Topic: cb750 sump capicity

[kezz32]

Err how much oil would one expect to find in sump after 20 mins raceing .. is 1 pint+ too much
newby sidecar racer kezz

[bear]

That sounds about right Kezz.

The thing you need to keep an eye on is the sump filling up after it's been sitting for awhile. Quite often the non return valve in the oil pump isn't up to the job. Not a problem in itself, unless you over fill the tank as a result. Then it can get a bit ugly.

We run a five liter tank. Any smaller on a chair and you can run into surge problems.

Glad to have another chair man on the forum.

Cheers,
Brian

[kezz32]

thanks for that Bear .
another question you could maybe help.. I have a breather on oil tank into a catch pot , i seem to get about 1/4 pint after a race but pressure is building up in catch pot and blowing oil out of catch pot breather . .. it has been sugested that I breath my oil tank into gear box at back off engine. not to sure bout this .

 thanks kezz

[bear]

Running a breather from your oil tank to the crankcase breather isn't a solution I'm afraid.
You probably need to run an oil tank with a lot more air space.
Crankcase ventilation is critical in these motors when you run them in a chair.
We run a one liter catch tank with lots of ventilation.
I'm heading out to the work shop this arvo, I will get a couple of pics of our setup for you.
A short term solution for the catch tank breather problem would be to stick a piece of plastic cut to the shape of the breather tank with a half inch hole drilled in the middle or a piece of course foam to act as a baffle.

Cheers,
Brian

[scottly]

kezz32, are you running a stock CB750 oil tank? If yes, then there needs to be a drain tube connecting the oil/air separator in the tank to a spigot on the rear of the crankcase. This fitting is often confused for a vent rather than an oil drain.
 

[bear]

Our crank case vent system.
You will need to reduce crank case pressure as best you can.

Cheers,
Brian

[kezz32]

Brian
have i got this right..you breath clutch case,starter motor apperture, oil tank and is the blue and yellow pipe from rocker cover into a 1 litre catch tank.
 thanks kezz
Im runing a 4 litre oil tank with a 3/4 litre deairater top , the idea is the oil swirls round the circumference of the round top and falls down the side thus removeing any air .

[bear]

Kezz,
You are right on all counts.
If we had 250ml of fluid in the catch tank with this system after a normal race it would indicate that we probably have some mechanical issues to deal with.

How long have you had the bike?

Cheers,
Brian

[kezz32]

hay Brian
I had chasis built by Rod Bellas ( top uk chasis builder ) 10" wheels ,motor refurbed , blue printed and race tuned, with dyno 2000 elect, web cam , new cr29 ,not bored out = 80hp on dyno..by Mike Smith.. real nice body work by Jon Perkins. I got it all together in may ,got 2 practice sessions then first race last w end, i came midfield and won the over 5os .. Iam realy pleased with it in fact its great.. previously raced a 18" wheel vintage triumph pre unit 650 outfit on dope .
bear youre in Auss right do you know a F2 racer called Dags he s rode at IOM TT a couple of times. ps i will try to post some pics .. its a real nice peice of kit

[Sam Green Racing]

Welcome to the forum Kezz, you'll probably find out all you need to know on here.

What size is the motor and are you in Melton ?

Sam.

[kezz32]

hay thanks sam
motor is 750 to run in the class in the clasic european rounds.. and yep ima in melton mowbray
cheers kezz

[kezz32]

sorted oil prob . i placed another baffel plate over breather outlet , problem solved.
heres some pics at mallory park

[Tintop]

Just found this thread, don't how I missed it.  Welcome kezz, as was prevoiusly mentioned nice the have another sidecar guy on the forum.  I've got a 16" with 750 Yamaha XS, would be a CRMC P2 over there.  Also have an 81 Fiddaman (basket case) that's likely getting an SOHC.

Brian