Barn Find 748 SPS In need of a lot of love!

853R motor?????

 

It may be beyond economical repair but if you throw a replacement motor in the numbers won't match and your desirable SPS becomes not quite so desirable.

What exactly is wrong with the engine?

 

Why not have the cams refaced by someone like Newman cams, it's a lot cheaper and better than new. SPS cams are very rare and go for good money on eBay, I paid over £300 for a spare pair years ago. This is what you can do with them.

CJS RACING Dyno ECU Flash Mapping Bristol Ducati Cylinder Heads Gas Flow

I believe this bike was actually my sons race bike or if not he had an identical tune by Chris Steedman for he used the same method.

If you get an old basic 748 engine you can probably swap out the rest of the parts and still get your original SPS engine in your frame, it will give it more value as noted above.

 

Beyond economical repair! 4 rockers resurfaced by Newman at £35 each and a cam re-furbish, haven't read all the thread only bits but an SPS is worth a little more expense than that.
Steve

 

^^^ I'd agree only 100 UK models imported over the three years they were produced (40,40,20), that's less than the 748R figures for their three year period.

 

There is a lot more to it than you might think. One difficult job is getting the primary gear off the crank and after that getting the correct preload on the crank main bearings when rebuilding. It is better left to an expert unless you an adept mechanic and you are used to working with tolerances.

The gearbox has to be just right also or the gearing will be out and won't change perfectly. Parts like gaskets are also dear so if anything did go wrong it wouldn't be a cheap strip and rebuild to rectify. I hope this doesn't put you off but these engines aren't cheap enough to strip and regularly rebuild if anything des happen to go wrong, it might be better to leave it to an expert.

I had to have my 748R rebuilt and i am glad I left it in capable hands as there were some things that I would not have checked because I was totally unaware of what was involved in some areas.

You probably want to check the mains and big ends if you do strip the motor, my main bearings went after 4,000 miles!! and the big ends were on their way out!!

 

Indeed, Newman's rockers are the way to go. I had mine done by them and don't expect to replace a rocker again - job done!

If I bought another Desmoquattro engined bike, I'd get the rockers done by Newman at the first service. I've got quite a few rockers laying around the workshop - at least enough to fit a complete engine, some new, some used, mostly good but I wouldn't use any of them in my own engine without getting them 'Newmanised' first, just not worth the bother and hassle of not knowing if they're good or not.

Don't know what they'd charge to repair the cam but I can't see it being uneconomical.

 

Repair it....

 

^^^ A new cam would be expensive and you would be lucky to get a second hand one, in fact I would say it's almost impossible, any on sale are going to be as a set. As mentioned Newman is the only really positive way to go.

 

JLC's motor is not the prettiest.............when he says barn find, you could read that as saying bottom of a pond in a barn........

 

It may be an ugly baby, but its loved-and that's important, and counts for a lot.

 

I paid £1400 to have my 748R rebuilt and it was worth every penny as it is now effectively a new bike and it runs perfectly. The engine is in an S frame so it's not a true 748R, but it goes as well as one, this conversion is considered one of the best as it uses the grunt of the 748R motor without the problem of the big injectors and it makes just a fraction under 105bhp at the back wheel. When I bought the 748R it came as a wrecked bike and it was obvious some money had been spent on it but the funny thing was that it came with a power commander and the dyno graph showing it made 101bhp at the back wheel. Chris Steedman did my custom fuel map for this bike so It shows what can be got with just a bit of tweaking.

Any decent SPS is always going to be worth something as they are so rare, as a hybrid bike will yours be? that's the question you need to ask. Whilst I love my "R" I know it will not be every one's cup of tea because it is a hybrid, my 1999 SPS is always likely to be worth more as only 20 UK models were imported in that year. These bikes a very rare now and certainly 100 do not exist any more as I know of two that have been written off.

 

Have a word with Nelson regarding cost and mechanical knowledge needed to fit a 848 motor in the 748 i think your original engine will be much the easier and cheapest way to go.
Steve

 

My 853R will drop in nicely...................

 

The SPS uses 10mm bolts for the front engine mountings any type of R motor has 12mm mountings you need to either drill the frame or sleeve down the motor (cases) to the correct size.

I sleeved down my cases so if you do that you really need to have access to a lathe, you will no doubt find the same if trying to fit an 848 or a later 996\998 engine.