquired an 81 XS650 Special II, it's in alright shape for a 33 year old bike. She runs and idles just fine and I only need a couple things to get her saftied and on the road (a little rewiring, some sprockets/chain and a tires). But of course having joined the forums and been lurking a couple threads I thought I could learn a couple things/save myself some money and be better of for it. So yesterday I gave the bike an honest look around, kicked her over and listened to her idle... TAK TAK TAK TAK and a bike could always run better right?

So today's project in the name of learning and self reliance I adjusted my valves. Looked up some literature, watched some videos, went out and bought myself some feeler gauges, all hoped up and ready to go. So my manual says that the intake should be 10mm, so I turn the crank, line up the timing marking with the mark besides the T and take my measurement; a little off. I adjust...perfect 10mm. Exhaust... turn the crank line up the T - 15mm gap.... do this three times and I've never had my bike run like such garbage...

Only kicks over with full choke at which point she revs through the roof and I dance backwards on the centerstand which while being entertaining was not my desired effect. Oh, and the TAK TAK TAK is worse. The only thing I can deduct is that maybe I messed up/got the wrong manual. Can someone with a little more wisdom point me in the correct direction? TEACH ME

 

[gggGary]

You don't say it quite right so I gotta ask; you know you do both intake and exhaust on one side THEN turn it 360 and set both intake and exhaust on the other side?

Generally set to .15mm exhaust .08mm intake. Have you set the cam chain? How many miles (or KM) on the engine? Doesn't hurt to spin the adjuster back and look at the top of the valve stem for dents and hammering that make accurate valve setting impossible.

 

[Uhlaf]

I'm 90% that's what I did. Haven't touched the cam chain. 10k miles and will do when I get back from work tomorrow and have another go.

 

[gggGary]

A loose cam chain has an erratic slap clatter noise where a mis-set valve sounds a bit more regular and frequent.

 

[Uhlaf]

That confirms it, I'll come back tomorrow after going over it all again. When doing this I found out a whole bunch of fun stuff about my carbs too. That's for another time.

 

[gggGary]

Also a bike that just came out of some garage runs right for a bit and THEN starts acting up is more common than not. Give that fresh ethanol gas and some fine XS vibration a chance to loosen up decades of crap from the fuel system and send it into the carbs and lots of fun follows.

 

[Uhlaf]

So I'm sitting in my garage having another crack at this. I have some questions;

When turning the crank and I get the intake to open while it also be open on the other side?

 

[Uhlaf]

Hold on. I'm recapping on 650Twins video

 

[gggGary]

I hope you are getting it now.

TDC intake AND exhaust on the cylinder that has TWO loose valves. Then 360 (a full rotation of the crank back to TDC) and do intake and exhaust on the OTHER cylinder.
Tell us how it sounds after you get that done.

 

[Uhlaf]

Just got finished! She kicks over again but the idle is a LOT lower than previous. Because I'm new to this I think that ever sound is my engine tearing in half and am super critical of everything. I hear the metallic TAK TAK TAK still and of course I find that to PO lost the cap on the left carb where you measure the vaccum which is probably why the right exhaust sounds so boomy compared to the other. I should have played more attention to the way she sounded before I started

 

[Uhlaf]

Also, the right exhaust is SCORCHING compared to the left. Hold on girl, I don't know what the guy before me did to you but I'm going to try to make it all better ;_;

 

[gggGary]

Well lets start with plugging that big ass vacuum leak! Put a cap on that vacuum port before you burn a hole in a piston. If the caps aren't wired or clamped to the pipe a backfire will send them flying. It's happened to me several times.

 

[ippytattoo]

With the vacuum cap off the left cylinder carb holder it is probably so lean that it is not going to fire which is why your a feeling such a huge difference in the exhaust pipe temps and also why the idle is low and why the right sounds louder than the left. As far as the TAK TAK TAK sound there are a few possibilities. Your best bet is to go through the "new purchase" maintenance from top to bottom and front to rear, if you do it now it will save you a lot of time and headaches later when "odd" problems start rearing their ugly little heads.

 

[5twins]

Go to the auto parts store and get a pack of these. They're the perfect size for those vacuum nipples, and you'll have some spares for when you lose one or it blows off .....

If it's still noisy after fixing the vacuum leak and adjusting the valves properly, check for the missing damper washer on your cam chain adjuster plunger .....

http://www.xs650.com/forum/showthread.php?t=35733

 

[XSLeo]

On a tune up there is a set procedure for the steps.
#1 Adjust the can chain tension.
#2 Adjust the valves.
#3 Adjust timing. On points any way the TCI is factory set and should be good.
#4 Carbs.
Always do the first three before the fourth.
www.amckayltd.com/carbguide.pdf is all you need for the carbs. Never buy anything before you do the tear down cleaning and inspection of your carbs. Quite often the only thing you need to replace is the float bowl gaskets. So most of the parts in a kit are just parts you can't use.
Other parts you might need never come in a kit, things like throttle shaft seals, float valve O-rings.
Leo

 

[5twins]

I find the original float bowl gaskets to be quite robust and usually still OK if the carbs haven't been monkeyed with too much in the past. The originals are still on mine and work fine. Careful removal of the float bowls is the key, freeing any stuck spots gently before a tear occurs.

I went through a set of carbs for a guy and was able to re-use everything except for a few o-rings. Then he let them sit for a year or two with gas in them (yes, he's a numb nuts idiot when it comes to bikes). I told him he better have a look inside and would probably need to at least clean the float bowls out. He promptly broke both bowl gaskets and yes, the bowls were green inside. That bike still doesn't run right, probably never will, but my free help has ended. A moron like that can pay me (and I think I'll charge him double, lol).

 

[angus67]

i run a vacuum line from one boot to the other. seems to smooth out the idle, and since the line is long, one side to the other, it cant blowoff and get lost, just disconnected.

 

[Uhlaf]

Just redid the cam and valves. Also got something to plug up the leak. No more TAK TAK TAK and the bike sounds a lot healthier. I'm sure you guys get this a lot but your the best. Onwards to carbs!

 

[ANLAF]

Sounds like Uhlaf is having fun, there. I worry when I hear of lean running and high temps.

Just a thought, Uhlaf, you don't say how you adjusted the cam chain. You will be a lucky guy indeed to find a bike with a cam chain that is not worn (stretched) beyond correct adjustment. A worn cam chain might be part of the TAK TAK sound you hear, and a loose cam chain makes it difficult to get those valve clearances right. XSLeo gives the correct sequence. I tend to find TDC and do the right cylinder first. When I have done both I turn the crankshaft a couple of times and check again. Strange, but I usually have to re-adjust. Then, of course, Uhlaf, the timing will need adjusting.

It's all good fun - and the fun keeps on coming. Well. it keeps us off the streets!

ANLAF

 

[Uhlaf]

Once again I watched The650Twins' video on cam adjustment and followed that (great resource for people who don't know what they're doing) and got mine into spec, even better 650Twin has an 1981 like myself. The cam chain was WAY off. And having adjusted the valves some many times I kind of learned that you'll have to rotate the crank and re-measure and then turn the crank and remeasure. Once I started getting steady results I moved on.

Also, I don't have points. Do I need to adjust my timing? (1981 Special II)