Anyone had experience of running with Avgas? Is it easily available and what type of Avgas should I be looking for?

How about running with this new 102 octane pump fuel that BP are selling. A local station has it so wouldn't be that difficult to get hold of. I know it's unleaded, but will that cause a problem with an engine designed to take leaded fuel?

Hi Racer,
I hope you find the information is of help to you, you will find that avgas is available from some small airports, however you must understand that the calorific value of avgas is very different to pump gas. You would not be able to run anything like standard jetting as avgas is a slower burning fuel. You would in addition, to get it running well in your motor proberbly need to modify, compression ratio,& or squish.
Some oils that are used in conjuction with Avgas100/130 will not blend without adding between 5-15% of benzol, or toluol (methyl benzine) but Castrol R & Castrol A747 both blend.(IT is prooven that additions to Avgas will, without doubt, accelerate piston to bore wear)
Take a tip from an old racer, stay with shell opimax, get the compression ratio right for that fuel, take some time doing plug chops untill you get mixture correct, a good pair of chambers and have good reliable fun.
Regards,
David.

Tom I can hold of Avgas, so give me a bell if you need some... Not going to make you any quicker though!! How's the back??

I can also get that stinky Elf race fuel, which is cheaper (just) than the BP fuel. As the comment above says though, you will need to make mods to compression etc when running them.
_________________
NSR300R - Why did i ever have a 250...

The back......well I can walk now, and ride a bike but it's still not right. Reckon it's old age. Anyway it's just another bike injury to add to the list.

The reason for the fuel thing is I want to run an RS and don't want to mess about with the motor or ignition curve too much. However if I could run on something easily avaliable at the pump that would be a good enogh reason to have a go.

How long does this ELF race fuel keep for? Is it OK to store it?

Current thinking over here in NZ is to run avgas/91 @ 50/50 mix. I have tried it and it seems to be ok and rev slightly better. Was originally running pure avgas but have just changed. Mind you there is no airbox fitted so I don't know whether that would enter the equation. Have just taken the front piston out and the burn seems even after about 300Km (about 190 miles) at track speeds. Plug colour seems to suggest that the mixture is o.k.My bike is running with RS250 ignition and coils but I haven't identified the pistons yet (oh the joy of owning an old 2 stroke) with so many variations.
_________________
Finish 1st? 1st Finish!!!

The Elf fuel is 102 octane also so just get the BP stuff. It'll run fine in anything design to take unleaded, but to take advantage of it, you'll need to adjust/increase the compression. All the guys local to me running RS's run Avgas/98 RON mix 80/20 with A747. The 20% unleaded just helps to increase the volatility...
_________________
NSR300R - Why did i ever have a 250...

I say forget the Avgas and just run pump fuel.

Instead, use the money you will save on a good Detonation Counter. The 2000 RS I had ran freaking awesome on pump gas. The extra heads that I got with the bike were a lower CR with narrower squishband. That thing flat out rawked, and made the NSR feel like a snail anywhere over 3k rpm.

I guarantee if you buy a Det counter you will absolutely LOVE it. Then you can actually get every drop of power out of ANY fuel you choose to run.
_________________
Paul Herr
'88 FZR4/GSXR/YZF Frankenbike
MY BIKE PICS

I spoke to Steve Patrickson at SP125.com and he didn't know of any det counter available specifically for the NSR... I know this is where Dave Ett saw them at very good prices, but they were for RS's or TZ's.

He explained that the counter has to be specifically calibrated for the expansion of the cylinder head, which is a different stiffness from model to model, as the counter detects excessive expansion of the head during pre-ignition.

If you know of one for the NSR paul I'd like the info!
_________________
NSR300R - Why did i ever have a 250...

Oh right, I assumed they were a standard piece of kit. Good bit of gen there, but I have no idea where you'd get an NSR specific one from. Are our engines that different they wouldn't work then?
_________________
MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Well that's what I asked him, and he said that it could give a reading that's way too high, or vice versa. Basically there's no base setting...
_________________
NSR300R - Why did i ever have a 250...

Dave Ett wrote:Oh right, I assumed they were a standard piece of kit. Good bit of gen there, but I have no idea where you'd get an NSR specific one from. Are our engines that different they wouldn't work then?

You'd need to run the long shortie sparkplug (R7282-105A) as the detector goes underneth the plug and probably get the head machined to allow the detector itself to clear the cast part of the head (look at an NSR head, the plug sits "in" it quite deep, probably more than a washer or two), a std plug is too short anyway and it's "nut" is too big to clear the detector at all. Kev Moose posted about these ages ago on twostrokes.com, he was selling the same ones, he reckoned there was not reason one wouldn't work on an NSR as "all" it does is listen for the right noise.

This is what he told me about them;

Detonation detection system

This system is optimised for RS125 / RS250 / TZ250 Engines

Overview
Detonation is the pre-ignition of fuel in the cylinder and can cause piston damage; a certain level of detonation is good (fuel dependant) to ensure that the engine is running at the optimal level. The detection system allows detonation to be detected and a bright indicator flash indicates a detonation has occurred to warn the rider. The number of detonations can be counted if the counter option is fitted.

The April systems detonation detection system allows a plug together system that can be simply expanded from a simple single cylinder system to a full dual cylinder system and to other data recording/logging systems.


