Need some fast advice - having problem with my XS650

Tim

Tim

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First, apologies for using the news section of the board for my personal gain - but hey, if I can't have that perk, what's the point!

:mad:

Ok, so today, being the bike's official 3 year anniversary in my hands, I took it to the office on its first long ride.

The engine is fresh. New pistons/rings (0.5 over), valve job, new stem seals etc. Maybe a total of 100 miles on the engine at this point, and I'm being gentle with it.

During my previous test runs, I had no issues outside the tuning work I was doing on the carbs.

Today, on my way to work in the morning, no problems. It was a straight run, cool air, not much traffic.

On my way home this afternoon though, it took me 2 hours to travel 40 miles. Lots of stop and go traffic, and of course the engine got good and hot. Ran fine - stalled a couple of times but that's mostly me still sorting out carb jetting and idles.

Anyhow - once the bike got hot, I started getting lots of white smoke (not blue) out of the crankcase breather. I don't have tubes or filters on it yet. It's pulsing air out the breather box, and spewing white smoke with it when it's hot.

Most of what I see on Google talks about blow-by etc. My compression (which I'll check again tonight) was really good of course after the rebuild.

So - guru's out there - what causes white smoke out the breather when the engine is hot on a freshly rebuilt engine?
 
midnightcafe said:
did you put too much oil in your motor? could be burning excess?
Click to expand...

Lord knows I've done that. On my first bike I couldn't see the air bubble in my oil window so I thought it was empty so i just kept filling not realizing that I was already overly full. I wound up trashing the starter when the oil level got high enough to back up into the starter.
 
Well later tonight I'll be out there changing out the oil among other things. We'll see. Horror stories on the web suggest I've blown rings etc. already. I'll be doing compression testing as well.
 
Don't know if it's any help, but if the motor was tipped during the rebuild, a large "puddle" of oil could have found it's way where it shouldn't be. Of course oil should be everywhere, but a large quantity in a unusual spot might take a little longer to burn off.

Good luck!
 
Big R said:
Don't know if it's any help, but if the motor was tipped during the rebuild, a large "puddle" of oil could have found it's way where it shouldn't be. Of course oil should be everywhere, but a large quantity in a unusual spot might take a little longer to burn off.

Good luck!
Click to expand...

plus 1. had this happen to me on my 350.
 
A buddy of mine had a similar problem on an old BSA. In his case the rings "traveled" before they seated and the openings in the rings aligned allowing excessive blow-by. But if your compression is good that would probably rule this out.
 
Start with a compression test for sure, but if it was excessive blow-by, woulden't you get smoke from the pipes too! And you should smell oil burning! I have heard of moisture being in the crankcase after a rebuild and it has to boil off to escape, makes since but I am not sure of its trueth! May be mythbuster material? Also I know that it is common for a new motor to smoke a bit the first few runnings, the stop and go is better to propperly seat rings rather than constant RPM cruising! You may have "slicked" the rings on the first ride if you did mostly constant RPM riding. At first after new rings, you should really try to vary the RPM range as much as possible to break in the rings and seat them.

Good luck!
 
Ok, so I spent a couple hours tonight and will continue in the morning. Lots of little kids in the area (mine included) and revving my engine at midnight is frowned upon :)

I started by draining the oil. Figured fresh oil was in order anyhow, as this oil has been sitting since last fall. Was never run, but whatever - fresh oil is never bad. Nothing strange came out in the oil.

I moved on to an unrelated issue - my exhaust. I was unhappy (and still am) with it, as my headers insert too far into the mufflers. There was about 8 inches of header sticking into the muffler. Don't know if that would cause any performance issues, but I decided to chop the headers anyhow, and improved the clamping at the joint. Still a tiny bit of an exhaust leak at both joints - gotta get new pipes.

Then I moved on, and filled up the oil after putting fresh copper gaskets on the two massive drain plugs. Made sure not to over do it :)

Next I took the plunge and did a compression test. Took both plugs out, installed the gauge, opened the throttle and kicked 5 times. Repeated on the other side. Nearly 150psi on both cylinders :) which is about the same as pre-run when I built the engine. So compression seems to be solid.

Next I re-synced the carbs and set the air mix screw.

Then I cracked open my new timing light and fired up the engine. The timing is retarded. Firing after TDC. It does advance when revved, as the Boyer blue box is supposed to do, but it is firing late.

No smoke out the breather. We'll see what it does once it warms up.

