As I have no clear information regarding when the belts on my 2002 Monster 750ie were last changed, I have decided to replace them myself. This will be the 1st time I have tackled this particular job. I have read lots of on-line posts and watched quite a few YouTube videos on the subject and am a bit confused. Which is the best method? Is it the “line up the timing marks” method or is the “mark the belts and count the teeth” method easier and more reliable for a beginner? Should I remove the plugs and use the back wheel to turn the engine over or should I invest in the proper tool to turn the crank? Is the tension set with a 45 degree twist, an Allan key or a tuner on my phone? Any help gratefully received.
https://lnx.desmodromico.com/cambio-cinghie-desmodue/ https://lnx.desmodromico.com/tensionamento-cinghie-distribuzione/
It doesn't matter which method you use. In the end the timing marks need to line up again. I personally don't bother marking the belts. I remove plugs and turn engine via the back wheel. I use the gates carbon drive app on my phone and tension with frequency. I used to tension by twisting the belt or pushing it so far etc but when I checked the frequency on 2 belts that I had declared tensioned equally and correct I found that they were too tight and not equal tension. Since then it's frequency for me.
I had a 900SSie many years ago and I used to do my own belts. TBH I marked them where they were with tippex. And then put the new belts on. I tensioned them with an allen key. This tip I got from Ducatisti forum many years ago. I think it was a 5mm and a 6mm key different for front and back and the idea was you had to just be able to get it past the tensioner and no more. I rode it for years without a problem. But like all things do not do as others do and be sure you are happy with what you are doing. Good luck, its a satisfying job.
Timing marks as they keep you focused on what you're doing and why ie. maintaining your valve timing. If you're not happy with the factory marks just make your own. Cam pulley to casing. Crank pulley to casing. Felt tip pen, tippex etc. The 2V engines are much more tolerant of imprecise belt tension than the desmoquattros. The design has Taglioni's genius written all over it. Very unstressed belts that don't need changing as often as the 4V. All tensioning methods you've mentioned are valid. Smartphone apps weren't around in the '80s.. Don't forget to check and replace the pulley bearings (if necessary) They're affordable and should be viewed as part of the 'timing system' along with the belts. Bearings in poor condition will readily precipitate belt failure.
Id go so far as to say this is the No.1 cause of ‘belt failure’. No.2 being turning the tensioner the wrong way do the belts are too close together when tensioned. FYI @midlifecrisis I put ‘belt failure’ because belts don’t just fail although they always get blamed for it. They won’t just break. They will however fray if they rub against each other (tensioner turned wrong way) or against something solid (eg seized pulley), and obviously they could, eventually, fray all the way through. Personally, I use both the tippex count teeth method and make sure my tippex marks on the new belts line up with the timing marks on the cams & crankcases as it’s all to easy to be just one tooth out otherwise IMO.
Thanks for all the advice. I did all the preparatory work, marking the old belts and the timing marks and had the old belts ready to come off when I got to the “undo the bolts holding the tensioner” part. I couldn’t shift the bolts. I tried a traditional Allan key first and then moved onto an Allen key socket on my 1/8th inch ratchet driver but it wouldn’t shift. I was a too timid to try any more brute force (it felt like my ratchet driver was about to break) so I just put everything back together and went for a run instead. I plan to buy a 5mm Allen socket for my 1/2 drive set and try that. The T- bar is much stronger so I’m hoping it will slacken the bolts. Is this a good idea or should I give up and take it to a proper mechanic?
Some sage will be along to advise the torque setting, so you'll have an idea how tight they are ( or should be)
Or some sage will advise moderate brute force, never had any difficulty removing mine and done a few on about 8 bikes now
As long as the Allen bit is a nice tight fit all you need is a longer lever. No brute force required. It will turn easily. If you're concerned that it might be corroded in place you could try some penetrating fluid (Plus Gas is excellent) and with a shorter lever try to tighten it first before undoing. Avoid undoing anything (under even moderate load) with a ratchet as the teeth can slip.
Just did the neighbours monster belts (she's cute if you ask). The guide for tensioning is that with a degree of effort you can pass a 5mm allen key between the belt and the non-adjustable bearing.. but you cannot pass a 6mm even if swearing.
The legend that is WCP knows the answer, make yourself a large drink and sit back. https://www.ducatiforum.co.uk/threads/seized-front-sprocket.71982/
