You'd need to get the pipe before bothering with the carb, just to get the gains from the carb which are substantial..if you change you air filter etc

It all works together afterall

 

Richard, that fella presents high velocity intake tracts like it's a new idea. It's a very old idea - even older than me. lol. From what I could tell, he only talks about port cross section - in reality it is an artful balance between cross section and port length. Same applies for exhaust tracts. Think about this - the higher the intake charge velocity, the longer the intake valve can be held open past BDC before incurring intake tract reversion.

 

Okay, I'm with you on that. :headscratch:

Guess I'll find out eventually about the cam mod vs bigger bores as I go along first adding the cam mod then the 331 kit and tune it with an a/f meter, then of course hopefully be able to accuately gauge performance before and after.

Lots of free time over here

 

so keeping the stock header is the best bet? many people have said that they felt more power with the powerbomb but i guess the dyno doesnt lie. so then what are the differences in fmf q4 qnd powercore 4? or what slip on should i get, and does taking the lid off the airbox make much difference when i have the snorke removed?
thanks for all the help guys!

 

If you are talking about the marelino cam mod, it will be of little gain, maybe even a hinderance, on a big bore kit. The mod just moves the powerband lower in the rpm range, making the bike more torque and spunky where we ride in it most often 3-6k rpm.

A big bore in essence does the same thing, except it ups the power with displacement AND brings the torque lower in the rpm range. A big bore with the marelino mod is taking a step backwards, your motor will be suffocated. Since the power gain on a big bore is high already down low you want a more aggressive upper rpm cam (grind 101 webcams?) in order to extend the powerband a little bit.

 

Found that post. Can you feel 1/10 of a hp?

 

One would suppose not...but why spend $200 on something that is possibly going to lose hp, and even then only gain maybe 1/10hp on another dyno?

 

with all due respect to Bill Blue, I find it hard to believe that a properly fueled bike would lose power with a header over the stock piece of trash head pipe. I think there was a variable they were missing with their test.

Many people who are a lot smarter than I and with a lot more experience with performance engines in general have said the stock header is simply to small, especially with a big bore kit.

I know i'll be getting one.

 

That's where the 40mm carb comes into play? I'll find out because mine will be here in a couple months.

This TM36 is doing so well on my 250, the additional 80cc should easily be up to a 4mm larger carb bore. Especially with an accelerator pump to counter low any inherent low speed speed lag.

Luckily the cam mod is easy to do and undo if I just take the spring off the ACR.

Someone here used Webcams and didn't notice much of an improvement-he said it'd kind of be the last thing to do after all other mods were exhausted





Supersonic nozzle

 

Well Frampton, while we will all debate the effectiveness of the power bomb/mega bomb until the cows come home ( Or until someone does a really good dyno test, before and after.) one thing I think you can count on is that the mega bomb will lower your exhaust noise. That alone may make it worth it to you.

As far as the airbox lid - My experience is that the lid restricts airflow to my bike with or without a snorkel. DynoJet seems to know this as well. Reading in here you'll find that lids are left on mostly due to the loud intake growl/noise - that noise is due to the stock cam timing and is fixed with the MCM and, I'm sure, with a BB kit. Recently, experiments done by Richard Avatar may indicate the open top airbox is still too restrictive on a stock bore. IMHO you are losing significant HP by forcing your 351 to breathe through a lid/snorkel - which will become more tragic after you put on a free flowing slip-on.