Valve Guide wear.

If you need technical information or help with your BOSCH ignition squarecase Ducati 900SS - Darmah engine - post your FAQs, comments & questions here.
machten
MHR / S2
Posts: 478
Joined: Sun Oct 29, 2006 8:37 am
Location: Perth, Western Australia

Post by machten »

whatever guides are used,paint a sealant into/onto the guide-rocker box juction of the guide bore. I have seen well built engines suck oil down the outside of the guide bores and smoke like crazy.
Me too. +1 on that - but I'm not familiar with Kibblewait guides others are talking about. My understnding is that a generally higher silicon content guide will allow a closer valve to guide clearance - I'm just not sure how valuable that is with a 50wt oil.

Kev
Ray O'Donohue
Parallel Twin
Posts: 119
Joined: Tue Oct 13, 2009 8:11 am

Post by Ray O'Donohue »

With any bronze guide,sealed or otherwise,on a bevel I'd go with nil plus,just a bit more than a drag fit.We once had to lightly polish the valve stems to get some heads assembled that way and it worked out real well.
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AndyCapp
Mariana
Posts: 29
Joined: Fri Jun 10, 2011 11:30 pm

Loktite

Post by AndyCapp »

I am just putting new guides in mine now - I noticed the old bronze ones were letting lots of oil past (between guide and head). I was going to use Loktite. Anybody think this is a bad idea? Also, mine never had the rubber seals (even though the workshop manual shows them on the inlets). The new guides appear to be steel - should I still use the rubber seals? Maybe the steel guides need a little oil for lubrication ?
wdietz186
Cagiva Alazzura
Posts: 707
Joined: Sun Sep 10, 2006 5:40 pm

Post by wdietz186 »

The guides should be about a .003" interference fit in the head. You need to measure the guide bore and the guide to assure the correct fit otherwise the guide can[will] come loose and wear the head even more. I know Kibblewhite makes oversize guides for the Ducatis. The only problem is they don't sell directly to the public,You need to find a friendly shop that deals with them and have them order them for you. I would be wary of using iron guides as the expansion rate is less than the alu/bronze and they could come loose when things get hot.
machten
MHR / S2
Posts: 478
Joined: Sun Oct 29, 2006 8:37 am
Location: Perth, Western Australia

Post by machten »

I would be wary of using iron guides as the expansion rate is less than the alu/bronze and they could come loose when things get hot.
Good advice, IMHO.

Kev
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