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Author Topic: APS/G 250 2 Stroke in the Land of Oz  (Read 41849 times)

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Offline Frank06

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Re: APS/G 250 2 Stroke in the Land of Oz
« Reply #30 on: November 03, 2012, 08:13:20 AM »
Great build - I love 2-strokes!
E-Racer

Offline SaltPeter

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Re: APS/G 250 2 Stroke in the Land of Oz
« Reply #31 on: November 22, 2012, 02:12:02 PM »
Went back to the Dyno to get final Readings and it was way down on Power

One cylinder had low EGT, and found that one of the Exhaust "Power Valves" (PV) was not opening consistently, I swore a lot. then I took it home.

Found the problem, the PV shaft had a Bush missing?? so it was running on the seal as the pivot.

You can't see if the Bush is fitted unless the seal is removed, whoever put these Cylinders together left it out.:shock:

All good now, other Cylinder OK, PVs readjusted, opening and closing as Mr Suzuki intended.

Oh well better to find it now.

So I went up for a few Test runs at the Drags last night with no fairing/tail section fitted.

I ran the same gearing as the last time I ran the Bike up there, when I had the stock Fairing fitted, still had difficulty getting it off the line, it's no Drag Bike.

It ran great once moving.

When the Bike was stock with Fairings on I got in one relatively clean start (2.3sec 60ft) and got down as low as possible to get one 14.4 - 100mph run.

I went 14.5 - 100 mph sitting up, no fairing off a 2.6 60ft last night.

EGTs 1168F both sides, so I am going one size richer on the Power Jet, (they loved a bit of the old Power this and Power that in the early 90's)

New Clutch worked much better than the Rider did. :oops:

Big relief,  :cheers:

Pete
The Mission is to go as fast as possible along on that old Road Less Traveled.

Offline SaltPeter

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Re: APS/G 250 2 Stroke in the Land of Oz
« Reply #32 on: November 30, 2012, 06:54:42 PM »

The Final Tuck. I do have clearance at the rear of the Bike off the stand.



 :cheers:
Pete
DLRA#866
The Mission is to go as fast as possible along on that old Road Less Traveled.

Offline wobblywalrus

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Re: APS/G 250 2 Stroke in the Land of Oz
« Reply #33 on: November 30, 2012, 08:00:55 PM »
Pete, leaded race gas together with lambda sensors is not working very well for me.  I am looking for another way to see if the Triumph has the correct mixture.  Monitoring EGT might work for that.  Is that what you are using your EGT readings for?   

Offline SaltPeter

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Re: APS/G 250 2 Stroke in the Land of Oz
« Reply #34 on: November 30, 2012, 09:55:51 PM »
Yeah that's it.

I understand that EGT's can be used to monitor the Tune once you have a Baseline Jetting/AFR. Not really suitable to do the baseline Tuning/Jetting.

I was having a problem getting a AFR reading with my own Innovate LM1 system and at the Dyno.

What really helped me out, was that Suzuki make a Race Kit and a manual to follow as a baseline. Not exactly right, but it at least got me in the Ballpark. I used recommended Jetting + 2 Jet sizes bigger as a start and then had to rely on Plug Chops. I ended up going down 3 sizes to get good power and plug colour and had 1168F both cylinders at the Drags strip testing I did recently.

I have since found that you need to use a brand new O2 sensor or one with very little use, to get a reading on my Engine.

The last time I was on the Dyno they had a brand new sensor and I got steady readings. It was consistent 13-13.2 AFR with my EGT's showing the 1168F and the engine made
the maximum power on the Dyno, but I believe is on the "lean" side for sustained WOT runs aiming for 1100F EGTs.

I will now increase the Power Jet by one size to stay on the safe side at Full throttle, find out at, hopefully, my final Dyno run on Thursday.

Pete

The Mission is to go as fast as possible along on that old Road Less Traveled.

Offline SaltPeter

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Re: APS/G 250 2 Stroke in the Land of Oz
« Reply #35 on: November 30, 2012, 11:48:37 PM »
A pic of testing the little beast at the Drags, they are Kevlar Jeans.



Pete
The Mission is to go as fast as possible along on that old Road Less Traveled.

Offline JustaRacer

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Re: APS/G 250 2 Stroke in the Land of Oz
« Reply #36 on: December 01, 2012, 12:18:54 AM »
Nice.

100mph traps in the quarter is smoking for a 250.
My doctor told me to go out and kill people.
Well, sort of.  He told me to reduce the stress in my life.

