Compression Readings

Timbo · Post by **Timbo** » Wed Sep 20, 2006 11:23 am

Im still having problems with starting the bike.The timing is now correct ,but bike wont turn over unless a small amount of oil is put into each cylinder then it runs fine
Im wondering if the piston rings and barrells( bike is only showing 17800 miles) are the problem or could it be valves. The bike does not burn any oil so when running.

Any ideas what compression reading for barrells should be?
Cheers Tim

Finnpaso · Post by **Finnpaso** » Wed Sep 20, 2006 7:34 pm

When You have checked Your valve clearances???? If they are totally wrong, it can happen that way..... I havent measured compressions in my 907, but its easy job in all car maintaining companies and if they are "low", or another is low, U have problems in valves.... I know, that if valve clearences are NOT correct, then U HAVE such starting problems and normally, when engine gets hot, it goes more worst....

Timbo · Post by **Timbo** » Thu Sep 21, 2006 9:49 am

Antti
Thanks for reply I will check what you say.I just cant understand what the problem is.When the bike is running it sounds fine no problems with it.I have left it running for about ten minutes and then switch off and try to start, no.....

Many thanks Ill let you know how I get on.
Tim

Finnpaso · Post by **Finnpaso** » Thu Sep 21, 2006 7:22 pm

WHEN valves were adjusted last time??? I think, check every 15 000-20 000kms is enough. Its normal, that new engine need adjusting "to 20 000km", but then it runs long time without adjusting, only check clearances, but when engine gets "old", it start to need more often adjusting. This have happen to many Ducatis since they started to make big twins... Surely Ducati NEED very good oil and and warming with idle some mins, before accelerate her higher....

many problems are caused by bad oil and shit in fuel system, plus surely bad battery and shit in connectors....

Timbo · Post by **Timbo** » Thu Sep 21, 2006 11:58 pm

Antti
I dont think valves have been adjusted for some time.I have done rough compression readings and they show 45lbs psi in horizontal and 85lbs psi in vertical cylinders not good

I am going to look at stripping top of engine and check valves seats and colletts I think they are worn hence low pressure and bike not starting.
Many thanks for replies

Tim
907 ie red
851 Strada red

Post by **jcslocum** » Fri Sep 22, 2006 12:30 am

Timbo,

Before tearing it down you can do a simple leak down test to determine exactly where the compressed air is going. Have you done this before? It not much harder than a comression test.

If the valves haven't beed adjusted for years/miles this could be the simple cause of low compression. Easier to check valve clearance than tear the top end off. Check out the Ducati Suite for instructions.

Finnpaso · Post by **Finnpaso** » Fri Sep 22, 2006 7:46 pm

It can be burned exhaust valves, totally wrong valve clearances, bad valve seats, bad valve guides..... But check valve clearances first !!!

Timbo · Post by **Timbo** » Fri Sep 22, 2006 8:13 pm

Thanks for replies
I will set to with the feeler gauges ths week-end and let you know what the findings are.
Many thanks
Timbo

907 ie red 1992
851 Strada red 1992

Finnpaso · Post by **Finnpaso** » Sat Sep 23, 2006 8:00 pm

We are waiting.... maybe some very intresting Paso problem again...