Supercharged CBR250 build

[gennyshovel]

Test ride #2 didn't happen as planned, although I was ready,,the 'lecTRICKERY wasn't
I hate batteries almost as much as I hate CDI's , If I could find a set 'o points who's spring would handle popping closed on time @ 18000 rpm,,I'd get 'em
The new battery no longer sits empty on the shelf, it's had a drink, a charge and will sit in its new home tomorrow.
Then I need to re-wrap, re-solder and tidy up a mess of wires, dialectric grease all the plugs and try again.
Rev's mate in China sold me a flash little LED gear position indicator for $20, so I won't have to remove my gloves to remember which gear I'm in now
And I thought I'd have been ready for 2012

(edit) Chinese wire & soldering are 2 words which don't get along
But,,,,I again have the long lost sparks I dearly missed, phew, while I'm on a roll, I'll shorten up a 1 mtr length of a stock jumper lead (from CDI, to Hall sensors) which involves dismantling a plug on one end, cutting 980mm of the wires off, and reattaching the plug, this usually involves puncturing at least one finger with a pointy object.

[Mossy]

Thats why I've stuck wih a magneto
Cheers Mossy

[Dr Goggles]

this usually involves puncturing at least one finger with a pointy object.

Like what? yer head?..

I wish I understood electricity better.

[gennyshovel]

The electrickery prob was a a lying battery, it showed 12.1 volts, load tested ok(ish) and maintained 12.1 V while cranking (remote battery for the cranking duties)
After 2 days of frustration, I filled and fitted the "spare" new battery, the sparks returned ?
On the engine cutout prob, according to the link Pete posted,providing they mean the 40/042 jets (the N100.604's dont go that rich) I need the following:-
N100.604-160 (lge rnd)=40/042-320 (lge hex) bore size 1.547mm
Multiplied by 2.2 = 705 (40/042 hex) 2.280 mm

The leanest I've been so far (the leanest jet I have) is 950 lge hex (.109"Maxjet)
It's drowning,,not parched (ain't this methanol sheet fun !
PS, Goggs,,I only punctured one finger, the hole looks just like a screwdriver tip , and My head feels better after its electrickery workout.

[AuotonomousRX]

40/042s thats the same as I use.

Pete
Smokin#866

[gennyshovel]

#.094" MaxJet looks like its well on the way to being rideable
WHAT A RELIEF !
I made a stand to hold the rear wheel off the ground while running the bike in 3rd gear, loading the rear brake,,opening the throttle as the load was increased, the brake lost, throttle won, 1/2 to 3/4 throttle from 6000 up to 15000 rpm cleanly.
I fattened it up with a #098", which had the dying problem re-appear, as did a #.096", then #.095", although the last jet was almost ok.
I had it so warm,,it boiled after the last pull.
I have a few needle and clip position chioces to make to try out on the track next.
ALL GOOD

[gennyshovel]

Test #2 has passed, well, actually, it didn't pass at all, but at least I'm getting there.
Yet more main jet changes to come , hopefully, allowing the use of an angry wrist.
http://www.youtube.com/watch?v=TVr_gdo52so

[gennyshovel]

After 2 months chasing carb gremlins,I thru a smaller carb on (the 42mm is too big).
Another problem with the 42mm , is tha fact that I have 20" of vacuum at idle, 'tween the blower and the carb, resulting in fuel being too happy to rush thru the pilot jet, making it too rich.
I backed off the pilot and cured the richness problem, but this made the transition from pilot, to needle jet a non event, the engine just died over 1/4 throttle, and wouldn't recover when throttle opened wide.
I had a feeling the ignition output may have been a problem, with methanol,boost and an uncorrected compression ratio of 17/1, I might have needed a stronger spark to ignite it ?
I had another test run today with the smaller more suited carb in a hope of eliminating the potential ignition problem, but I wasn't holding my breath.
Well, eliminate it did,,holy snappin' duck poop robin, full throttle in 2nd, 3rd, 4th and 5th gears, 14000 rpm !!!
It did start to nose over due to fuel supply problems? but that can be cured.
1 gear,,1000 rpm to go .

[AuotonomousRX]

Onya Tiny how good is that

Pete
2 Smokin Barrels

[ROSS BROWN]

Been interesting following this fuel carburator drama Tiny.. here and on landracing.com..
Drawing fuel up through the idle jet became obvious ... once it was pointed out
Drawing up through a leaking choke passage could also be plauseable..

An option with your " IGNITION " most electrical gizmo's will handle 18 volts ...without destruction
Many of the speedway outfits today use batterys from 18 volt cordless drills or made up battery packs.
Methanol just loves those extra couple of volts..

If you have a spare "IGNITION " It would be worth the try....

Cheers
Ross
PS: No responceabilty taken on advice given..

[gennyshovel]

Thanks Pete 'n Ross,
Yup..I have a spare everything, and will keep the upped voltage in mind.
It's running a flash thing called an alternator too, another miracle of modern science !
I might be a popular bloke next year if I take my selection of Maxjets (holley) to the lake, I have from .093" to .118" gathering dust in a rather large plastic box (Ya might have to chop ya Holley in half though, 'cos I only have 2 of each)
I didn't take my data logging with me yesterday (GoPro cam) as I wasn't really confident I would have been so close ! (it was obviously way too lean on the pilot jet), but the plan was just eliminate carburation from my my mid/top end bugs.
It was brilliant to share the 50+ years of experience of the blokes from landracing, it reinforced some ideas that had crept into my head, and offered a few potential problems I hadn't thought of.
Anyone need an alcohol ready HSR42 Mikuni ?

[gennyshovel]

Lean ? yup !

"She'll be apples"

[ROSS BROWN]

Interesting picture Tiny..
For methanol ,that is extremely close to a melt down,
if it has'nt allready started to change the shape of things in the hole.

I don't have a CR9EHIX-9 plug here to have a look at, but am interested to know if the cut back earth is
standard for that plug... or did you cut it back.... or did it melt.......

Ross

[gennyshovel]

Ross, the box is the plug's replacement, the melted one is a CRr9EH9, and no, I didn't trim the earth strap.
I felt it happening, and rolled off.
It still passes the thumb in hole wind over test, so hopefully, nothing else melted.(plug screwed out easily too)
I new I was light on the pilot jetting, but lacked an alternative, as for the main,,I needed a 550, but had to rely on a drilled 540 (close to 540)
A 550 would be 2.2 times gas jetting, usually that would be on the safe side, but not this time.
I'm waiting on some more jets to arrive, and will fatten the pilot AND the main, pees orf the 1.5 needle and seat and put the 2.5 back in, and hopefully it won't flood @ 4psi , before running it again.
I may need to up the fuel pressure if it still noses over in the taller gears, and run a bleed off line back to the tank, with a " remember to turn off before floggin' " tap in the line.

[gennyshovel]

Yet another test run today, all good, then EVEN BETTER
Started with #90 pilot, and # 580 main, slight disagreement with full throttle in the taller gears, but I managed a plug chop which revealed heat discoloration where earth strap joins the plug, so I was in the ball park.
I went the safe way and put a #600 main in, if the disagreement remained, or was worse, I'd try a #560 .
I didn't need to , the following gearing graph will explain the result of test #4, seeing as I forgot to turn the GoPro on

A mate did manage to video the run though, and I'll post it when it becomes available.
I'M READY FOR 2013