CBX250RS-E Engine Rebuild 06/04/2012

With the tensioner in place the next step was to fit the idle gear that sits in the middle and drives the two cams. With the flywheel having the "T" position at the inspection point this gear should have two lines on it showing level with the top of the head.. This took about 5 goes to get right the first time, and a couple more the second time with the tensioner properly in place. The tensioner also has to be let off by sticking something in the hole on top of it and levering it the wrong way so that the tension is taken off the chain, leaving just enough slack to get it into place. Quite a game getting it all lined up, but finally it was done..

The next step was to torque up the stuff on the bottom. All the big bits (clutch centre nut, primary drive and the flywheel bolt) were somewhat straightforward although I used a tool meant for undoing oil filters on cars to hold the flywheel in place while I did it up. The manual reckons it should be torqued to 100-120Nm which is twice as tight as the head! We got to 90Nm, then with the torque wrench set to 100Nm the filter tool snapped.. I reckon it's good enough though. I also had a problem with these 10mm bolts that hold the clutch release mechanism in place:

The manual doesn't give a torque figure for these but the usual is about 12Nm. They torqued up to 10Nm just fine, but come 12Nm one stretched and then snapped! I took the bolts out of the other engine and fitted those instead, again 10Nm was fine but with the wrench set to 12 two of them started to stretch.. I gave up there. Maybe I should buy some new ones?

Next up was the cams! They have a spring loaded sub gear on the outside to stop chatter and this had to be taken off and fitted to the new cams I have bought.. Another game laid in wait.

Taking a pair of circlip pliers to the old ones they exploded in a shower of springs and washers, I knew it was going to be fun straight away!

The manual says to simply press the springs into the troughs (or whatever you want to call them) and fit the sub gear over the top. As if! Of course the springs would ping out with nary a care in the world, in the end I put them half in and put the sub gear on top, and then twisted and pushed it into place, occasionally poking the odd misbehaving spring back into its hole. Eventually this was done, and with a bolt holding the sub gear in the same position as the cam gear (thanks to s screwdriver in the teeth and someone else tightening the bolt..) it was time to fit the new cams! Timing it up is easy, simply line up the marks..

Oddly Honda seem to have gotten the intake and exhaust sides mixed up on these markings, my other cams are the same. Save for some snapped bolts in the clutch which were easily extracted it was all going well, right until I tried to fit the cam holders. The bearings on the cams simply do not want to fit their cut outs in the head, there is a rather large gap underneath them:

I tried simply tightening the holders down, and one snapped in half! I won't be trying that again in a hurry, but it leaves me wondering what to do. Can I simply heat the head enough to let the bearings drop in? Is there a special technique for this that the manual isn't telling me about? I'm stumped!

1 x inlet camshaft (14110-KE5-010) - £70.80
1 x exhaust camshaft (14120-KE5-020) - £70.80

Running total: £971.72