Author Topic: CB750 Wet Sump Conversion - Sumpthing  (Read 73062 times)

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Offline Captain

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #75 on: February 16, 2018, 02:17:23 AM »
 No problem Rob and only trying to help.
For the benefit  of others ,all I am doing is to explain the workings of both systems and point out the areas that need to be addressed to get it to work.  Depth and baffling are the key’s to successful wet sump systems. Ignor this at your peril.

Captain
« Last Edit: February 16, 2018, 02:24:27 AM by Captain »

Offline voxonda

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #76 on: February 16, 2018, 02:24:37 AM »
Thanks again Brent.
Better sorry for failing then for the lack of trying.

Online MRieck

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #77 on: February 16, 2018, 05:16:08 AM »
 Scroll to the bottom and look at the 2 engine pics. That is how a wet sump can effectively work in race engines.
https://www.asphaltandrubber.com/bikes/184000-honda-rc213v-s-street-bike/
Check out the crank, con rods and pistons too.......nice!
« Last Edit: February 16, 2018, 05:18:58 AM by MRieck »
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Offline gschuld

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #78 on: February 16, 2018, 06:48:46 AM »
FWIW, this is a modified factory Kawasaki Z1 pan advertised for use in a drag race application.  Not sure what is common for the typical Z1road racer, but there sure were a lot of them.

George

Online MRieck

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #79 on: February 16, 2018, 07:07:05 AM »
Baffles, scrapers, exotic pickups....what hasn't been tried. Obviously wet sump works even under tremendous acceleration rates, braking forces etc
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Offline bear

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #80 on: February 16, 2018, 07:36:07 AM »
My question would be, what works best.
And in my application I have no doubt it's the dry sump system.
The older I get the faster I was.

Offline turboguzzi

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #81 on: February 16, 2018, 08:10:29 AM »
like many aspects of engine design, god is in the details. badly designed systems (dry or wet sump) will not give the reliability needed.
all the crank and cam bearings in my stock wet sumped GPZ750/810 look like new after 5 years of road racing and i honestly didn't do anything to improve the system's design. So a well designed wet system can work (as all the wet sump superbike motors post the CB750 have proven).  on th eother hand, the crank bearings in my CB500/4 didnt look as good and i can imagine that air getting into the system could be a reason. two examples of wet systems, one perfect, the other not so much.... sorting out that sort of borderline problems takes time, re-design testing iterations and pushing the bike to it's limits while testing.  not exactly an easy endeavor for a single enthusiast.

Offline voxonda

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #82 on: February 16, 2018, 08:20:47 AM »
I will wait till I meet up with Bert Jan, and discuss these matters further.

Rob
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Online MRieck

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #83 on: February 16, 2018, 08:33:47 AM »
My question would be, what works best.
And in my application I have no doubt it's the dry sump system.
There you go. F1 cars dry sump with something like 3g lateral forces at work. Smokey Yunick wrote extensively about the benefits of dry sump in NASCAR....they tried everything he said to get wet systems to work but the corner loads keep getting higher  and higher. He had swivel pick ups etc but in the end the dry system was the only thing that worked for NASCAR.
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Offline turboguzzi

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #84 on: February 16, 2018, 10:09:54 AM »
indeed, sidecars are like cars in the sense that they dont lean, so at cornering the oil will pull away from the sump's center line, doesnt happen in bikes, or at least not due of lateral G's.
acceleration and braking G's are another issue of course...

Offline gschuld

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #85 on: February 16, 2018, 10:27:08 AM »
My question would be, what works best.
And in my application I have no doubt it's the dry sump system.
There you go. F1 cars dry sump with something like 3g lateral forces at work. Smokey Yunick wrote extensively about the benefits of dry sump in NASCAR....they tried everything he said to get wet systems to work but the corner loads keep getting higher  and higher. He had swivel pick ups etc but in the end the dry system was the only thing that worked for NASCAR.

There is one unique difference between sidecar racers and “normal”😉 road race bikes.  Sidecar racers stay flat laterally.  So when a sidecar engine gets put into a hard corner, the oil is pulled to the outside of the pan.  Road race car owners (Smokey included) have gone nuts trying to overcome the occasional dry pickup problem.

As a motorcycle leans into the turns, I’d expect it pretty much eliminates any of the lateral forces of the oil in the pan that tend to starve the pickup.  Being that the pickup is at the back half of the pan, the most obvious oil sloshing concern is under hard braking, shoving the oil fwd and up to the spinning crank.  A well designed hinged trap door (as is so common on road race V8 car pans) mounted fwd of the pickup should help alleviate that issue.

The issues with oil aeration...I can’t even hazard a guess on that one. 

Being that Rob tends to favor near stock displacement engined endurance racers, rather than huge maxed out stroker big bore engines in a sidecar, this seems to be a great initiation for a racing wet sump system.


Edit:  TurboGuzzi, you beat me to it

George
« Last Edit: February 16, 2018, 10:30:17 AM by gschuld »

Offline bear

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #86 on: February 16, 2018, 04:16:55 PM »

There is one unique difference between sidecar racers and “normal”😉 . 

