Well, well, well............I think we may have found the problem. After rebuilding the complete top end and almost three months of having the bike running poorly I think I found the culprit.
All this time one cylinder was running way off from the other. So I tried jetting , I swapped boxes, I swapped coils,I re wired the pick ups...all with no luck.
When I put the pistons in I figured I should send th heads to someone that knows them. I foud one local Ducati dealer that had a shop manager that has been working on these bikes for years. He agreed to lap the valves and put in my new seals. After getting back my heads I trusted that all was well inside them.
I had one plug looking much different than the other. The rear seemed to be running well while the front was dark and wet. I assumed it was losing spark or something, and so did lots of you! We were focusing on the ignition being at full advance on one cylinder. Makes sense right?
Wrong! At my wits end, and under my friends advice I took off the exuast valve cover. Lots of oil spilled onto to the floor and in the pool of oil was my intake valve seal!!!!!!!!!
Im guessing it came off upon start up on the first kickover. It was almost torn in two. Im also guessing that the break up at high rpm was do to oil blow by fouling the spark. The bike never really smoked and ran fine below 4k rpm. I just never thought to look there.
Now I have to figure out how to put a seal on. Can I do it without pulling the head? Will I have to re shim the rockers if I pull them out?
Any thoughts? Mike
I think I found the problem!!!!!
If the seal was ripped it was probably damaged during installation.They are pretty easy to tear when trying to stretch around the lip of the guide.OR the seal was squashed hard when the closing rocker was depressed to install the closing shim.They can be replaced with the head in place but it being the horiz. cyl it would almost be easier to yank the head[exhaust,carb,four nuts,and its in your hand].While you are in it I would recheck the valve clearances to make sure they aren't too tight and see if the valves are sealing properly.I say this because just a torn seal really shouldn't cause a miss at high revs.It may smoke and foul the plug but it would take more than a few miles and the guide would have to be pretty worn to allow that especially on the horiz. intake as its position doesn't allow oil to pool around the top of the guide.
I have the head off and just took the intake valve out. It amazes me that he seal is just supposed to bareley grip the guide. My big issue now is that when the valve opens and the closing rocker slides down the stem toward the seal it grabs the seal and pulls it off. It happens every time I put the seal on. It really gets stuck between the forks n the rocker. You have to pull it off. Why is this? Anyone had this happen before?
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BEVEL DAVE
- Diana
- Posts: 62
- Joined: Sat Jun 13, 2009 7:22 pm
- Location: SYDNEY, AUSTRALIA
Mike, you may have two different styles of guide in your head. The earlier guides had the oring in the bore of the guide and the top of the guide didn't have the small groove at the base of the lip to help retain the external seal.That is probably the reason the seal is coming off the top of the guide. I seem to remember a service bulletin years ago that told of the updated guides that used the external seal and it also outlined the need to relieve the bottom of the fork area on the closing rocker to clear the seal when the valve was fully open.But the result of that interference would be squashing the seal and tearing it.As for the side play on the exhaust you have to remember that the ex. runs much hotter and needs a bit more clearance.The only real result of a loose ex. guide is smoky exhaust when hot unless it is really loose and not sealing but then it wouldn't idle or start very well.Have you swapped the ign. boxes yet?
We were looking at the fork on the closer thinking it would be very easy to relieve a bit a material, then the whole seal issue would go away. Did ducati actually recommend this? I was thinkng of just taking the outer seal off altogether since it has an inner oring in the guide. I brought the head to another duck mechanic with bevel experiance. He looked at the head and thought that the seal issue was no big deal and I could just take the seal out. He also thought that all was well within the head and if anything, the exaust valve could be adjusted a bit. He seems to think that this head has nothing to do with my misfire. Yes I swapped the boxes.
Guide seals.
Hi Mike,
We were discussing the Seal issue on one of my posts and you pointed me to this post. Just to let you know I just got my Bevel back from Gowanloch's and had the Guide seals replaced. My bike had the "while" seals installed which are very soft (dont look or feel very effective) and all seals were floating except for 1 (bike has only done 3500KM). All the seals were replaced with later model seals from a belt drive ducati. These seals are black (Viton) and are sturdier and apparently do not come off the guide. Also some material had to be ground off one of the closing rockers to prevent it touching the seal.
Hope the info helps.
Regards
john
We were discussing the Seal issue on one of my posts and you pointed me to this post. Just to let you know I just got my Bevel back from Gowanloch's and had the Guide seals replaced. My bike had the "while" seals installed which are very soft (dont look or feel very effective) and all seals were floating except for 1 (bike has only done 3500KM). All the seals were replaced with later model seals from a belt drive ducati. These seals are black (Viton) and are sturdier and apparently do not come off the guide. Also some material had to be ground off one of the closing rockers to prevent it touching the seal.
Hope the info helps.
Regards
john
John in Sydney Australia
Darmah 900sd
900ss
Darmah 900sd
900ss