Crankcase compatibility

Hobot · Jan 24, 2015

Alrighty Dirt we are all hoping the alignment issue was either not an issue of taken care of. Was this a runner prior with the differing sides?

Dirt2Oil · Jan 24, 2015

Yes it was running when I got it but smoking badly and leaking oil like a sieve. The new hole drilled for the oil pickup should help with the oil leaks

. We'll see how things hold up.

SteveA · Jan 26, 2015

Dirt2Oil said:
I just finished rebuilding my engine with a 72 primary side case and an 850 TS case. As mentioned in previous post the oil pickup hole has to be drilled in the primary side case as the two do not match up. I plugged all the extra holes in the TS and used the CNW valve on the primary side. Will see have things work out with this setup. The bike was bought from a previous owner with the two cases mated but the new oil hole was not drilled. Just have to put the engine back in the frame now.

Obviously its not easy to see phom this photo, but I think I do see an oil drain hole drilled under the oil pump, but it doesn't look like you plugged the big air holes up behind the timing chain, but you must have...right...so the breather set up will help with the oil leaks too.......

Hobot · Jan 26, 2015

the extra vent holes above oil level in TS case should have little influence on a decent one way valve to keep case pressure enough below ambiant it sucks air in and not push oil out. OF COURSE Comnoz has found sealing the TS except for oll equalizing hole down low can develope a bit more negative case pressure if flapper is installed right on case but that only matters if ring blow is on the excessive side so can get away a bit longer before ring renewal. Much as comnoz is a guiding light and providing neat venting gizmos Kelly George detailed me on his leak free 850 flat track racer w/o any thing in the long breather hose open path he made me stick face near to feel a few strong puffs on starts then nothing felt or seen coming out. Don't sweat tear down cases just for a little bit of extra suckion that makes no difference unless some other fualt to compensate for. Peel ran oil tight at extreme rpm WOT for season at a time and stayed oil tight even after over rev event and I double checked TS vent hose with Q-tip wipe to find prefect white cotton. My factroy Trixie Combat operated into good 2S cam breathing rpms stays oil tight till filters let grit in so more than one way that successful.

Dirt2Oil · Jan 27, 2015

SteveA said:
Obviously its not easy to see phom this photo, but I think I do see an oil drain hole drilled under the oil pump, but it doesn't look like you plugged the big air holes up behind the timing chain, but you must have...right...so the breather set up will help with the oil leaks too.......

Yes the big air holes have been welded from the inside and a new drain hole is drilled under the oil pump, which can be seen better in this photo.

SteveA · Jan 28, 2015

hobot said:
the extra vent holes above oil level in TS case should have little influence on a decent one way valve to keep case pressure enough below ambiant it sucks air in and not push oil out. OF COURSE Comnoz has found sealing the TS except for oll equalizing hole down low can develope a bit more negative case pressure if flapper is installed right on case but that only matters if ring blow is on the excessive side so can get away a bit longer before ring renewal. Much as comnoz is a guiding light and providing neat venting gizmos Kelly George detailed me on his leak free 850 flat track racer w/o any thing in the long breather hose open path he made me stick face near to feel a few strong puffs on starts then nothing felt or seen coming out. Don't sweat tear down cases just for a little bit of extra suckion that makes no difference unless some other fualt to compensate for. Peel ran oil tight at extreme rpm WOT for season at a time and stayed oil tight even after over rev event and I double checked TS vent hose with Q-tip wipe to find prefect white cotton. My factroy Trixie Combat operated into good 2S cam breathing rpms stays oil tight till filters let grit in so more than one way that successful.

May all be perfectly true Steve, but my tendency is to listen to someone who supplies me with specialist components that they have developed when it comes to the recommended installation. Of course that does not always work! And you can't always comfortably achieve what they suggest. But it seems like a good start point.

Dirt2Oil already had the cases open at that point, so no problem for him to do it. Interesting he chose welding not plugging, but just as effective.

What you are in effect saying is that if you are doing the installation without stripping the motor; try it without blocking the holes or drilling the drain hole, that saves a lot of work and may be fine. I can accept that. But you may just end up stripping the cases later to do it, but again if that is when you need to do something else, not much lost.

On the other hand, if someone doesn't do what the supplier recommends, gets frustrated because the expensive part didn't achieve what was expected, and comes on here or goes to his local meet slagging of said supplier.....Hmmm.....I didn't say you did or even would.....but I bet there is someone out there who has, and will do again!

Hobot · Jan 28, 2015

Yep SteveA my remarks are perfectly true so if not understanding or experimenting then one is left following instructions blindly and sour opinion for those that don't. The fact is if rings are sealing well and cases sealed well factory breaather, even the poor cam timed '71's like my buddy Wes and Combats, stay oil tight to red line use. Granted w/o the close mounted flapper and sealed TS volume you may not get the few extra hp availabe near redline so agree comnoz has a great gizmo- that I hope to exceed with active powered case pump down, in simipler cheaper lighter compact unseen method no one else has tired yet in Commandos. Peel's may back pressure the cases at low rpm but if no leaks no worries but if leaks then an inline flapper, away from cases should solve it.

Crankcase compatibility

Hobot

Dirt2Oil

SteveA

Hobot

Dirt2Oil

SteveA

Hobot

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