Diagnosis help If I can get it?

[webbrs]

Hi all again, my '81 is starting and running well but I was noticing an odd difference in sound between the two pipes (shorty megaphones with one of them crushed up pretty good and it says thump thump thump thump but I think the baffle is opened making it ineffective-ish) and remembered the dollar bill test. The right side that is crushed up blows the bill almost out of my hand but the left side wants to suck it in. I remembered the test I don't exactly remember what its telling me other than the valve is open somewhere too long or not shutting all the way. have not yet adjusted the valves because I am unclear of the measurements. I have a set of feelers that read .002" and .0025". They are very thin. No .0024" to be found locally.(I live in a craphole) Not sure how to proceed before I go fumbling around in there. No compression test numbers as I don't have a gauge but both holes pop my thumb off on the stroke. No black smoke but the plugs have a very light dampness and not sure if it is oil or gas and soot. I am getting a slight leakage down the left side cylinder and looks like from the head gasket, but is heard to trace with fresh oil. I am running rich I know, but I feel that until I get the valve train right, tuning is a waste of time. Would anyone mind giving me a idea about the remedy or what the dollar bill is telling me and what the feeler gauges being - .0004" or +.0001" off is going to do to my adjustments?

 

[Brian902]

Start by reading this post and then ask questions.

http://www.xs650.com/forum/showthread.php?t=13083

 

[gggGary]

And this http://www.xs650.com/forum/showthread.php?t=367

When we get an old motorcycle there are always multiple issues. Anything less than a systematic "service" of the bike will have you pulling your hair, because any ONE problem you fix will still not be the "answer". You won't really know if what you just "fixed" worked or not.

BS34 leaky float o-rings is one typical "gotcha".

 

[XSLeo]

.003 intake and .006 exhaust works well for most years.
Leo

 

[webbrs]

Thanks. My journey has been pretty systematic so far. I have seen the videos and read the other thread before but I watched them again anyway. Was still informative. Can never know to much. All of the O-rings in the carbs are new as are the gaskets, the old ones were in good shape but I changed it anyway. Adjusted the cam chain, no timing adjustment on my year. Running shorty pipes and Velo-stacks so I had rejetted because it was popping on decel and I set the needle too high (rich). No more popping at least. The feeler that reads .0025" is marked .06mm so I will see where the valves are set at and go from there.

 

[TwoManyXS1Bs]

The sucking up of the dollar bill (or shop rag) usually means a sync problem...

 

[webbrs]

Thanks for the input. I needed to sync them up but after nine hours to change a fuse, I sort of tuckered out and was glad it was running. I don't know why some ppl do things the way they do.

 

[webbrs]

Thanks for the help 2many. Sync up nailed it. standing at the rear wheel I can feel both blasts pretty strong. sounds good too. I want to cut off the mufflers. My Harley runs straight pipes but it isn't 360* like the XS. I have read some threads that say there is a loss of low end? just something to toy with.

 

[TwoManyXS1Bs]

Not sure if you've seen this, DogBunny's carb sync thread:

http://www.xs650.com/forum/showthread.php?t=33791

The main issue with chopping off mufflers and running straight pipes is the reversion pulses that upset induction during valve overlap. Normally mitigated by the mufflers (what folks call 'backpressure'), these pulses improve power at certain rpms (provide scavenging), and reduce it at the 'between' rpms. Pipe diameter/length selection controls this effect, much like tuning a pipe organ. Most folks choose to rejet the carbs to manage this.

For more info, search using 'reversion' and 'anti-reversion cones'.

BTW, what is the current CHL wait period?

 

[webbrs]

I was reading that earlier. real informative. I used it for the mixture but I used a gauge for the sync. The plugs are dry but still have a slight fluffy soot that doesn't cover the plug face so I am getting closer. I will have to get some clear tubing that fits the drain to check the float height. I want to get all the readings I can before I pull the carbs again.

I am not having luck for cones for stock pipes. Any ideas?

The CHL wait depends on the person's background, but average is about six months.

 

[TwoManyXS1Bs]

Probably won't find cones for stock pipes, they're normally for larger diameter pipes. That was just for search and learning purposes.

6 months!!! I gave up back when it was only 2...

 

[webbrs]

The class room portion was shortened and more people are taking the class. They have always said around two months but it is more like 4 to 6. there are only two investigators I think so the background takes the most time. Back when I took it I waited 7 or 8. the process has been streamlined since then. Now it is all online and they only allow digital fingerprints. With the shortened class it just killed my profit margin, lol. didn't do it for the money anyway I guess.

AS for the pipes it seems hard to justify $300 for a quarter inch and a bit more sound. Better spent elsewhere I think. Like turning my 1.5 gallon tank into a 3 gallon with a sight tube.