AV 7 tuning (english)

[ukmoby]

Can anyone help me with tuning an AV 7 engine?

There is no information in the uk on these engines.

Exhaust opens 113 degrees ATDC
Transfer opens 130 degrees ATDC
Intake opens 48 degrees BTDC

Can anyone help with better timings?

Merci
Ray

[fluke]

Have a look here :

viewtopic.php?t=11516

I hope you can read French, even you don't speak it



and

[pépé l'arsouilleur]

Hi guy,

We can't really help you, because the timings of an engine depends on what you wanna do with your engine, and on where you wanna drive.

Are you looking for a better speed ? Or are you looking for a powerful engine ?

Please tell us more, and then if you want the previous document sent by Fluke to be translated, just let me know, and i'll do it.

[CalimeroTeknik]

Hi ! Some people here speak english, you're lucky.

Note that our diagram measurements give the time the port is open, and unlike yours, the time after TDC before it opens !

For us, your values give :

Exhaust opens during 134°
Transfer opens during 100°
Intake opens during 96°

Note that this method is much more easy : we just need a graduated disc and a piece of paper !

But then, what about your carburettor ? Your exhaust ? Are they genuine ?

I will give you, for example, values that run best with a 14 or 15mm carburettor and a Doppler ER1 exhaust :
Machine the exhaust upwards, so that it opens during 145° (so it opens 107° ATDC), and the intake downwards, so that it opens during 130° (so it opens 65° BTDC). Do not touch the transfers for this tuning.

[ukmoby]

Thanks for that article fluke , I have already had it translated.

pépé l'arsouilleur

Are you looking for a better speed ? Or are you looking for a powerful engine

I want more speed and power!

Note that our diagram measurements give the time the port is open, and unlike yours, the time after TDC before it opens !

I have never seen it done that way before.

Carb is 15mm and exhaust will be made to match the porting. I have bimotion software to calculate the exhaust dimensions.

What sort of hp and rpm does a tuned engine work at?

[pépé l'arsouilleur]

A competition engine can reach about 15000 rpm... But it's not possible with an av7 engine Maybe you can reach 7000 rpm with "high" port values.

[bigluck]

hum..a little more I was take 8000 rpm

I have already prepared a av7 before I got a av10,
the diagrams was

Exhaust opens 150 degrees
Transfert opens 110 degrees
Intake opens 115 degrees

with this configuration I could take 80kmh

[ukmoby]

You are all so helpful, thankyou

bigluck wrote

Exhaust opens 150 degrees
Transfert opens 110 degrees
Intake opens 115 degrees

Did you fit a spacer under the cylinder to change the transfer timings?

[bigluck]

hum, I think your obligated to put a joint (spacer)


p.s where do you live??

[ukmoby]

In the uk Suffolk

[bigluck]

oh yeah! in england

[DataMAX]

AV7 isn't a very good motor, i think you can change with a AV10 motor, setup fixation are similary, and you can find very great parts for it

And, if you really want to keep AV7 motor, don't made a exhaust, buy it and remade fixation (?)

In french, gasket = joint

And, just for my personal knowledge, can you take pictures about your monster ?

[CalimeroTeknik]

I have already prepared a av7 before I got a av10,
the diagrams

Exhaust opens 150 degrees
Transfert opens 110 degrees
Intake opens 115 degrees

Well, here the difference between transfer and exhaust is too low.

I would advise a larger difference between transfer and exhaust, so with a transfer diagram of 110°, exhaust should open during 160°, and not 150.

If the exhaust is home made, you can reach relatively high values.

[bigluck]

Did you test it??

I belive the answer is no!

so when you don't know you don't talk

[ukmoby]

And, just for my personal knowledge, can you take pictures about your monster

When its back together I will take a picture but it looks like this but mine is white and blue. http://www.users.globalnet.co.uk/~pattl ... 010405.jpg

I have put the numbers into 'bimotion port and pipe' software and it recomends some timings.


This should give peak power of 5hp (3.9kW) @ 7500rpm with a exhaust to match the pipe. That sounds very high and the motor may go bang quickly but its fun

[fluke]

Quite old machine, but very nice.

A lot of HP's with such poor brakes

[ukmoby]

Mine has a drum brake on the front and also forks with springs so its a little better at stopping.

[CalimeroTeknik]

But it won't brake as much as this :



(this is my moped )