I'll have to break out my Snap On leak down tester I picked up on eBay a couple years ago and see if I can figure out how it works - would like to do a thorough compression test with it, but initial findings are very good at 150PSI.

So now apparantly typing is too loud for 1AM, so time to shut it down!

By this time it was too late to continue running the bike
 
Well, at least it's good to hear about the compression test!

You'll figure it Tim, we have faith in ya.
 
Ok - so timing was WAAAAAY off. Boyer's instructions and setup are a bit flaky and short on details. They do say set timing with a strobe light, and really, they do mean it.

I broke down and bought a timing light the other day and tore into the blister pack this morning. Glad I did, and it was $50 well spent. No fancy advance or RPM gauge on it.

Anyhow - adjusted the timing. It was really, really retarded. Now it's where it ought to be and the bike sounds a ton better. Re-synced the carbs, put the mix screws at 1 turn out and it's running nicely.

No smoke out the breather tubes, but we'll see what happens when it gets hot. I fail to understand why it would start smoking when hot vs warm or cold, but hey, I'm no mechanic.

Buddy Dave is on the way over and we're headed out to the Forks of the Credit. Will snap some pics, if I make it ;) Should be fine.

Also started sorting out the new Suzuki 4LS front wheel.... it's gonna be awesome and the Suzuki axle will fit in standard 35mm Yamaha forks with just a small modification to one fork leg. So that's next week.
 
May be completely retarded here, but I know when I helped my buddy put together his 1640 VW motor for his Baja, he over did it with assembly lube and liquid gasket on a few spots. It burned up and blew bright white smoke out of the breather when we really opened her up on the road. It went away after a bit though. Just a thought...
 
VonYinzer said:
May be completely retarded here, but I know when I helped my buddy put together his 1640 VW motor for his Baja, he over did it with assembly lube and liquid gasket on a few spots. It burned up and blew bright white smoke out of the breather when we really opened her up on the road. It went away after a bit though. Just a thought...
Click to expand...

This would be high on my list of suspicions. also with timing that far off there is bound to be a lot of residual fuel that wants to go somewhere, what do I know anyway. :p

Good luck and keep us posted.
 
If oil level is too high on XS650 it blows oil out not white 'smoke'
Most likely condensation and some oil vapour.
Needs a few hundred more miles break in

PJ
 
So today I took the bike out on a good 60 mile journey at all sorts of different speeds / loads. Nothing outrageous :D No redlining.

Anyhow, the bike ran flawlessly. Nice low idle, never stalled, no real hesitation. I'm getting a bit of a studder at 3/4 throttle at highway speeds, so maybe I'll raise the needle a notch and see what happens.

Regardless - bike got good and warm, and not a trace of smoke. Here's my layman's theory.

The timing was WAY WAY retarded. Firing after TDC. Sorted that out with my timing light this morning and got it lined up with the Full Advance as per Boyer instructions when revved. At idle it's right around the advance mark before TDC. Runs great like this.

So, I figure with way late ignition, I'm going to be left with all sorts of uncombusted mixture, which maybe was forced down past the rings into the crankcase, where it burned up and emitted white smoke out the breather, once the engine was super hot. This all happened during a 2 hour stop-and-go commute home, which normally takes 40 minutes.

Bottom line is the bike runs great and no more smoke :)
 
Tim, i have rebuilt everything from 3hp briggs to 16cyc RR diesels. It takes a bit to get every one just right. You seem to have done a fine job. That smoke is very normal. As long as it clears up. Rings gotta seat, water vapor has to burn off. Sometimes you gotta get the motor hot as it can get two or thee times for it to settle down and quit huffin. Nice job!
 
If you had previously just been riding it on short runs, the oil would have probably had built up condensation, which has steamed up when it got really hot (retarded ignition will make it run hot too). I had this happen on my old XJ900 Diversion when I used to ride it to work (about a 6 mile round trip). The oil would look milky after a bit and it would steam up on a longer (weekend) run.

Now you've changed the oil it will probably be OK (as long as you don't do a bunch of short rides again).
 
The oil I drained out definitely looked 'milky'. Things seem back to normal. Just gotta fiddle with the carbs to get the top end power. I think I need to raise the needle one notch. At WOT things seem good, so the mains are ok I think, it's when the needle is working with the mains that I get into a bit of a studder.

Now on to making the Suzuki 4LS wheel work. The brakes on the bike as it is suck, fading pretty bad as they warm up.
 
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