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XJ900F - getting a new home


IKE
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So, today I secured a fairly old (J reg) XJ900F. I'll be collecting her during the week and then starting a tlc project. I've just retired so am in no hurry to complete so this thread might be a bit slow to show progress.

Anyway, I'll post an update when I collect her.

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  • 2 weeks later...

Ok, she is now at home in my garage. 1992 with 34k miles on the clock and needs some tidying - but that's the fun of a project, isn't it? Oil and fuel were all clean and I wanted to at least find out if there were any pistons in there. Anyway, engine turned over OK but didn't fire up. First thing, take a plug out and see if it sparks. Could only see a very weak orange spark so took them all out and they looked normal, perhaps a wee bit sooty but certainly not fouled. No matter, a new set of plugs and air filter would do no harm. The new plugs produced a nice fat blue spark and the engine fired up instantly with the choke out. Great, at least there were moving bits inside her. However, the engine revved quite fast but, when I pushed back the choke, the engine stopped. I tried again, with exactly the same results so am now planning an eyeball check on throttle cables, settings and carbs. No hurry but at least I know what I'm working with and I do intend to tidy up the frame with the engine out.

So, any ideas what to check for this choke/stopping problem?

Thanks

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Check the plastic stand offs that the carbs sit/bolt to they can crack and let air in so spoiling the fuel air mixture, try spraying with water or wd40 to get it to seal and see if that makes any difference. DON'T forget to check that the pipe from the carb to the tank is not leaking as well as that can cause it to sod about. Usually on carb number 3 to the 2nd connector on the fuel tap.

If you have them a set of vacuum gauges will come in handy as well as mine would not run till I balanced the carbs, do you have the YICS system on this bike? cos if you do then you will need a YICS tool to shut it off before you can balance them. If you need one (VERY expensive) then give me a PM and I will let you borrow mine, although you can make your own from odds and sods, check the net for descriptions on how to do it, I have some copies some where so if you can't find them I will send them over to you. :jossun:

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Thanks Slice, good call. I will do a careful examination. Although I can't see any obvious fuel leakages, there is always a strong smell of petrol when I go into the garage so that might prove to be from a leak.

Sorry to sound like a numpty but what is a YICS?

Cheers

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OK, now know what the YICS is (don't you just love the Haynes manual) and will check for the blanking bolts.

Cheers

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No Problem just not sure if your year had it or not? If you do then it's easy to get over it just expensive to buy the tool, and it's only a few bits of tube and some rubber grommets, real easy to make but a pain in the arse if you find yourself without it.

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I can confirm that my Yammy does indeed have YICS so I will be following the Haynes guidance when I get to that bit.

I fancy making my own tool so some guidance would be appreciated.

Thanks

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Not a problem really, if you scour the net and ask for "YICS tool" you should come up with a load of diagrams and other stuff that should help you out, there are a lot of American guy who have made these things and they have posted pictures and dimensions on various websites, all you need to do is find a picture and parts list your happy with and go from there. The only problem some might have is that the Americans use Imperial (inches) rather than Metric so as long as your old like me it's not a problem, sure you can cope with that. Anything else you need then give me a shout, good luck.

PS one thing I almost forgot, CLEAN OUT the YICS pathways BEFORE you insert the tool, undo both bolts either side of the head and run a cloth through to take out the accumulated crap that will be in there, it will rip the rubber washers if you don't do this, I know this from experience!!! DO NOT turn on your fuel until you have replaced both bolts, YICS tool stops cross flow of fuel but NOT from running out the sides if you leave the bolts off.

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Thanks for these tips, hopefully I'll be able to make a start early August - daughter's wedding taking priority at the moment. As far as imperial is concerned, yes, my age means feet, inches as well as shillings and tanners are all very familiar to me.

Cheers

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Just a quick update. Ordered a balancing kit and reckon I'll make my own YICS tool. Only problem is that when I investigate, they all say to have the engine running (for balancing) but I assume that means with the choke back in, and my one stops when I put the choke back so it looks like the carbs have to come off for a proper, deep, clean - then I'll take it from there. Haven't really had time to investige for leaks yet but itching to get stuck in. Spotted a great YouTube vid for cleaning mikuni carbs but seems to contradict the Haynes manual for removing the pilot/idling jet. Video suggests the jet is screwed all the way in, but Haynes says to note how far in it is screwed. Anyone any ideas, or am I missing something here?

