Building a race bike

Hi Greg,

Gauling of the rods was another of my reasons for not going roller on the big end,  the plain bearings hold the rods much more stable and although do touch the sides so will be coated anyway, the side load in nothing like as much as on a roller.

Nice and interesting to hear of your projects, those FZR250/4s are one hell of an engine to start with!  imagine a short stroke 125/4  :LOL: :LOL:

J
 
Full-blown porn thread, fantastic stuff. And the best bit is full disclosure, makes for a great learning experience for this pleb.
 
Thanks for sharing your knowledge and experience Julian. All very interesting.

More questions though ?  :D

Given that you have a mixture of shell and rolling element bearings, I assume your oil pump will send HP oil to the shell bearings first, then allow it to flow through to the roller bearings. In that case, do you need a pressure reducing valve to maintain high pressure to the shell bearings?

I suppose the alternative is 2 oil delivery circuits - one high pressure and one low pressure. But that would have inherent complications too, like 2 oil pumps.

Cam

 
Hi Cam,

My idea is pretty much as Greg has mentioned,
No direct feed to the roller or balls, although I will probably feed oil to the modified main oil gallery and leave the std bleed holes in place.
I was looking last night and figuring out my plans, as this is a very recent "cunning plan"  :D

I think I can quite easily drill the entire length of the crankcase starting with the std main oil gallery, and then insert a steel tube into this drilling,  then I can end feed from the front centre into the main gallery,  drill off of this to feed the HP centre bearings, use a reduced size for the roller and ball bleed feeds, the oil pressure regulator will then be on the right side by the pump but will see oil pressure after the mains which is more reliable to get good pressure where you need it.  Obviously I will plug the old oil pump end.
I will come out of the pump to the cooler, then from the cooler drop down to a main junction to feed the head and main gallery.
Sounds simple but I bet it won't be.  :LOL:

I had actually considered running the std pump for a low pressure side but due to the excess revs decided to leave that side purely for the ignition drive.
The gearbox bearings are also splash fed etc so I can't see any reason for problems as long as we are not negligent.

I once watched an engine spin up to 6000 revs with a perspex window that we made in the side of a grenaded block, We put a strobe on it and it was an absolute jaw dropper.
Imagine a spoon full of treacle being turned over to keep the treacle from coming off,  this was what we saw from 2000 revs on it got worse and worse instead of as expected the oil being flung off it was sticking on. AND big globules of oil seemed to be moving forward and back up and down the crank!  Astonishing!
After making a 3mm steel scraper that closely fitted the crank and rods etc the oil was removed only to be splashed back on again by the force of the oil hitting the back wall and floor of the sump,  we needed careful design to remedy this and we learnt that dry sump systems need careful thought before they do what is expected of them.

For this reason I will design the system as a dry sump / wet sump with a heavy duty close fitting scraper and baffles to direct the oil into a quiet spot in the sump so as not to send it back splashing around everywhere.

Questions are welcome and may uncover a fatal flaw in my thinking or help to simplify things etc, so please feel free.

Jules





 
Ok. Sounds reasonable. But you won't want your oil cooler to spring a leak with 80 psi oil in it.

I don't suppose it would be a simple thing to plumb the oil cooler into the suction side of the pump to minimise risk of spraying hot oil all over the place if the cooler or its hoses develop a leak. Cracking of oil coolers is not unknown on bikes that vibrate, even if they're rubber mounted.
 
Could be an argument for a second oil pump just to circulate oil through a cooler at low pressure but high volume.

Cheers,

bazzee
 
Questions are welcome and may uncover a fatal flaw in my thinking or help to simplify things etc, so please feel free.
Click to expand...

