ESE's works engine tuner

[wobbly]

Re the lever arm height on the pumper - the free end should be set such that the middle of the arms end thickness is flush with the floor of the body.
Some say the top of the arm flush with the body floor, but most tuners raise this a little to 1/2 the thickness.

[ac3_snow]

Cheers for the explanation wobbly! I read RV and kept thinking reed valve.

Have also been thinking about getting some race gas to use in my bike this weekend, with the high compression probably not a silly idea. Any way stumbled across this site, was an interesting read.
http://dirtbike.off-road.com/dirtbik...ers-12920.html

perhaps not all relevant as I don't think its a NZ site, but couple of points I found interesting.

The bottom line is this: let's say your motor needs 92 octane to run correctly and you fill up with 125 octane wonder gas. You will not run any faster. In fact, you might end up running slower because of a radically slowed flame front.

Guess I should sort out the squish and combustion shape soon.

Probably the single best option is to test with a hydrometer several containers of the racing gas you're considering buying. This will give you the specific gravity of the fuel, and if it varies from container to container, it will tell you a very sad story about quality control.

You can buy a gas testing hydrometer for about four or five bucks. All savvy tuners test with them BEFORE they start tuning, or if they cannot use their regular gas.

Q: What about using AV, or aviation, gas?

A: There's an old wives' tale about AV gas out of World War II and I don't know who started this, but it says that if you put AV gas in your car, you'll burn the valves. There's no doubt that aviation fuel can be used in any internal combustion engine that's driven up and down the highway at cruising speeds.

It doesn't make much sense to use it for that since it goes for something like $1.75 or $1.85 in this area, and is not easily obtainable.

A motorcycle and an airplane really live in two different environments. An airplane generally takes off, climbs to its altitude and the general outside temperature is at or below zero. Even in the summertime, it maxes out at 10 or 20 degrees above. And an air-plane does not turn high rpm. A typical prop job loafs along at two to three thousand rpm. Of course, there are some high perfor-mance exceptions. The engine just drones along at low power settings, except for take-offs.

[husaberg]

Re the PV and floating cranks.
All the engines I have worked on with a RV, the valve has a boss in the centre.
This boss slides on crank splines to give the correct rotational alignment, and also allows the blade to float in the gap between the case and cover.
Thus allowing the crank to float the recommended 0.2 to 0.3mm on the mains, has no effect on RV alignment.
Here is pic of a RV splined boss

Didn't really consider that bit did I Whoops

Can you give the Snow a heads up on a approx comp he should be aiming for with the bucket legal fuel with his approx spec. My gut feeling is he is still a bit OTT at the moment.

[TZ350]

Ariel Arrow racer.......

I have one of these (road bike) in bits, could be a bit of fun building one of these racers up to chase the pre 76 Bennelli 240 boys.

Anyone have any Ariel Arrow engines/gearbox bits and bobs? please PM me.

Might even convert it to rotary valve and will most certainly run it on methanol.

[wobbly]

Well its a bit of a stretch to try and be specific with so many variables involved but I will try.
What you are dealing with is a combination of static com and the dynamic com created by the efficiency of the engine spec, along with the added quirk of small bores being able to withstand more of both.
The more an engines overall spec is synergistic and SOTA then the less static com is needed nor is it in fact desirable.
So - with very average port/duct geometry, a very average pipe design, a very average ignition curve but using Avgas, then at the very least we need 15:1 full stroke com to get close to optimum, with EX durations between 196 and 202, where you need to be to make any power at all.
Avgas burns so close to 105 unleaded race gas, in power and reaction to com that its indistinguishable on a dyno, except that Avgas will always withstand more com or a lean condition better. Unleaded hates com but loves timing - as a general rule, the opposite of proper race gas or Avgas.
As Avgas is allowed, and we are discussing small bore race engines with sub optimal ports/pipes etc then I would say around 15.8 would work fine.
On pump gas, be it 91/95 or crap 98 then reduce this to 13.8 and wind in lots of static advance.
Avgas isnt created for what we are doing, but its cheap enough,available at any airport,and works real well when pushed to the edge of the tuning envelope.
The other issue is that to be effective, the squish clearance should be just above what would give zero clearance in an overev situation.
Thus any 50 or 100 cc bucket is able to run down at 0.6mm with complete safety, without running into issues of excessive squish velocity, unless you are well over 50% SAR.
But dont give me any grief when the thing melts using an 8 plug when any engine making any power at all, should have a 10 iridium as a baseline.