Offline Koncretekid

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Re: APS/G 250 2 Stroke in the Land of Oz
« Reply #37 on: December 01, 2012, 06:01:15 AM »
Is that a cool air induction tube I see at the right front, and is it factory or one you made?  The reason I ask, is that I made an airbox for my BSA that was at least 3 times the cubic inches of my motor and on the dyno, it wouldn't flow enough air.  It had two 2" diameter inlets, and reduced my hp by 10% even without the duct work.
Tom
We get too soon oldt, and too late schmart!
Life's uncertain - eat dessert first!

Offline SaltPeter

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Re: APS/G 250 2 Stroke in the Land of Oz
« Reply #38 on: December 01, 2012, 09:29:59 PM »
It a simple system I made to direct air into the top of the open air box. It's not a sealed Ram Air box.

Suzuki's Race Kit specs recommends taking the lid off the Std air box and removing the divider inside the box, then fitting a flex hose air feed into the back of the open box.

Because I have lowered the seat, I have removed the lid and cut down the height of the Std air box, and left the Divider in. The flex hose directs air into the top of this set up.

Seems to work given the curve from the Dyno is nice and straight once the Engine is "on the pipe". Often this is not the case with these engines.

 

Pete
The Mission is to go as fast as possible along on that old Road Less Traveled.

Offline wobblywalrus

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Re: APS/G 250 2 Stroke in the Land of Oz
« Reply #39 on: December 01, 2012, 09:56:20 PM »
Thanks for posting that stuff on the EGT.  A variation of that method should work good for me.

Offline SaltPeter

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Re: APS/G 250 2 Stroke in the Land of Oz
« Reply #40 on: December 02, 2012, 09:41:30 PM »
No worries that was how I was shown how to use EGTs.

Here is my Air Box and the Air is directed over the top of this. On a stock RGV the Air Box lid had 2 x 35mm or 1 1/4 inch Tubes at the back of the box and sits under the Fuel tank, that is all that feeds the air in. It the goes through the Foam Filter and into what you see here. The new intake tubes are 2 x 50mm or 2 inch.

I tried running without the Air Box and I ended up with inconsistent fueling. Apparently the Carbs vibrate and have an effect on the Floats/Needle and seat in the Bowls. The Flexible Bell Mouths hold the end of the Carbs and eliminate the problem.

I left the divider in for no other reason than to help to stop the box flexing. Usually the box is bolted to the seat frame, I can't do this so the Box is held in by the Bell Mouths onto the Carbs and the Air Feed plate up top. It seems to work really well.



 :cheers:
Pete
The Mission is to go as fast as possible along on that old Road Less Traveled.

Offline SaltPeter

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Re: APS/G 250 2 Stroke in the Land of Oz
« Reply #41 on: December 06, 2012, 02:37:51 PM »
I finally got back to the Dyno.

My first Chart was not right, I knew it was too high  :-), there was a Hardware Problem,  but it looked impressive.

This is a bit closer to reality.



A nice Linear Power delivery  :cheers:

Pete
The Mission is to go as fast as possible along on that old Road Less Traveled.

Offline JustaRacer

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Re: APS/G 250 2 Stroke in the Land of Oz
« Reply #42 on: December 06, 2012, 03:51:43 PM »
What shut the engine down?  Looks like it hadn't peaked before the throttle was cut.

My doctor told me to go out and kill people.
Well, sort of.  He told me to reduce the stress in my life.

Offline SaltPeter

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Re: APS/G 250 2 Stroke in the Land of Oz
« Reply #43 on: December 06, 2012, 07:15:04 PM »
No that is what happens with these engines.

They "hit the wall" where the Power Band that comes from the Expansion Chamber Porting etc has peaked and then it drops off.

To stop any risk of Detonation in this over rev area the Ignition Timing is quickly retarded from 19 Degrees at 11000rpm to 8 Degrees at 12000 rpm.

The power characteristics of a small twin cylinder 2 Stroke is nothing like any Four Stroke.

It happens in a relatively narrow window with very little power developed either side of this window and everything else is designed around this fact.

You have to get the gear ratio spread and the shift points spot on to maintain acceleration. If you fall out of the Power Band then there is no Torque to get you going again. It's change down a Gear and have another stab at it. If you hold it in Gear too long you can feel the Power Drop off and more wasted time.

Probably sounds weird unless you have ridden one, but they are great fun.


 :cheers:
Pete

 

 
The Mission is to go as fast as possible along on that old Road Less Traveled.

Offline SaltPeter

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Re: APS/G 250 2 Stroke in the Land of Oz
« Reply #44 on: December 11, 2012, 09:27:47 PM »
The Final piece of the APS Jigsaw.

This is the first stage of the Plug for the Front Mudguard Mould.

It's 1 Part RGV, .5 RM 80, 2 Parts 1mm Ally and a few rivets and Sikaflex.



It is getting filled in and finished by a Panel Beater mate for Beer.  :cheers:

Pete
The Mission is to go as fast as possible along on that old Road Less Traveled.