Any Performance tuners

[Ivan]

Hey are there any guys who race buckets and know some good performance tuning tips on 2 strokes


I have an AX100 Suzuki it has been ported by the looks of the barrell and I think it has new rings in it, Other than that I cant think of anything else to do I know expansion chambers. It is going in a Aprillia RS50, Oh yeah I forgot to say I'm trying to get it similar to a RS125 Honda pulling high horses and handling like an aprillia

[crashe]

pm "Speedpro" as he races Buckets etc etc...
He has also just moved down to Wellington.

[Ixion]

Hey are there any guys who race buckets and know some good performance tuning tips on 2 strokes


I have an AX100 Suzuki it has been ported by the looks of the barrell and I think it has new rings in it, Other than that I cant think of anything else to do I know expansion chambers. It is going in a Aprillia RS50, Oh yeah I forgot to say I'm trying to get it similar to a RS125 Honda pulling high horses and handling like an aprillia

Stuff the crankcases. Crankcase compression ratio is the forgotten part of two smoker performance. and mill the heads of course

[geoffm]

Measure the ports - width, height, duration and calculate the port time area and opening. There are a couple of useful books around, depending on how well heeled you are. AG Bell's one is probably the best for the DIY. Prof GP Blair's 2 books are kinda spendy and heavy going for most people. No you can't borrow mine...
The 2 strokes mailing list is useful.

Check the port timing matches (transfers and exhaust). You don't know how well it was done before, unless you know the history. How well does it run?
At least being a single cylinder, then the development is easier. Making a good expansion chamber, designed to match your porting duration, would be the biggest benefit in most cases. Plan on making several iterations....
If you are serious, buy IWT's Mota software. It works and is good value, but takes a long time to measure everything up properly.
Brinig it up to Auckland and run it up on the dyno if you want.
Geoff

[Ivan]

Measure the ports - width, height, duration and calculate the port time area and opening. There are a couple of useful books around, depending on how well heeled you are. AG Bell's one is probably the best for the DIY. Prof GP Blair's 2 books are kinda spendy and heavy going for most people. No you can't borrow mine...
The 2 strokes mailing list is useful.

Check the port timing matches (transfers and exhaust). You don't know how well it was done before, unless you know the history. How well does it run?
At least being a single cylinder, then the development is easier. Making a good expansion chamber, designed to match your porting duration, would be the biggest benefit in most cases. Plan on making several iterations....
If you are serious, buy IWT's Mota software. It works and is good value, but takes a long time to measure everything up properly.
Brinig it up to Auckland and run it up on the dyno if you want.
Geoff


Nah I allready am borrowing A Gramham Bells 2 smoke tuning book of a mate, Sweet all that helps I know some history of the motor from RG100!! he said it belonged to Goatee he raced buckets a few years back and his bikes all seem pretty damn quick Expansion chamber is a must at the Momment i'm gonna use an Aprillia RS50 one Dont know what the motor runs like as I only just got it and it is a freebie it needs a coil and after about 3 weeks of hunting for one dad remembered he had one so thats good am going to test it today for spark. Thanks for the Dyno if I'm down or up cant remember which way it is I'll come try it out. When I get it running right and get my restricted I'm coming to Auckland to race the GP's I hear you got some pretty fast machines there

Laters

Ivan :done:

[geoffm]

Some links of interest

http://www.amiles.com.au/rmr/SparkPlugReading.htm
http://users.oc-net.com/dgriffiths/twostrokejetting.html
http://www-staff.lboro.ac.uk/~elvpc/bikes.html?http://www-staff.lboro.ac.uk/~elvpc/links/links.html
http://www.macdizzy.com/2stroke.htm
http://www.eric-gorr.com/techarticles/basic_two_stroke.html
http://adardaine.free.fr/articles.php?lng=en&pg=66
http://adardaine.free.fr/download.php?lng=en
http://www.bimotion.go.to/ (2 stroke design program + some freebies)
http://fpp.hamradio.si/roost/ (exh design proggie based on Jennings book)

http://www.iwt.com.au/MOTA.HTM - MOTA engine simulator ($) - has a cone program as well for free. I used to have this program until some lowlife broke into a car and stole it along with the dongle and other stuff :-(

Geoff

[speedpro]

Stuff the crankcases. Crankcase compression ratio is the forgotten part of two smoker performance. and mill the heads of course

Not neccessarily. There is an optimum crankcase volume and in fact in my new motor I had to increase the volume to get the horsepower (calculated) that I wanted.

If you 'stuff' the crankcases you reduce their volume. This will of course result in increased pressure when the transfer ports open but will also result in a faster drop in pressure as the flow up the ports will deplete the smaller volume quicker. This would result in lower port flow later in the transfer cycle. In actual fact most of the flow up the ports when everything is "on song" is due to 'suck' from the pipe rather than 'blow' from the crankcase compression.

I'm willing to compare my tuning theories and bucket against others, on the track.