OzVMX Forum

Clubroom => Tech Talk => Topic started by: philthy on October 31, 2009, 02:57:14 pm

Title: yz250f pipeand muffler
Post by: philthy on October 31, 2009, 02:57:14 pm

As my rebuild of my yz250F is nearing completion it is time to think about a pipe and muffler combo.The original chamber is unmarked so I am thinking of leaving it for show,however as I want to race this bike I need a complete system.Does anyone recomend a good system for the 79 YZ?As far as I know there are three available,DG,PROFORM,or a Geoff Morris Concepts Pipe. 

Title: Re: yz250f pipeand muffler
Post by: oldyzman on October 31, 2009, 03:31:49 pm

Gday Phil, I have just rebuilt the same. I am running the std pipe with an old DG Mufler from a YZ400D, sounds ok, but i will be interested to see what the others recomend.
Brett

Title: Re: yz250f pipeand muffler
Post by: Viper666 on November 08, 2009, 11:07:29 am

I run a DG pipe & std muffler. Find it to be a great combo, sounds good & spreads the power a bit better than standard.
 Viper666

Title: Re: yz250f pipeand muffler
Post by: oldyzman on November 08, 2009, 08:26:19 pm

Hello Viper can you please tell me what jets you run, also was wondering what air bled jet you run-the one in the bell intake side of the carby.
Cheers Brett

Title: Re: yz250f pipeand muffler
Post by: Viper666 on November 09, 2009, 02:04:21 pm

Ports cleaned up but nothing drastic, running carbon fibre reeds with spacer, squish not done. Got it dyno tuned and cant remeber the jets but they are close to standard. Standard slide #3, standard clip position.
Must say it pings at Blue rock no matter what I do to it but OK at Wonthaggi, go figure?
As far as I know anything above a 32mm doesn't run an air jet, just the hole straight through, at least none of mine do?
My 125 does, IT175 did but used a 32mm.
If I'm in the shed over the week I'll have a look and get back to you.

My opinion take it to Jay Dee Motorcycles in Gisborne (0354281331) with as many different size jets that you've got and let them do it. They didn't do mine but I'm told they are real good with the old stuff.

Make sure all your electrical stuff is up to scratch. Check everything with a digital multimeter before bothering to jet. I have all the specs if you need them.

Viper666

Title: Re: yz250f pipeand muffler
Post by: oldyzman on November 09, 2009, 10:51:17 pm

Hey viper, thanks for that info re the air jet... The elec specs would be great, so i can test further. By the way is yours white or yellow
Cheers Brett

Title: Re: yz250f pipeand muffler
Post by: Viper666 on November 10, 2009, 01:10:42 pm

Timing 1.37mm BTDC

Pulse Coil (Red/White to Red) 500 Ohms +/- 10%
Source Coil (Brown to Red) 1437 Ohms +/- 10%
Quick test Red/White to Brown 1940 Ohms +/- 10% (Just proves both coils are not open circut)

Ignition Coil Primary (Yellow/Orange lead to metal body) 0.6 Ohms +/- 10%
                Secondary (Plug lead to metal body) 6200 Ohms +/- 20%
Quick test Yellow/Orange lead to Plug lead 6200 Ohms +/- 20% (Just proves both coils are not open circut)

White

Viper666