Timing GP125

[LeeH]

Hello

Is possible that someone would be able to give me this information, it's not that I am lazy, but I still have to keep the bike on the road for a couple of months, cant strip it down.

I am building a expansion pipe for a SUZUKI GP125, I have a computer program that works all the dimensions out after you put the info in,

What I need is..
Exhaust open period in Degrees
Main-Transfer port open period in Degrees
Secondary transfer port open period in Degrees
Rear Booster port open period in Degrees

Would really appreciate any help
Kind Regards
lee

[Grub]

Hmmm, nothing on Google exceot this which is the summary but the main page is broken
Port timing Exhaust/lubang buang = 90deg Transfer/lubang bilas = 121deg ....

Next best idea is to spend $4.23 at warehouse stationery for a circular protractor, bluetac it to the crank and measure these things through the ports

[LeeH]

Thanks for the reply

I do have a degree wheel somewhere but my Bike is always in use, I don't want to go messing with it, my only means of transport to work at the moment until I get the car, I can strip the bike down then.

Regards
lee

[speedpro]

"TZ350" races a number of these in the bucket class. He will be able to provide the info you want plus probably make usefull reccommendations regarding chambers etc.

[TZ350]

The factory specs in the reply above will be spot on I expect but for what its worth here are my measurements.

Measurments taken using large protractor from the Warehouse.

On a Standard Suzuki GP125.

Inlet opens 145 BTDC closes 55 ATDC.

Exaust opens 91 degrees ATDC Duration 178 degrees.

Area of exhaust port is 85mm# and 64% of bore width.

Exhaust port flange diamater is 36mm.

Trans1 opens 120 degrees ATDC Duration 120 degrees.

Trans2 opens 120.5 degrees ATDC Duration 119 degrees.

Boost opens 122 degrees ATDC Duration 118 degrees.

To work out duration, subtract opening degrees ATDC from 180 and multiply the resultant by two.

Ie., Ex opens 91 ATDC so 180-91=89 and 89*2=178 Duration.

People have had very good results adapting an RG250 chamber to the GP125.

The hot setup is to trim 1.75mm from the barrel and "O" ring it. No head gasket for more compression and no changes to the inlet, it works just fine as is. Use a RG250 chamber with this setup. For racing use a KX80 ignition.

Others have used part of the header section from the RG250 pipe and welded there own cones to make the rest of the pipe. Use 1.25mm sheet. This gives a heavy but strong pipe that can be rigidly mounted and surives bucket racing crashes, easy to weld too.

What kind of software are you using?

Good luck and let use know how you get on.

[LeeH]

That's Brilliant TZ350, thanks for that!

Here's a link to the software, see what you think!

http://www.buildandclick.com/html/more_info.html

There are a few other things that I not sure of, I've not had much motorbike tuning experience, If you look at the software , it ask for Target HP and target RPM, to me it seems like you would be the person who would know this as you know what levels of tune work for what the bike will be used for, what I want is a fast street bike, and as we have a race circuit not very far away from Where i live (Castle coombe race circuit) then maybe I can take it around there on their open days
Wish I would of known about the RG Chamber, Ive been and got the software program for building cones as well and bought the steel 22Gauge ,I don't mind the welding part as I do welding for a living, 'live and learn I suppose' here's the cone layout program http://www.pulserate.com/

Not sure what to do now?

Regards
lee