Supercharged CBR250 build

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RGV
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Re: Supercharged CBR250 build

Post by RGV » Tue Apr 22, 2014 7:25 pm

Hey Tiny, I know ya not using a Lectron but, Lectron Alcohol carbs use 2 Power Jets, gas only one. They cant supply enough fuel at top end with only one.

This is from their (Lectron) site but they are talking about one carby per cylinder, not one per 4 cylinders like you have.

"Can I convert my “gas” Lectron to an “alcohol” ?
Yes, first you must have a power jet carburetor to start with. When you are using the carburetor for a 2 stroke engine you must add an additional power jet, for a total of two power jets. For a 4 stroke this is not necessary. he other modifications is changing the needle & seat and metering rod. We HIGHLY recommend using a fuel pump to keep proper fuel flow. We have found with Alcohol applications gravity feed is not sufficient."

As for tuning, I jet mine blubbering rich at home and start from there at the lake after seizing my motor on the first run on my first attempt in 2010.

Dave

Last Minute Racing "its a 2-stroke ya twit - Its supposed to smoke"
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2010 MPS/G 250 118 MPH:)
2011 Washed Out:(
2012 Washed Out:(
2013 MPS/G 250 131 MPH (RECORD):)
2014 MPS/G 250 140 MPH (RECORD):)
2015 MPS/F 250 DNF:(

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dplecko
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Re: Supercharged CBR250 build

Post by dplecko » Tue Apr 22, 2014 8:17 pm

with a roots, no intercooler and methanol you may need to run richer than what the wideband can read ...

think they were called Gunstons back in my day.

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AuotonomousRX
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Re: Supercharged CBR250 build

Post by AuotonomousRX » Wed Apr 23, 2014 3:57 pm

dplecko wrote:with a roots, no intercooler and methanol you may need to run richer than what the wideband can read ...

think they were called Gunstons back in my day.
Tiny

I'd say Paul is right on the money,

The Drag Racers generally use different Tuning Data: Turbo/Methanol Engines generally use AFRs, but the Rootes/Methanol Engines use EGT's .

The big difference is the Engine RPM you run at is so much higher than a usual Rootes set up.

I wonder if the Pulsing from the Rootes is also a factor here? Can be an issue on V Twins, just a thought.

The info Dave posted also touches on something as well, I think I posted the Jetting on my Bike? anyway with an "Open" Air Box.

Genuine Mikuni Jets: 4/042 - #370 (cc/min) x 2 and N10222 - #50 (= approx 35cc/min) Power Jets x 2 for straight Petrol (not pre mix).

That means I have a total available flow rate of 370+370+35+35 = 810 cc/min of Petrol for 250cc making 67hp @ 11000rpm reading 1330 F peak temps, so that's not Rich.

I hope this info is some help :?:

Pete :)
Metric Target 250 on a 250 on a Red Bike

Pete :shock:
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rgn

Re: Supercharged CBR250 build

Post by rgn » Thu Apr 24, 2014 12:59 pm

I'm not sure what brand Wide band O2 set up you have, but I know the dynojet wideband I use needs the chip re-flashed if you want to run methanol and get readings that make sense. I have the files for flashing for methanol and for petrol back from methanol if you need them.

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gennyshovel
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Re: Supercharged CBR250 build

Post by gennyshovel » Thu Apr 24, 2014 4:01 pm

Innovate MTX-L, re calibrated for methanol, I'm onto my 2nd Bosch wideband O2 sensor (in 10 miles)
Ive contacted their help feature, one of the errors I've had is a power supply problem, according to the rep, if so (and the EGT's are fed from the same source) HTF does an unpowered gauge tell me anything ? they have yet to explain why it gets bogged on it's max lean lie of 9.7, usually after throttling down after a run.
And is a overly rich mixture reads as a lean mixture, what's the good of that I ask ?
Iv'e wasted 3 months relying on a gauge that lies, if I had done the plug reading after a flog and chop I would have made it to speedweek 2014, with a bike AND beer, maybe I'd have melted another piston ? maybe not, a few GPS flogs with chops & turnouts followed by a fist full of new plugs between runs, I'm sure I'd get down the main track, eventually.
I had hoped technology would have made tuning easier, silly me, not with methanol it wont .
Dave P, I'm aiming for 4 to 5 @ wot
Dave rg, I'd worry about 2 x power jets obstructing too much air flow
Tiny
Tiny DLRA# 484
Postiebike Racing , created & funded by TwoBob Engineering

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Greg Watters
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Re: Supercharged CBR250 build

Post by Greg Watters » Thu Apr 24, 2014 5:46 pm

Problem is sensor temp, it cant run enough power to the heater circuit to work right on methanol

use egt and keep wideband for a less than reliable backup or extra info

went through the same frustration on my busa

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gennyshovel
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Re: Supercharged CBR250 build

Post by gennyshovel » Thu Apr 24, 2014 8:23 pm

Thanks for that Greg, so I'm not alone eh !
With Wilso's proposed 250 chair build, using my engine (or another built similar, if(when?) mine dies, bugger the methanol, megasquirt,turbo, VP, intercooler and a zillion new pieces of information to put together and get to work.
Tiny DLRA# 484
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Greg Watters
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Re: Supercharged CBR250 build