[husaberg]

Well its a bit of a stretch to try and be specific with so many variables involved but I will try.
What you are dealing with is a combination of static com and the dynamic com created by the efficiency of the engine spec, along with the added quirk of small bores being able to withstand more of both.
The more an engines overall spec is synergistic and SOTA then the less static com is needed nor is it in fact desirable.
So - with very average port/duct geometry, a very average pipe design, a very average ignition curve but using Avgas, then at the very least we need 15:1 full stroke com to get close to optimum, with EX durations between 196 and 202, where you need to be to make any power at all.
Avgas burns so close to 105 unleaded race gas, in power and reaction to com that its indistinguishable on a dyno, except that Avgas will always withstand more com or a lean condition better. Unleaded hates com but loves timing - as a general rule, the opposite of proper race gas or Avgas.
As Avgas is allowed, and we are discussing small bore race engines with sub optimal ports/pipes etc then I would say around 15.8 would work fine.
On pump gas, be it 91/95 or crap 98 then reduce this to 13.8 and wind in lots of static advance.
Avgas isnt created for what we are doing, but its cheap enough,available at any airport,and works real well when pushed to the edge of the tuning envelope.
The other issue is that to be effective, the squish clearance should be just above what would give zero clearance in an overev situation.
Thus any 50 or 100 cc bucket is able to run down at 0.6mm with complete safety, without running into issues of excessive squish velocity, unless you are well over 50% SAR.
But dont give me any grief when the thing melts using an 8 plug when any engine making any power at all, should have a 10 iridium as a baseline.

Shit With an air cooled we can still push that high broadly speaking (of course)
I thought Snow was at the edge of the envelope at 14.67:1 Shows I know well F all. As I suspected. I would have ball parked 13.5 or so Max with a Air Cooled 125 on AV Gas.


PS I will only give you grief if the new top secret hush hush engine fails to deliver less than 35 hp at the rear wheel with a power spead that makes my husaberg look like a peaky old school 2 stroke.
When do you think you will have pics of the new baby. I hear she is cute. I haven't told the misses about her yet so I expect there will be fireworks soon. As she already thinks I am in love with another. Girls can be so jealous sometimes. Does she have a name yet? I hear she does have lovely almond eyes.


TZ I have some info for you. I will post it when I trip over it. Herman Meijer and co I think the factory one got a 3 or 7 at the TT one year. Although you may struggle against the Bennellis. I would say 30hp before radically rework is needed of the bottom end. Shit I just had a proper look at the pics, is that a Krober ignition and Twin mikunis and a Belt drive as well the gearbox. I suggest would be your greatest hurdle on that thing. Love those flanged rims. mmm........
TZ and can you Post Wob A pic of the Std rod in An Ariel Arrow. I think he would get a kick out of it.

[Kickaha]

and Twin mikunis

Wouldn't that make it ineligible for Classic register events, where does it race?

[wobbly]

Sorry my mistake - I was referencing to water-cooled numbers.
For air - cooled, take one ratio less in both cases,ie 15.8 down to 14.8, again as the small bore/displacement allows alot more leeway..

[teriks]

Sorry about the late reply, have been working ridiculously late the last couple of days.

Mikuni Powerjet PRO
MEG-024 med elektrisk styrning



Universalkit för alla typer av förgasare. Kitet är till för att ge extra bränsle under accelaration då det behövs som mest med bränsle. Det här kitet är det som topptrimmarna använder tillsammans med programeringsenheten till tändboxen eller liknande. Den aktiveras då pipan börjar dra för att stänga av då man har paserat max vridmoment. Därefter behöver motorn gå magrare igen.

"Universal kit for any type of carb. The kit is designed to provide extra fuel during acceleration. This kit is used by top tuners together with a programmable ignition or other electronic control. It is activated when the pipe starts to pull, and turned of when you pass max torque. At rpm's above max torque the engine needs to run leaner again."

I think the correct usage of a power jet was explained by wobbly some pages ago.

En annan användbar arbetsplats för den här magnetventilen är att använda den på lustgasaplikationer. Då kan man placera den mellan trotteln och insuget. Ventilen kan då ge motorn extra bränsle vid avslaget då resterande lustgasmängden läcker in i motorn efter avstägningsventilen till lustgasen. Annars är risken för haverier överhängande på grund av uttorkning av cylinderväggar och lager.

"Another useful application is together with a NOS-system. The power jet can then be placed between the throttle and the intake. The valve can then be used to provide extra fuel when shutting the throttle [and the NOS-valve] to prevent breakdown caused by rest amounts of NOS destroying the oil-film on cylinder walls and bearings."

Powerjet munstycket måste alltid beställas separat av kunden.

Beställningsnummer MICPJ 30 upp till 100 Du hittar munstyckena på ett annat ställe här på sidan.

"Jets have to be ordered separately. -Order no. MICPJ 30 up to MICPJ 30.
Jets are found elsewhere on the site."

Thanks for the offer most appreciated.
I struggle enough with Engerish.

Doing the translation, I just realized I struggle with Swenglish myself

[husaberg]

Sorry about the late reply, have been working ridiculously late the last couple of days.

"Universal kit for any type of carb. The kit is designed to provide extra fuel during acceleration. This kit is used by top tuners together with a programmable ignition or other electronic control. It is activated when the pipe starts to pull, and turned of when you pass max torque. At rpm's above max torque the engine needs to run leaner again."

