Bike is a barn find I got in September. I'm told last time it ran was 15+ years ago. I've been going through it and got it running a few times but it smokes a lot and I'd like to know why it might be smoking. This is the 3rd or 4th time I've had it running and it's smoked each time. I guess the carbs are not set exactly right because I had a little fuel coming out from the fuel overflow sometimes and I was getting a slight backfire from the carb intake once in a while which seemed to come from the carbs that were pushing fuel through the fuel overflow. Link below for video of today's smoke session. To me the smoke seems sort of grey or grey/white. It's definitely not black. The smoke seems to intensify when I rev the engine rather than go away.
https://www.youtube.com/watch?v=BkKfJiQ6wn8
1986 FJ1200
20k Miles
Single Inlet Carbs (hooked up to a small plastic bottle)
115 Mains
155 Air Bleed
40 Pilot
The little needs under the carb floats are sized for single inlet carbs since the carbs were originally built for a Legend car. I figure for my driveway sessions this should be ok.
Stock Headers and collector with Cobra F1r Slipons
Uni Pod Air Filters
New Spark Plugs
New 10w-40 Synthetic Motorcycle Oil with about 5% Marvel Mystery Oil
I'd like to keep the bike and get it ridable but want to make sure I don't have a money pit. Exhaust smoke aside it still needs new clutch slave, clutch lines, brake caliper rebuilds, brake lines, sprockets, chain, tires and the stock gas tank is filled with rust so I either deal with that or I also have a 91 fuel pump tank which is clean inside but then I need to convert my gravity fed bike over to fuel pump. So There is considerable time and money ($1500-$2000/) involved to get the bike in running order and I'm not sure if it's worth doing all that if it needs something major like piston rings or valve seals. I don't know how to do internal engine work so that's either another cost for me to send it to RPM all the way from NJ or I try to do it myself and hopefully don't botch it.
Looking for help diagnosing the smoke and for opinions if bike is worth continuing to get running and can be ridable or if I should cut my losses and sell it or part it out and put that $ towards something newer?
I'll add that I checked compression the 2nd or 3rd time I had it running and it was:
Cylinder 1: 150 psi
Cylinder 2: 135 psi
Cylinder 3: 140 psi
Cylinder 4: 140 psi
That video was over 10 minutes long....How many minutes do you typically let your engine run?
Hi
if it was my bike i vould start checking it like this:
1 smell the exhaust .on the video t look maybe a little blue so it is most likely oil .But then where does it coming from?
2 it might just be overfilled so check the oil level it should not be too high i like to keep it in the middle of the min and max mark in the sightglass
3 with engine running open the oilfiller cap does it blow much? if it does the piston rings might stick allowing air blowby down into the case.Or in i worce situation the rings and bores are so worn that it blows by .
4 check airfilter and box are there oil in there if there is you might be lucky that it is just overfilled ?the oil can find its way all the way from airbox into the combustion chambers.
5 .Next i vould take out the plugs an look for oil on them (or actually i vould do that earlier) only one is oiled it may just be a problem with that cylinder.
maybe a valvestemseal vorn out.
if all 4 is oiled it pointing toward sticking rings or worn bores. but check more first.
6 i would have used my tiny cheap usb to phone snakecamera down in the cylinderbores with the cylinder at btdc.
That is a great way to check what you got. It will show the honingmarks or if you can not see any it indicates that
the bore is vorn. you can also se the top of pistons if they are dry or oily. But the best with the usb snakecamera is
that you can turn it upside when down in the bore using a steel wire .(i will post a pick of that tomorrow) then you can look at the valves from underside if you see oil hanging from a valve you can be sure it is has a bad valveseal.
you can also se if the bore has a deep grove almost at top of the bore if it does it is vorn.
6.5 in the vid i looks like is smokes a little from the front of engine.Check if the it is coming from valvecover gasket
or more likely from the rubber grommets on the coverbolts. then check if it is coming fom the exhaust flanges
if from flanges it can be a leaking valstem seal. you can also take off the headers and have a look if it is oil there.
check if there are any leaks from the headgasket!!
7 .but first thing i would do with your bike is since it has been sitting so long there is a great chance that the rings are sticking.
use some teaspoons or more with marvel mystery oil or wd_40 in the bores and let it sit over night. next day look in the bores that the oil has drained down or just turn the engine over with the plugs out to be sure there is not a load of oil down there making a hydrolock.
Then i vould take it for a ride and slammed the throttle accelerating hard several times and also using engine brake hard often. push the engine with high revs this can free up the rings again.
