Oil Level

Hi all
how much to put in ? and what type

Are your engine sprocket centre and clutch/gearbox mainshaft centre parrallel to the ground?
If so half a pint. However if your engine is at a funny angle - you'll need more ??

To add my helpful information to this piece, I actually used 750ml of oil, when the engine was in the std position in the frame, but when my engine was tipped forwards 9.deg, I upped the oil amount to 850ml, according to my notes.

Type of oil will I'm sure depend on what clutch you are using, I dont like the steel to steel plates favoured by a lot of racers, although I have used these, my engineering background, (even with magnets) they cause all sorts of issues, like excessive wear on the gear flanks, shafts slider gears internal bores and problems for bearing, Selectors etc the list is endless. I have not had one gearbox problem since I returned to Racing my Bantam, but then I use the Rex Gaunt clutch plates that are so superior to the original plates, once they bed in, even with a lot of stick they do not wear out, unless you have one of those light switch power curves.

I use a good quality 20/50 engine oil, mixed with a heavy duty gear oil, to protect the all important bit "the gears".
I understand others use EP80 - in the steel clutches, we use to seperate the clutch and gearbox when running these, and run different grades of oil in each side, however the extra drag from the seal, increses the frictional dragg a too high a price to pay in my opinion on this old mod, better to tune a better power/torque curve.

The best piece I have seen written on this, with some meaningfull recormendations are those done by Peter Tibbetts his "1985 Ramblings" on the techinical tuning page on this site, on all aspects of the "transmission side".

Thanks Mike and Derek
Sound advice which I have taken on board
Was running 350 mls of EP80 in the past and at mallory on thursday was running 600 mls and last night put in 200 mls more for today at brands but its that cold here may need to.put a.blow lamp under the engine lol
Thanks again Robbie

Hi Rob,
your very welcome,

and yes good information line is the way forwards, leve the bolertics alone, I'm going to try and just give info out rather, putting other view points seems infringe others opinions and clearly not popular so this is good.

Now: on the clutch gear oil, Top secret we have had a small rotating arm on the rear of the clutch, inside my clutch cover this I idea I picked of a crank as it rotated it puked up some oil, what it does do is stops the (pressure)build-up of oil in this area, at higher RPM'S this presurises the chain cases, and can push oil into the gearbox above the gears, quite a phenimenon and only visable with a intrascope under load. In reality it forces the oil out but mainly to the rear, this is known about, by others but only as a guess, im sure of this, I actually filmed this on the Dyno for the first time recently even though since my return Ihave been running it, it failed at snetterton, and the bike would not pull the tall gears I use due to my low reving engine, this failure was as a result of the cases cracking clean all the way through and may well be due to vib caused by this device, amazing the difference it makes /without one, anywat the oil build up at the rear of the chain case limits the volume of oil we should be using or more importantly it pushes it to the TOP side, it has othere effects in the gearbox too, this pressurises the oil that no joint seal no mater how good on the joint line will hold the oil in and usually a lot ends up on your rear tyre.

This is a very old mod I believe done in the early days, 1960,s but I've never heared of anyone talking about it in your camp, but it was talked about in others.

My dad did this Mod first in late 60's early 70;s to stop this happening, I discarded it, but from my notes I had it fitted when I whent through the speed trap at the 50 miller that I won, at over 96MPH, it's a very effective mod, especially when you push up the oil content.
lots of development needed, to get it to work, but if you look at a Honda 25 tin crank that has a hook like devise on it fro throwing the oil around you soon get the idea, where you fit it and how is somthing Im not prepared to say,

Talking on power outputs from clutch and 175cc, I'm amazed you guys need to run steel plates with your 186 or 190cc 175's, if I were building a 175 which have started (finished Engine). I would use a lower port openings, especially on the exhaust, use a std Crank with proper rod, and run it peek torque at 8,000, with an over rev to max 9.0, this way the clutch gearbox problems would go away, Im sure of this, as you then could use proper oil by using a suitable clutch material, this at these revs would also do away with needing to mod the gearbox to needle rollers, these bearings do give less support and allow the shafts to flex more than normal, I'm of course taking about the mainshaft when we talk about flex, the layshaft "does not flex", I'm estimating that the mainshaft high speed filmed on the dyno has seems to flex at least 1.0 mm underload, or changing between gears.

I would imagine a 175cc with all that extra torque at least 50% more to my mind even with the losses of a greated piston cron surface area, and the bore area to fill efficiently this can not be an easy project.

But Rob I would not go over 750ml without these mods, may be even stay nearer 600 max 650ml -

Rob 350ml you are asking for trouble.
regards Derek

Hi Derek


'I would use a lower port openings, especially on the exhaust'

Could you give any figures?

Arthur

I had to smile at this question Arthur, I only last sunday morning asked the very same question, you could have heared a pin drop at this point where it seemed like most stopped to hear the answer "that did not come", after a chuckle Trevor said the exhaust should not be not too big, as it can have adverse affects on the torque curve,

some know more than me on this subject, a good 125 has perhaps 24/26 hp with one or two either side of these figures, anyway I have in my Engine built it for torque, drivability, and over a very wide power band, as I want to run gear ratios that will give some distinct advantages with a low reving 175cc.

The Engine I have just finished has std flywheels with a bored crank pin holes, to accept a 250cc maico rod, I'm using, I wanted to use a shorter rod, but due to limitations in the barrel material under the inlet port stopping me from machining some of the base of the barrel, I have for now used a longer rod, besides I think the rules should be changed to dictate a 125mm conrod along with limiting it to two transfers, one exhaust port and of course one inlet port, without this I can not see even the best 125cc keeping up with some of the spoken about mods that could be done on a 175cc, kind of limits them as they will need to be so, if we allow these multi port specials to be built we push the abiolity of new starters to start with a 175 to whatch other disappearing into the distance.

Anyway back to your questions (my barrel currently has a 62.5mm bore), I have a very square exhaust port with sharpish 4mm corner radi, exh port window width is 65% of the bore diameter, I think the Exhaust timing is a good starting point at 96deg, I have the Tansfers at 64deg only the trasfers are cordal in shape, they come with the old Knife edge, and no upwards angle, But after the last two midlands racing meetings, I have to modify these
I did on the 125 short stroke I currenlt run, this did wonders, achieving big improvements in both low and the mid range, did nothing for top end.

I.ve also started with the inlet at 88 deg, as this is a good starting point, but I dont think it will be changed by much in the future. i think a good 175 shoul be capable of 35 hp without too much cost. The biggest problem is having a gearbox that will cope, take the Rex Gaunt 4 speed box, an excellent box, wider ratio than a close ratio box, I may at some point try one of these, but its all down to time.

Hi Aurther note I see now that Trevor has posted edited my typo!!!! error?, but I would still start off lower on the exhaust port then lift the port once you start dyno/track work.
Regards Derek

Will do Derek and Aruthur , can`t do it tonight though , just about to go out on the town , have to be tomorrow !
Sorry about that

Regards , Trevor

PS , what is all of this doing on Oil LEVEL ?

Trevor Amos wrote:

PS , what is all of this doing on Oil LEVEL ?

good question Trevor, like many things, I don't know the answer.

Derek

Many thanks for your speedy reply and kindness in providing secrets just to me!

Arthur