TW200 Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
889 Posts
Discussion Starter #1
What do you guys believe is the best performing header pipe for the TW. I know the TTR fits and the aftermarket has some products out there. What works the best and do I have to re-jet...again? I am running a 130 and a 30 off the procycle kit with a flex jet. I have a DG slip on. Thanks MBW

Also,what is the torque spec for my header bolts? Thanks
 

·
Super Moderator
Joined
·
4,856 Posts
The TTR is widely used, ‘cos they’re out there and they’re cheap(ish). The TTR header also has the advantage of being Stainless Steel, so is lighter than the TW counterpart. In theory, because the thickness is less, it will be more noisy, but no-ones complained yet. It’s also rumoured they polish up quite nicely too, though keeping it that way could present some difficulty

The diameter of the header pipe isn’t likely to make any difference to jetting, as at one end, it’s restricted by the hole in the cylinder head the gasses come out of, and at the other, by the speed at which that gas can escape, eg the muffler. What goes on in-between those two points is largely academic in the world of exhausts. You could delve into the world of “power bombs” et al, but on a TW, the issue of recoil is pointless

Anybody who’s trying to sell something will tell you what you want to hear, and other than the “smug grin”, mostly from the seller, it all becomes a placebo — stick with the TTR

Here’s your torque setting, be gentle, the bolts are old, the threads are dry and rusty, and getting a busted stud out of there is a complete pain …..


xxxcc.JPG
 

·
Super Moderator
Joined
·
4,856 Posts
Here’s a link that should help to explain it a bit more - https://thumpertalk.com/forums/topic/1075515-megabomb-header-explanation/

But until we all get to know what bike you have and your elevation, I’m gonna have to “generalise” a bit ….

The principle of the “power bomb” has been around a while, but usually applied to highly tuned “old style” racing cars with straight exhausts. FMF have taken that theory, expanded the market to bike exhausts, and managed to convince (not many) customers that this alone is what fixed the bike for them

First, take a bike that’s set up wrong, add a custom muffler, re-jet it, add a power bomb – and the customer will swear blind it was the power bomb header that did it. It’s a bit like sticking a custom muffler on “your” bike, re-jetting accordingly – and then saying “I’m so glad I bought this muffler, it’s brilliant”

It’s everything you start with, and every component you change afterwards that makes the difference. If you’re looking for “night and day”, it helps if you started in the dark

IMO, the primary things you can do to a TW to improve (throttle) response, is:

Stage one: Start out with a slide carb, get a slip on, and get your jets right
Stage two: Add one of Tom’s CDI’s to stage one
Stage three: Add a slide pumper carb, and pay attention to stages one and two

If you can do all of the above, fair play to you, the lot will cost around a grand. You will then feel that extra half a horse power via your butt dyno – well, some of the time anyway. In fact, most of those above will only give you better throttle response, mostly giving you more immediate access to power you potentially had already, but with a couple of exceptions ….

Slide carbs perform better - brutal, but true. CV carbs are more fuel efficient, which lessens performance (and emissions, which is why Yamaha uses them on the TW). So a slide carb is your starting point. The average slider, can have a few “flat spots”, as the way these work can’t get enough fuel in there to compensate for sudden throttle increases. Introducing the “slide pumper”, which can squirt extra fuel into the mix at exactly the point where an ordinary slider would need it. So now you have a “full range” carb, though not perhaps “fuel efficient”

The next thing is your muffler – because if you have the fuel going in, you need to get it out of there – right ? But the jetting is important at this stage, and if you starve that pumper, you’ll know about it. Ditto the slip on, they work at getting the exhaust gasses out of there, but only if they’re in there to begin with. With both the input and the output now sorted, we are now “cooking with gas”, and your butt dyno is going to start to “twitch”

Enter the “Tomwhateverhisnameis” CDI – the timing curve of the ignition is crucial to delivering power smoothly and progressively, and is perhaps the singular thing you can do (other than re-jetting) to improve the performance of your bike

Now we get back to “power bombs”. As we’ve discussed before, unless you have a race tuned 30 year old Lotus with straight pipes, they’re only going to complicate things, and throw your jetting and balance straight out of the window. With the inclusion of a slip-on - (ironic, as they’re marketed by FMF) - self-defeating. On a racing bike, perhaps, but even so, the “fine tuning” would be insane – “off the shelf”, it’s simply not going to happen in TW world

So - Michael Bryce Winnick – fancy getting “complicated ? – because it is going to get “very complicated” …..
 

·
Super Moderator
Joined
·
4,856 Posts
OK Purple. What slide/slide pumper carb fits and works on these bikes?
TM28-1 - Mikuni TMR seems a plug and play deal - Yoshimura — Keihin — basically any pumper that’s 28 or 30 mm — even the Chinese ones

We all have our favourites ….


413Gb56Du3L.jpg
 

·
Registered
Joined
·
889 Posts
Discussion Starter #9

·
Registered
Joined
·
562 Posts
It couldn't hurt to take a dremel and grind the weld smooth at the ID of the header. That's a critical flow area.
I did and I've wasted 2 rear tires doing smokey burnouts. I probably will extend my swingarm 12" just to make it rideable.
Seriously though,it couldn't hurt just don't get greedy and grind through the weld or tubing
I feel the TW is in such a low state of tune that no single modification will do much other than making sure there is fuel in the tank
 

·
Super Moderator
Joined
·
4,856 Posts
Yes – those are the part numbers / years that fit. You will need a new gasket, other than that, maybe a hacksaw on standby to get it onto the muffler …..

I’ve edited my earlier post as I’d inadvertently used “power core” where it should be “power bomb” – “powercore” is a muffler, “power bomb” is a lump in the header pipe (and you asked about header pipes)

IMO there is negligible difference between the DG and FMF mufflers ….
 
1 - 11 of 11 Posts
Top