In the Uk i think drilling of the wheel rims is banned for racing - maybe they've lifted the ban  now? - and maybe not applicable in Europe. - Just a thought  - Phil
 
Hi Guys,

Did think of leaking oil but will either risk it or do as suggested and run it on a separate circuit with lower pressure,  however a funny lesson from experience.  Low pressure is not always low pressure.  We once had a car running a dry sump system and the oil cooler was routed on the scavenge side so in theory almost no pressure on the oil cooler. 
Well, this may have been true as long as the pump was pulling and pushing aerated oil,  however one day it managed to blow our oil cooler up like a balloon (without splitting) and then split it wide open while we were trying to find the cause in the pit,  so, it proved to us that even though we imagined there was little pressure in the oil cooler with the pipe just simply running open, the cooler was giving enough resistance in this instance to create very significant pressure.  We were running 120psi oil pressure on the engine in this instance to overcome a front main bearing issue running a 6 cyl engine with 3 main bearings at 8500 rpm and had no oil cooler issues for several years so god only knows what pressure it took to balloon the cooler like it did. 
The high oil cooler is not really new, many race bikes run coolers in the fairing nose,  I am only routing the air a little different, nothing much really.
in fact I think it is BMW who have an oil cooler wrapped round the head stock. nice looking unit but blocks the airflow very badly so silly design.

Problem however with the second pump idea would possibly be that we would have two suction pickups in the sump,  not clever if I end up robbing the pressure pump. and predicting flows like this is extremely difficult.
Another idea in my head is to run the oil cooler on the blow-off side of the pressure regulator.  If capacity is ample which I think it easily will be, then this may be my preferred option.

Phil, you mentioned this before,  answer,  If they don't like the holes then I will machine half of the flange off to make a nice wobbly milled pattern,  and if they don't like that I will machine the lot off,  lighter still  :LOL: :D    Or I'll cover them with ally tape  :P

J

 
I've got the same two-pickup quandary here at present. Longish term rebuild of a big-bored GSX750 engine built by Hone and Phyllis back in the day which went into a braced GSXR400 chassis....It's got an additional oil pump and drive off the crank end. Which has never been hooked up or plumbed in. probably because they couldn't work out how to put in a pickup. Looks like it'll stay decorative as the owner has decided it will only be paraded. That decision was driven by the condition of the bottom end after what was reported as only two outings. On the point of total destruction...

Big increases in oil pressure can have unforseen consequences. I once saw a Pre-unit Triumph engine with a Rickman 8v top end conversion - and a gear oil pump conversion too. In a small speedway car. Came into the pits with oil spraying out everywhere. Full pressure was going to the top end - and it had lifted the rocker covers and literally sheets of oil were spraying out. Impressive. 80 odd lb going in - and next to no drainage.

I'd think that taking the oil cooler feed from the relief valve outlet should work. If the passage sizes are adequate pressure should be safely low. Most of the Jap fours since the late 80's have the relief valve open from around 5000 rpm. I'd assume your pump size will be more than adequate so there should be significant flow out of the valve.
 
Big thanks to Will he went to the wreckers and rummaged through the oil coolers till he found one that matched the cracked one off the 6 plug racer. It is from a TLR1000.

Now this is plummed into the fairing under the twin headlights, but is set up with the hoses at the bottom. Doug machined up a wider set of gears for the oil pump, which is also in my 3c and Vince?s as well, can?t remember the size, Vince?  Maybe 11mm.

Anyways, all modern triumphs are plummed with the banjos as you stated, at the top. I never thought of the problem of air pockets in the cooler, wouldn?t oil from the pump fill the cooler, and the pipe up to the cooler would remain full as the oil would stay above the gears. On the output side of the cooler, it runs back down hill to the cases but them up to the top of the motor.

Having tested pressure and flow on the triple motor and seeing how the oil gets to the cams, there is low pressure but high flow, but on initial start up with cold oil, pressure is very high. Wouldn?t the high pressure on startup push the air pockets through?
 
Standard oil cooler fills from the bottom. I don?t have enough room to run the banjo joints above the cooler, what about some sort of check valve in the line to keep oil in the cooler?
 
I heard that some fit taps in oil lines to stop wet sumping sounds like a hand grenade waiting to blow. Marty Doug told me that 11mm oil pump story as well, but during one of my rebuilds we found my oil pump was a 9mm RGS pump, better than the std 6mm one at least. There have been threads in the past about whether to have oil coolers right way up or not, a search might be helpful on past posts.
 
I also remember reading about thermostatically controlled oil cooler bypassed, that heat controlled so cold oil bypasses the cooler.
 
You must log in or register to reply here.
Back
Top