Engine teardown after 90k miles

[tntmo]

I picked up a 2005 FJR with 89,xxx miles several months ago that didn't run, got a smoking good deal on it and bought a used 2010 engine from Ebay for $500 for a swap.

While waiting for the Ebay engine to show up, I got the old engine running. The shop I got it from had diagnosed it with low compression, in fact two cylinders were almost zero. They said the air filter was really dirty and probably caused piston ring wear. I did notice a lot of dirt on the throttle bodies, so much that it was almost like mud. I pulled the spark plugs and put a tablespoon of oil down each cylinder and it started right up. I rode it for about 300 miles this way while waiting on my Ebay engine. It was low on power but still went over 100 mph easily. I even took it to work one day.

After the engine swap, the old engine was in the way in my garage. I put it up for parts here and on a few other sites but since these bikes are pretty reliable I haven't gotten rid of too many bits. Today I decided to take the engine apart.

First of all, these engines are stout. The crankshaft is amazingly heavy as are the transmission gears and all the bearings. I broke two Craftsman 12mm six point sockets trying to get the head bolts off, so didn't get the head off today. Maybe I will try my Harbor Freight sockets later?

The lower end looks solid, the bearings on the mains showed almost no wear and the lower piston rod bearings also were in beautiful shape. All of the transmission bearings and gears seem perfect as well. I'm looking forward to removing the head and the pistons to check that out, but I wouldn't be surprised to see that they are in ok shape even though the compression was so low.

So all of this tells me that if you have an engine with high miles and have been religious about oil changes and keeping the air filter clean you shouldn't have too many problems. These engines are built tough, I've been working on bikes for a long time and this is one of the most impressive engines I've seen. Fairly easy to work on, too.

 

[RossKean]

Yep! No surprises there.

Many engines out there over 200,000 miles. I expect to hit that in another year and a half. I would be interested in the condition of valves and rings once you get it apart. Did you do a compression test after running it? I'm betting there really wasn't that much wrong with it. Stuck rings, broken rings or just worn? Guess it depends upon whether the previous owner used an air filter or not!

 

[Geezer]

Yep, my guess is stuck rings. I would be surprised if there was enough wear on that low mileage engine to cause such poor compression.

 

[RossKean]

Yep, my guess is stuck rings. I would be surprised if there was enough wear on that low mileage engine to cause such poor compression.

Agreed! The fact that it started right up and made good power after oiling the cylinders makes me less inclined to believe there is a really big issue. With "almost zero" compression on two cylinders, I have to think it wouldn't start and run decently. If it had been mine, I think I would have tried chemical treatment (Ring Free etc.) and check the compression afterward before I elected to replace. By the time you're into major overhaul, a replacement (used) engine is cheaper than the parts and labor for the work (valves, seat regrind, rings etc.).

 

[tntmo]

There is no doubt that it was run with a dirty intake system, I used over two cans of carb cleaner to get the throttle bodies clean. After the oil in the cylinders, it ran but it was obviously low on power. I didn't do a compression test after running it, wish I had. The shop didn't do a compression test, they did a leakdown test. The best cylinder of the four had 20% leakage, one at 30%, one had 90% and another had 100%.

I guess it would have been interesting to try Ring Free or some other product and see how long I could have ridden this bike, but for $500 (shipped!) I got a really nice used engine with 35k miles. I thought about rebuilding the engine but I decided it would be too expensive.

 

[dcarver]

Regarding dirty throttle bodies, many have been seen here over the miles.. Clicky Me For Pics.

 

[NMRoadRunner]

The compression issues may be valve clearance related.

 

[ckuhns]

There is no doubt that it was run with a dirty intake system, I used over two cans of carb cleaner to get the throttle bodies clean. After the oil in the cylinders, it ran but it was obviously low on power. I didn't do a compression test after running it, wish I had. The shop didn't do a compression test, they did a leakdown test. The best cylinder of the four had 20% leakage, one at 30%, one had 90% and another had 100%.
I guess it would have been interesting to try Ring Free or some other product and see how long I could have ridden this bike, but for $500 (shipped!) I got a really nice used engine with 35k miles. I thought about rebuilding the engine but I decided it would be too expensive.

If the shop did a leak down test the lack of compression should be easy to pin point. rings , intake valves or exhaust valves

 

[Fred W]

The compression issues may be valve clearance related.

