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The story of Fj1200 '86 maintenance and an ongoing learning experience

Started by fj316, July 31, 2022, 07:32:38 AM

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Last year my cousin was taking his motorcycle license and needed some additional practice driving. And seeing as my old FJ1100 was (and still is) not in the best of shapes I needed something a bit more reliable to be able to help him pass his final test. First I looked at an VFR750 that at first glance seemed to be all right, but gave a rattling sound from the engine when the clutch was engaged/pumped even while standing still. So naturally I apologized for not being able to buy the bike in good conscience and continued my search. Found a fairly affordable FJ1200 that looked all right and had no indications of larger faults apart from "the usual" clutch engagement problems, a little oil seepage and some slight gas dripping.

I initially gave it an oil change, swapped out a pretty worn clutch slave and checked that the rest of the clutch was all right. The oil seepage was fixed with a "simple" change of the valve cover gasket in addition to the bolt gaskets. The rubber was completely hardened in some places and was way overdue for a swap.

The brake calipers were also overhauled as the front ones were stuck. Here I learned another valuable lesson as the rotor kept grinding on the caliper edge with no aparent misalignment of the front wheel. Turns out I had torqued it too hard and when I invested in a suitable torque key and adjusted to spec the front rotor was clear of the caliper.

The petcock was another issue entirely and I should have checked it sooner as it started leaking pretty hard after a longer practice session. So the tank had to be taken off and looked over. The elbow coupling was completely loose in the petcock and not safety wired. So I was basically lucky I didn't end up with a toasted bike. And can only reiterate what others have said that a safety wiring is paramount to a safe ride and operation. I tried with some gasket silicone first that didn't take and ended up epoxying the elbow coupling and safety wiring it in place. No pictures of that unfortunately though. There was however no more drip and the bike lasted the rest of the season without incident.

My cousin and his friend both passed their drivers test but alas they did not join this years (2022) motorcycle parade on our national holiday the 17th of may.

All however was not sunshine and roses as the bike had been stored outside the previous winter (lesson learned and paid storage seems to be a sensible option going forward). It started and ran a bit rough in april but got better after some fresh gas and some revs on the highway. But during the summer the symptoms of a rough 2-3K RPM became worse and the bike eventually gave up on a test run early in july of this year and had to spend the night on the parking lot of my workplace after a shameful waddle the last couple of hundred meters :sorry:

This forum was helpful as ever though and there is still hope that I might be able to ride again before winter once I can overcome the present day challenge and rite of passage of a carburettor overhaul that will be documented further with accompanying pictures in this thread.

Old Rider

Hello and welcome Nice to se some other Norwegian poeple in here.God luck with the carb ovehaul !


Thank you for the well wishes Old Rider. I'm indeed gonna need some God luck if the bike is gonna be back on the road this season. But I have faith that it will ride again. It's just that time and resources aren't totally on my side now that summer is waning and work has started back up.

On a more positive note a pair of fresh tires were added to the bike so now there is all the more reason to get it back to kookaloo town again.

But the carb project seems to be a bit more of a challenge than initially expected. The diaphragms once inspected all had one or more pinholes and look like they are done and done...

I ordered some loose ones and will do the old dull end of a butterknife trick to get them fitted. And the trick of a spring loaded punch to get the pin out of the floats was golden!

Now all that remains is to remove the rust crud that when inspecting one of the T couplings between the carbs seems to be originating from the tank itself. So I'll just keep on disassembling and bagging the tiny parts in marked ziplocs so that they aren't lost and that I can reassemble it in due course. I am acutely aware of eye protection while doing the cleaning especially on the carb bodies and with sprays. But if anyone has any other tips for "easy" cleaning both of bodies and parts and how thorough I need to be when disassembling I'd appreciate it. Both in method and in cleaning medium. For now my aim is to unscrew any screws and get the floats off while leaving anything that is press fitted and in brass well alone and to use brake cleaner as my solvent.


Have you considered ultrasonic cleaning? If you know anyone who's into shooting and reloading chances are they'll have an ultrasonic cleaner you can borrow. Otherwise, the biggest one from Biltema is recommended by many people.


Back on the proverbial saddle again after a much too long hiatus. But this time with renewed wind and a mission to get her back on the road once more before winter. Especially since I sold my '85 1100 earlier this year. The idle time has not been spent totally inactive though as I've read and printed out guides and came across a very decent howto ( on yotube which fit my carbs 1:1. There was also the question of acquiring a dremel to get a wedge for a flathead into a very resilient screw, fortunately the only one of the bunch. All other screws subdued to tender pliers and gritted teeth.

I have replaced one of the rubber diaphragms and I'm leaving the rest of that process for last as it was a pain to align to the notch in the carb. Other than that they are now taken apart and cleaned with a huge amount of grit and rust both in the bowls, bowl filters and fuel intake channels. Otherwise there was one stuck and clogged emlusion tube but otherwise they looked pretty decent. Going to do the smart thing and overhaul the fuel tank before they get hooked back on.

I took one carb off but I'm going to put it back on as there is no need to have them all in more pieces than this for a decent cleaning.

Quote from: Domino on September 08, 2022, 02:21:27 AM
Have you considered ultrasonic cleaning? If you know anyone who's into shooting and reloading chances are they'll have an ultrasonic cleaner you can borrow. Otherwise, the biggest one from Biltema is recommended by many people.

