Brad The Bike Boy: Ducati main bearing failures

Sunday, November 8, 2015

Ducati main bearing failures

I rebuilt an ST3 engine a couple of weeks ago due to a bad main bearing. I didn't video that one beforehand, but I do have a little video that shows the noise they make well.

The bike in the video is an M400 with 22,000km on it. The owner had bought it in a private sale, been on several rides with his mates, and was generally happy with his bike. It wasn't until he took it to someone for a service that he first heard the phrase "WTF is wrong with that!" A bit shocked by this, he then headed to Ducati City at the recommendation of the someone to see what they thought. They too asked "WTF is wrong with that!" Because Ducati City won't deal with the grey import bikes, they sent him to me. I heard it pull up out the front, with the noise making my skin crawl so badly I had to go out and turn it off. The high idle wasn't helping the horrid noise either. This is what it sounded like.

Luckily for the owner, I found Michael at AdrenalinPB had a second hand engine. We popped that in, and all was happy again.

The ST3 I mentioned at the start was in for a service, and when I fired it up afterwards I had a feeling it was noisy. It had around 42,000km on it, and 1,500km later it had gone from a bit of a noise to what the video shows (it might have been a bit worse). It took about $6,500 (including some Pistal high comps and a head reco) to make it quiet again.

I had an S4 Monster in for some work last week, and when I fired it up I heard the dreaded noise again. It had around 15,000km on it.

I've heard of quite a few MTS1200 doing it around the 20,000km mark. This is a bit surprising as the 1198 or Diavel don't do it, and theoretically they're all the same thing bottom end and production wise.

The cause is usually the inner race of the RH main bearing pitting. Sometimes the balls and then the outer race pit as well. I guess it might depend on how long you let the noise run for as to how far the damage travels.

4 comments:

Unknown said...: This comment has been removed by a blog administrator.; December 25, 2015 at 7:56 PM
Unknown said...: Hello,

Im rebuilding a 95 900ss.
Very interested to know what main bearing you would use these days since the RHP items are no longer available?

Originals:

7307X2TB RHP and 7207X2TB RHP.

Many thank in advance,
Chris.; January 19, 2016 at 4:11 PM
Brad The Bike Boy said...: I always use the Ducati bearings.; February 14, 2016 at 6:04 PM
Unknown said...: THE MTS has very different bearings to the 1198.; October 4, 2020 at 3:53 AM

Post a Comment

The 851

The 400SS

I bought this 400SS (genuine 93 model Australian delivery! Woo hoo huh.) after seeing it in Ebay for what was possibly an good price. As ever, good was too good to be true. Badly repaired and rusted out fuel tank, badly repainted side panels, lots of km (83,000 of the bastards), etc. You know, the usual. Purchased in October 2012, as of now (Jan 2014) I've nearly finished a major service. The cam timing is done with some of the Madasl adjustable pullies that have been drilled in 4 different settings for easy dyno testing. And I have some 900 headers to try a 40mm dual exhaust set up on it (ala M400). Not a great deal of progress for 15 months, so it's taking on a long term feel. There's an F1 endurance style seat base (more taper at the rear) and front fairing sitting around, which will require frame mods to fit. It's a bit of a mental sticking point as this time. But hey, it's not like I can devalue it much more.

The Mighty KR1S 250

How it looked the rainy night someone came to take it away. Painted all black when I bought it, at some point later I realised i could rub the black off and have much of the original colour scheme underneath. Although the main fairing was originally from a red KR1 I think, and definitely badly repaired more than once, so it stayed black. And the tail panel shown was bought to replace the one I smashed the only time I crashed it and the last time I rode it at a Sandown track day. A sensational little bike, holed pistons and frequently failing stator windings aside. The first bike I rode on a race track and the first bike I had my knee down on. And a great commuter too I found. It's sometimes nice to have a bike that won't wheelie past the city speed limit in first gear.