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Author Topic: CB750 Wet Sump Conversion - Sumpthing  (Read 29554 times)

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Offline 754

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #350 on: February 24, 2020, 06:12:03 pm »
I am just seeing a normal unheated discussion...... which I have been enjoying the different point of views.
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It's All part of the ADVENTURE...

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Lost quite a few CB 750's along the way

Offline seanbarney41

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #351 on: February 24, 2020, 08:25:37 pm »
+1...not much conflict around here since the great steering dampener war lol
If it works good, it looks good...

Offline scottly

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #352 on: February 24, 2020, 09:20:00 pm »
I must apologize for derailing the topic to air filters. :(
Frank, the wet sump Harleys and Bmws run at much lower RPMs, so are not a fair comparison.
For now, I'll wait for Rob's assessment after the tear-down and inspection of the Sumpthing equipped race bike. ;D 
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Offline Bert Jan

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #353 on: March 05, 2020, 12:36:31 am »
I don’t have strong opinions on this either way, but I enjoyed my interactions with Bert Jan as he was finalizing the details of the Sumpthing, and checking in with Rob during fitting and a season of endurance racing with it.

I’ve come to the consensus that though the dry sump system by design is a “superior” system all things being equal, there seems to be no fundamental reason why the Cb750 engine in particular requires such a system for an effective oil system.

Dry sumps were exceedingly rare on motorcycle engines during that period, even for Honda.  The cb500 came about just two years after the cb750 and was by all accounts the result of a great effort by Honda engineers to take the Cb750 and build a mid displacement, lighter, better handling, more refined version of the 750.  Clearly Honda chose to go back to the wet sump.  Kawasaki made an enormous effort over a 3 year period to study and develop their own answer to the hugely market dominating Cb750.  The result was the well loved Z1.  Wet sump like all their other bikes. 

Since nearly all the other bikes of the period (even top level road racing variants) performed just fine with wet sumps(again including Honda), it would be hard to argue there was in the end a significant advantage to the dry sump oil system Honda employed.

The point about oil cooling being better with the Sumpthing wet sump system was most likely a bit of over exuberant wishful thinking on Bert Jan’s part.  Regardless, any road racing or other performance application will have an oil cooler regardless of wet vs. dry oil system.  Easy to install, and they can be sized to suit needs.

So in my view, history would suggest that our cb750 dry sump system was wonderfully designed, and has performed admirably under every racing situation.  But that’s not to say that the dry sump was a functional necessity on the engine, or that the minor benefits of the system outweighed the extra cost and complication(and aesthetics or packaging results) over a tried and true wet sump.  Honda themselves clearly seemed to feel that way anyway(cb500f, cb400f, ch350f, cb350t cb450t, cb750a, cb900f, etc, etc) and the wet sump system was their baby.

Therefore, I can’t see a reason logistically why a properly done wet sump conversion on the Cb750 could not equal the admirable oil system performance delivered by, well, all the other wet sump bikes designed during the period(including all the other Honda bikes)

Rob(Voxonda) offering to endurance road race test the system offered a tough real world trial by fire.  It should take more abuse than about any other situation(other than a big bore sidecar racer or a sit in traffic on a hot day situation perhaps). Endurance bikes will need to stabilize the oil temp(sprint races less so), see many deceleration events pushing oil toward the crank, and deal with all sorts of abuse that may induce air bubbles into the system.

So we have only one racing test subject, but after a full season, all reports so far have been positive.

So I wouldn’t suggest everyone start abandoning their arguably overboard design dry sump oil systems.  They work VERY well.  But if someone felt the desire to convert to a tested wet sump design for whatever reason, I don’t see any fundamental reason why they shouldn’t.  I don’t see it as any type of existential threat to the function or longevity of the engine.  Especially for non racing engines....

Bert Jan has worked really hard on this project.  He will never realistically get his development time back. The profit margin isn’t big enough for that.  He seemed to be doing it because he primarily wanted to offer a “solution” to an aesthetic “problem” for those who liked to build custom road bikes(like he does).  For that I believe he succeeded and I applaud his effort and hope he sells a bunch of them to like minded people.  Potential racing use was an afterthought though it even seems to have promise there too.

George

Thanks for the kind words George! During the early stages we discussed the need for a oil slosh plate and therefor i designed a set of tabs inside the kit so you can theoraticly build a a anti-sloshplate yourself and mount it inside the kit. As 90% of the users will never race their bike consistently, there is no need to make a sloshplate and with that, a higher price for the kit. The tabs offer 6mm mounting holes which CAN be used, but can also be left alone. No worries there. All kits have those tabs.