George

Many would say there are far more than one George. ;D ;D ;D ;D

Cheers,
Brian
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Offline Bert Jan

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #87 on: February 16, 2018, 04:58:04 PM »
Not exactly an easy endeavor for a single enthusiast.

It is definately not an easy endeavor for a single enthousiast. I never intended to have a 4 page thread in a racing/performance topic on a well-known forum either. It's a journey for sure and as much as i know the SumpThing will work just fine under normal usage, i'm just as curious as all you guys to see what happens during extreme conditions.

FYI the instruction manual is online now;

http://sumpthing.net/installation-instructions/
« Last Edit: February 16, 2018, 05:21:11 PM by Bert Jan »

Offline gschuld

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #88 on: February 16, 2018, 05:29:23 PM »

There is one unique difference between sidecar racers and “normal”😉 . 

George

Many would say there are far more than one George. ;D ;D ;D ;D

Cheers,
Brian

Touché 😁

George

Offline NickRafAcosta

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #89 on: February 17, 2018, 05:04:35 PM »
I never expected when I asked this question at the beginning that it would turn out into such a nice debate either!
Rob, I would love to see what you find out when you experiment with this wet sump conversion, I want to bore out my next CB750 build to an 836 (and obviously adding a good oil cooler as well), so knowing if this conversion can hold up to it, getting the performance I want, and still accomplishing a minimalist type build would be perfect. Hopefully you and Bert can work things out soon and we can all see how it goes!
Nick

Offline voxonda

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #90 on: February 18, 2018, 08:12:17 AM »
I never expected when I asked this question at the beginning that it would turn out into such a nice debate either!
Rob, I would love to see what you find out when you experiment with this wet sump conversion, I want to bore out my next CB750 build to an 836 (and obviously adding a good oil cooler as well), so knowing if this conversion can hold up to it, getting the performance I want, and still accomplishing a minimalist type build would be perfect. Hopefully you and Bert can work things out soon and we can all see how it goes!
Nick

First I will be in contact with Bert Jan and we see from there how we will progress. As you can read there is some sceptism against going wet sump with our lady. Most is based, and say this with upmost respect to everyones opinion, on hear say and or theory. How many have actually done this???
To fully use this I need to adapt my exhaust system, either a different 4 into 1, or a four megga setup.  So it will take some time and effort to do this right but that is the challenge. Also there is another one here in Holland who does it, altough from a different perspective.
Keep ya'll posted!

Rob.
Better sorry for failing then for the lack of trying.

Offline 754

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #91 on: February 18, 2018, 11:03:18 AM »
Sounds like you need a loan of a Yoshi style pipe, or other low hanger..
Maybe someone can help, curious to see this test get underway.
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Offline voxonda

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #92 on: February 22, 2018, 02:09:00 AM »
Started to prep the bike for coming season, and take the opportunity to prepare for the installation of the wet sump.
First of all have to remove all the obsolete parts, tank, lines, oilfilter and adaptor and (small) cooler in nose of the fairing.
Made a new adaptor to take both the screw-on oilfilter and new cooler lines.
« Last Edit: February 22, 2018, 02:19:53 AM by voxonda »
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Offline Tintop

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #93 on: February 22, 2018, 06:57:26 AM »
I thought about using a DOHC cb750 engine in a sidecar but decided against it because it was wet sump, and the oiling issues in corners.  The Yamaha XS engine has a fairly deep wet sump, but did suffer issues with oil pressure drop in some corners.  It had a roller bearing crank that seemed to tolerate this.  I did look at adding a sump extension to increase volume, but it would have put the rig below the minimum ground clearance rule
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Offline voxonda

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #94 on: February 22, 2018, 07:05:22 AM »
There where kit to convert them into dry sump engines. See the superbikes of the early 80's. But parts are not commonly found. I do have a original RSC dry sump pump for, maybe a future build DOHC 1123.
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Offline simon#42

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #95 on: February 22, 2018, 10:10:00 AM »
 ironic that honda made a dry sump conversion for there dohc racers and you are fitting a wet sump conversion to your sohc bike

Offline voxonda

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #96 on: February 22, 2018, 10:13:24 AM »
Yep, that is me............doing my own thing. If it does not work, at least I tried. And for the DOHC, numerous bikes did not use the kit even in endurance racing.
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Offline bwaller

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #97 on: February 22, 2018, 05:48:58 PM »
Apples & oranges Rob, but I have a deeper pan (16mm deeper) on my 550. Just to say I had to modify the exhaust around it, nuisance work but simple for you. By the pics this sump is no further below the frame rails than mine, but by keeping the collector tight to the pan I still had plenty of clearance with the lower fairing. You might even consider a flat collector.



Offline voxonda

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #98 on: February 23, 2018, 01:18:43 AM »
Looking good there Brent, have a second exhaust to play around with. Will see what to do when oilpan has been mounted.
Curious to see what will happen......

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Offline Bert Jan

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Re: CB750 Wet Sump Conversion - Sumpthing
« Reply #99 on: February 23, 2018, 02:53:57 AM »
You guys probably know this, but the CB650z oil pan fits on the 500/550 engines. It's deeper also ;)