Good point. If the owner had been that sloppy with his maintenance he may have never bothered to do a clearance check. 100k miles is about where you'd expect to run into serious trouble with valves not closing.

The intake being dirty is not unusual at all for even a well cared for machine. It seems to get sooty from crankcase recirculation back into the air box. This afflicts all high mile FJRs but shouldn't cause any added wear.

 

[lele]

I never understand a thing...when an engine breath dust and dirt which part is more prone to wear? Cylinder wall or piston rings?

 

[RossKean]

If it had been valve clearance related (or simple leaky valves), compression would not have been restored sufficiently by oiling the cylinders to run the bike - especially if a couple cylinders were "near zero". Restoration of compression by oiling is the classical test for leakage from rings vs valves.

I never understand a thing...when an engine breath dust and dirt which part is more prone to wear? Cylinder wall or piston rings?

lele - I would expect ring wear rather than cylinder walls - the FJR cylinders have a ceramic coating that is very hard. As I mentioned, above, rings can be stuck, worn or broken.

 

[tntmo]

Regarding dirty throttle bodies, many have been seen here over the miles.. Clicky Me For Pics.

While those are dirty, that is nothing compared to the ones on my bike. It was thick muddy crap on the airbox side and on the intake valve side. Worst I have seen.

I checked the valve clearance and all were in spec. The main reason I tried the oil was because of the shop write up from where I bought it said leakage from rings. Old farm trick to get vehicles going was to put oil down the cylinder, works on John Deere tractors and it works on FJR's as well.

 

[Geezer]

Regarding dirty throttle bodies, many have been seen here over the miles.. Clicky Me For Pics.

While those are dirty, that is nothing compared to the ones on my bike. It was thick muddy crap on the airbox side and on the intake valve side. Worst I have seen.

I checked the valve clearance and all were in spec. The main reason I tried the oil was because of the shop write up from where I bought it said leakage from rings. Old farm trick to get vehicles going was to put oil down the cylinder, works on John Deere tractors and it works on FJR's as well.

The fact that pouring oil down the cylinders brought the compression up is what makes me believe that the problem is stuck rings. The oil would help seal between the rings and cylinder walls and allow improved compression. Once running the rings might get enough action to work free enough to keep that compression up for a while.

It is possible that some nasty stuff got drawn into the intake past the filter, maybe even a small amount of liquid. Only the original owner would know. It would not take much to get the rings to bind in their grooves. I suppose a regular habit of lugging the engine could also cause rings to bind. Rings generally move around in their grooves at high RPM which helps keep the grooves clean.

 

[dcarver]

Time for a tear down! Let's quit speculating and see some facts! Chop-Chop, OP!

 

[tntmo]

As soon as I make it to Sears to get some new sockets, I'll have the head off. The rest of the engine is torn down already. Wish I knew if the clutch was original, it looked good as well. The cams look great, no wear on the lobes or on the journals.

 

[Geezer]

Time for a tear down! Let's quit speculating and see some facts!

Chop-Chop, OP!

Speculating on what happened to someone else's engine is a lot more fun than shoveling snow. No need to hurry, some of us still have at least a couple of months before riding season.

 

[RossKean]

Clutches last a very long time on these bikes if not abused. Never heard of excessive wear on cam lobes, either. A few issues from some folks on the transmission - mostly slipping out of 2nd. Probably has to do with the way it is ridden and how many missed shifts that occurred along the way (damaged shift forks usual cause).

The thick muddy crap on the airbox side makes me wonder if the original owner even had an air filter in place! Airbox on these bikes tend to stay pretty clean with most of the goo appearing downstream on the throttle bodies. (If he simply never changed the air filter, it might prevent the engine from running well due to air starvation but shouldn't allow more particulates in - a partially plugged filter stops finer stuff than a brand new filter.) Don't suppose he was using a K&N filter? Over-oiling sends goo downstream and under-oiling results in poor filtration of particulates.

Question: Is this a "California Bike" with the charcoal canister for scavenging vapor phase hydrocarbons from the tank? If so, the original owner MAY have bypassed the charcoal canister but may not have sealed off all the tubes etc. If this was done, there is nothing to prevent unfiltered air from making its way into the downstream side of the airbox. (This can happen on a Gen II Cali bike; not sure if the Gen I is set up the same way.)

 

[Fred W]

Good call on the rings being the most likely if compression is restored by oiling. Also good call about this being more fun than snow shoveling! :lol:

 

[lele]

do u see blue smoke from the mufflers?