So far, we hadn't have a single complaint about the working of the kit. We've had some serious trouble with delivery times but are finally back on track!

Somebody asked a question about making a fillhole higher than the oil level so you dont have to put oil in thru a tappetcover. The kit took 2 years to design and test and as much as we thought about it, filling thru a tappetcover seemed the easiest, design, engineeringwise. You dont need to do an oilchange every 100 miles anyway..

Offline Bert Jan

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #354 on: March 18, 2020, 12:56:25 am »
Did a little write-up on our website, you might like it.

http://www.outsidersmotorcycles.com/bikes2/honda-cb750f2-sumpthing/?v=796834e7a283

Offline Sam Green Racing

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #355 on: March 18, 2020, 10:26:29 am »
Great write up Bert Jan. Keep it going mate and stay safe from this Covid19.

Sam. ;)
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Offline turboguzzi

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #356 on: March 18, 2020, 10:42:23 am »
Nice story indeed! The final result is not my cup of tea, but i guess the current hordes of "builders" will appreciate not having to deal with an oil tank and lines.
Good to hear that Roel Scheffers is still around bikes, liked his early creations, they were totally wacky, in the good sense of the world.


Offline Bert Jan

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #357 on: April 21, 2020, 11:01:11 am »
Nice story indeed! The final result is not my cup of tea, but i guess the current hordes of "builders" will appreciate not having to deal with an oil tank and lines.
Good to hear that Roel Scheffers is still around bikes, liked his early creations, they were totally wacky, in the good sense of the world.

Thanks! I think it's important to keep everything as clear as possible before i become the dodgy shoe-salesman again ;D
Roel is on another level really haha.. he's a Dutchie orignally but moved to Norway couple years back. Funny thing is we shook hands for the first time last year at a local motorcycle show when he was in Holland.

AAAANNNDDDD although the Corona is hitting everybody worldwide, i have some good news aswell...

Drums please.....
All open orders are finally ready and all backorders are out the door. We've been working long days last couple months but it's finally time for a big fat cake HA! Doing the first 'in stock' kits next week so from the moment they're 'in stock' in the webshop and you order one, it's shipped within 24 hours. Thank you all for your massive help, feedback and orders. Keep on rocking in the free world and stay safe!

Offline HondaMan

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #358 on: April 21, 2020, 02:54:36 pm »
I'd surely suggest using a NON-DETERGENT oil with it, as the gears of the countershaft may be buried in the oil. With the dry sump, this doesn't happen. It could, IMHO, cause significant drag on the countershaft gears, likely degrading high-RPM performance, unless the oil level in a running engine is studied to see how far down the level falls? I distinctly remember the guys who made 3/4" deep extension pans and fittings for the oil pumps to drop the pan oil further away from the countershaft in my old racing days: they also made [complicated] crankshaft baffles (aka windage trays) for the crank area. I don't have any results of their success/failure with the effort, though, as I moved out of Illinois that season and never talked with them afterward.

What are your plans here Hondaman..?  Are you blending your own conventional formulation of AeroShell or GM Dexos2 oils, a semi synthetic and full synthetic oil. The Shell Aero-offering as a very low or no detergent oil premixed with Lycoming's 16702 load/press/wear additives.  Or the Gm's gen 2 offering of no calcium detergents mixed with their own additives. The calcium detergent,some believe, is responsible for low speed full throttle pre-ignition in the newer direct injected gas engines. Some newer studies suggest the high detergent additives are counterproductive to the friction, load, wear additives. Most commercial diesels still recommend High Detergent Oil.

Since most non-detergent oils  are only API rated SA, what additives do you have planned for the top end.?


It is tricky to find the "right" oil today. I have [temporarily] settled on the mineral-based EXL from Bel-Ray (not cheap, but my 750 deserves it) with some added zinc for the top-end duty parts. It's doing well, no foam in the tank even after 100 MPH runs (did I say that?  ::) ) in the hills. If I can find a local AMSOIL guy, I have some other choices to try...
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Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

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Offline cbr954

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #359 on: April 21, 2020, 08:06:48 pm »
I have run Amsoil in my 750 but it makes my starter clutch slip.  Switch back to mineral based and the clutch works normal.  But I run amsoil in everything else and I love it.
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Offline scottly

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #360 on: April 21, 2020, 08:15:29 pm »
I have run Amsoil in my 750 but it makes my starter clutch slip.  Switch back to mineral based and the clutch works normal.
Really? When the clutch slips does it mack a nasty chatter sound?
Don't fix it if it ain't broke!
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Offline macvit7906

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #361 on: July 19, 2020, 09:09:58 am »
Hello all. running into issues with the sumpthing (or maybe just my oil pump) - tips/help appreciated!

