xj900f ignition trouble

Hi i have a 1992 xj900f and have covered 39k miles in 13 months with only the expected minor niggles. But now it has me stumped. I started it yesterday and it would only run on 2 cylinders, the right hand coil which runs the tacho isn’t working. The tacho kicked in once and the ignition fuse blew. I replaced the fuse and now it will only run on cylinders 1 and 4.
I have disconnected the instrument console + tried – no difference
I have isolated the tacho – no difference
I have checked the resistance of the pickup coils – ok
I have checked primary winding + secondary windings resistance on ignition coils –ok
I have swapped the wires to the coils over – no spark on any plugs
Have swapped non-working ignition coil with a known good one – sparks on 1+4 only still
I have checked the wiring and connectors
I have beaten the damn thing to death with a 14lb sledge hammer (not yet but may be the next step)
As i see it the only thing left is the tci unit, which on mine is a pattern one. So has anyone got the Yamaha part number for the tci unit on a 1992 xj900f (4bb model)? Is this unit used on any other bike? Has anyone got any ideas or can see something i have overlooked?
Thanx in advance for your help this has been a fantastic bike, it now has only 71k miles on it + i have done most of them and would hate to scrap it now.

 

Sure sounds like TCI - I don't have the number but they should be available. Have you checked salvage yards or ebay?

 

hi bill. thanx for the reply. have checked e-bay here in jolly old blighty and nothing. have found an xj600 unit at a breakers but not sure if it will fit, thats why i am after part numbers.
have just noticed i am a biker wannabe. have bin riding for 26 years, done nearly half a million miles in the last 12 years alone and i am a wannabe. jeez it gets harder to be a biker the older i get.

 

Yea they have a sliding scale of designations. The more you post you start to climb. I'll see if I dig up a number - is there not one on the unit?

Also PM Chacal he might have one (he is our local parts guru and supplier).

 

Have you checked continuity on the coil wire coming from the TCI to that RH coil? It might have got pinched under the seat or tank maybe?

 

Reabo, no tach is classic pick-up coil/TCI failure. Best of luck getting a used one, they do pop up now and again.
If you can't find a new one, you might try sending your TCI to me to look over (I overhauled a 900 TCI for Redcenter last year). If your TCI can be opened, I'd be happy to check the unit out for faulty parts. I cannot test it on a bike however, I had to send Red's unit to Rick-O-Matic for an operational test. You might give him a shout and see if he can set up an appointment.

 

hi, thanx for the replies. have checked continuity of the associated wiring and all is good. thanx for the offer robert but i live in the uk, its a long way to go. have found the coils on the 900 are numbered
TID14-37
58L-10


have found one that is numbered TID14-78. does anybody know if they are compatible, or how the numbers work. thanx

 

UK, Australia, Timbuktu, matters little. Just giving you options. I do hope you find a low-buck solution.

 

thanx again for the offer robert. but i found one---yipee.
spent two hours going thru e-bay + found one hiding away in the wrong place. photo showed the numbers so i know it is correct one. auction finished late last night, one other bidder looking for a bargain, got it for £8.50 included postage. i feel like a small child at xmas. cant wait for it to drop thru the door.

 

I did find a bad switching transistor on RedCenter's unit. Still waiting for Rick to test it and let me know if I hit the nail on the head. I went through it and replaced all of the electrolytic capacitors, the transistor and I lifted the leads on the final output transistors (which checked out good). If your new unit works, you might want to get your old unit repaired for a backup...

 

bugger. back to the begining. tci arrived today. fitted it, the tacho kicked once and nothing else. now i dont know where to look. looked inside unit and cant see anything burnt out (unlike other one which is deffo scorch marks in it). could this be a tacho led problem? or poss dirt on the pickup coil? am going to go back to the begining and start again. oh happy days

 

You need to ensure that the pickup coils are intact, the tachometer wire is still intact and the input voltages are getting to the connector. Start with one section at a time amigo, it makes an otherwise daunting task much easier to wallow through.
Sorry to hear your flea-bay find didn't fix the issue. Let's hope it's something simple you overlooked (simple problems are cheaper to fix). Here is to hoping... I'm curious to hear of the outcome of this problem.

