Mito 421 cheetah dyno and improvement

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alex2218
Posts: 33
Joined: Sun May 22, 2016 8:27 am

Mito 421 cheetah dyno and improvement

#1 Post by alex2218 » Thu Jul 13, 2017 8:40 am

Hi guys,

Finally passed the engine @ the dyno this weekend, i was racing at Magny-cours for the RD500 track weekend.
Off course, this curve is rear wheel power on 5th gear, add 20% for engine HP.

Video here ==> https://youtu.be/GsoJgAIYiz8" onclick="window.open(this.href);return false;

I passed some Tz and 500 RD/RG easy so i think this dyno is really pessimist according to the owner.
I'm really proud of my setup and work, engine have plenty of torque, but know i'm looking for a way to improve mid-range power to boost the range between 6000 and 8000 because this range make the engine very hard to ride specially out of corner

So if any of you have some tips i'm listening

Image


:smt023

(F5)
Posts: 630
Joined: Mon Sep 27, 2010 7:21 pm
Location: Wellington New Zealand

Re: Mito 421 cheetah dyno and improvement

#2 Post by (F5) » Sun Jul 16, 2017 1:51 am

Yeah my 496 has a dip there. I pulled the ypvs fuse and got a bunch back. Hold on you say. Well mine is converted to servo motor, sorry no more kits being made. My next step is program later PVopening when iI wire in the Ignitech that'sjust arrived.

So you could try a little more preloaded on your power valves. Perhaps the air bleeds which are drilled out jets might be made smaller to delay PV opening.

Make sure the valves in closed are close to piston.
Feed some more advance at the lower end, it should be safe as you haven't got much pressure going on with combustion.

Try leaner needle or position, it may just not be able to recover from a dump of rich gas when you whack it open on the dyno.
496 Cheetah. TSS PVs, PWK35s, Ignitech, RGV(ish) chassis

alex2218
Posts: 33
Joined: Sun May 22, 2016 8:27 am

Re: Mito 421 cheetah dyno and improvement

#3 Post by alex2218 » Mon Jul 17, 2017 4:30 am

Sorry, it's not a cheetah but a cheetah CUB, there is no valves :smt003

But i'm assuming it is way too rich, changed jet from 170 to 165 and it still bit too rich... Engine should be 95hp with the good jetting
I'm going to lean the needle a little too
Timing is already very high from 3k to 6k (about 30°) but i can gadd a little more

(F5)
Posts: 630
Joined: Mon Sep 27, 2010 7:21 pm
Location: Wellington New Zealand

Re: Mito 421 cheetah dyno and improvement

#4 Post by (F5) » Mon Jul 17, 2017 5:35 am

They get a little optimistic with their power claims I understand.
Yeah 30 isn't mild. I do wonder how suitable the air correction jets (well, drilling) are at producing a suitable curve with pwks.
496 Cheetah. TSS PVs, PWK35s, Ignitech, RGV(ish) chassis

alex2218
Posts: 33
Joined: Sun May 22, 2016 8:27 am

Re: Mito 421 cheetah dyno and improvement

#5 Post by alex2218 » Tue Jul 18, 2017 4:35 am

Yes, a lot of riders are using very very optimistic dyno since they have 105 HP at the wheel..... :smt015
And even if true, engine is unrideable.

Stock PWK idle jets were way too rich, i'm 50 now and still bit too rich but it's to prevent seize on the gaz throttle closing.

If you see my friend Etienne post : viewtopic.php?f=5&t=6593&p=116934&hilit=etienne#p116934" onclick="window.open(this.href);return false;
His bike is one of the most powerful i know and it is "only" 80hp like me... but i has much more mid range :smt001

I really would know too what needle and drilling is the best for this engine mid-range power

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