250 noisy top end

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briggy
Posts: 5
Joined: Tue Mar 06, 2018 12:10 pm

250 noisy top end

Postby briggy » Mon Jun 18, 2018 8:58 pm

i have recently bought a 250 moto trans scrambler that has a ducati 250 mk3 engine fitted i believe the engine has been rebuilt to me it sounds very noisy from the top end a tappet noise i would have thought i have checked tappets and they were set very tight the noise gets worse as the engine warms up would appreciate any advice
Thanks ian

Jordan
Posts: 795
Joined: Fri Dec 24, 2010 11:29 am

Re: 250 noisy top end

Postby Jordan » Tue Jun 19, 2018 10:41 am

Could be the bearing housing for the bevel drive shaft is loose in the head?

Bevel bob
Posts: 773
Joined: Thu Apr 15, 2010 8:01 am
Location: Bromley Kent UK.

Re: 250 noisy top end

Postby Bevel bob » Tue Jun 19, 2018 3:48 pm

Can you see plenty of oil in the valve chambers?, They can run for a long time with no supply at all to the head .run it with the cam drive cover off to check the pump is working.

ranton_rambler
Posts: 154
Joined: Sun Jun 04, 2017 11:33 am
Location: Stafford UK

Re: 250 noisy top end

Postby ranton_rambler » Tue Jun 19, 2018 7:24 pm

I've never had mine running (getting closer....) but I've heard they can be a bit noisy. Anyone nearby that you can get to listen to it?

blethermaskite
Posts: 23
Joined: Thu Mar 01, 2018 1:06 am
Location: northern ireland

Re: 250 noisy top end

Postby blethermaskite » Tue Jun 19, 2018 8:54 pm

If it were me, I would run the engine until it was at least a little warm and then drop the engine oil into a clean drain pan, look for any metal sparkles in the oil.....if the oil is clean......well that's a good sign that things are maybe ok.....but.....if there is ANY metal in the oil take the head off and strip it down for a close inspection of all the moving parts. In comparison to some other engines a valve spring ducati single can sound a bit 'tappy' arround the cylinder head and that is normal, however it should'nt really get any louder as the engine warms up unless there is a problem with the bevel gear set up or the cam bearings.
Cheers,
George

briggy
Posts: 5
Joined: Tue Mar 06, 2018 12:10 pm

Re: 250 noisy top end

Postby briggy » Tue Jun 19, 2018 9:43 pm

thanks to all who replied , top bevel drive has a see through cover and seems to have plenty of oil getting up there , i changed the oil when i got it and all looked clean,would a loose bearing housing give a loud tapping noise? Getting someone who knows these engines to have a listen would be ideal im in the kettering area if anyone has any suggestions
Cheers Ian

Jordan
Posts: 795
Joined: Fri Dec 24, 2010 11:29 am

Re: 250 noisy top end

Postby Jordan » Wed Jun 20, 2018 12:54 am

briggy wrote: would a loose bearing housing give a loud tapping noise?


Yes.
As has been suggested, the noise you hear might be normal, but if it's loud enough to be alarming then it could be contributing.
It's not the best engineered detail in the cylinder head, relying on a gasket to do double duty - seal oil leaks, as well as press against the bearing retaining sleeve (or bush) to hold it in place.
A good suggestion I read here is to give priority to firmly locking the bearing sleeve, and use supplementary gasket paste to ensure oil leak control.
Maybe even delete the gasket altogether.

A possible complication is that the bearing sleeve has been loose long enough to make the hole for it in the head over-sized.
A fix might then be to use a new bigger one, or copper plate its OD, or use Loctite.

Otherwise, could it be that as you say the engine has been rebuilt, the bevel gears are not perfectly adjusted? Any play there will make noise.

The good thing about Ducati single heads is that removing one to check the above is not a huge job.
The trickiest part is probably getting the bevel drive synchronised correctly on assembly.

briggy
Posts: 5
Joined: Tue Mar 06, 2018 12:10 pm

Re: 250 noisy top end

Postby briggy » Wed Jun 20, 2018 9:19 pm

think that,s the route im going to have to go, appreciate the advice
thanks ian

graeme
Posts: 593
Joined: Sun Mar 25, 2012 12:00 am
Location: Australia

Re: 250 noisy top end

Postby graeme » Wed Jun 20, 2018 11:00 pm

Hello Ian,

also worth checking the rocker pin wear.
Pin to rocker pin bush wear - and also but less likely rocker pin to head wear. (where the pin inserts into the bevel side of the head)
I had a 450 Scrambler make very loud tappet noise and the pins were loose in the head casting.
Any of these can make the setting of the tappet gap impossible as things move and the gap changes.

Worth a look before you tackle the bevel side.

Graeme


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