Last weekend at a trackday someone mentioned that my clapped out 06 GSX-R750 (unknown mileage) was burning oil, but only when decelerating. No burning oil was noticed on the straights, but it apparently puffed a bit when I downshifted. Quick observations that I can think of: 1. There is no noticeable loss in power. 2. Last oil change was in March, just before the first trackday of the year. When I was told about the issue, I immediately checked the oil level and it is still right in the middle of the sight glass, so it's not burning much. Now, I don't think the bike is about to blow the engine and oil down the track, but I am planning on heading to Barber in the next couple of weeks, and the absolute last thing I want to do is oil down the track and screw up someone else's day. I am not an engine guy, obviously, or even a competent mechanic. I can throw parts at the bike, but I prefer to make sure I'm at least throwing correct parts at it, or even checking appropriate things to make sure I'm not completely wasting my time, or the actual mechanic who will end up working on it. I ride a motorcycle around racetracks, so I'm willing to accept some risk, but I won't knowingly take an unsafe bike out on track. If it were burning oil all the way down the straight it wouldn't even be a question, I wouldn't go. So, in the esteemed opinions of the actual professionals, am I taking this too seriously or not seriously enough? What else can/should I check? I've got a couple of days next week set aside specifically for bike prep, and I can check stuff throughout the week before then, though my garage time is limited somewhat by working nights and me not wanting to wake up the kids on a school night by starting it up if I don't have to.
If that is the case, what am I looking at, in terms of cost? As in, is it worth getting the work done to a 16-year-old engine? I reckon tracking down a known good engine may end up costing as much as just fixing this one, due to it being old enough to drive now.
I guess I would be confused why you would not fix what you have versus getting another unknown component of questionable condition. Guides are like $4 each. I would think putting a couple few hundred bucks towards a basic top refresh would pay dividends. Or ride around waiting for a spring to fatigue & fail.
I'm mostly thinking out loud about how soon I'll be doing it at this point. If it's less than $1,000 I'll get it done during heat exhaustion season and end up with a known good top end. I'm probably conflating different problems but I vaguely remember people opting to replace an engine instead of repairing them in the past, but that may have been a complete rebuild 10 years ago back when these engines were far more available. Either way, sounds like I should be okay for Barber next week, but I'll also go ahead and start planning on a top end refresh this summer, even if I end up skipping a couple of days of track fun.
1. Make a list of parts and tools including seals, gaskets, lapping tool, spring compressor, valve shims......beer? 2. Set aside a full day (2?) 3. Get organized, fair amount of table space, keep everything so that each valve goes back in it's proper location. 4. measure valve clearances before you start so you know beginning point. 5. Drink your beer and find a mechanic to do the work....who were you kidding?
If you can source a suitable candidate for rebuild so you dont suffer down time. I was given an R6 engine with spun rod bearings a few years ago... Ive got ~$4500 in parts & machine shop as a complete rebuild in SS form.
I had this exact same issue happen to my gsxr 750, it was the valve seals. But mine blew a lot of oil! You probably just have 1 or 2 leaking. But maybe you can replace the valve seals with the engine installed and maybe use compressed air in the spark plug hole fitting, this will hold the valves from dropping into the cylinder, when you pull the locks, springs, and seals off.
If you are going to keep the bike, I'd recommend removing the head and having it refreshed - valve job, new seals, probably springs and retainers. If not, keep running it until it blows up, which it will. When part of the valvetrain lets go, it will destroy the engine.
Thanks to everyone who has smacked some sense into me. My current plan is to get the top end refresh done this summer and have a known fresh valvetrain at least.
