Should I rebuild the engine?
 

So I'm planning to take my '89 3AJ Tenere to Morocco this year, ride around some off road pistes and explore a bit. My reasonably trusty 3AJ is getting on for 20 years old now and has 40,000 miles on the clock. I've had it for couple of years in which time I've done about 9,000 miles but there was no history at all with the bike. Nothing major has fallen off yet.

I'm wondering whether I should rebuild the engine before I go, and if so how much (top end, bottom end, both)? I'm aware that this can't be answered with certainty but I'm keen to poll the opinions here.

I'd check the compression and if within service limits and all else is well, leave it alone - if it ain't broke, why fix it?

SW

If it were me i'd have the head off, reseat/replace/inspect valves, springs, rockers guides seals etc, new camchain, top end gasket set and away. Would obviously give it a full service and consider fitting or taking a new clutch if you're going to hit the sand. Just my opinion but imagine the annoyance of getting there or halfway there and something preventable going tits up?

Cheers guys. I like Docsherlock's advice, partly because I don't have a garage to put my bike in while I take it to pieces.

Alfow, your advice sounds wise too. I have new clutch plates and springs which I'm planning to fit soon. To take the head off I'd have to borrow garage space somewhere but it's certainly less effort than doing a full rebuild. Hmmm.

If the compression is sound and the bike does not use any oil, or at least not more than is normal for the model, it is very unlikely there is anything wrong with the valves, guides, bore and piston/rings. Big end problems are unlikely to strand you anywhere and if the oil has been changed would be pretty unlikely in any case.

The only caveat I would wonder about at this mileage is the cam chain and the degree of wear can be assessed by checking the amount of play left in the tensioner. In the first instance, if it doesn't rattle, it is probably good for several thousand more miles at least. However, at 40,000 miles, it would be worth at least checking.

Good luck,

SW

PS If you only doing a return trip to Morocco of a few weeks (as opposed to a RTW jaunt) I wouldn't worry about it - just go! The chances of having problems in the next 5-10,000 miles are not high.

SW

I have same bike with similar milage. However a few years ago I treated it to a total rebuild, it wasn't knackered but I had the time and a garage to do it in.
Pulled it apart and only real problem was the teeth on the second (and possibly fourth) were slightly worn (a common fault with these bikes). I'm sure if I hadn't pulled the engine apart I would not have never noticed this, no strange noises or bad gearchanges and I'm sure the bike would have ridden ok for many miles. It was an easy fix using stronger gears (from a later model I think).
The rest of the engine was in very good condition. No wear to cams, tappetts, valves, seals, oil pump, bearings, clutch etc etc. I could have put it all back together but, well as I had the bits and time I treated it to a Wesco 620cc big bore, gas flowed head, new stainless engine bolts, new seals and bearings. I havn't needed to touch the engine since. Though I may fit a new cam chain soon, no rattles but something to do.
The 3AJ is a very very tough old bike. If it is running ok now it will easily do a few 1000k around Morocco. Just check tappetts, change clutch plates, oil and filters.
Also take spare air filters, cables, spark plug, inner tubes, fuses, you probably wont need any (except for air filter and tubes) but it's a resurance.

When are you planning on heading to Morocco, I'm thinking of going in April/May or September (on my 3AJ).

Take your bike and enjoy..

p.s. fitting new clutch plates will only take an hour. Cam chain might be easier have it done at a bike shop, it's an easy job and wont cost too much.

Brian, it's reassuring to hear of a similar bike being pulled apart and being generally ok. I like to do as much as possible myself on the bike within the constraints of my tools and lack of garage situation, I'll definitely do the clutch and check the tappetts. I'm thinking of going October/November time, but I am itching to get away so may go sooner:)

All good food for thought.

They are pretty easy bikes to work on.

One reason I bought mine (in 2000) was that 1996 whilst in Morocco (on my KLR650) I swopped bikes (due to one guy dropping a borrowed XT600 and snapping gear change peddle). So basically I was riding an XT600 3AJ along Atlas mountain dirt tracks on a bike with NO gear peddle, so stuck in 3rd gear, this bike had also previously done a London-Kenya trip so was kinda 'worn'. Much slipping of the clutch and slow progress, but it never gave in. Sure the clutch was rather cooked but a bodged repair was made and it contiuned to run. I'm sure that on my KLR or on just about any other bike such abuse would have been 'terminal' but the XT just plodded along.
They just don't make them like that no more.