8 in the video it looks a little like it smoke more when letting off throttle that can indicate vorn valvestemseals.
but first try to ride the bike a little hard.or harder but be careful! good night sir
Pat, 10 minutes is about how long I let it run for, enough to let it warm up. I'm trying to get a sense for how well the engine runs before taking next steps. Wish I could ride it but before I can ride it I'd have to do clutch, brakes, tank, chain and tires (tires are 20 years old). I could do clutch, brakes and chain and maybe go around the block slowly a few times with the water bottle gas tank I guess.
Sorry if I wasn't clear the video was not exciting it was the only thing that came to mind about how to show everyone the smoke.
Oldrider,
Hi
if it was my bike i vould start checking it like this:
1 I suspect it's coming from the valve seals but I'm not expert.
2 oil level is about 3/4 up to the top line so I don't think it's overfilled and I am running the engine with the bike on the center stand.
3 I will do this next time I run it.
4 I don't think it's overfilled, I was running no air filter and now pod air filters and didn't see any oil.
5 I'll start it another time and then pull the plugs after that and check them thanks.
6 I'll check amazon for this camera.
6.5 Valve cove gasket definitely needs to be replaced. I don't think the small amount of oil leaking past the valve cover gasket could cause this but maybe?
7 Before starting the bike for the first time I filled all cylinders with Marvel oil for about a week or two, then pulled the plugs and turned it over.
8 I lean towards the valvestemseals being old/dry because they are likely original to the bike and I know the bike sat for at least 15 years in a garage. Is there a thread on here about how to change those out? I searched around but couldn't find a tutorial. I wouldn't just do that now I agree I think I need to ride it a little first to see what happens with the smoke over time. I'm just nervous about putting more $ into it if it needs a major overhaul.
Your compression numbers are ok so I think it's your valve seals.
Funny thing about valve seals, they do dry out and harden from long term storage, but they also soften up once some hours are put on the engine.
They also get cooked from overheating the engine.
That big displacement air cooled engine absolutely needs air flow to prevent the burning of exhaust valves, valve seats and valve seals. 10 minutes idling is too long without a box fan to cool those cylinders.
You can (and will) ruin your engine by letting it idle too long without airflow.
My recommendation: Run the bike, see it the seals get better.
Thanks Pat. It's about 30 degrees here in NJ the days I've been idling the engine so I thought it was ok but maybe you're right and I'll put a big fan on it next time to be safe.
Just to add to Pat and Red have said, you mentioned backfiring through the carbs, and with good compression etc off suggest that the carbs you're using need cleaning and proper setting up (float heights, balancing and ask passageways in the carbs clear) before you take the bike out for its first test rides. I'm a big fan of ultrasonic baths for cleaning carbs.
I understand if the tires are rotten you can maybe check them for cracks in sidewall they might be okay, but with hard rubber. I would try to ride it with the tires if they look okay and take it easy. anyway you can at least start checking the sparkplugs for oil.and test if it is a lot of blowby by opening the oil filler cap.
a usb mini snakecamera down in the bores will tell you more. if it is oil hanging from valve you know that a valvestemseal is blown. or you can losen the exhaust bend and look for oil .One other thing is that if a seal is blown it should start smoking very fast at startup from cold and smell oil.
it is possible to change the valvestemseal with the head in frame. i have done it. i just can not fint pictures of it now
.Basically you put rope down the bore and slowly rotate engine so the piston rises and push the rope up under the valves .
Then you use a 17-18 mm socket with a small magnet tool placed inside .Then you place the socket down on the
valve retainerplate and push down hard use glows. that will losen the valvekeepers and they stick to the magnet in the socket.
Then after you have replaced the seal and spings back you place the valve keeper plate back and now comes the tricky part.
You then place the valvekeepers on the valvestem end so they sit losely in place on the upper side of the valve keeper plate jammed losely on the end of the valvestem .And then you use a clear solid
ziplock plastic bag and place it over the valve keeperplate and the valvekeepers. then you place the socket on top of that and push down hard .Almost like magic the valvekeepers are now in place .
it may take some tries but it works. i have done it.
i will se on my other pc if i can find some pick how to do it.
by the way it was cold outside when you had the bike running and that also make it smoke more .Check the smell of the smoke !.
anyway here are some pick of the cheep snake camera i got. I dont have pick from inside the bore of the fj but these are from a kawasaki that has run about 2000km after engine rebuild bored and honed.
I try to check my other pc tomorrow to find som pick from replacing a valvestemseal on the fj
while head is in frame
I did not find picks from when replaced some seals with the engine in bike dont think i filmed that =)
you can also use a valve spring compressor tool that fits at least on the exhaustvalves.(have done that too)
I have a video from when i did the same on another head i did some work on, but that is not with engine in bike.
It does not matter it is the same thing .Just remember to fill the bore with rope !! I took some still picks from that video and made a mini toturial.
