Fort Worth Motorcycle Riders

So before I went to the track last weekend I checked the oil level on the SV and added some since it was a little low. When I was unloading the bike on Monday I looked at the oil level again and it was off the sight glass. One of the instructors had told me that he saw a puff of black smoke when I downshifted. I fired up the bike yesterday and rev'd it up while in neutral and cut the throttle a couple of times. Sure enough, black puffs of smoke. They were small puffs, but puffs nonetheless. Been reading that if the rings were going out that it would probably smoke a lot more than just under throttle cuts. Most alluded to the valve seat seals as the culprit of the oil burning. Anyone ever changed out the valve seat seals on an SV? Worth it to do it myself? Any idea what it might cost?

Derek

How many miles does your bike have on the odometer?
Of these miles, how many are commuting short distances?
If you do commute short distances, how often do you warm up the bike before you use a lot of throttle?
I know you work at GM - whats your job? Are you mechanically inclined?

The main cause of black smoke out the exhaust is worn piston rings. Each piston has whats called a scraper ring, its designed to clean the inside of the cylinder on every stroke. This is an iron ring which is relatively soft, not steel, and it scrapes against a cylinder wall coated with a nickel-silicon matrix which is very hard because its a lot easier to replace a ring that costs fifty cents than a cylinder which could cost thousands of $'s.

An engine that is used daily for short distances and doesn't get a chance to warm up before getting a handful of throttle will wear these rings much faster than a bike that has the same mileage but gets used mostly on long trips or gets warmed up every time.

The reason a bike smokes when you rev it at a standstill is the vacuum generated on the overrun - when you let go of the throttle and the engine winds down. At this moment the pistons are moving up and down rapidly but the throttle bodies are closed. The falling piston generates a huge amount of suction - just like pulling a trash bag out of the trash can. This suction pulls oil from the crank cases , past the rings and into the combustion chamber where it burns.
Valve seal has nothing to do with this issue as valves are never intended to keep oil in or out of anything - that's the job of the piston rings. So when the oil makes its way into the combustion chamber it burns, makes smoke, and is then blown out of the exhaust valves with the normal exhaust.

A good way to test your motor is with a compression tester. This will measure how much pressure the rings and valves in each cylinder can hold. The service manual for your bike will have a compression PSI rating, what it should be plus or minus a certain amount, and what the minimum value should be before the motor should be stripped and refreshed.
An even better way to test each cylinder is with a leak down tester. This will fill the cylinder with compressed air and you can find out where the leaks are based on where the air is escaping. But with a smoking motor you already know that the piston rings are bad so this is not strictly necessary but is always a good test to see exactly whats going on in there.

For the SV motor I built recently the customer had noticed no problems at all, despite it being a high mileage commuter bike now being used as a track bike. The problem he had was the loud clanging noise caused by a melted bearing...
We swapped out the crank, found some good pistons from his collection, put in new rings, checked everything and bolted it all up. He now has a motor almost as good as new, with perfect compression from new rings and valves that sealed just fine after more than 40,000 miles.

The SV motor is incredibly easy to work on if you were inclined to fix it yourself. The only problem with that is that replacement motors are so cheap its rarely worth fixing one. Swapping a motor is always cheaper than fixing one unless you do the work yourself.

So like I said, if you want to really know exactly whats going on with your motor, get a leakdown tester. If you have any questions on how to use it or how to read the results just let me know.

If you don't need to use your bike any time soon, fixing it yourself could be a great education on mechanical repairs. Don't expect to save a huge amount of money doing the work yourself though - the special tools required to do the work usually eat up most savings, and rework often costs parts. But once you finish you can do the same job again in a fraction of the time for a fraction of the price.

If you decide to take it to a shop, make sure you find one that you know other people trust. I've worked at several places where the mechanics find minor problems and the service managers report huge issues to the customer. If you're lucky to find a place you can trust that will take on the work, don't be surprised if you get quoted more than $1000. Remember shops charge over $100/hour for labor (and pay the mechanics around $20/hr). This is a job that would take at least 2 days to finish so it wont be cheap.
If you find a low mileage motor, you might be able to find a shop to install it for less than $1000. If you're lucky and find a good motor cheap the final bill will be less because it will take a lot less time to swap the motors than pull yours out, fix it and reinstall it.

Either way, this is a big job that will take a significant amount of time. Doing it yourself will be cheaper, but will take a lot longer.
Do you want it fixed quickly, cheaply, or properly? Pick two, you can never have all three.

Motor has a little over 27K on it. I bought it with 17K so I can only comment about the last 10K. I've probably done 400 miles on the track with the bike and the rest was on the street commuting mostly. Probably 3K of that are long distance highway miles. It is used mostly for commuting. Most of the time very little warm up. I'm fairly mechanically inclined even though I'm an IT guy. I've never cracked open a motor before. Pretty much anything else on a vehicle I've done myself. I guess I'll have to invest in a leakdown tester.

Any oil in your air box when you did your last air filter change?

Nope...

JTChiTown wrote:Any oil in your air box when you did your last air filter change?

The air filter needs changed?

haha

Well I found a guy (Bubba Russo - CMRA site #54) that says he has a 2004 SV motor with 4552 miles on it for $750 that includes everything (tranny, wiring harness, throttle bodies, etc). Sound like a decent price? He has a shop here in Cedar Park. Thinking I'm gonna just swap out the motors and part out my old one on Ebay to offset some of the cost.

I would by buy a new motor just because of that. You might get another 20k out of it as far as you know. From the sound of it, it's not all that bad and doesn't seem to be hurting performance. Then again if you got money to burn a bit, by all means...

It's all guesses without a compression test.

What's the name of the shop in Cedar Park? The Amazon company that was a dick to me over my jacket is in Cedar Park Texas. Based on that interaction, I would be very hesitant to trust him if it's the same company.

Like Rick said without a compression test and an oil filter exam, this thing may be worse than your current motor.

Cedar Park, N of Austin off old 183, 111 - D N Bell Blvd. 512-904-9117

They said they do parts and salvage...

Let me look it up, but doubt it's the same company. They did all mail order stuff, and didn't have a storefront to have people at.

Gonna pick up a compression tester tomorrow hopefully and see what the compression is like. I'm guessing the I need to remove the fuel pump fuse, remove a spark plug, put the tester in the hole, crank the engine, and read the gauge? Rinse and repeat for the other cylinder.

http://www.sears.com/craftsman-compress ... Redirect=y" onclick="window.open(this.href);return false;

Seems to have decent reviews...

There is a good mechanic in this group who has plenty of engine work under his belt and has reasonable rates...

Yeah, but I'm also in Austin...

Just don't tell me that it's Rick...lol

Can any of you SV guys identify what kind of upgrade might be in the front forks of this SV? It's using stock tubes, but the adjusters aren't stock.

I just rebuilt my TLS motor (bought used with wrecked transmission). As long as you have the tools and the service manual for the bike, it's really not that hard to do what you need to on your SV.

If that guy in Cedar Park is named Bubba, I met him, seems like a honest guy. Almost bought a motor from him but he wasn't sure about the tranny so I passed.

Just an update to this thread...

Last track day, it didn't use any oil. Weird...

RC30rdr wrote: The main cause of black smoke out the exhaust is worn piston rings.

Perhaps I just don't have enough experience with repairing motorcycle engines vs auto engines (and absolutely no experience with SVs), but I thought black smoke usually meant an exceptionally rich condition (choke still on, clogged air cleaner etc.) and blue/gray smoke meant worn rings and burning oil. I'll admit that may be overly simplistic for all engines, but isn't it still a good rule of thumb for most 4 stroke engines as a diagnostic starting point?