Gas/Oil (Petrol/Oil) Ratio Mixture Charts

Wildly Insane SS

Active member
Messages
25
I looked at the bottle of oil from HPI Part #Z191 it says 30CC oil for 750CC tank of gas followed by 1L gas (1/4 gallon) =40CC oil, then 2L gas (1/2 gallon) 80CC oil makes 25:1 ratio and for those confused about ML and CC its the same thing =) hope this help
 

2nd Gen Designs

Well-known member
Media
Messages
787
You can buy a ratio rite at your local atv shop for around $6. You'll have perfectly mixed gas every time
 

fireblade rr

Well-known member
Messages
272
Location
Perth Australia
Fuel and oil debates usually end in fist fights on car forums :). You guys are really civil :)

I have run 50:1 in my Banshee for years. I was running 100:1. But not just any oil, specifically Amsoil synthetic oil. You'll be amazed at the extra power you will get. I've been running 50:1 racing oil for 5 years and have no lack of power what-so-ever. Haven't had to change the piston and rings either.

Once a 2-stroke is warm, the bearings will absorb the oil out of the gas for lubrication.
5 years on same pistons and rings in a banshee (Yamaha 70's engine tech) at 50:1 ????. :)

The problem with comparing a Banshee, is its liquid cooled, and that is a HUGE factor in how a engine will survive and hotspot. Some people may get confused by that. Running a aircooled low disp high rpm engine with no overdrive gearbox on anything more than 40:1 is pushing it from my exp. Blasting around in subburbia, no probs at 40:1, but doing dunes on hot days, id go down to 32:1 and wind the main jet out a tad to get the A/F back again and get the EGT's down a tad.

And the bearings wont be absorbing oil, not much else is harder or denser on our buggies than bearing steel.

I'm using Silkolene Pro 2 2T. It's the real deal and it costs £16 per litre - thus you could use up to 50:1 according to Silkolene themselves.
Trying to not be bias, ive been a ex Rock Oil sponsored motocross racer as a pro (i was also the engine builder), and now run a Silkolene powered CBR1000RR superbike, and use it in my workshop, and for my customers. The Brits make 2 things well ... engine oils, and Aston Martin DBR9's !. Amsoil is incredible too, (as are many more) but Rock Oil and Silkolene are the pinnacle ive ever had the chance to use as a racer and a builder.

And then confuse it all the more ... castor oils. They can work GREAT in non powervalve 2 strokes like we have. Dont ever discount them on high rpm engines.

But your on a point, there arent many very high quality cheap synthetic oils around.

As for fuel octane ratings, I have to use Super unleaded (98 Road Octane Number) for my Prodrive STI, so I top up my Baja's fuel can when I need to at the same time usually. It may be a sore point for some, but the higher the octane rating, the more power [potential].
Yes, and no. At a point a higher octane fuel will be too cold, as better fuels run cooler, and provide a cooler more controlled burn. If you took a stock 1st Gen Toyota Camry and filled it with elf105, it would make less power than on the cheapest regular unleaded.

In your EJ Subi engine, it is a tad different. Your turbocharging, and the engine will learn the map, off a given line in the tune, of say +/- 10%. It will add timing and pull fuel till the knock sensor starts to wake up, and so on.

Same in the stock non ported baja engines, it will get to a point where if we run elf105, or a VP product, it will need timing, and need compression, more fuel etc etc.

And in the USA the grade of petrol is lower than in most parts of Europe in any case, so straight off the bat, people are using different grade fuel with their Bajas. I haven't heard any complaints of knocking!
Its not actually. In the USA they measure RON + MON / 2 (Research, and Motor octane Numbers divided and totaled called AKI Anti Knock Index) and in Euro they measure in RON (Research Octane Number) as the do here in Aus. Ours sound really exotic, but its not.

If you have 100 RON and 90 MON, the US system will say "95 octane". Thats the same as Euro 100.

And even then when selecting a racing fuel, one wants to know what RON and MON they are before making a choice. The spread is a key factor, for eg a 80 MON and 120 RON is actually a 100 when divided. As is a 90 MON and 110 RON , but the latter is commonly a better quality fuel.

If you really want a INCREDIBLE punch from your little 2 stroke, drop in a 10-20% mix of Toluene (industrial thinner, its 111 RON and 95 MON). Its not nice to sniff, drink, wash your eyes with, and it eats main and big end bearings (dries up) but wow does it work on 2 strokes. On my Suzuki race engines (250cc) id get 2 race meetings and the whole bottom end (and top) needed a full build.
 

phazewun

New member
Messages
2
Fuel and oil debates usually end in fist fights on car forums :). You guys are really civil :)



5 years on same pistons and rings in a banshee (Yamaha 70's engine tech) at 50:1 ????. :)

The problem with comparing a Banshee, is its liquid cooled, and that is a HUGE factor in how a engine will survive and hotspot. Some people may get confused by that. Running a aircooled low disp high rpm engine with no overdrive gearbox on anything more than 40:1 is pushing it from my exp. Blasting around in subburbia, no probs at 40:1, but doing dunes on hot days, id go down to 32:1 and wind the main jet out a tad to get the A/F back again and get the EGT's down a tad.

