DT 125 2003 Exhaust = loss of power

[Ekki91]

Hi,

I recently bought a 'Big One' complete exhaust and fitted it to my 2003 DT 125 with no problem at all.

The bike runs like a dream; in gears 1-5 the RPM freely runs up to 9-10k, with the powervalve kicking in at 8500 rpm.

However!

If I'm in fifth gear and kick up to sixth I lose RPM instantly and the bike bogs down to 55-60mph, with the RPM sitting at 7000.

For example:

Fifth gear = 70mph & 10,000 rpm no problem

As soon as I kick up to sixth gear = RPM goes down to 7000 rpm and regardless of the amount of throttle, the bike reclines down to 55-60mph.

If I put it into sixth at 45mph (before the exhaust swap it still had some acceleration at 40-45) it doesnt even climb speed, it just sits at 45.

I was told to up the jets one size but I thought I'd ask people who know what they're doing!

Thanks in advance

## EDIT ##

Also, although the seal is tight and it's not blowing, it sounds like the exhaust is blowing where its fitted to the engine, at high speeds/rpm there's a very loud vibrating noise which sounds like a very loud rattling/vibrating/blowing... whats that all about?

Edited July 6, 2010 by Ekki91

[2 Wheels]

For example:

Fifth gear = 70mph & 10,000 rpm no problem

Ya will have huge problems if ya keep doing that!!

I was told to up the jets one size but I thought I'd ask people who know what they're doing!

This will work if ya do some other things along with it!!

at high speeds/rpm there's a very loud vibrating noise which sounds like a very loud rattling/vibrating/blowing... whats that all about?

This could be your little-end in the crankrod because you are driving the guts outa the little motor!!

Now that i have that off my chest ill try and help in my next post !!!

[Ryan09]

Did you put a new gasket in with the header? I re-used mine and it spat un burnt oil everywhere even got it on my boots.

Could try up jetting, although i had a similar problem but with a dep but not to that extreme but you had to change gear just right and it would just take off in 6th but catch it wrong and well it bogs like you said,

hth