Exhaust suggestions?

[dirtdigginjoe]

Hey guys,

   Finishing up my 4mil build, and want to get an idea of what to expect, and have a few questions. My setup is listed below:

 

• 4mil longrod stock cylinder (65.50mm)
• MX/Woods port by Diggin Racing
• 35mm PWKs w/pods
• CoolHead with 21cc domes (Sea level)
• VForce 4's
• Adjustable timing plate (Not set)
• Toomey T5's

 

RIding at sea level usually

Woods/Fast trail riding

Staying on 93octane!!

 

My question is, am I missing out on performance due to the bottom/mid port and a topend pipe?

The domes can be swapped out once i do a compression test when it's all together, but what would you recommend for timing advance?

 

Thanks!

[Colby]

i wouldnt go past +2 on the timing ..  and a the T-5's are about as good of a pipe as your going to get for all-around performance w/ a MX port .

[sprinklerman]

Hey guys,

   Finishing up my 4mil build, and want to get an idea of what to expect, and have a few questions. My setup is listed below:

 

• 4mil longrod stock cylinder (65.50mm)
• MX/Woods port by Diggin Racing
• 35mm PWKs w/pods
• CoolHead with 21cc domes (Sea level)
• VForce 4's
• Adjustable timing plate (Not set)
• Toomey T5's

 

RIding at sea level usually

Woods/Fast trail riding

Staying on 93octane!!

 

My question is, am I missing out on performance due to the bottom/mid port and a topend pipe?

The domes can be swapped out once i do a compression test when it's all together, but what would you recommend for timing advance?

 

Thanks!

In my experience, T5's SUCK for an MX/Woods port. Id look for some Pro Circuits . You'll throw rocks at those T-5s after you try them. The PC's (for me) came on a lot sooner, and pulled just as good on top...after all we are talking about a Trail/MX style port. Its more about the midrange and how the power comes on from the bottom.

  This was all done on a 350 and a stock cyl 4mm with a mild "MX" style port with Pump gas.

[dirtdigginjoe]

In my experience, T5's SUCK for an MX/Woods port. Id look for some Pro Circuits . You'll throw rocks at those T-5s after you try them. The PC's (for me) came on a lot sooner, and pulled just as good on top...after all we are talking about a Trail/MX style port. Its more about the midrange and how the power comes on from the bottom.

  This was all done on a 350 and a stock cyl 4mm with a mild "MX" style port with Pump gas.

 

Yeah I'm looking for usable power, as I just want to compliment the porting with the proper pipes.

What about the DMC pipes?  I hear they're a good bottom/mid pipe, and the 916's sound badass...thoughts?

[sprinklerman]

Yeah I'm looking for usable power, as I just want to compliment the porting with the proper pipes.

What about the DMC pipes?  I hear they're a good bottom/mid pipe, and the 916's sound badass...thoughts?

Ive never personally owned them,but i have rode a bike with them,and they were nice. People who own them swear by them.  And they do sound good. My PC sounds pretty good,but are what most people would call on the quiet side.

[So Cal Suspension]

In my experience, T5's SUCK for an MX/Woods port. Id look for some Pro Circuits . You'll throw rocks at those T-5s after you try them. The PC's (for me) came on a lot sooner, and pulled just as good on top...after all we are talking about a Trail/MX style port. Its more about the midrange and how the power comes on from the bottom.

  This was all done on a 350 and a stock cyl 4mm with a mild "MX" style port with Pump gas.

Couldn't agree more. Ditch those T5's. They are one of the worst pipes to run on mx porting. PC's are the way to go. They can be purchased pretty cheap, or you might be able to find someone to swap you straight across for your t5's.

 

Regarding your timing advance question, absolutely. Go to +4.

[dirtdigginjoe]

Couldn't agree more. Ditch those T5's. They are one of the worst pipes to run on mx porting. PC's are the way to go. They can be purchased pretty cheap, or you might be able to find someone to swap you straight across for your t5's.

 

Regarding your timing advance question, absolutely. Go to +4.

Yeah those PC's were my second choice pipe, as I knew people had great results with them on a 4mil. 

 

And I was leaning towards +4 timing, as that's what most go with on a pretty stock machine. If I ran 110 octane, would I see a noticeable difference? I can get it at a local gas station for about $7.10 a gallon.

[So Cal Suspension]

Well, I will never own a bike that runs on anything other than pump gas. I have a 535 cheetah that runs on pump gas. The horsepower loss isn't drastic enough for me to want to pay $8 a gallon for race gas. I'd rather be able to pump it straight from my trailer into a 5 gallon can, and not have to worry about running out because I didn't buy enough.

 

You don't gain power just simply by running high octane fuel. That is a misconception. The reason you run high octane fuel, is because it burns slower, which allows you to run much higher compression, and more advanced timing. The power increase comes from those two things, rather than the fuel itself.

[dirtdigginjoe]

Yeah I shoulda mentioned I'd obviously get smaller domes and advance the timing a bit more. But I'll stick with 93, since it's a lot easier to just run to a station for fuel. I actually used to use my coolant bottle (obviously capped off) as a container for 2stroke oil when we went out riding all day, in case we had to fuel up.. wasn't always dead on, but I had a sharpie marking 12oz, so it was damn close! 

[apeik]

That's not a bad idea, the coolant bottle that is.

[dirtdigginjoe]

That's not a bad idea, the coolant bottle that is.

 

I just capped off the holes, measured 12oz in a measuring cup, and poured it in, and made a sharpie mark. Stupidly simple, and will help you in a pinch if you forget oil at home. I always keep it there, just in case. It might be ghetto, but it's saved my ass more than once when out riding upstate!

[Jgspahn]

I just capped off the holes, measured 12oz in a measuring cup, and poured it in, and made a sharpie mark. Stupidly simple, and will help you in a pinch if you forget oil at home. I always keep it there, just in case. It might be ghetto, but it's saved my ass more than once when out riding upstate!

Genius!!!!

[rjdgriff]

I like it