System variations:

Single Cylinder Option A : Simple detonation detection @ £130.00
1 detonation detector
1 power lead and blue indicator flash


Single Cylinder Option B : Detonation detection and counter @ £280.00
1 detonation detector
1 power lead and blue indicator flash
1 detonation counter

Twin Cylinder Option A : Simple detonation detection @ £260.00
2 off detonation detector
2 off power lead and blue indicator flash

Twin Cylinder Option B : Detonation detection and counter @ £380.00
2 off detonation detector
1 off power lead and blue indicator flash
1 off detonation counter


All the above options are built from the basic components of:
. Detonation detector
. Power lead
. Counter unit

The power lead can be either blue indicator or a connector to a data logger.

Detector unit


The detector system compromises of: a detector sensor plate and a small amplifier unit. The detector sensor plate detects the physical head deformation and passes this signal to the amplifier. The amplifier produces two output signals:
a) An indicator drive for the blue indicator
b) A standard detonation profiled pulse

The (b) output can be coupled to other type of detonation detection systems such as
Honda detonation counter and logger
BPS CDi ignition and engine control systems
Cougar Data Recording motorcycle logging system
If connection to one of the above is required then request a power cable with a logger output connection. Note that the BPS/cougar cylinder pressure cannot be measure by this type of sensor

On powering up the unit will generate a detonation signal and/or flash the indicator this is normal.




Counter unit


The counter unit (for single or dual cylinder) has two detonation detector inputs labelled (1) and (2) and a power connection. The detector amplifier/s are then powered via the counter unit.

. The count values are stored in a non-volatile memory and so are unaffected by having the power removed.
. The value normally displayed is the addition of cylinder 1 and cylinder 2 count values
. Pressing the button briefly once will cycle through the count values
The display will show ….

1=
{Cylinder 1 count value}
2=
{Cylinder 2 count value}
Total
{Addition of cylinder 1 and 2} the normal display

. When cycling through the cylinder counts the counter system will continue to count any detonations
. 20 seconds after a button is pressed the display will fade to reduce power consumption
. To reset the values: press and hold the button for 2 seconds
. The inputs to the unit are compatible with standard detonation sensors
. The counter unit does not have a compatible output for loggers this signal would be taken from the detector unit/s.

Installation Procedure

The detonation detector requires the use of an extended length spark plug. The assembly order is to place the detector plate on the head and then the copper washer (or two as required) screw in the spark plug and tighten to 24 N.m or 18 lbf.ft

The tightness of the plug is critical on the detection process, too tight and the sensor will be over sensitive.

If the head is recessed then fit the copper washer/s first then the detector plate.

WARNING fit copper washers only on one side of the plate not on both, as this will inhibit the operation of the detector

Check that the head volume is now correct. Tape all unused connectors to stop water ingress.

WARNING: The detector amplifier unit must be mounted at least 80mm away from the ignition coils. Also route all detector cables away from HT leads or the coil.

Honda Power connections
Wire behind the tachometer:
Red positive power to Honda black
Green Chassis to Honda green

Yamaha Power connections
Wire behind the tachometer:
Red positive power to Yamaha Brown
Green Chassis to Yamaha Black


. Mount the blue indicator in the dash foam pointing towards the rider.
. Velcro mount the detector amplifier unit to the inside of the chassis.
. DO NOT MOUNT ON THE SIDE OF THE COIL
. Ensure all cables are away from the HT leads.
. Velcro mount the counter unit in a visible position and ensure that the button cannot be pressed accidentally or pushed by other cables.



Specifications:

Detector
Voltage range 9V to 20V
Input Current 5mA nominal 20mA peak
Detector plate temperature range -10degC to +130degC
Amplifier temperature range -10degC to +60degC
Weight Approx 50g
Detonation output -40V 1mA 16uS
Led output +5V 5mA 200mS

Counter
Voltage range 9V to 20V
Input Current 50mA nominal 150mA peak
Temperature range -10degC to +60degC
Weight Approx 60g
Inputs 2 off –40V 16uS piezo
Led output +5V 5mA 200mS
Max count 99999


 
_________________
Please do not PM me technical questions, if you can't find it on the Forum start a thread

OR you could try a couple of egt sensors in the header part of the expansion pipe. Easy to put in to and much cheaper sort of. Aim do dashes that take them and they are a good way to get the jetting right. And can save you some cash in pistons etc.
Use avgas on my nsr and rs(aprilia).NSR uses hrc ignition and the rs uses a kit suzuki ignition 23d10 i think.Both advance the ignition a bit and this is not a bad excuse to use avgas fot the higher octane and slightly less risk of pre det, ah but then you increase comp because you think ah i am running avgas now so.... mister melt comes back and........

Saw det counters on Jha's NSR in Japan way back. AP Honda here in Thailand also used RS125 det counters on their NSR150SP's.

I set up the RS's for Harc-Pro using the det counters. Oh so easy.

I've now got EGT sensors 'cos I'm a tight arse, but need to know temps for pipe dimensions as well.

Matt,
if you could share the exact location you are running the EGT's in your exhaust and the temps you are running? I am also setting up an EGT system in my bike.

Thanks!
_________________
Paul Herr
'88 FZR4/GSXR/YZF Frankenbike
MY BIKE PICS

Scott V has an EGT system installed on his MC28. Looked easy enough to use, only trouble was it took all my powers of concentration to keep the thing on the straight and narrow. No time to look at two pointy needles as turn 10 rapidly approaches.

I was wanting to move away from avgas as it's not the easyist thing to get hold of. I might look into lowering the compression to allow me to run pump 98 oct. That way I can ride the thing to Tesco's to fill up......road tax????? what's that!