888SP4 Go Bang!
 

I love Ducatis me! Even when they do blow up!
Some of you may remember my tale of woe regarding my SP4 that snapped it's crank last year (see pic).

I've since had the engine rebuilt using a very low mileage 851 bottom stitched on to the SP4 barrels and heads.

The bike's running again but not without it's problems. Some of which I'm hoping you real Ducati experts can help me with.

Firstly, I've got an oil leak behind the rear cylinder. I noticed that the engine was overfilled with oil when I got it back from the dealership (which has since gone bust!) so I lowered the level to the upper mark. Can anybody tell me if this could have caused a rise in pressure resulting in a blown base gasket?

Secondly, the 851 gearing isn't working well. I feels like I'm pulling away in second. Will changing the rear sprocket help? If so, any tips on sprocket size would be welcomed.

Thirdly, and this relates to question 1, could it be possible that the oil cooler has been clogged with debris from the blow up? This could explain the higher oil level. Is there a clever way of checking ie: compressed air, flushing etc?

I'm saving up to have a total engine rebuild, re-using the SP4 crankcases (which were surprisingly unscathed) and returning to pure SP4 gearing and of course keeping the 888 engine number to retain the bike's value.

All advice will be received with appreciation.

Cheers

Fred

888SP4 Go Bang - picture
 

Here's the pic I mentioned in my text.
Somehow didn't go before. Bloody computers!
Waste of time!

I was told in my old home bodge tuning days (cars as bikes were too dear when I was a poor student) that after an engine blow up you should trash the oil cooler as theres no way you could flush out all the debris and it would come back to haunt you later. now that isnt a cheap way to get u back on the road and 2nd hand oil coolers need to be treat with caution too unless u can verify the history. Suspect this is not what you want to hear. But an oil cooler shoul dbe cheaper than a new set of crank and conrod bearings (or trashed crank/cams if debris blocks an oil way)

[Edited on 17-5-2006 by IainMac]

Are you sure you've got a rear base oil leak. It's far more likely, especially as it's been overfilled, that the oil is coming from the breather that's right next to the rear pot.

just my £0.02.

Rgds, Rob

I did check the breather but it seemed dry all around and the pipe clamp was tight.
I've noticed the oil level was still above the max. So I've emptied the sump completely and will refill with new oil to just under max level..
The old stuff was completely free of swarf as was the drain plug magnet (good sign). I'll remove the filter and have a look there also.

cheers

Fred

Overfilling vehicles with oil can cause all sorts of odd oil leaks so as Rob points out don't panic just yet. If your drain magnet and screen are clear it sounds like you didn't get much swarf into the engine/oil cooler (and I would have thought the filter would catch anything before it got to the crank in any case). If worried, you could always check the oil pressure if you have a suitable gauge to hand?

Keith

Looking at the way the crank has gone,i doubt that there would be that much swarf/bits of metal anyway-You have the gauze filter and the oil filter to protect the engine,so i wouldn't worry about it too much.I would agree with Rob,highly unlikely to be oil form the rear cylinder,more likely from the breather.My SP5 used to get a fair old pool laying at the back of the rear pot until i put an STM breather on.

Thanks for the input guys.
It does sound like the engine was overfilled on the rebuild.
I'll change the filter and refill to between the marks and take it for a run to see what happens.

Cheers

Fred

overfilling the case will definitely strain a std breather, especially the old type with the silver band. even once you refill it to the correct level you may still have a leak, they often leak from the crush washer between the breather and case or pool around the top of the breather from a leak where the silver alloy ring joins the plastic top. it's amazing too where fast moving air will push fluids around the back of the rear cyl. i too doubt it's a base gasket..........but then i am wrong......often.:burn: