petroil mix

[crosby12]

I am about to commission my 1929 TT Rep after 15 years on-again/off-again restoration. What is the optimum petrol/oil mix, and what octane petrol and what grade of oil? NZ only has 91 & 96 octane petrol available.
Is it necessary to maintain use of the Pilgrim in order to lubricate the bottom end, or is petroil sufficient?

[al perry]

in order to use petroil as your primary oil supply , your engine must be modified for it use, this involves some lower end modifications, cross over pipes etc. more learned members can elaboate! however if your pilgrem pump is functioning , you can set it to about 6 drips per minute with 30 or 40 weight oil ( most modern 2 stroke oil is to thin to work reliably in a pilgrem) and include a light 50 :1 twostroke oil mix in your petrol this acts as a “belt and braces” and upper cylinder lube.
my best suggestion is to have your pump converted to a dripper (gerry Howard) and use two stroke oil through it for the mains, and a light mix in the petrol, however use oil sparingly as two much oil lowers the octane of the fuel to where poor perfomance can result
almost any gas (petrol) is fine!

[Shaun Matthews]

I followed Al’s advice for my 1930 Replica and have just done over 300 fast and trouble free miles round the Isle of Man. – Initially I had starting problems due to too much oil in the crankcases but duriung the week I sequentially cut it back and by the end she would always start 2nd or 3rd kick warm, 5th or 6th cold.

The only problems I have found with Gerry Howard’s dripper conversion are over oiling in heavy traffic ( If you can trust your memory turn the oil tap off if your going to be stuck for a few minutes) and it flows more oil when warm so you do have to regulate it on a daily basis. The solution works but you do have to think about it.

[Jan Buchwald]

I run my Brum on octane 95 with 1% two stroke oil, plus 6 drips a minute from the pump (also two stroke oil), but; two stroke oil is not just two stroke oil, there are different types, depending on the temperature of the engine. Too high, and you will have oil in your exhaust, too low, and you won’t have oiling in the top.
As I find the radiator only to be a little more than hand warm, and I can stand with the plugs in my bare hands, I use outboard two stroke oil, as this has a lower working temperature.

[Mark Scott]

Al and Jan,
6 drips a minute? Is that at idle, I suppose? Seems less than I thought it should be. I have been running Amzoil 100:1 in the gas, with Belray 2 stroke in the oil tank at about 20 drips per minute. I have been too afraid to back it off! I don’t seem to have too much smoke and the plugs look fine.
What is Gerry Howard’s dripper conversion?
Thanks,
Mark

[al perry]

hi mark;
the gerry howard dripper conversion is: a pilgrem pump modified into a dripper, with no moving parts, the beauty of it is, it looks stock and can be
set with the engine not running at all ( with line disconected) it works by gravity, although some crankcase suction occurs and the motor tends to suck oil as it needs it, as far as how many drips per minute, each engine is a little different with a 50 ;1 mix in the tank, my engine works well with one large drip about each 10 seconds ( on each side) very little smoke, a few more drips per minute are ok, as long as you dont over oil, you can judge by the exhaust smoke, and how your engine “picks up” too much oil
and the fuel octane is affected and poor “pick up” and four stoking occur
i would think that 20 drips per minute would be too much, but if your engine is happy, it must be ok!

[Roger Moss]

Hi All. Just for interest, if you look at John Underhill’s 1913 TT bike with the rotary valve, there is no provision for lubricating the valve. It follows that he must have used petroil. With a racer, you need lubrication to be in relation to the load and speed and petroil delivers this. I use a modern oil at about 50:1 but with drippers to lubricate the synthetic seals I use. I notice one thing though, unlike historic castor based oils that tended to remain on the surfaces, the thinner modern oils tend to drain down into the bottom of the crankcase quite quickly. When you go to start again, the oil rich liquid has a tendency to drown the plug. If you try just draining the wells before you start, I think you will find it starts very much more easily. With petroil, it gets oil as soon as it gets fuel, so it will not suffer. Kind Regards Roger

[Colin Hough]

Guys,

I am soon to face the decision of how to set up the oil supply to my re-assembled ’59 model, hence reading this post and also looking at the Technicalities (which only leads to confusion!!!!)

I offer the following for information:

1) With my first Scott (also a ’59 model) which I bought in the late 1960’s there was the original instructions from Geoff Milnes with it (and I still have them so I must have planned to get another Scott someday). This says: “Check the oil pump to see that it gives 15 (fifteen) drops per miniute each side with the engine idling. Add an eggcup full of oil to each gallon of petrol”. I don’t know what a ‘standard’ eggcup size is, but I guess this was around 100:1. I used conventional single grade car engine oil and all worked fine for general use around home and trips on ‘ordinary’ roads. However, holding 70+ mph on the motorway going to the IoM TT races resulted in a big time seize after about an hour. This was ended my Scott ownership at that time!!! There was no comment about turning it up for long distance high speed riding (but then, motorways were not around when this was written).

2) 35 years, a wife and two kids later, I have now returned to Scott ownership and am reading the Technicalities in trepidations of having to set up the oil supply to my ‘new’ Scott after I (finally) re-assemble it following an engine overhaul by Tim Sharp. The key reference I have found is from Brian Marshall (Yowl V20/9 April 1998 article headed NO SMOKING):

In summary, he recommends a fully synthetic two-stroke oil such as Castrol TTS and Silkolene Pro 2 & Comp 2 and says “personally, I think that a combination of Pro 2 and Comp 2 is the complete answer” to no smoking and good lubrication. “Pro 2 is a self-mixing grade and can safely be used at 40:1 in a petroil lubricated machine. In a more typical Scott with a Pilgrim pump or drippers, I would use it in the perol as an upper cylinder/top-end lubricant cum belt-and-braces [that’s belt and suspenders for our American cousins] measure at perhaps 50:1 or 60:1, and then use Comp 2 in the oil tank, at a delivery rate of NO MORE THAN HALF A DOZEN DRIPS PER MINUTE in each side of the engine at a fast tick-over. That is ample to keep the glands and big-ends happy. I cannot over-emphasise that such a low delivery rate is unreliable in a Pilgrim pump unless it is in good condition AND geared down. This combination gives excellant lubrication and very little smoke. Later Scotts (e.g. 1946 onwards) have no oil tap as standard, and as a result oil tends to seep through the pump and flood the sight glasses and crankcase wells”.

As my machine is fitted with both a reduction gear and an oil supply on/off tap, I intend following Brian’s advice.

However, Glyn Chambers (our local supply source for Silkolene oil) noted back in Jan 1972 (V7/9) when writing about the problems of getting Pilgim pumps to work reliably at the low rates need by Scotts that the “biggest sin you can commit (I know, I did it) is that on finding the pump somewhat unreliable, you turn it down a notch and put some oil in the petrol thinking this is ‘belt and braces’ technique. Unfortunately, this makes the pump worse. Please don’t put oil in the petrol, it doesn’t need it. Turn up the pump to the maximum you can get away with without becoming a pollution hazard e.g. one in 5 or 6 for normal running or about one in 3 or 4 for fast work . This is far more oil than it will ever need but it keeps a good pump reliable. If you drive in the Metropolis – buy a Honda. If you are a fast bloke – develop an instant left hand”.

Remember, this was 1972 so the environmental issue of smoke has moved on!!! Having talked to Glyn when I first got my ‘new’ Scott, he strongly recommended getting a reduction gear to slow the Pilgim down and hence avoid this problem – it was on his advice that I got this mod. I include this as a warning that simply use a ‘half and half’ approach may result in the Pilgrim failing to perform – note that both Brian and Glyn advise fitting a reduction gear.

I will discuss again with Glyn when I go over to pick up supplies of Silkolene and see what his current recommendations are.

3) I am also challenged by how to do the initial start-up i.e. with the oil tank full but the pipes empty. My plan is to:

i) Fill the oil wells and then close the doors.
ii) Turn the Pilgrim to max open so the oil runs through fast.
iii) Put in the first fill of perool with a relatively high pertroil mix (say 40:1)
iv) Kick the machine over a number of times with the plugs out to get petroil distributed.
v) Put in the plugs and kick it for real (and pray).
vi) Turn the pilgrim down as soon as I get a lot of smoke coming out (I will warn the neighbours first!!!)

Does anyone have any advice on how better to do this?

Regards,

Colin

[Jan Buchwald]

I read somewhere (and I can’t remember where) that oil consumption should be 1000-1200 mpg.
Petrol 65-70 mpg.
Jan B

[Roger Moss]

I noted earlier that I used a synthetic oil. So I did, on the reccomendation of my friend Paul Dobbs who has raced modern two strokes for several years. Alas I had a seizure, and when I stripped the motor, the aluminium from the piston looked like it had been metal sprayed on the bore! I also noted that all surfaces looked dry. I had been used to running on castor R40 for racing. It smokes quite a lot, but when you strip it, everything is nice and oily. The oil film does not totally run off. This suits my purposes but would not suit normal riding perhaps.
My conclusion is that the Scott engine likes a thick oil ie one with a good film thickness. As regards which, I suggest you ask those who do a lot of road riding. As regards the proposition that if you use two stroke oil in your fuel, it prevents the pilgrim from working correctly, then with the very greatest respect, I cannot follow the logic and I used this system for years without any problems. Whatever system you use, do drain the wells before starting if the engine has stood more than a couple of days. It saves a lot of kicking and perhaps, swearing!
As regards “Technicalities, Please Please remember that this is a collection of personal tips from owners with very diverse life experiences and facilities. All the advice is given in good faith but IS NOT warrented by the SOC. Perhaps one day we can get together a technical group to write a new owners handbook and workshop manual. We can dream!
Kind Regards
Roger

[John Farrar]

I have used petroil on my racing and road Scotts for many years. I use the cross over system with one way valves. This ensures that the mains are lubed. I use 25 to 1 mix with Silkolene Comp 2 or decent equivalent. The semi-sythetics seem OK for most uses, but I do like R40.
I have run std oils at 20:1 but they seem to be marginal and this ratio is very smokey. Running a good oil at 32:1 is probably OK for the road, but oil is cheap compared to engine rebuilds!
I fill in the crankcase oil resevoirs , not to increase the primary compression ratio(which I prefer to lower from standard) but to reduce smoking on start up or after long periods in traffic.This works well.

John Farrar

[Colin Hough]

Roger,

To respond to your comment re the lack of logic of petroil and impact on a Pilgrim pump:

My understanding is that when running primarily on the Pilgrim then about 15 drops per minute – dpm – each side at tickover is required (possibly with the help of some oil in the petrol at around 100:1). In this case a directly connected Pilgrim pump is operating at the very bottom of its operating range because of the high rotating speed. It is because it is operating so low down that there is a chance of it not functioning as required i.e. not giving enough oil over the engine’s full operating range and hence leading to seizures.

The suggestion is than to ‘play safe’ by switching to a ‘half and half’ approach i.e. turn the Pilgrim DOWN to say 6 dpm (as recommended in an earlier post) at tickover and go to petroil at around 50:1. In this situation, a directly connected Pilgrim is being asked to work below its operating range so the result may be ‘half and nothing. Hence, trying to partially substitute petroil and turning down the Pilgrim is not a good idea. The solution if going down this route is to fit a reduction gear (I have). In this way the Pilgrim may be reliable enough to turn down the rate.

The critical message is that the oil rate must be set at a level that allows the Pilgrim to work reliably (which is also a function of oil viscosity). The question is then: what are the majic settings for the selected oil????

Glyn Chambers now supplies Silkolene Comp 2 Injector to go into the oil tank and Comp 2 for mixing with the petrol. His advice is to use ‘a little’ Comp 2 in the petrol and ‘as low as possible’ that can be RELIABLY delivered by the Pilgrim (i.e. the rate needed by the engine is less than that which the Pilgrim can reliably deliver if not fitted with a reduction gear). When fitted with a reduction gear, the Pilgim can be set to the level needed by the engine for which his advice is ‘1 in 4 or 5’ – thats drips per spits.

This is all theory so far based on various (conflicting) readings of the Technicalities etc. My plan is to start at 50:1 plus about 15 dpm with synthetic oil and ‘suck it and see’. Note: the Book of the Scott suggests 20 dpm for the first 1500 miles “whilst the use of petroil is an additional safeguard” so that it is “liberally” supplied with oil initially. After that, it recommends 10 to 15 dpm, but to use the exhaust smoke to judge if it is correct.

Regards,

Colin

[Colin Hough]

All,

Having got closer to starting up (but still not there as I still have various bits to refit), I have read more of the Technicalities and the message is clear – running ‘half and half’ needs the Pilgim pump to be geared down or drippers fitted. Both are supplied by Gerry Howard (long time SOC member) – contact Dickens Vintage Motorcycle Parts, Wissey View, Meadow Lane, North Pickenham, Nr Swaffham, Norfolk, PE37 8LE UK, Tel: 01760 440323.

He has been making the reduction gear since the early 1980’s, is listed in Yowl and advertises in The Classsic Motor Cycle. I bought my reduction gear off him in 1999.

Regards,

Colin

[Author]

Posts