Re-build of my blown engine + upgrades

[slawenm]

Dec 10, 2011 16:53:32 GMT -5 stroker said:

WHAT SIZE BORE IS THAT ANd where did you get the variator?

Its the Naraku 47mm 72cc BBK and a Naraku sports variator with 5.8g weights and 28mm driveboss and a 1k corta spring thats not installed yet as I dont have a 38mm socket for my impact wrench.

www.centralscooters.co.uk/high-speed-race-variator-set-p-3195.html this is the product.

[slawenm]

throttle cable snapped today I've known its been on it way out for awhile but ahh well got one on order, fitted the heavier 6.3g rollers and put the 30mm drive boss back in my gearing seems a lot smoother and my bike is idling better (back wheel not freely spinning as much) not sure if its effected top speed as only rid about 5 minutes before my cable broke, with 5.8g weights my belt wasnt fully riding up my variator so hope 6.3g will push it all the way out, I'm a light person about 120 lbs.

got a GPS reading of 43mph before my cable broke and felt like it was still slowly climbing up speed.

[slawenm]

need a larger idle jet for my carb just wondering if anybody knows which type they are? not come across any sites selling idle jets only pilot and mains

Oh and does anybody knnow the stock sizes?

[Deleted]

'idle' jet, 'pilot' jet and 'slow' jet are all the same thing.

the bikes i sell that are 72cc from the factory are jetted 78/30. I have seen 31 pilots in a few. I have a true 49cc bike here and its jetted 75/28

the pilot jets are KEIHIN N424-21
www.jetsrus.com/a_jets_by_carburetor_type/jets_keihin_N424-21_slow_26-xxx.htm
that site goes down only to #35 but here are some #32:

www.smebike.com/index.php?route=product/product&keyword=N424-21&description=1&model=1&product_id=2351

Smebike is in New Zealand but i have had no trouble getting my Jets from them.

With a 72cc i found an 88 main and a 30 or 31 pilot worked well for me using a UNI filter and a TZR 50 cdi.
When I went up to 82cc i went to 95/32 in summer and 98/35 in winter. Obviously a cam and exhaust would handle more.

[slawenm]

Brilliant thanks I thought the idle jet was a different one because I have three jet holes in my carb and I knew one is my main one was pilot, I'm having trouble now its winter idling my bike without setting the idle to max and also sticking the throttle on atad too.

so thought I'd just up the jet size for winter think my airbox has had it so might swop to a uni filter, is a company in the UK that claims to have designed one for road use in all british weather =\

[Deleted]

i forgot to mention that my jetting is with the needle to its highest setting. not all these carbs have adjustable needles though.

[slawenm]

20mm carb and manifold came today put it right on set the idle and went for a spin its bogging on 1/4 throttle but it started to rain so I packed up for the day, even with the slight bog at 1/4 throttle seems a lot smoother going through the rest of the throttle got a jet pack here so going to tinker until I have it spot on

got my heavier clutch springs and corta on now and its fixed my idle problem and given me a burst of power when I come off the line, might go lighter on the clutch springs because I dont want to rear end somebody at the lights.

just need to get one of them Naraku metal intake manifolds now

my engine is breaking in nicely dosnt feel as tight now changed oil, spark plug with fuel filter a few times already they are cheap enough.

very happy with hitting a GPS 46 mph the other day so I doubt I'll go for taller gears. that speed is more than enough for me and it gets their in a good enough time.

[vvtr]

hi m8 i put a similar bbk in mine from an ebay seller in the states called robotechlegacy (or something) it came complete with uprated oil pump, new larger valve head, full gasket set etc and even with postage to the uk was an absolute bargain.
i used the naraku variator, same as you have but ended up using the oem backplate as the naraku one was sticking on the shaft a bit.
its well worth getting the naraku gear up set though.... they keep the rpm down and make good use of the low - mid torque of the bbk.
regarding carbs, i got best results (smoother on the road) with the oem carb jetted to 95 with std idle jets and cone filter.
it didnt like the bigger carb at all regardless how i jetted it!
the original coils are crap as well so its well worth changing it for something a bit beefier - there are some good reasonably priced coils on ebid (not ebay!)
and get the larger bore header... makes a big difference to the pick-up

www.youtube.com/watch?v=6M-akqZiPO0