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-   -   3AJ + 2KF = trouble? (http://www.horizonsunlimited.com/hubb/yamaha-tech/3aj-2kf-trouble-5779)

POB/London 16 Dec 2002 03:34

3AJ + 2KF = trouble?
I took my bike apart this weekend to do an electrical overhaul, repair the headlight cowling, and paint the underside of the tank, to find shocking news.

On the head is stamped "2KF" but the bike is a 3AJ Mk1, as indicated by frame and all other engine numbers. Does this mean it's on it's second head? Are there any differences?

Cheers in advance. I'm banking on having to do a top end and g/box rebuild in the New Year, so any info I can get before then would be great.

The bikes an 89/90 ("G" reg) 3AJ with 37500 miles.

giorgioXT 16 Dec 2002 14:49

No problem ! : the 2KF code on head and cylinder it means that it's the larger second series , with an additional bolt , and is the same for all XT's 2KF and 3AJ .

aukeboss 16 Dec 2002 15:00

No panic.
Yamaha part numbers (almost) always start with the codegroup indicating the model the part was first used on.
For instance, 3TB engines (far later) still have the 3AJ cilinder and the 2KF cilinder head.


POB/London 16 Dec 2002 16:40


Originally posted by giorgioXT:
No problem ! : the 2KF code on head and cylinder it means that it's the larger second series , with an additional bolt , and is the same for all XT's 2KF and 3AJ .
Thanks guys! If it has the second series head, shouldn't it also have a long (30cm +) oil cooler? I don't think I'll ever find out the real history of the bike, since 12 years is a long time, but the more information the better.

Another thing I discovered is that some idiot has used roofing bolts (!) and not fairing fasteners when attaching the front fairing to the tank. This has caused the tank to rip *very* slightly, where the brackets are welded on. Although I have wire brushed and cleaned the area, and then painted it, I will definitely have to have it repaired at some point. Can it be brazed/welded? Do I have to drain and rinse the tank?

In the meantime, I have an electrical short flattening my battery, which I have been unable to trace. The joys of owning an XT! And one more thing - DL, can you get the front brake switch sender? (Forward of the multiplug near the headstock, all the way to the switch at the lever)? I have pbroken mine, and have to switch on the brake light with the rear lever. Annoying and illegal, ahem.

Cheers guys, I'll post some pics soon. The tank looks ace with silver detailing and my lights no longer shake rattle and roll!

http://www.horizonsunlimited.com/ubb/smile.gif http://www.horizonsunlimited.com/ubb/smile.gif

POB/London 18 Dec 2002 01:31

OK - something strange is happening to the bike. Although I rode it over 100 miles since reassembling it yesterday with no problem, this afternoon there was a noiise I have never heard before.

The noise *only* happened around 2400-2600 RPM, and sounded like a high-pitched yet irregular "dink-dink, dink, dink." It might have been my imagination, but I swear the gearbox was clunkier then normal too.

The rev (not speed) relationship makes me think that it may just be a crazy vibration somewhere causing a harmionic, but I am also worried that something's broken (possibly some valvegear component in the head?) The pickup and drive is fine, there's no engine lumpiness, just this quite loud noise...

Have you ever heard this before? I am simultaneously stumped and worried! HELP!

david lambeth 18 Dec 2002 03:59

Why dont you ride it down here sometime and I could have a listen and a look, Im only an hour from London (kent/Sussex border near T-Wells)
David L.
01892 853913

POB/London 18 Dec 2002 06:34

Okey Dokey David - thanks for replying. I've been spending all this time meaning to come down anyway, perhanps this is the motivation I need!

I'll give you a call tomorrow (19th). I also wanted to speak to you re: the usefulness of IMO computers for overlanding, and whether they're a weekend job to fit. The dealership sponsoring me for my expedition have said they'll try, but they're open about never having done one before, so it could take days!

I have the 100R300 model with the temp sensors etc, and would be willing to replace the whole dash. Perhaps we can also chat about some wheels, and the spare (straight!) 3AJ frame and swingarm my friend has...

Speak 2morrow, cheers.

david lambeth 19 Dec 2002 00:47

Its always nice to meet the people inside the monitor....

DAVSATO 20 Dec 2002 15:14

can it be brazed or welded? do i have to drain/rinse the tank out first?

if you dont, have the fire service and an ambulance handy when you do it.


POB/London 20 Dec 2002 17:30

Yay! After a couple of minutes with a spanner on the engine mounts the problem appears to be solved. DL tweaked the rear mounts near the shock linkages with a torque wrench.

No more knocking sounds, anwhere in the rev range. Thanks DL! I'm tellng myself they only came loose because of my rigorous linkage maintenance...

I think the tank has to drained, rinsed thoroughly (and then aired), stripped of paint and then silver soldered - carefully! Not a DIY option, I don't think!

POB/London 24 Jan 2003 21:54

An update:

I thoroughly cleaned and painted the area of the pinhole leak. A month has now passed and there has been no more leakage. When I put the whole thing back together I ground down all the bolts so that they don't touch the tank.


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