Quick one for you desmo heads.... just been checking my valves and I've got a bad opener (vertical intake, LHS). Looks like the only one, fortunately. Is it possible to remove and re-fit an opener without pulling the cam? Had a search but can't find a conclusive answer. Belts aren't due for renewal and look fine so don't really want to replace/disturb them if possible. But if the cam needs to be pulled is it ok to slacken the vertical belt and then re-tension it when done (leaving the horizontal undisturbed)? Bike is a 2000 bip with 14k on the clock with no evidence of previous rocker failure in the history.
Hi Pete, not really fella, you cant really see what rockers have failed properly without pulling cams. Its not a big job to remove/slacken belts and pull cams, you can re use belts no problem providing that their condition is still ok. Please make sure that you turn the tensioner the correct way when you reassemble it. Darren.
Yes you can. I had a horiz exh opener needed replacing on my ST4s. I put the head back together while I waited on the new rocker arriving. I was able to pull the rocker shaft, take out the old rocker and fit the new one without taking the cam out. Luckily it didn't need the shim changing.
Yes you can. I had a horiz exh opener needed replacing on my ST4s. I put the head back together while I waited on the new rocker arriving. I was able to pull the rocker shaft, take out the old rocker and fit the new one without taking the cam out. Luckily it didn't need the shim changing.
Plus its good practice to mark the direction of rotation of the belts so that they go back on the same way.
Yes you can. I had a horiz exh opener needed replacing on my ST4s. I put the head back together while I waited on the new rocker arriving. I was able to pull the rocker shaft, take out the old rocker and fit the new one without taking the cam out. Luckily it didn't need the shim changing.
Bear in mind that you will need to check valve clearance and may have re shim the opening clearance afterwards. It can be done in place as Derek has pointed out, I just have a habit of pulling cams to check as its not a whole lot more work if your already in there. Darren.
Thanks for the quick replies and tips fellas. I know the job will be much easier with the belts off, so I think I will probably do that and inspect all the rockers properly. Ive stripped a 2V head before but this is my first 4V. just wanted to keep the job simple and get on the road. I'm kicking myself for not doing it over winter. I'm thinking of using Newman cams for re-plating. Good plan?
The 4v heads are much easier to strip than the 2V ones, just more bits to deal with. Getting your rockers done by Newman is a good idea. There is every chance that replacement factory ones will just fail again.
You need to take the cams out to properly check the rockers anyway, so no point in just changing the one without looking at the others. The rear exhaust rockers/shims are a pig to get at, the others not so bad. Removing the cams and opener rockers is easy enough but belts need to come off, more tricky changing a closer rocker (although unlikely to need it).
Yes, the rear exhaust rockers are a sod to get a good view of, especially when working from one side of the bike, as I am having to do. I ended up dangling a small mirror from the frame spar and tying myself in knots trying to get in feeler guages using the reflection. Any tips for loading up the closers? I kept slipping off the bloody things.Tried reaching in and levering down but without success.