And the bearings wont be absorbing oil, not much else is harder or denser on our buggies than bearing steel.



Trying to not be bias, ive been a ex Rock Oil sponsored motocross racer as a pro (i was also the engine builder), and now run a Silkolene powered CBR1000RR superbike, and use it in my workshop, and for my customers. The Brits make 2 things well ... engine oils, and Aston Martin DBR9's !. Amsoil is incredible too, (as are many more) but Rock Oil and Silkolene are the pinnacle ive ever had the chance to use as a racer and a builder.

And then confuse it all the more ... castor oils. They can work GREAT in non powervalve 2 strokes like we have. Dont ever discount them on high rpm engines.

But your on a point, there arent many very high quality cheap synthetic oils around.



Yes, and no. At a point a higher octane fuel will be too cold, as better fuels run cooler, and provide a cooler more controlled burn. If you took a stock 1st Gen Toyota Camry and filled it with elf105, it would make less power than on the cheapest regular unleaded.

In your EJ Subi engine, it is a tad different. Your turbocharging, and the engine will learn the map, off a given line in the tune, of say +/- 10%. It will add timing and pull fuel till the knock sensor starts to wake up, and so on.

Same in the stock non ported baja engines, it will get to a point where if we run elf105, or a VP product, it will need timing, and need compression, more fuel etc etc.



Its not actually. In the USA they measure RON + MON / 2 (Research, and Motor octane Numbers divided and totaled called AKI Anti Knock Index) and in Euro they measure in RON (Research Octane Number) as the do here in Aus. Ours sound really exotic, but its not.

If you have 100 RON and 90 MON, the US system will say "95 octane". Thats the same as Euro 100.

And even then when selecting a racing fuel, one wants to know what RON and MON they are before making a choice. The spread is a key factor, for eg a 80 MON and 120 RON is actually a 100 when divided. As is a 90 MON and 110 RON , but the latter is commonly a better quality fuel.

If you really want a INCREDIBLE punch from your little 2 stroke, drop in a 10-20% mix of Toluene (industrial thinner, its 111 RON and 95 MON). Its not nice to sniff, drink, wash your eyes with, and it eats main and big end bearings (dries up) but wow does it work on 2 strokes. On my Suzuki race engines (250cc) id get 2 race meetings and the whole bottom end (and top) needed a full build.
This is a very good write up i have been an EJ tuner for about 17 years now and you cannot compare anything on a baja to a liquid / turbo'd engine, not to mention alot of these have ways of testing for knock.. im currently driving a 2011 sti and i have 4 different maps for different octane / boost number... using 116 octane race gas the timing and fuel load are way different.

every EJ past stock will require some sort of modification the baja doesnt have that limit to be safe for everyone running 25:1 or 32:1 with proper tuning is the best bet always use a quality oil and CHECK THE PLUG !!!

My sand rail is using a crawford performance EJ long block putting down around 615 to the wheels with a 32r twin scroll on meth that i have yet been able to tackle with perfect tuning... everything requires knowing how to read what is going on and understanding what adjustments do and alot of checking and re checking.
 
Last edited:

Horatio

Well-known member
Messages
112
Thanks Fireblade, that does help solve a couple of mysteries! The point you made about ambient temperatures is food for thought - if I'm honest, I only gave it consideration regarding nitro engines, not so much for the Gassers.

So whilst some of us will be swearing blind that 40:1 is the perfect blend, across the pond in a californian dune others may need to be playing it safer due to the heat.

When I was (much) younger, I used to race a YZ 125. It was a 1984 model! :D Back then, for our 2 stroke, power valved, water cooled engines it was Castrol R all the way. What a distinctive smell - soil, grass and Castrol!

What a shame that 2 strokes are going the way of the Dodo in motoX these days, thanks to silly rules that give 4 strokes a massive capacity advantage. Bring back the 500 2 stroke class and put it on the telly!
 

fireblade rr

Well-known member
Messages
272
Location
Perth Australia
When I was (much) younger, I used to race a YZ 125. It was a 1984 model! :D Back then, for our 2 stroke, power valved, water cooled engines it was Castrol R all the way. What a distinctive smell - soil, grass and Castrol!
Hahha, tops, i had a '85 model (in 87) :). Dad got it for me, as a practise bike, i was still racing 80cc in 1987 ... i remember how awesome that was :)

And truth be told, im still running Castrol R in my leaf blower, and whipper snipper (weed whacker?) hahaha.