Post by Greg Watters » Fri Apr 25, 2014 7:50 am

Turbo..... injection......intercooler :D :D :D :D :D

Stayt`ie
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Re: Supercharged CBR250 build

Post by Stayt`ie » Sun Apr 27, 2014 3:30 pm

hay Tiny, as im to lazy to go back and read your posts, a few questions,, how much advance are you running :?: , also im thinking your head is Pentroof :?: ,, Pentroof heads "DONT LIKE" advance with methanol,,, with a hemi head ive seen out to 47* no problem, pentroof, thay start complaining with as little as 3* over standard,,
First Australian to ride a motorcycle over 200mph at Bonneville,,,

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gennyshovel
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Re: Supercharged CBR250 build

Post by gennyshovel » Sun Apr 27, 2014 4:46 pm

Stayt`ie wrote:hay Tiny, as im to lazy to go back and read your posts, a few questions,, how much advance are you running :?:Non ADJUSTABLE, 11 BTDC @ IDLE, DROPPING TO 5, RAMPING STEADILLY UP TO 48 @ 12,000 THEN UP TO 51 TO 15,000 , also im thinking your head is Pentroof :?: ,YUP, Pentroof heads "DONT LIKE" advance with methanol,,, with a hemi head ive seen out to 47* no problem, pentroof, thay start complaining with as little as 3* over standard,,
Iv'e just found the ign map recently mate, it's stored under "the cone of silence" located in the bowels of the Honda Tardis
Most of the changes Iv'e made to the jetting were probably a knee jerk reaction to my misfortune in 2013, which was a result of putting my faith in the gravity feed setup. :oops:
Now I have a good pump, 3 times the float bowl capacity, and needle & seat from Holley controlling fuel level, and as a result of believing a stupid O2 gauge, I recon I could fuel a Hemi, too much fuel, WAY too much fuel.
New plugs in, slightly leaner needle jet, hole blowing main jet + a bit, a bit too fat pilot (but it starts well cold) and a flog will tell me more,,,,,,
Tiny DLRA# 484
Postiebike Racing , created & funded by TwoBob Engineering

jpbyron
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Re: Supercharged CBR250 build

Post by jpbyron » Wed Apr 30, 2014 7:49 am

Hi Gen,

We use a O2 sensor from "Fast" (fuel-air-spark-tech). Without it our speed week would have been different as you just don't get the runs to check all. The gauge works great, their customer service however is shit house, still waiting on replies from many email questions sent months ago. We try and keep our numbers below 6. We were running 4 to 5 most the time, one issue that took a few runs to work out was when we gassed it the sensor would go to 7 straight away so we would roll off the throttle. But it came down to our carby being a little big for the bike, gas it and it would grab a huge gulp of air, we would not stay into it long enough to see the number come back down. If we rolled the throttle on gently the numbers would stay under 5. Anyway new head and crank on the way to replace the stock one, so hopefully the extra hp will make our carb just about the right size. Unless we find a GP somewhere we will be keeping the one we have but adding a 2nd bowl, as the new head is 4 hp better then the stock. This is 8hp when under 18psi. So we will go from 21hp to close to 30hp. So more fuel needed. Need more power to keep up with Dave!!!

As for a carbs mate, come on only one answer Amals!!! The Mikuni, Flat slide, Electron boys won't see you coming!!! I can hear them bitchin already....


JP
APS-BF 100 109.589mph
Worlds fastest 100cc motorcycle

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gennyshovel
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Re: Supercharged CBR250 build

Post by gennyshovel » Wed Apr 30, 2014 3:46 pm

:D :D :D :shock:
Tiny DLRA# 484
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gennyshovel
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Re: Supercharged CBR250 build

Post by gennyshovel » Mon Sep 08, 2014 9:20 pm

After a 3 month rest, warm weather combined with the GREAT audio from Bonneville, I got off the butt and went for a blast today with the pre holed piston jetting, + the power jet
run # 1 after a very stubborn start up, Laslo had a miss from 1/4 throttle, right thru until the mains kicked in, at this stage, the power jet was turned off.
Run # 2 with 3 turns of power jet the miss was still there, but less
Run # 3 with power jet maxed out , the miss was almost gone, so I rode thru it (I actually remembered to operate the piston cooling jet solenoid !) pulling 6th @ WOT for about 1/4 mile, nowhere near max rpm, but that's ok, wot is wot regardless of the rpm
I got these for my trouble (after a chop)
Image



Image
Nearly there,, need to upp the pilot now, 'cos no amount of air screw fiddlin' will change the a/f, so I'm thinking (dangerous thing thought) I might need to drill the pilot orifice in the carb throat a few thou ?
Tiny DLRA# 484
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gennyshovel
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Re: Supercharged CBR250 build

Post by gennyshovel » Mon Sep 08, 2014 9:21 pm

Image

Image

Image
Tiny DLRA# 484
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gennyshovel
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Re: Supercharged CBR250 build

Post by gennyshovel » Mon Sep 08, 2014 9:22 pm

Image
Tiny DLRA# 484
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