UK Karting - Notice Board (2-Stroke Karting) : Low end power

Notice Board (2-Stroke Karting)

Low end power - Exhaust / Exhaust Valve
Posted by 'ChristianWood' on 13 Jul 2010 @ 12:53

| View Message Thread | Reply to this message |

ChristianWoodJoined: March 2009
Total Posts: 1
[ View User Profile ]

I'm having issues with low end power. I have always known the Rotax engine is rather poor low down the revs, so had assumed my karts pathetic pace below ~7000rpm was normal in testing.

It's only since I've been doing more races that I've seen my low end is significantly worse than other engines. Rolling starts absolutely kill me if starting from low revs, always dropping to the back of the field before the first corner. I find I have to keep the engine above ~7000 to maintain any amount of power and even coming out of the pits is a torturously slow affair until a certain point where all the power comes in at once.

After talking to people in the pits, these are the things I've covered:

Gearing - I'm actually running a slightly bigger sprocket than most people in my class, so this isn't the issue.

Jetting - I've checked and have been running sensible jetting, the same as the other people in my races.

Driving Style - I run wide lines to try and keep the corner speed as high as possible, but anyway, this issue happens even in a straight line, next to a similarly set-up kart, so have ruled this out too.

Only thing I can think of is the Exhaust / Exhaust Valve. The fact that I receive no power up to ~7000rpm, then a kick in the back points towards this too with the switchover of powerbands supposedly occuring here.

Few questions then:

My exhaust is not 100% flush with the engine mount. The chassis mountings have made this difficult, so it is slightly misaligned. Some have told me this is no problem, some have told me this a big problem. Which is it?

How do I know when the PV is actually engaging / disengaged? I have rebuilt the PV and adjusted it in testing from fully in, all the way to fully out. This has no effect on the low end at all.

Any ideas what's causing my Chandhok-like speed at low revs?

Message Thread:

Low end power - Exhaust / Exhaust Valve by 'ChristianWood' << You are here!

Re: Low end power - Exhaust / Exhaust Valve by 'DDD' (13 Jul 2010 @ 13:11)

Re: Low end power - Exhaust / Exhaust Valve by 'DDD' (13 Jul 2010 @ 13:15)

Re: Low end power - Exhaust / Exhaust Valve by 'DDD' (13 Jul 2010 @ 13:17)

Re: Low end power - Exhaust / Exhaust Valve by 'ChristianWood' (13 Jul 2010 @ 15:57)

Re: Low end power - Exhaust / Exhaust Valve by 'DDD' (13 Jul 2010 @ 17:08)

Re: Read this by 'John' (13 Jul 2010 @ 20:05)

Re: Read this by 'raceinstructor' (13 Jul 2010 @ 21:49)

Re: Read this by 'HappyWheels77' (13 Jul 2010 @ 23:56)

Re: Read this by 'ChristianWood' (14 Jul 2010 @ 0:28)

Re: Read this by 'Ditch' (14 Jul 2010 @ 6:02)

Post a Reply:

You may post a direct reply to this message which will appear in this thread.
To post a new or unrelated message use This Form. Top of Page
Notice Board Index

[ UK Karting Main Index ]


News	Karts & Karting	Notice Board	Market Place	Companies Directory	Tracks Directory	Events Calendar	Race Results	Photo Gallery	Links