 

its 2.00 am here and i am a very happy bunny. have sorted bike and it is now back to its old self.I replaced the instrument console including tacho( the facia was cracked so needed doin) but made no difference. still two sparks. went back over electrics with a multimeter and found he secondary windings in the right hand ignition coil were showing infinite resistance. this is the third time i checked and both times it showed ok. so replaced coil and played with wiring. this showed my e-bay bargain was in the same state as the original.
wot i think is the coil went and took one side of the tci unit with it. i replaced the tci unit coz everything checked ok and the coil took one side of the replacement tci.
the bike now has the an ignition coil from a kawasaki gt750p on it. the ignition has been adapted so one coil is operated by the working side of one tci unit and the other coil is operated by the working side of the other tci unit, with the second tci unit located in the tool tray under the tailpiece.
hey presto bike works, all four cylinders firing and the tacho also works. all alterations to the wiring are iutside the original wiring loom so can be removed and the bike put back to normal when i find anothe tci unit. the only bad bit was that i only had two colours of wire, blue and yellow, so was a nightmare checking and double checking each connection was right.
i have however learned never to trust electrickeral components and also testers, i am mechanicaly minded and my foray into the world of magic black boxes and electrickery has been a bloody nightmare. anyhow than for all yer help and i can get on with the important stuff like fiding her again now.

 

Holy cow that doesn't sound like the easy way to fix it! Two half-baked TCI's to run the bike??? Sounds like more problems are in your future, best be getting started looking for another TCI. If you can solder, I'd suggest you lift the final output transistors (they act like high speed switches) and check them with a meter. I'm betting you have toasted the finals. NEC sells a good replacement component for a few dollars.

 

do you have a pictuer showing where each bit is? that would be fab. the repair is temporary to get back on the road to get to work. have uploaded a photo of the old girl in an album called reabo's ride.cheers robert

 

Wow, good job Reabo. This info will doubtless help someone else down the line.

 

Reabo, I don't but I can photograph a 750 box and it will illustrate what to look for. Let me get back to you.
Edit: Check in our Links section under DIY and How-To's, there is a link to a fellow who overhauled his turbo TCI and the photos there show the final transistors very clearly. There is a bunch of good info on this site so take it all in if you have the time. http://www.jetav8r.com/Vision/IgnitionFAQ.html

 

thanx or the link. had a quick peep and it looks awesome so have downloaded the whole thing as a pdf and will print in the morning so i can read and learn. seems to cover everything i need to know. are the transistors the tall black round things ? as i remember they are three way switches depending on what current is going thru them??? will learning how these black boxes of magic work make me a druid?

 

The tall, black round things are capacitors (which should be replaced as they do dry out in 10-15 years). The transistors are shorter round bodies that have one side sliced away and will have three leads on them. There are heaps of self-help videos on the internet to teach electronics basics, take a look. Another resource is a book called Beginning Electronics by a fellow named Forrest Mims. Radio Shack used to carry it but you can purchase the book from his website. Worth every penny I paid for it, it got me a promotion of $1k a month!

 

i found a book called electronics for dummies last nite, which sounded like it would suit me to the ground.

 

hey bro........yes it is me, thanks for the link!! If you need some help with the lektroniky stuff let me know, I knew doing the electrical fitter apprenticeship would pay off one day!!

 

oh my god i am being stalked by my own bruvver on an american website.

 

anyhow electrickery fitters are witches practising only the dark arts. mechanical fitters are the only true way to nirvana

 

Hmm do we see a bit of sibling rivalry? :evil:

 

no rivalry here. he is the dark lord darth vader and i am the path to light and enlightenment luke skywalker. the glory of mechanical engineering will always outshine the arcane, invisible world of electricity. its a fact.

 

LMAO - I come from the Darkest of darksides, electronics and software engineering. Although I can turn a wrench ...

 

oh no, i have been lured by treachery into the lair of the beast. my very mechanical soul is in danger of being tainted and scorched by the flames of the sparkies. heeeeeeeeelllllllppppppp!!!!!!!!!!

 

you know lektrickery is the only true path - redeem yourself while you still have time.......the elektrons can see right into your mind and will guide you onto the right path..