Installed the sumpthing yesterday. Very well made piece and BertJan has been great to work with.

Running into issues with oil pressure though. I'm using a freshly rebuilt pump that worked great just a few days ago on a freshly rebuilt engine and first start up (60-70psi).

Installed sumpthing successfully, filled the sump with 3 liters of oil. Using the starter motor to check pressure (this usually gets me 40 psi) - I get no oil pressure. So i remove the oil filter housing and get no oil squirting after 3 or 4 30 second bursts - so the pump isn't taking oil.

For some reason my oil pump is really touchy. If any air at all is introduced, it loses prime. I've had to re-prime the thing working the air relief valve many times just go get it to work initially. (maybe the new air relief spring is too strong? )

How exactly is oil pumped with the sumpthing if the intake port is blocked? If initially the pump has to suck any air, then that is for sure what happened.

I'll pull the pump again today to check things out, but does anyone know what could be going wrong?

I'm thinking about attaching the oil tank with just the oil intake hose hooked up and pumping till the sump is full, that way the pump stays primed?

Offline macvit7906

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #362 on: July 19, 2020, 02:46:10 pm »
Solved!

Took apart, re-primed the pump and got pressure after a nice long crank with the starter. Just takes a bit longer.

FYI, I have even better pressure with the sumpthing!

Offline nsxguy7

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #363 on: November 25, 2020, 08:09:30 pm »
I just received my sump thing. It looks like a great quality part. Just a couple of things...there are no instructions in the installation manual for priming the pump as it would be very difficult to prime using the typical "pump in a bucket of oil" method. Second, the area in the sump thing that has been machined away to allow clearance for the drive gear on the pump looks a little small...like maybe the gear could contact the sump thing if the gear walks out a little. Thoughts anyone?

Offline macvit7906

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #364 on: November 27, 2020, 09:42:51 am »
I just received my sump thing. It looks like a great quality part. Just a couple of things...there are no instructions in the installation manual for priming the pump as it would be very difficult to prime using the typical "pump in a bucket of oil" method. Second, the area in the sump thing that has been machined away to allow clearance for the drive gear on the pump looks a little small...like maybe the gear could contact the sump thing if the gear walks out a little. Thoughts anyone?

I followed the instructions you can download from the sumpthing website to attach the oil pump to the sumpthing.

You NEED to prime the pump again, and it is difficult because now the oil pump is attached and built around the sumpthing.

I took the whole assembly, bought a tub just big enough to fit the whole assembly and bought 5 quarts of oil to completely sumbmerge the whole thing. Primed it as you normally would by spinning the gear, then installed on the bike. (its a messy job, have lots of towels handy) After installation wipe off the oil on the outside with some brake cleaner.

Then I poured 3 quarts of the oil through a valve cover to fill the sumpthing, and saved the extra 2 quarts of oil for a future oil change.

Just run it. It is a quality piece, I havent had any reason to believe the gear was hitting any part of the sump
« Last Edit: November 27, 2020, 09:44:56 am by macvit7906 »

Offline HondaMan

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #365 on: Today at 07:06:29 pm »
I just received my sump thing. It looks like a great quality part. Just a couple of things...there are no instructions in the installation manual for priming the pump as it would be very difficult to prime using the typical "pump in a bucket of oil" method. Second, the area in the sump thing that has been machined away to allow clearance for the drive gear on the pump looks a little small...like maybe the gear could contact the sump thing if the gear walks out a little. Thoughts anyone?

I followed the instructions you can download from the sumpthing website to attach the oil pump to the sumpthing.

You NEED to prime the pump again, and it is difficult because now the oil pump is attached and built around the sumpthing.

I took the whole assembly, bought a tub just big enough to fit the whole assembly and bought 5 quarts of oil to completely sumbmerge the whole thing. Primed it as you normally would by spinning the gear, then installed on the bike. (its a messy job, have lots of towels handy) After installation wipe off the oil on the outside with some brake cleaner.

Then I poured 3 quarts of the oil through a valve cover to fill the sumpthing, and saved the extra 2 quarts of oil for a future oil change.

Just run it. It is a quality piece, I havent had any reason to believe the gear was hitting any part of the sump

One thing I have also found: on most of these pumps the thin paper gasket in between the pump and its baseplate has broken down and doesn't seal real well. This reduces the pickup suction by a surprising amount! Once it gets wetted and oil is keeping it wet, it will have suction, but not as much as if you swap out the thin gasket for the new one.
The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com