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From: Chet on 14 Jul 2010 23:31
I removed the muffler on my Honda CRF230L from the header, the header ID
is 1.250 Dia, so I slipped an 1 3/8 id tube over the header and clamped
it the tube is 18" long near the end I drilled a series of holes and
used a larger dia tube to make a muffler and packed it with fiberglass
cloth, so the over all length is 18" including the muffler and the tube
id is 1.277, took the bike out and rejetted the carb along with a modded
air box lid, the bike has good mid range power but a little flat on the
top, with this in mind If wanted to tune the exhaust for more top end
power. what would I need to look at, larger id tube or adding a few
inches to the overall length, shortening ect, ???

thanks

Chet
From: XR650L_Dave on 15 Jul 2010 08:23
On Jul 14, 11:31 pm, Chet <c...(a)epix.net> wrote:
> I removed the muffler on my Honda CRF230L from the header, the header ID
> is 1.250 Dia, so I slipped an 1 3/8 id tube over the header and clamped
> it the tube is 18" long near the end I drilled a series of holes and
> used a larger dia tube to make a muffler and packed it with fiberglass
> cloth, so the over all length is 18" including the muffler and the tube
> id is 1.277, took the bike out and rejetted the carb along with a modded
> air box lid, the bike has good mid range power but a little flat on the
> top, with this in mind If wanted to tune the exhaust for more top end
> power. what would I need to look at, larger id tube or adding a few
> inches to the overall length, shortening ect, ???
>
>     thanks
>
>         Chet

Could be you've given it enough flow in and out that now you're seeing
the limits of the camshaft.

What you're attempting is non-trivial even with a dyno to measure the
changes, but 18 inches may be a bit short.

How loud is this pipe?


Dave
From: john on 15 Jul 2010 08:32
exhaust mods are tricky to say the least, normally on 4 strokes
if you open them up a bit for added top end you loose the
low end torque.... factory exhaust usually works well and
any HP gains with aftermarket exhaust are minor... the sound
is usually louder, which some folks like, but most spectators do not...

removing the stock defuser makes the bike too loud and
the exhaust back pressure drops significantly scrubbing off the
low end torque, if you drill out the stock diffuser front hole
slightly and enlarge the side hole a bit.. you will gain a noticeable
top end performance without sacrificing the bottom end all while keeping
the bike relatively quiet (and the mod is cheep)
I think neighbor used the 11/16 drill bit for the front and a 3/8 for
the side holes, not sure... he also remove his airbox baffle
and went up one main jet size.

the popular mod to the 230 is to drop a tooth size on the
front sprocket (go from 13 to 12) this scrubs a bit off
the top speed, but enables most crf230 rider to keep
up or out grunt the 250 / 400 riders in the 2-15mph range
while in tighter woods type riding where a lighter agile bike


"Chet" <chet(a)epix.net> wrote in message
news:Giv%n.9800$Bh2.4306(a)newsfe04.iad...
>I removed the muffler on my Honda CRF230L from the header, the header ID is
>1.250 Dia, so I slipped an 1 3/8 id tube over the header and clamped it the
>tube is 18" long near the end I drilled a series of holes and used a larger
>dia tube to make a muffler and packed it with fiberglass cloth, so the over
>all length is 18" including the muffler and the tube id is 1.277, took the
>bike out and rejetted the carb along with a modded air box lid, the bike
>has good mid range power but a little flat on the top, with this in mind If
>wanted to tune the exhaust for more top end power. what would I need to
>look at, larger id tube or adding a few inches to the overall length,
>shortening ect, ???
>
> thanks
>
> Chet


From: Chet on 15 Jul 2010 12:43
On 7/15/2010 8:23 AM, XR650L_Dave wrote:
> On Jul 14, 11:31 pm, Chet<c...(a)epix.net> wrote:
>> I removed the muffler on my Honda CRF230L from the header, the header ID
>> is 1.250 Dia, so I slipped an 1 3/8 id tube over the header and clamped
>> it the tube is 18" long near the end I drilled a series of holes and
>> used a larger dia tube to make a muffler and packed it with fiberglass
>> cloth, so the over all length is 18" including the muffler and the tube
>> id is 1.277, took the bike out and rejetted the carb along with a modded
>> air box lid, the bike has good mid range power but a little flat on the
>> top, with this in mind If wanted to tune the exhaust for more top end
>> power. what would I need to look at, larger id tube or adding a few
>> inches to the overall length, shortening ect, ???
>>
>> thanks
>>
>> Chet
>
> Could be you've given it enough flow in and out that now you're seeing
> the limits of the camshaft.
>
> What you're attempting is non-trivial even with a dyno to measure the
> changes, but 18 inches may be a bit short.
>
> How loud is this pipe?
>
>
> Dave


Thanks Dave

the overall length is 18" which is a straight thru, vs the stock
muffler with internal baffles and the catalytic converter is around 3-4
inches longer, I can experiment easy enough to add a extension on the
tip of the muffler like maybe 3 or 4 inches and see what it does for the
bike.

Chet
From: Tiago on 15 Jul 2010 13:06
The CRF230F is a sweet bike.
Lots of aftermarket.
Use google translation if you're not good on portuguese language:
http://www.adrenalinamotoracing.com.br/navegacao.php?busca_nome=crf230

-- T

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