Wow this is very helpful to see thank you, I will have to read through this a few times to sink in, I'm mechanical but never did anything inside an engine so it's new territory for me
ok i see . I then i recommend you to get someone that has been doing some engine-work to help you if it turns out you will have to replace seals.
I can not take credit for the "trick" i found that on youtube.
Here is a vid from oldschool mechanic doing it ,but make sure you dont keep the metalrod down in the bore when turning the engine because then you may bend a valve !!. i like watching his other vids to after i got saved :good: https://www.youtube.com/watch?v=8Oj6hNX0SyI
IDK what RPM would charge if I took the heads off and mailed them to them to do the job but I'm confident I could take the heads off without issue, if RPM redid the heads for me then I would just need to figure out how to re-install them properly and set the cams/vales etc..... but I imagine that's a bit easier to do than replacing the seals myself?
If you are willing to take the head off - it's a fairly simple job utilizing a valve spring compressor tool - looks like a specialized c- clamp. The voodoo magic comes in when you are trying to do it without taking the head off!
This is the tool I have:
https://www.amazon.com/Pit-Posse-Valve-Spring-Compressor/dp/B005SUXFQS/ref=asc_df_B005SUXFQS?mcid=2d57f87d640d386e86764afc168111df&hvocijid=13743799821111782351-B005SUXFQS-&hvexpln=73&tag=hyprod-20&linkCode=df0&hvadid=721245378154&hvpos=&hvnetw=g&hvrand=13743799821111782351&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9028746&hvtargid=pla-2281435177858&psc=1
Have used it on several FJ heads, on ford 4.2 V-6 heads, Dodge 5.7 hemi heads. It is a fairly simple task with the heads off.
If going to take the head off and send it to someone to get the work done, why not get it gas flowed too while they're at it, for a bit extra performance? :good2:
Not sure what route I'll take yet although strongly leaning towards trying to ride it a little and see how it is although with 20yo tires need to be careful. What is gas flowed?
"Gas flowed" is English for American "ported".
A ported head with oversized valves really wakes up the FJ!
Quote from: Old Rider on January 14, 2025, 02:55:15 PMI understand if the tires are rotten you can maybe check them for cracks in sidewall they might be okay, but with hard rubber. I would try to ride it with the tires if they look okay and take it easy.
Quote from: 86FJNJ on January 17, 2025, 11:44:30 AM.....strongly leaning towards trying to ride it a little and see how it is although with 20yo tires need to be careful.
Riding an FJ with rock hard tires is a hoot, right Dan? LOL
What could go wrong? Dunno, maybe like, turning a corner?
With all I've heard so far - I'd definitely invest in a set of tires - this is definitely a bike worth sitting out!
Story Time:
I found a pristine low mileage white '89 in Wisconsin that came with rock hard 20+ year old tires. Dan (aka giantkiller) picked up and held the bike for me until I could fly out from Arizona. (Thanks again amigo) Dan laughed when he told me, "Hey Pat, I took your bike out for a ride and I knew the tires were old but...I thought you had a slipping clutch, I would roll on the throttle and the engine would rev up madly....it wasn't your clutch, it was the hard old back tire spinning..."
Quote from: fj1289 on January 17, 2025, 03:58:40 PMWith all I've heard so far - I'd definitely invest in a set of tires - this is definitely a bike worth sitting out!
Crap - definitely a bike worth SORTING out. Worthy of a set of new tires!
If you dont want to use money buying new tires and then discover that engine needs a rebuild and the cost of that.
You can load the engine by doing some burnouts that will get pressure behind the rings and free them if they are stuck.
But first i would buy a snakecamera and inspect . You can remove the headerpipes and use the snake camera in there to .if it is a lot of oil on the valves it may be because of dried hard valvestemseals. Same on the intakevalves you can open throttle and stick the snakecamera thru the carbs all the way down in the valve intakes and look for oil.
And of course look inside the bores how it looks there .
And if you used marvel mystery oil in the bores change to new oil.
You can pull the head to change the seals,but be prepared that you then will need a new headgasket and also a new
basegasket and you will then have to take the cylinders off and by doing this job you will need new pistonrings and
if lucky you get away with only honing the bores.By taking the head off it will also fall loads of dirt and rust
down in the engine/bores. So taking the head off will be almost the same as doing a top end engine rebuild.
So try to inspect the valve seals first maybe that is only thing you need to replace.
Quote from: fj1289 on January 17, 2025, 12:34:42 PM"Gas flowed" is English for American "ported".
A ported head with oversized valves really wakes up the FJ!
Yep, the vagaries of how the English language has developed in far-away lands :lol: - for "gas-flowed", in the USA read "ported"