I think the correct usage of a power jet was explained by wobbly some pages ago.

"Another useful application is together with a NOS-system. The power jet can then be placed between the throttle and the intake. The valve can then be used to provide extra fuel when shutting the throttle [and the NOS-valve] to prevent breakdown caused by rest amounts of NOS destroying the oil-film on cylinder walls and bearings."

"Jets have to be ordered separately. -Order no. MICPJ 30 up to MICPJ 30.
Jets are found elsewhere on the site."
Doing the translation, I just realized I struggle with Swenglish myself

Thanks very much for that. Most appreciated. Do you speak any other languages? I struggle with one. I am guessing if your originally from Sweden, You didn't move here for the hot looking Chicks.

[TZ350]

TZ and can you Post Wob A pic of the Std rod in An Ariel Arrow. I think he would get a kick out of it.

Ariel Arrow rod (right side) is a similar size to a 70's TZ and has oiling slots like a racing Yamaha TZ's (road RD's did not have oiling slots). The Arrow has bushed little ends and two crowded rows of 1/4" rollers for a big end brg.



The Arrow crank is joined in the middle by a taper and key held together by a big cap screw.

The whole motor can be dissasembled, heads/barrels off, crank and gear box taken out for a major overhall without removing the cases from the bike.

[husaberg]

Ariel Arrow rod (right side) is a similar size to a 70's TZ and has oiling slots like a racing Yamaha TZ's (road RD's did not have oiling slots). The Arrow has bushed little ends and two crowded rows of 1/4" rollers for a big end brg.



The Arrow crank is joined in the middle by a taper and key held together by a big cap screw.

The whole motor can be dissasembled, heads/barrels off, crank and gear box taken out for a major overhall without removing the cases from the bike.

Well I be buggered. I knew about the center joint (Hence my 30hp reference)Looking back the twin engine I was thinking with the even odder centre joint is the Exselsier twin 2 stroke which I think in hindsight more like a Harley/aermacchi twin 250.
but I always thought (The Ariel) had hollow oval section rods.
Edit and according to this most of them did is yours an early arrow or is it a leader or is the article toss.EDIT

With the Alcohol fuel and a bit of modern attention. I guess based on my wrong assumption of 24hp being the max of your AC125.
I guess Will have to ramp up the target to 38hp.

But it stil leave you with a Burman Gearbox though whats your plan there to get around that one. http://www.novaracing.co.uk/ariel-arrow.htm
http://www.flickr.com/photos/profess...on/5601273533/
http://3.bp.blogspot.com/_VDCGGBYmNC...7215130b_o.jpg
http://www.google.co.nz/imgres?q=ts5...&tx=148&ty=109
http://www.k21.co.uk/smf/index.php?a...ge;topic=148.0
http://www.flickr.com/photos/5359190...7603882388495/
http://www.t20suzuki.com/

I was most interested in the pipes on the old Arrow (bellow) as they still look almost right today bar the stinger and the plain design.
As well as the current then philosophy regarding primary comp and other design aspects.

I guess you are aiming for post classic racing rather than CMRR.

I would go with a Silverstone/Outon greeves but in BRG or a stamaker powered replica.
http://motorbike-search-engine.co.uk...reeves-250.php
http://www.flickr.com/photos/smeraci...n/photostream/
http://www.kellymotodepoca.com/image...erstone_65.jpg

Added bellow and below again is some of the Aprilia development story leading to the first 250 GP championship with Max (I'd Do that for a dollar) Biaggi

[teriks]

Thanks very much for that. Most appreciated. Do you speak any other languages? I struggle with one. I am guessing if your originally from Sweden, You didn't move here for the hot looking Chicks.

No problem, been lurking this excellent thread for some time and finally found something I could give back. No additional languages unfortunately.

You are right in that I'm originally from Sweden, only I still live here. So no, I did not move for the hot chicks, I didn't move at all.
Now, this time of year with winter approaching...

[husaberg]

No problem, been lurking this excellent thread for some time and finally found something I could give back

You are right in that I'm originally from Sweden, only I still live here. So no, I did not move for the hot chicks, I didn't move at all. Now, this time of year with winter approaching...

Hello
Welcome to the thread I am sure the Auckland boys will give you an official welcome as soon as they stop watching the rugby.

Had you heard of the Swedish tuner I was linking the posts too
Roffe is it?

Neat stuff below.

[teriks]

I feel welcome as it is

No I haven't heard of Roffe, but that might say more about me than of him.
EDIT: To clarify, my main interest is two-stroke racing technology in general, not road racing motorcycles. So, basically I don't have a clue about what goes on in vintage racing etc.
(Flying radio controlled pylon racing with 6.6cm^3 two-strokes. Actually Fritz Overmars was involved in the development of the type of engine I use. He mentions some of it here: http://www.pit-lane.biz/t117p390-gp1...es-aprilia-rsa )