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| Valve cam timing, 1990 750 Sport http://ducatipaso.org/forum/viewtopic.php?f=13&t=3395 |
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| Author: | Desmo/Duc [ Thu Jun 11, 2009 6:33 pm ] |
| Post subject: | Valve cam timing, 1990 750 Sport |
First let me introduce myself to the forum. I have been surfing the posts for some time and decided to join yesterday...so HI! I have a cam timing issue/question: I recently purchased a 750 Sport. I have owned a Monster for some time so am "somewhat familiar" with the Ducati engine. I have collected vintage bikes for years. When I brought the Sport home it had set for a time. I had run it at the sellers home prior to purchasing and it did have a miss. I identified it as the vertical cylinder (A later a carb adjustment remedied the miss). But otherwise all was sound. I am currently in the process of going through the entire machine before operating it. Carburation has been converted to Mikuni flat slide in the past. All else is original. Upon checking the cam belts and preparing to set tension I found that the marks on all cam/crank pulleys did not align with the horizontal cylinder at TDC. The vertical cam pulley mark is 130degrees CCW of the mark on the casing. If I rolled the crank around to where the vertical cylinder was at TDC the vertical cylinder cam mark was exactly 180 degrees out. Compression checks at 153# horizontal and 155# vertical. The engine ran. My concern: Can this be possible? Should I attempt to align the marks? I can roll the engine with care soas not impact the valves too severely. Should I attempt that? I do know if I attempt to align the marks on the vert cam with the piston at static TDC the valves hit the piston. I understand that actual cam profile might not allow interfernece with the piston if the belt were in place. But I don't know that. I am a retired conservative mechanical engineer............HELP! Good to meet you all and thanks in advance. |
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| Author: | carlopalmas [ Thu Jun 11, 2009 10:13 pm ] |
| Post subject: | Re: Valve cam timing, 1990 750 Sport |
I can pull the covers off of mine and snap a pic if you need. I did this work a few years ago before I sent the bike into semi retirement so I don't remember the specifics any longer. btw.... how are the mikunis? I had them on the bike when I bought it 17 years ago but could never get them to run right, I think the fuel pump would overwhelm the float bowl and so if I went into a curve and rolled off the throttle the rpms would just keep high. Enough was enough so I put the webers ack on. Carlo |
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| Author: | jcslocum [ Thu Jun 11, 2009 11:19 pm ] |
| Post subject: | Re: Valve cam timing, 1990 750 Sport |
The marks should be aligned. I can see no reason at all that they wouldn't. Maybe this page will help: |
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| Author: | Tamburinifan [ Thu Jun 11, 2009 11:38 pm ] |
| Post subject: | Re: Valve cam timing, 1990 750 Sport |
| Author: | Desmo/Duc [ Tue Jun 16, 2009 1:24 pm ] |
| Post subject: | Re: Valve cam timing, 1990 750 Sport |
I want to thank you all for your replies. Carlos, thanks for the offer to take the time to take pictures and John for being so confident about the marks being aligned. That and the comment from the Ducat Suite article on belt replacement. "If not careful the vertical pulley can move". That was exactly what had happened, to the previous owner, in the case of my machine. And, it actually was operated for a period of time 180 degrees out of alignment. I have properly aligned the marks. Gert, it was a nervous time but all is well. Carlo, the jury is still out on the Mikunis. I have tuned them for shop running but as yet have not been on the road with the machine. They're 41mm and I suspect they are going to be too big for street use. We'll see. |
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| Author: | Tamburinifan [ Wed Jun 17, 2009 1:20 am ] |
| Post subject: | Re: Valve cam timing, 1990 750 Sport |
| Author: | Desmo/Duc [ Wed Jun 17, 2009 2:29 am ] |
| Post subject: | Re: Valve cam timing, 1990 750 Sport |
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