A few days ago the two new cam (timing) chain tensioners (AP0236253) arrived ……. and as if she knew, the Capo started to rattle the rear cylinder for a second or two at almost every start-up! So as soon as we got home yesterday, it was off with the bike kit and into the workshop-wear and time to seriously twiddle some spanners.
Thankfully the rear tensioner is nice and easy. Fuel tank up, pop out a couple of spark plugs to make rotating the rear cylinder to top-dead-center nice and easy, then rummage under the wiring on the right hand side and find the cap requiring a 6mm hex-key.. Remove the cap and the copper washer underneath and then use something pointy to hook the tensioner out enough to get a grip with podgy fingers.
The tensioner shows definite signs of movement and rotation and the plunger could be pushed in about 1/2 its travel ….. I think FUBAR best describes it! The new tensioner was oiled up and before it was dropped into the motor I did a little experiment. Both old and new parts were flushed and filled with new 15w/50 and gently pinched in a vice. The new tensioner remained snug for a long time, only a small amount of oil could be seen coming out ….. next up the old one. This remained snug for no more than 1-2 minutes and oil could be seen leaking from it the second it was compressed. So all in all a major difference in performance between old and new.
After a few more jobs were carried out, it was buttoned together and warmed up …. no rattles and in fact the idle was smoother than it has been in a while.
The tensioner that came out is an original Mk1 (AP0236252) that was superseded by the new version a good few years back. From what year they were fitted as standard I don’t know. Looking closely at the old one I found ‘INA F-46807’ printed around the edge. I can’t find much about it unfortunately. However ……..
……. I did find something that might be of interest. It looks like the tensioner fitted to the BMW 650 (late models) and F700/800 bikes could well be the same. Now this can only be corroborated by direct comparison, so I might tout the other new Aprilia one around a few BMW dealers to see if I can find out if they match. If they do fit, then they are available for substantialy less than the £68 each from Aprilia.
Sorting the rear tensioner yesterday took all of 20 minutes, but I knew that the front was going to be a different kettle of fish altogether because of the coolant pipes. No worries, I thought – a good excuse to change out the coolant as well.
So in I went and oh what fun it was! Off with the crash bars, side panels and sump guard, move the coolant bottle and release the radiator bottom hose and drain the system – so far, so good. Remove the airbox and release the clamps holding the throttle bodies in the inlet rubbers ….. hmmmm – looks like they’ve got a few deep cracks I’m thinking.
Take off the rest of the hoses, cables and electrical connectors, now a gentle pull and twist to release the throttle bodies and ……………… oops! I think the cracks in that rubber were a tad deeper than first thought and a touch beyond repairing with a splash of rubberised goo. Luckily I’ve a spare pair to hand from the l’Aquila stash. However, this momentry inconvenience isn’t the task of the day ….. so onward once more. Hoses, cables anything and everything moved so I could at last get to the two clamps holding the ‘Y’ hose in place – then finally the goal was in sight, the pot at the end of the rainbow …. the front cam chain tensioner!
With a heave, a grunt and too many fingers trying to get into too small a space I managed to retrieve the tensioner from its hide-away, gave it a squeeze and ……… it was fine, solid as a rock! Never mind, a flush to clean out any debris and a refill with clean oil never hurt.
Then it was rebuild time. The tensioner’s in place and the cap torqued down to 30Nm with a swanky new copper washer. The super-shiny inlet rubbers torque down at 19Nm and the rest of course is then a reversal of strip-down – with the intention of NOT ending up with any washers, screws or clips left over! And so with the sun ready to slip behind the mountains it was test-time. Glad to say she fired up first hit of the button and sounded so much smoother, funny how you get used to little noises and ‘character’ over time – now she’s idling smooth as can be, a tweak on the throttle body sync screw had the manometer within a couple of mills AND it stayed that way when the motor was reved, something it didn’t do last week. So I’m guessing the cracked inlet rubbers were an issue after all! 😳 So that’s it for today, other than updating the Capo’s history spreadsheet ….. the Capo has now done a pinch over 74,400 miles and other than a couple of valve shims and plugs, it’s the only work the motor has ever needed.
Next stop – tyres, chain and sprockets. 😯
Yesterday I spent a lazy morning installing a couple of sensors inside the airbox (more in another post) and with the tank propped back in place, fired the Capo up to check the fuel lines…….
…… and just for a second or so after she fired up there was a distinct rattle from the rear cylinder and frankly it didn’t sound too special as the bike warmed up. To be honest, I’d heard it before on a couple of occasions but couldn’t pin down which cylinder it was. With the tank lifted and stood in just the right position, it was obviously the rear. As it was lunch time, I decided to have a look a bit later – and promptly forgot! Well I got back to it in the evening and pulled the cam chain tensioner out. Soggy as a knackered bed spring! 🙁
So it had a thorough flush out and re-charge with fresh 15/50w oil and firmed up nicely (phew!) …. it looked as though contamination had built up in/around the ball that seals the oil in, in this case letting it out just as easy. Buttoned it all back together, fired the motor into life and revelled in a quiet(ish) Capo motor – just in time for a cold beer and MotoGP on the box, bliss! As I sat watching the race I kept having a niggling thought … what if the front one is the same?
Tomorrow feels like a let’s-check-the-front-one day ……….. 😕