Ducati.ms - The Ultimate Ducati Forum banner

1 - 18 of 18 Posts

·
Registered
Joined
·
442 Posts
Discussion Starter #1
Bought a 748 on Saturday.

Background:
Bike had been raced three seasons in WERA, but it ran when I picked it up and the former owner said that he had adjusted the valves before last season, during which he only ran three races on the bike. Bike had 6500 miles before the 3 seasons racing.

My ownership experience:
Took it for 1 hour ride--all of a sudden starts backfiring massively.
Traced backfiring to plug in the upper cylinder...no gap and carbon fouling...fixed that, ran fine.
Took it for 1 hour ride--am accelerating from a stop, am at about 60 when I hear this sound that sounds like something breaking inside the engine. Engine is suddenly off and I'm grabbing a handfull of clutch. I shut off the electrics and pull it over. Engine maybe starts to turn for half a second (not sure) but after that it is seized. Plenty of oil in the engine.

What I think I know so far:
I'm being told that the bike probably lost a timing belt, which probably resulted in between 2 and 4 smashed valves, but know way of knowing without a teardown. Ken at SuperbikeItalia in Chicago (very nice guy) says he can maybe get it running for 600 bucks. I'm thinking that if the belt broke, that means the engine is going to need 6k service, and who knows what to get it back to spec.

What I'm thinking:
New engine. Is that stupid? What about going to a 996 motor or a Testastretta motor? Can that be done? There is a guy on ebay selling a 749S motor for $1500 bucks.
 

·
Super Moderator
Joined
·
8,235 Posts
Bad luck..

But checking the timingbelts is something you can do yourself. Atleats to see if they are broken or mistimed. unbolt batterybox and central cambelt cover. Inspect.

Inspecting the valves isn´t much harder, but you´ll need to disassemble the airbox, injection and exhaust to do it. ou´ll atleats see if major damage was done.

My guess is timing belt broke, which means that one of the cylinders mashed that cylinders valves..

Hope it doesn´t get to expensive for you..

//amullo
 

·
Registered
Joined
·
3,448 Posts
Yeah, sounds like a broken belt. You can probably check for this yourself by pulling out the battery and battery tray and taking the horizontal belt cover off to inspect it for 1) broken belt 2) shredded belt parts 3) excessive belt dust and small pieces if the belt that broke was the vertical one

Also, a 916 or 996 engine will fit, but a 749/998/999 engine will not fit in the frame. $600 sounds like a pretty good bargin, if the guy really can get it back up and running for that. Most 6k services will run more than that, so if it needs new rockers, valves, valve guides, and possibly piston/rod/crank/crank bearings. A broken belt can result in a LOT of damage that is not very easy to repair. Actually, I'd be leery that he can repair it (and repair it properly) for $600 without tearing it down to give you an accurate quote.


amullo said:
...and central cambelt cover. Inspect.
I had a pain of a time trying to pull the central cover off of my 2002 748. It was a pain until I removed the oil pressure sensor to be able to pull the cover out. It just didn't want to come out any other way.
 

·
Registered
Joined
·
442 Posts
Discussion Starter #5
Would it really be much improvement to go to the 916 engine, it looks like it makes pretty similar horsepower and torque figures to the 748, albeit at lower RPMs. Never driven a 916.

Thx,
Trent
 

·
Super Moderator
Joined
·
8,235 Posts
The 916 has slightly more HP compared to a slightly tuned 748R, but alot more torque through the rpm range.. The "normal" diffrence would be about 10-12 HP and 15-18 ft/lbs "top" power and torque, but the 916 has ALOT mor torque all through up to revlimit

The good thing about the 748 is the close ratio gearbox, which the 916 or 996 never got. Having a 916 or 996 engine with a CR gearbox would be a blast!
 

·
Registered
Joined
·
3,448 Posts
amullo said:
The good thing about the 748 is the close ratio gearbox, which the 916 or 996 never got. Having a 916 or 996 engine with a CR gearbox would be a blast!
I've heard of some people doing just that. My understanding is that the trannys are interchangeable, so he can find a 916/996 and swap the tranny out of the 748 engine. Personally, I think the route to take would be to rebuild the 748 with an 853 kit. ;)
 

·
Registered
Joined
·
263 Posts
+1 for the 916 motor if you can find one for a good price. While I love the 748 power delivery, sometimes there's no replacement for displacement. ;)
 

·
Registered
Joined
·
442 Posts
Discussion Starter #9

·
Registered
Joined
·
207 Posts
ericS4 said:
Sorry to hear about this major bummer.

Another alternative might be a 916 pulled from an S4. I know it uses an ST-based frame, but it has the close-ratio gearbox, same HP as the 748 with another 10 lbs of grunt.
Won't work with the 748/916 swingarm, wider engine case.
 

·
Registered
Joined
·
442 Posts
Discussion Starter #14

·
Registered
Joined
·
7 Posts
Why won't the 998/999 engine fit in the previous gen frame? With all of the talk about the improvements to the Testastretta engine, it would be nice to drop one in a 996.....isn't that essentially what a 998 is? There is a 999 engine for sale on ebay right now. Has anyone done this swap? I assume as with any swap, it is possible as long as you have time and $$$$$.
 

·
Super Moderator
Joined
·
8,235 Posts
Eh?

Why not just get a 998 (which HAS the Testastretta) and call it a day. That would be alot less expensive then doing the 998 engine in a 996 chassi. The 998 IS that same package from Ducati.

//amullo
 

·
Registered
Joined
·
409 Posts
Even though I am chomp'in at the bit to do something like a 749 or 999 engine in a 748 because I do have the skills to figure it out, I still vote for a 853 kit with High Compression pistons. Go all out lightening every internal and get it all balanced right (FOX Performance for instance). Make the engine wicked and still rev high like a 748. Get the squish (distance from top of piston to head) minimized too but have someone who understands rod stretch so they don't screw it up. Have the tops of the pistons ceramic coated to keep'em cooler (prevent detonation).

If compression is too much, sweeten the 93 octane gas with a shot of E85 (104 octane) to boost overall octane. It'll keep the valves and internals cleaner too.

Ok..that's just my 2 cents :)
 

·
Registered
Joined
·
18 Posts
748..1999

hi ...just purchased ....yellow..21k...this is my first duc. i had to lower the forks in the trees...cleaned the filters...they looked new..but i didn't notice much oil on them. i oiled them..replaced and that was it. it's the yellow one..beautiful..has the termig..exhausts...lots of carbon fibre but no hugger...bummer..oh well. just purchased a rear stand. i noticed on the left side of the frame that it is a 748s..what's that mean? looks as though it has showas front and rear....where do i find all the info on this model? thanks the maj :D :confused: :think:
 
1 - 18 of 18 Posts
Top