What a shame that 2 strokes are going the way of the Dodo in motoX these days, thanks to silly rules that give 4 strokes a massive capacity advantage. Bring back the 500 2 stroke class and put it on the telly!
The capacity isnt the problem, as they dont fire as often, but the emissions and global red tape have killed the 2st. The 4st are much more user freindly now, and pretty reliable, but very exxy to fix when it goes bang. I read about a guy who was working on a close to nil emmission 2 stroke oil that burns up in the dome, and with direct inj at the bottom end and top end secondary stage, would significantly decrease emmisions. They said the RX7 rotary was dead too ... only when corner'd Mazda made the N/A RX8 engine pass emmisions.

Many years ago 5 mins up the road here was Orbital engines (Ralph Sarich), and via a freind i was able to check out some injected two stroke Mercruisers (i think from memory) and the results were ... wow. Two high pressure rails, one for fuel, and one for oil, mixing at the injector pintle. When cruising in a marina, the ratio would be on say 150+:1 where cyl temps are low and unable to burn a 35:1 mix, yet when you punch it, and go WOT it would map the oil to a 40:1 for eg based on many sensory inputs, ambient air temp, manifold temp, EGT, cooling jacket temp etc etc.

Ive always wondered why not a rotary into MX bikes ... seen the Axial 50cc kart engine ? :blink:. 500's open class, what a era. Gobe, Kinigardener, Thorpe, Mahlerbe, Bailey, Johnson, Leisk ... such a great time gone for good. In 93 i had a deal with Suzuki via a Harry Everts contact to race in Euro ... was my life long dream, 2 weeks prior i was in a NZ north island championship and broke my back. Now i roll around on 4 wheels daily ... such is life.
 

Horatio

Well-known member
Messages
112
Hahha, tops, i had a '85 model (in 87) :). Dad got it for me, as a practise bike, i was still racing 80cc in 1987 ... i remember how awesome that was :)

And truth be told, im still running Castrol R in my leaf blower, and whipper snipper (weed whacker?) hahaha.



The capacity isnt the problem, as they dont fire as often, but the emissions and global red tape have killed the 2st. The 4st are much more user freindly now, and pretty reliable, but very exxy to fix when it goes bang. I read about a guy who was working on a close to nil emmission 2 stroke oil that burns up in the dome, and with direct inj at the bottom end and top end secondary stage, would significantly decrease emmisions. They said the RX7 rotary was dead too ... only when corner'd Mazda made the N/A RX8 engine pass emmisions.

Many years ago 5 mins up the road here was Orbital engines (Ralph Sarich), and via a freind i was able to check out some injected two stroke Mercruisers (i think from memory) and the results were ... wow. Two high pressure rails, one for fuel, and one for oil, mixing at the injector pintle. When cruising in a marina, the ratio would be on say 150+:1 where cyl temps are low and unable to burn a 35:1 mix, yet when you punch it, and go WOT it would map the oil to a 40:1 for eg based on many sensory inputs, ambient air temp, manifold temp, EGT, cooling jacket temp etc etc.

Ive always wondered why not a rotary into MX bikes ... seen the Axial 50cc kart engine ? :blink:. 500's open class, what a era. Gobe, Kinigardener, Thorpe, Mahlerbe, Bailey, Johnson, Leisk ... such a great time gone for good. In 93 i had a deal with Suzuki via a Harry Everts contact to race in Euro ... was my life long dream, 2 weeks prior i was in a NZ north island championship and broke my back. Now i roll around on 4 wheels daily ... such is life.
Sorry to hear about your back dude - it's a tough old game, MotoX. You clearly were on the way to MX stardom when disaster struck and that's very tough. All my mates got injured racing, but all limb injuries nothing too serious.

Interesting about the variable oil mix - would it be possible to electronically control it in a compact fuel injected Baja-sized engine?
 

fireblade rr

Well-known member
Messages
272
Location
Perth Australia
Interesting about the variable oil mix - would it be possible to electronically control it in a compact fuel injected Baja-sized engine?
No not really. You need a battery and charging system (you could run total loss, ie no charging stator but be charging often) to run the two high pressure fuel pumps 12-13.5v. You would need a regulator, injector (larger than the NGK plug itself) crank angle sensor (5v) IAT (inlet air temp 5v) TPS (throttle position 5v), MAP (manifold absoulte pressure sensor 5v) EGT probe among other items, then a ECU. A Vipec, Motec or Haltech for eg are around the size of the battery box and fuel tank combined.

The primary harness itself is thicker than the bore :lol:

Perhaps current MX bikes, smaller everything but impossible to erase and re-write alternate ecu maps as far as i know. Would be fun tho :)
 

joker636

Member
Messages
17
Location
central georgia
I read this thread from page one to six so i have a question. I just got my baja two days ago. It has a cy 29cc engine ( allegedly ) i have zenoah synthetic oil and i mix 32:1 as the bottle instructs. Is this a good oil and mix? And how can i verify which cy engine is actually in my baja.
 
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