Cheers

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The mixture screws are set at the factory and should not be messed with, the balance screws are at the front of the carb and can be reached by reaching down between the head and the carb body (sure you know that) but adjusting them without the YICS tool in is pointless as the others compensate through the balance tube, they are not hard to take apart but be careful when removing the float bowl screws as they are made of some kind of toffee or pot metal!!! and round off when you look sideways at them, if it stops running without the choke then try turning the CENTRE fast running screw thingy all the way in, it will rev it's nuts off but then you can turn it back till it sort of ticks over, mine still will not tick over after 3 years and numerous attempts to get it to balance properly, when I get it just right and take it out by the time I have done a few miles the thing will rev it's nuts off till I reach round and turn the fast running screw down at which point it then will not tick over at all and I'm left with holding the throttle in the right spot or stalling, I think it must be just the age of the carbs that cause it to do this as I have replaced all the jets and anything else that might be a problem. I didn't buy a YICS tool I bought a YICS blanking rod from a guy in Australia for about £8 + p&p if I can find his details I will send them over to you. This is supposed to sit inside the YICS system and blank it off permanently but I just use it to balanced the carbs and then remove it afterwards.

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Synchro kit arrived today and I have sourced the bits for the YICS tool. I might even post a metric version of the design drawing once I prove that my one is dimensioned correctly.

Cheers

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Just an update and a question...

Took off the carbs today, cleaned and stripped them and at least one diaphragm has a split along an edge so that will need to be replaced. I also took off the inlet rubber mounts (wanted to check them for cracks or splits), and they look OK but the oval gaskets were crispy hard and broke into little pieces. Here is my question... Are these gaskets a standard size that I can just pick up from the local bike shop, or do I need to buy specific gaskets for the XJ900F and, if so, can anyone recommend a good Yam dealer?

Cheers

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I think the gaskets are a standard size but not absolutely sure so best if you measure them and see what's out there, WEMOTO are very good for spares but a gasket set can be picked up for about £50/60 off of EBAY which will have them in it and then you will also have spares if you need them, I made my own a couple of years ago with gasket paper and a ball pein hammer so if you have the patience it can save you a few quid, also be VERY careful bolting them back on as when I did mine I stripped 2 off inside the head, bloody threads are really fine and a major pain to get the things tight had to drill and re-tap them other than that quite easy really, sounds like your starting to enjoy yourself!!!!!

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Thanks for that, I'll check out the site. I am having a great time and happy to tackle DIY gasket paper. Any idea how thick the paper needs to be? I see 0.4 and 0.8 mm sheets on e-bay, but my old gaskets are showing 0.5mm on my vernier.

Cheers

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I would use the thicker of the 2 papers myself and then tweek it down a tad tighter than normal (bearing in mind the thread on the head) I did hear that it's best to give the paper a light coating of engine oil to help seat them but never tried it myself, otherwise just your usual gasket seal "hermatite" or something similar.

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Have ordered some paper and a set of hole punches. You never know, if I can make a good job of these, I might make more for e-bay!

I had to "dremmel" cut some slots on the carb screws to remove the tops and float bowls and am planning to replace these cross heads with nice new shiny Stainless socket cap and button screws.

Oh, the joys.

Cheers

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  • 3 months later...

Ok, just an update and now back on the project...

After removing and stripping the carbs, I bought some Honda rubber cement stuff and "repaired" two of the diaphragms which had splits in them. Replaced a couple of small "O" rings under the jets and cleaned all jets and ports. Also noticed that the floats had different heights so I adjusted these according to the Haynes manual. When I had rebuilt the carbs, I checked the return speed of the diaphragm sliders to see if they were all the same (if they are not, there is a leak in the diaphragm) and they all seemed to match. Just lift them up and watch the return speed through the vacuum. Didn't measure them with a stop watch, just the mark 1 eyeball. I reset all the jets and idle screws etc. (when I stripped the carbs, and noted the original settings, they were all different!) and slackened off the master idle-adjuster. Just for cosmetics, I also painted the two angle-brackets holding all the carbs together as the originals were looking a bit grubby. I finally did a complete bench-balance using a digital vernier gauge to measure the heights of each carb slider and adjust each one as needed (and they were all different too - so I can only assume that the previous owner had attempted to adjust them).

Fitted the carbs and rubbers back on the bike, hooked up the throttle cable and clutch cable and put back the air-filter and housing. The battery had been sitting for three months on my bench without being charged but the test meter suggested it was fine so back on with the tank and battery. Fuel cock to "prime", choke out and press the button. Wow! Immediate start and running at 2000 rpm. I let it run for a while to warm up and I checked for leaks or knocks. I listened to the cam chain (ear on a long screwdriver - like a doctor with a stethoscope) and there was only an occasional slight rattle so that will probably need adjusting. Tested various revs and it sounded responsive and clean and after suitable warming up I slowly reduced the choke and screwed the idle-adjuster to maintain just over 1000 rpm on tick-over.

So, am very pleased with the carbs and the engine - no leaks and no knocking. Next step is to remove the engine for a bench-overhaul and tidy up any bits of the frame that have suffered road-chips etc. I'll do a proper carb balancing when I put everything back again but at least I know I've got a "good un" in there.

Really enjoying this restoration project and I like it when a plan comes together...

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Nice one Ike, sounds like a plan.

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