I have thought about trying an ultrasonic clean but the crud that was present yielded to carb cleaner and blasts from an air compressor from Biltema  :biggrin: Mostly turned to fine dust once the carbs were dried out and easy enough to remove. I don't think any of my shooting/reloading friends wants a stanky in-line four carb assembly in their bath either, plus most reloaders I know do the tumble cleaning with abrasives :lol:

The hurdles I face now is just getting back to it, and to figure out if the two plastic T-connectors at the top of the float bowl chamber should be a loose or snug fit. I suspect the latter so I'll also need to hunt for O-rings. But progress shouldn't be long since I have to have a look at my CBR1000F carbs too and FIFO is king  :wacko1:

Will edit in some more pictures later.

Old Rider

Hei fj316 godt å se en Viking til her :drinks:  I strongly recomend that you separate  the carbs .I was thinking like you that i will skip that step when i rebuildt my engine,but
the guys in here recomended to separate the carbbodies .I did and it is not hard to do at all if screws are stuck you can use a mini torch you can buy at claes ohlson  just be careful so no gasoline is nearby also buy a scew extractor in case the screws are really stubborn .Im glad separated the carbs because the O-rings rubber was stone hard
and i found a lot of crud and rust in the holes where the oringed T bars fits. I really recomend buying the carb kit that RPM sells then you will have all the orings needed and all screws with allen head. I think i wrote about it in the splitting the cases tread in project writeups. I also have replaced the diaghprams
and made a uppdate on that tread in the maintanence section today. you can read how i did expanded the slot so fitting them is a little easier.
Good luck !


Thanks for the tips and headsups guys! I had the foresight to order the o-ring and screw set which Robert's post reminded me I had laying around. For the moment I'm leaning on just taking off the outside carbs, since the o rings that are on now are pretty tattered, hard and surely needs replacement.

As for the screws I think I will need some viking skills indeed :drinks: Used some pliers but gave up for this evening. Might try heat or just straight up dremel a slot for a flathead at my next session. I'll check out your thread Old Rider in preparation for a probably crease free install of the last 3 diaphragms  :crazy:


I have made some progress and while not out of the woods yet I am peeking at a slow downhill stretch. I have removed a decent amount of crud and rust-dust left over from the flakes in the fuel intake. Most part should be clean but not polished now. Still dreading to wrestle with cleaning the tank itself. But I now have access to all the O ring joints and can start to use the ones from the RPM kit for reassembly. And figure out which replacement screw goes where  :crazy:

Bought a set of JIS screwdrivers last week and BOY did I regret not getting those sooner. Got off the end carb with only one screw needing heat treatment. Now all is well and ready for the phase of replacing the rest of the diaphragms. The first one I installed doesn't look perfect but at least it seems better than those that were on originally. So if I don't really cock up the rest of them I'll gamble on this being adequate for now.

Now only the rest remains...  :diablo:

Old Rider

Nice work ,But i think i spot a problem... that is the diaghpram you have mounted .It seems that the outer ridge is facing upward .I did that mistake also when i mounted on my carbs.If you take a look at picture  nr12 in my tread you can see it mentioned. If you tear the diaghpram when trying to take it off and turn it i think i have one extra i can send to you. Good luck  :good:


Thanks, and huge facepalm there as it seems you are right. At least it got discovered before I did the same mistake on the rest of them  :dash1: I went out and tried a removal process just now, and as luck would have it I got it off with it staying in one piece and just looking a little scuffed aroud the edges  :lol:

Gonna take more care during reinstall and for the rest of them so I don't have to play the "will it tear" game more than i have to.

The only issue now is a stuck drain screw for one float bowl which I am going to leave to be future me's problem unless I can source a bowl from the local chop shop. I can't see it having any consequence for immedate usage and with pod filters on I figure removing the assembly is easy enough should I have a dire need to drain the carbs.


Now I'm really tasting the home stretch of this carb adventure. Done some thinking and will put it back together with the original air box since I have done nothing to the jetting and will let the pod bois be for a future revision. Slapped an inline filter on the petrol hoses to keep an eye out and maybe get her running before the snow comes  :biggrin: Juggling the maintenance and repair of two motorbikes demands some compromise. And as I looked over my FJ1200 the other day the clutch handle was not doing much of anything, so I'll need to look long and hard at the state of 'er once I get ye ol lady up and running again. But while I wait for the gasket/glue on my CBR's airbox to dry I can make some hedway in re-assembly of a farily clean carb. The only thing that is left are another go at the main jets but I did a visual inspection and the pinhole was visible on all of them.

Kudos to my fellow viking Old Rider that led me on the path of good diaphragm work. I ended up managing with just a credit card (plus oil) and got all tabs fairly decently aligned. All the O-rings that i have been able to clue out where belongs have been replaced. Some confusion about the screws still but where I can't figure out what's up I will just reuse existing ones since I now have the power of JIS  :yahoo:

I will look into ultrasonic action down the line but for now carb cleaner and proper compressed air has done a decent enough job for me even though it's not totally white room clean. And I'm pretty hopeful about a ride before the season is over.

Pat Conlon

Don't store your FJ with ethanol laced gas (E10) in the carbs.
1) Free Owners Manual download:
2) Don't store your FJ with E10 fuel
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire:
Fuel line:

Old Rider

Bra jobba fj316 !  I want to recomend  another thing before you put the carbs back in bike .That is plasing them in a wice i a little tilted forward angle
then check that the float height is set correctly by using this very good method :

And use good quality floatbowls gaskets .Sometimes if using old gaskets or bad quality gaskets they will shrink and  when put back on they might
bulge a little and make the side of the float rub and stick so it is not able to travel free doing its job. 
And one more thing i remember from rebuilding the carbs with the RPM kit is that you will have some O-rings leftovers i think it is 2 but not sure it is
because the fj with a fuelpump use more o-rings. Amd be careful not trying to brake free the went tubes that is pressfitted into carbbodies.I almost did
that because i thaught the leftover O-rings was supposed to sit there ,but Robert from RPM saved me and told me they are pressfitted .