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Old 09-14-2014, 10:05 AM
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electron electron is offline
Motorized Bicycle Member
Join Date: Sep 2014
Location: Adelaide
Posts: 39
Default Re: what did you do to your motorized bicycle today?

MIXTURE PAIN, never need to use choke?
Note, if this is too long, sorry, but how else would u get the whole pic

First 50cc was stolen a few years ago. Was fast and reliable. All factory (some carb and exhaust manifold matching) inc old style black filter carb with replaced throttle and kill sw. as was the case years ago.

Now ive seen my mate with his 50cc (27" stock, flies!) and when he gave me a bike (700) i couldnt help myself (80 (66?)cc).
Sometimes under load it starts to pull hard and "purr". Played with plug gap. Plug lead "head" fell appart: replace with nice automotive lead (unscrews from coil (coil/cdi). Less speedo interference, few dollars, may need to be reduced in thickness at coil.
As allways i started messin with it too early, slowly increasing speed for short moments, playin with the needle. Soon to come down to 20 to 1 (200km). I think 16 to 1 is extemely oily. Ill soon compare 30 and 20 to 1 to c how it compares in performance (stick with 20 if neglagable difference). Plug has been black and oily during all conditions (flash tests, or whatever theyre called) for all needle settings, which is strange and i never need to use the choke?. China plug, but ive never had a prob with em, the coil/cdi or magneto. May consider ngk for after run in fuel mix. Ngk 6, 7 8? for south australia (med hot, dry), bpr7hix (with washer if u hav high comp head) or bosch wr7ac. Im guessin 6 is too hot. Need a spare is my excuse.

Prob should have stopped messin with it untill i was on my final running mix, but even though its obviously too rich and chocking on all that oil, i read about .8mm jets and blindly decided i will drill out the jet (nothin to loose). This made it worse, of coure. I need more air!

Dont really want high compession issues (although cooling may b eventually beneficial) or to spend on exhaust, carbs, gears, balancing, major engine work. Chaint tensioner and Solid rear hub mounting would b nice, but kit style can b satisfactory. Run the best fuel, why not, it s peace of mind.
Did 43kms p hr (44t) briefly a few times and the vibes are reducing to very smmoth now.

Most of the time it sounds like a 2 stroke, but sometime, often under load such as uphill just starts to pull hard and "purr" (thats not 4 stokin is it?). So opened up the 2 manifold gaskets, bit better. Take off exhaust cap, just more noise, too much, no back pressure.
The kit i got had the old black filter carb, bummer i thought. Open it up 2mm dia. and insert o ring as manifold seal, more low end power. I had opened up carby so much that an oring would have been the limiting factor, remove o ring. Still good torque.
What about this exhaust, drill holes? Weld in curtain rod? Bugger it, cut the removable pipe (an aside, im still waitin on the replacemrnt exhaust i was promised, as my end cap and a weld leaked) and drilled out the remainder inside retaining the outer and weld, of course. Bit louder, dirt bike sound than i wanted (agressive and attracts a bit more attention, even when slow cruisin (which helped a bit today with pedestrians) and heaps of torque!

Today After a few more 43kph (27mph) spurts i got home and52.5 (33mph) was on the speedo (accurately calibrated). Sure their were a few declines and i did pedal hard.

Must leave it for now, but my can is empty of running in mix and the scr for my "roll your own cdi" is on its way, (got free quad coil from friend) . Will try to match base timing. 1 microF cap seems more aporopriate, but thats just the start of experimentation. Again "need a spare" is a good enough reason.

I do like to go fast sometimes, but im not after revs (or should i say these engines arnt). Eventually ill at least rebuild with proper mounting hardware, some intake porting/matching, exhaust matching, exhaust porting?, bearings?, piston skirt trim, piston lightening? Then its a matter of selecting the appropriate drive ratio. I want 20 to 50kpm (14 to 31 mph) @ 2 to 5 thousand rpm not 45kph at 5500 rpm, screamin (cheaper to stick with this rpm and it seems to love it. Sounds gr8 too. Maybe a little more compression. Is compression only good for higher rpm???

But for now i cant wait to try some lean mix fuel and some other jet sizes, but will have to wait due to studies being neglected because of this legal (not) chinese drug. Thanx for any sugestions. Sorry about the punctuation, it's soooooo hard on my tab. Sorry no pic, they are too high res for this site. Cheers'

Last edited by electron; 09-14-2014 at 10:16 AM.
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