Compression Test - I Think I'm Screwed

[Mitragorz]

I did a compression test on the bike today:

https://youtu.be/R5k1VCqXnP8

Results:

Cyl 1:  75psi
Cyl 2:  55psi
Cyl 3:  25psi
Cyl 4:  40psi

Unless I've totally botched the test, I think this is the end of this project.  I don't have the time to hunt down a good motor and digging into it and replacing valves isn't something I really want to get into on this one. 

Cylinder 3 had water in it when I got the bike.  #3 and #4 carbs were in bad shape, if you watched any of the videos I posted (FYI, attn mods:  Let's update the forum and allow video embedding!) so I can understand the low numbers.  The jugs and valves are probably toast. 

Unless anyone has any wild ideas, I think this bike has 'part out' written all over it.

[RPM - Robert]

You don't need to look very hard for a used motor. the Legends cars that used these motors from 1993 to around 2018 have switched to the 3 cylinder FZ09 engine. With this, the fz09 has less torque and they get a significant 200 lb weight break over the 1200 and 1250 cars. So most every one is switching to the FZ09 as it is easier drive due to less torque and lighter overall weight, which in turn makes them quicker. Some of the 1200/1250s around here are quick on certain nights but they have to nail the set up.

Long story short. People are dumping 1200/1250 motors in the Legends community left and right.

If you are fixing this up to sell you will never get your money back out of it, so part it out. There are many here who would like nice fairing parts etc.

If you are restoring it to enjoy the greatness that is the FJ, then find a motor and drop it in. All the 1100-1250 motors are interchangeable. If you get a 1250 you will need to run an offset sprocket as the output shaft and shift shaft are about 1/4" longer. You will also need to curve the cylinder head fins on the 1250 as they are straight, they came from a spineback frame XJR bike, not the perimeter frame of the FJ

[Mitragorz]

I live pretty close to a racetrack.  They run legends, modifieds, etc.  My cousin drives late models and street stocks, I could reach out and see if he can ask the legends guys if they have any motors to unload.  But really, the bike needs a tank too, and anything in good shape is more than I'd like to spend.  I hate to call it quits, but I think I just cut my losses here and move on.  I've got three other bikes!  Plus if there's fellas here that could use parts, I know they'll be off to good homes.

[Pat Conlon]

Were the throttle plates wide open?

Was that bike under water?

[Mitragorz]

Were the throttle plates wide open?

Was that bike under water?

Carbs were off when I did the test.

Bike was likely underwater at some point.  It's tough to explain, but just the "way" that it's dirty, and where it's dirty.  I've seen it before in a truck I bought that was flooded by Hurricane Sandy.  If you have experience with flooded vehicles you know exactly what I mean.  It's not an outside dirty, it's a silty/sediment dirty.

[fj1289]

I still vote for get it running if you can, put a couple heat cycles on it, and then try it.   It could simply have some stuck rings that might free up.   If not, no real effort wasted - after all you will need a functioning fuel and ignition system at some point!

[Pat Conlon]

I still vote for get it running if you can, put a couple heat cycles on it, and then try it.   It could simply have some stuck rings that might free up.   If not, no real effort wasted - after all you will need a functioning fuel and ignition system at some point!

I agree with Chris, get her running...if you can....then after a few tanks of fuel and an oil change, retest the compression. Let the engine loosen up.

Underwater bikes, uuugh. Under seawater bikes, double uuuggghh!
I suspect low compression is the least of your worries, is there water in the ignition box or generator? Speedometer? (there is a place in San Diego that can rebuild the Speedo) Sounds like the starter motor is working...Obviously all the connections come apart for cleaning.
Engine wise, FJ engines are stout. You could fill them with water and sand and they would still run.
Carbs are rebuildable.....It's the electrics that may be the killer....

[Mitragorz]

I agree with Chris, get her running...if you can....then after a few tanks of fuel and an oil change, retest the compression. Let the engine loosen up.

Underwater bikes, uuugh. Under seawater bikes, double uuuggghh!
I suspect low compression is the least of your worries, is there water in the ignition box or generator? Speedometer? (there is a place in San Diego that can rebuild the Speedo) Sounds like the starter motor is working...Obviously all the connections come apart for cleaning.
Engine wise, FJ engines are stout. You could fill them with water and sand and they would still run.
Carbs are rebuildable.....It's the electrics that may be the killer....

