Idle Question

[bpd106]

Hey everyone, I'm pretty new to the site, and have only posted once before. I bought an 81 XS650 Special II from a co worker a few months ago. Turned out the rotor was bad, I got it rebuilt, and with a new battery, she fires up. Anyway, with the choke pulled out on a cold start, this thing idles at what I think is a pretty high rpm, with some slight popping out of the exhaust, which is leading me to believe I have an intake leak. Once its warmed up a little, you can push the choke in and it idles at an rpm which still seems a little high still with slight popping outta the exhaust. I can't give exact rpm's cuz the tach is screwed up. I also have some top end tapping, which I'm thinking is caused by the valves being out of adjustment. I also plan on checking cam chain tensioner, etc.
Anyone have any input as to some things I can check on this bike as far as the idle/popping and the top end noise. I used my mechanics stethoscope and pretty much pin pointed the noise to the top end/valve area. I have some bobber type ideas for this baby, but I wanna get her runnin' right first obviously.

Thanks in Adavance!

 

[gggGary]

set the timing chain tension, set the valves. test compression (slightly optional), synch the carbs then see how it runs. Any other changes without doing these first will be no more than a crap shoot because you don't have a good baseline to work from.

 

[bpd106]

Well, so far so good. I adjusted the cam chain tensioner last nite, it was definitely out of whack, and it's running better already. Sprayed some carb cleaner around the carb to intake seals and the rpms went up, so there's another problem. I'll mess with that tonite. There's alot of loose nuts and bolts on this baby, mainly from a lack of mechanical knowledge from the previous owner.

 

[TeeCat]

bp, it sounds as if you have found that your intakes/boots are cracked and pulling air between the carbs and the head. This is common. Just so you know, there is a vendor on here called JBM, if memory serves, who makes quality boots for us that are impervious to ethanol fuel. Just so you know, since you'll be needing new boots.

TC

 

[bpd106]

Well here's my latest dilemma, I went out and was checking out the carb holders. I fired the bike up, and let her warm up to the point where I pushed the choke all the way in, as she was warmed up. After a couple of minutes of idling, if I gave it some throttle, it would just sputter, but if you let off, it'd idle, and finally die. Then, trying to restart it, it wouldn't start, and eventually the battery weakened. I waited for a few minutes, and it fired right up and ran fine, then it did it all over again. I put the battery on a battery tender and according to the charger, the battery was almost fully charged. Anyway, it would only turn over slow, and then nothing. I'm thinkin a couple of things happened here, she got too hot, it's overloading with fuel and fouling the plugs, or...I did pour about an ounce of Berryman's B12 fuel cleaner in the tank last nite, and this lil scooter just does not like the cleaner. Oh yea it's still giving little pops outta the exhaust when it is running.
Any thoughts and help would be appreciated. Sorry for the long posts, I'm just not familiar with the XS650 yet.

Thanks!

 

[XSLeo]

Do you have a repair manual? There are places that have them as downloads. biker.net is one. These will help you with many of your problems.
Air leaks can cause your popping.
Have you ridden it yet? With the cleaner in the tank you need to ride it to get the cleaner through all the carb circuits.

 

[bpd106]

I haven't ridden it after adjusting the cam chain, or after putting the cleaner in. The P.O. gave me a Clymer manual, which is ok, but not extremely detailed. I'll take it down off the lift after work and maybe take it for a short putt and see what happens. I'm kinda thinking that it was loading up with fuel while idling and possibly fouling the plugs. I'll pull 'em & check those out as well. It was doing ok the nite before after I adjusted the cam chain, but before I put the cleaner in, that's why I'm thinking the cleaner may be the culprit here. I'll post an update as soon as I can.
Thanks!

 

[nj1639]

Stock exhaust?

 

[bpd106]

Yes, stock exhaust. As near as I can tell, everything on it is stock. It does need new air filters, these are pretty ratty looking. I've got it up on my table lift, and it looks like the exhaust is in decent shape, including the little crossover tube under the frame. Matter of fact, the entire under carriage looks pretty clean. It's got around 7800 miles on the clock. It's been adult ridden but she just hasn't had alot of upkeep and maintenance in her life span.
Last nite when I had it running, I attempted to find the air leak again with carb cleaner and I couldn't locate it again. I went back out after about an hour, and it fired right up and ran normal (with the exception of the slight exhaust popping)

 

[grizld1]

You might find this link useful for the carbies: www.amckayltd.com/carbguide.pdf . If you need carb mounts, have a look at www.jbmindustries.com .

 

[bpd106]

I took the bike down off the lift and put some fresh fuel in her. Rode her around a couple of country roads by my house for about 1/2 hour, although I didn't venture too far away, just in case. The bike actually ran great, and I'm starting to think that it was damn near outta gas, and that's why it was shutting down
The clutch definitely needs to be adjusted, it was having some shifting issues amongst other signs of the clutch needing adjustment, and I noticed that when I came to a stop, the bike was idling high, around 2000rpms, and then would eventually settle down to around 11-1200rpms.
I'll go ahead and order up some new carb holders and get the clutch adjusted.
The popping out of the exhaust seems to have simmered down, but I'm thinking that things swelled up after riding it around and may have sealed up the air leak temporarily.

Thanks to all,
BPD