Info Required for 1968 Ducati Scrambler

**madmal64** · 22nd September 2005, 11:07

Help!!! Is there anybody out there that can help me with this bike. Im looking for a manual. Or any workshop info I can get my hands on.
The thing is backfiring like a bastard and I would love to get this sorted.
Thanks guys

**Motu** · 22nd September 2005, 11:27

The 450? Nice....they were desmo I think,look for any info on 450 desmo's.All I know about them is that I'd like one....

**Brian d marge** · 22nd September 2005, 13:02

I had a 250 single with a fully sorted engine, While I dont have the engine I may be able to steer you in a direction.

The single was built in 50 150 239/250 350 and 450 sizes in both normal valves and desmo ...

You say yours is back firing ?? when ,,, is it when you try to accelarate ore when you shut the throttle off??

Does it have points or magarelli ( sp) electronic ignition???

As on accel the spark could be breaking down due to crappaelli ignition ...or on deaccel you have an air leak or a weak mixture....

Stephen

They are a lovely bike !!!!

**TLDV8** · 22nd September 2005, 16:03

If the ignition and jetting is ok (Dellorto's are screw out for rich,opposite to Mikuni's etc) and it is backfiring through the muffler it may have a burnt exhaust valve worse case.....

**madmal64** · 22nd September 2005, 16:42

Awesome guys! Thanks for the info. Im doing this for a mate who has the problem we will look at the ignition and fuel mixtures and take it from there.

Ive done a quick google and I have stuggled to find anything worth while. So you guys rock! What a great forum!

**Eddieb** · 22nd September 2005, 16:42

That would still be a narrow case being a '68 wouldn't it?

I've a Haynes workshop manual in english and original parts exploded diagrams booklet in eyetie for singles. They both cover most models & I think they both go up to the 450's.

Even better I'm in Wellywood.

Got any spare parts?

**madmal64** · 22nd September 2005, 17:51

No spares Im sorry. Have you got some to sell?

**Brian d marge** · 23rd September 2005, 02:28

The burnt valve idea raised a point ..Desmo dromic ,as u know it uses a cam to open and close the valve. And the closing one is zero clearance ...now zero doesnt mean zero ..u need oil between the faces of the cam and rocker ..So ,,,You can set the clearance with the head installed ,,,but You cant set it reliably soo its easier to take the head off ..I made a jig ..( this was for the 860 ..) anyway by lapping away at valve cap shim thing ( this is done from 15 year ago memory !!

) you set it so that if you squirt a bit of oil on the cam you can feel the cam sort of get tighter as you rotate it ,,it is noticeable ..as in I could notice it ..old clod foot me !

The point of all that is ...as the seat wears the valve clearance decreases ,,, you got it ,,and if you had a tight zero to start with the valve can be held of the seat which will burn the seat ,,and ( thinking allowed here..... under accelaration will back fire as combustion is either allowed into the inlet tract or the exhaust tract ,,,) had a z1 that was a burnt inlet valve ,,but then it tended to catch fire as you opened the throttle ...:slap:

Good luck and let us know

Stephen

**TLDV8** · 23rd September 2005, 11:12

I don't know about the singles but on twins..if a exhaust valve is burn't bad enough flames will come out of the muffler at idle and the good cylinder will keep the engine running...it can happen quite quickly...it would depend on the history of this particualar engine,has it had any work done on it etc etc..it may be something very simple as in the various posts above,time will tell..good luck..a decent manual would be a must have.

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