I've got fresh carbs and rebuild kits, just have to put it all together.

Electronics seem solid.  The only thing that doesn't work is the left rear turn signal, and that's just a broken wire.  Everything looks dry minus cylinder #3, which is the one that had water in it.

The bike didn't have any oil in it, so I topped it up before I ran the compression.  Afterwards I drained a little bit out via the filter housing and it's milky and smells like gasoline:




Tasty!!

[fj1289]

Definitely want to flush that out - maybe a couple times before really running it.

If you do your own oil change on your car(s) - maybe fill it up with used oil, crank it through a bit, drain and repeat until most of that is gone.   You might not get rid of all of it until you get the engine and oil fully up to temp though to boil off any residual moisture. 

At the end of all this you might very well have a problem with number 3, but you'll know at that point the rest of the bike is worth the effort for a set of pistons, rings, and a quick hone - or a big bore kit ....

[FJ1200W]

You don't need to look very hard for a used motor. the Legends cars that used these motors from 1993 to around 2018 have switched to the 3 cylinder FZ09 engine. With this, the fz09 has less torque and they get a significant 200 lb weight break over the 1200 and 1250 cars. So most every one is switching to the FZ09 as it is easier drive due to less torque and lighter overall weight, which in turn makes them quicker. Some of the 1200/1250s around here are quick on certain nights but they have to nail the set up.

Long story short. People are dumping 1200/1250 motors in the Legends community left and right.

If you are fixing this up to sell you will never get your money back out of it, so part it out. There are many here who would like nice fairing parts etc.

If you are restoring it to enjoy the greatness that is the FJ, then find a motor and drop it in. All the 1100-1250 motors are interchangeable. If you get a 1250 you will need to run an offset sprocket as the output shaft and shift shaft are about 1/4" longer. You will also need to curve the cylinder head fins on the 1250 as they are straight, they came from a spineback frame XJR bike, not the perimeter frame of the FJ

Fantastic info, always nice to be able to build up a nice hotrod on a budget!

I hope the FZ engines are good to you

[RPM - Robert]

We are still running 1200s in our legends. The FZ09 is completely sealed and has to be sent back to North Carolina just to have the valves adjusted. In our roadsters we are running Hayabusas now. Then we have the LS Miata, building a spec Miata, and I bought a late model roller for some reason as well. Probably drop an LQ4 in it and shoot for around 600hp to the wheel NA and find a road race stock car series to go run. So many projects, so little time!

[Mitragorz]

Definitely want to flush that out - maybe a couple times before really running it.

If you do your own oil change on your car(s) - maybe fill it up with used oil, crank it through a bit, drain and repeat until most of that is gone.   You might not get rid of all of it until you get the engine and oil fully up to temp though to boil off any residual moisture. 

At the end of all this you might very well have a problem with number 3, but you'll know at that point the rest of the bike is worth the effort for a set of pistons, rings, and a quick hone - or a big bore kit ....

Yeah, I've got 15 quarts of cheap Fram oil.  Was going to run it, drain it.  Fill it back up with fresh oil plus a bottle of Motor medic.  Run it and drain that out.  And refill again with fresh oil and see what it looks like.  Then take it from there.

Granted, that's assuming the bike will run.  I just finished getting the carbs back together.  Thanks again to Robert for splitting the rebuild kits up since I already had bought bowl gaskets from RPM.

I should be able to get the carbs back on the bike tomorrow.  I'll hook it up to the remote tank, maybe help it out with a few squirts of starter fluid, and keep my fingers crossed.

[fj1289]

Good luck!   

[Pat Conlon]

Yes, good luck, keep us informed on what you find..

[Millietant]

Just out of interest, how much "fluid" came out of the drain hole?

I'm working on a '78 Suzuki GS 1000 at the moment that's been stood for about 8 years. The owner said he thinks the carbs might be blocked, but from the amount of smoke coming from the exhausts I think the carbs are the least of his problems. I checked the compression (cold, hot and after putting a little oil through the plug holes) and they're all at or below 100 psi on every test. I noticed on the sight glass that the engine was possibly overfilled with oil, when I took out the filler cap I was hit by the strong smell of petrol - when I drained the "oil" I got almost 6 litres, of something with the viscosity of water, out of it - it's supposed to only have 4 litres of oil in it - so at least 2 litres of petrol/gasoline in the sumo !!!!

I doubt that "oil" in the FJ is all "oil".