Teaching 14 y.o. son to install BBK- What lessons to stress?

[stopsign31]

Going to install our 50mm BBK from Taz this weekend. Would like to teach my boy the key points for a successful build (i.e. keep everything completely CLEAN, use 2 stroke oil to coat all moving parts, arrow facing towards exhaust port, rings in the groove lined up with the marker pins, etc). All of you guys that have been thru this a couple times probably have some words of wisdom to impart -- that's what we are interested to know. For example,what 's the best way to squueze and install the circlips, what are the torque targets for head, what do you use to drive in the wrist pin, do you grease the roller bearing in the connecting rod,?? etc. Any advice, shortcuts or knacks that would come in handy would sure be appreciated. He'll think his father is a genius whan we get the Elite fired up!!

[Bear45-70]

keep everything clean and oil the bee jeezes out of any parts inside the motor. Oh and if it does not go on easy, DO NOT force it. Last but not least, always finger start all nuts and bolts, it eliminates cross threading. Oh and last for sure, a torque wrench is your friend, use it always, it generally stops striped threads from over tightening things.

[Fishman43]

Proper use of a torque wrench for sure! Slowly approach the torque setting while moving from bolt to bolt so that no one bolt is way more tight then the rest.

[mr pibbs]

Number one lesson:
Don't be afraid of the job. You don't have to pay someone else to do it.

Number two lesson:
Money can always fix your mistakes.

[Wheelman-111]

Greetings:

The piston wrist pin pushes in with pinkie-tip pressure, well-oiled. Pay very close attention to the G Clips. They are programmed to seek storm drains or the space beneath the nearest water heater. Use your best longnose pliers or go buy some good ones. Double-check that they are seated in their grooves and that the gaps lie across the installation slot on the piston. Check again.

The rings can be squeezed into the cylinder chamfer by fingertip pressure, also well-oiled. Don't forget that base gasket, which can be painted with hi-temp grease on both sides for easy removal next time.

After assembly, consider the setup. Keeping it healthy is the hard part, as the Taiwanese cylinders can be finicky. The stock carb is a liability since you can't upjet the slow circuit. The engine may overheat off-throttle. Arreche makes a 21 that fits Honda manifold and is easy to tune.

I recommend you plug the pump hole and go straight premix at 25:1 for break-in and use a BR8 or 9 plug. If it oil-fouls, use the 8 or a 7. Go easy until the 3rd tank of gas.

Stock and even 9:1 gears may be too low for the power, resulting in over-rev and heat issues. Sustained WOT then puts the new bore at risk. 8.44 should be OK.

HTH

[Bear45-70]

Greetings:

The piston wrist pin pushes in with pinkie-tip pressure, well-oiled. Pay very close attention to the G Clips. They are programmed to seek storm drains or the space beneath the nearest water heater. Use your best longnose pliers or go buy some good ones. Double-check that they are seated in their grooves and that the gaps lie across the installation slot on the piston. Check again..........................

I have a pair of needle nose pliers that the ends have notches for the clips to fit in. I got my made that way, but a guy could always just grind some notches in regular needle nose pliers.

[maddog]

teach your son and enjoy it, i had to do it myself at age 8

[stopsign31]

So what are the torque targets for the cylinder head bolts? I've read about too much compression being a problem -- what is a good range to shoot for? What cylinder head temperature range is safe? I'm thinking going up to 105 jet and 25:1 premix this time. Will I have a 2 cycle smoker?? I guess next mod will have to be an aftermarket carb. Any opininios on OKO 28mm vs Arreche 21mm? (anybody have a good used carb for sale? ) If this heat subsides this weekend in Southern Indiana, we're going in!!!

[mr pibbs]

I believe the stock torque is 8 ft-lbs, might need to check the manual on that. I ran my bbk at 11.

[Bear45-70]

Manual says 6-9 ft/lbs for the cylinder head bolts. Over torquing steel bolts into an threads in an aluminum case is asking for striped threads in the aluminum case. The BBK should require no higher torque setting to seal and hold properly.

[maddog]

its 12 in. lbs but that torque wrench costs big bucks, i torque by feel x3 and tune by ear

[drizzle]

my torque wrench cost me 15 bucks or so at harbor freight.

[tazland001]

I think that is great. I have been teaching my twin boys also how to work on there dirt bikes(yz85's). They can do alot now. It is so nice to have the extra help. But they are terrible with my tools. lol

Taz

[stopsign31]

Please clarify, does the G-clip gap that hold the wrist pin in place have the gap lined up with the indentation in the piston side, or should the clip gap be 180 degrees opposite the piston indentation? Also, the paper gasket at the base of the case is only 2 months old, looks to be in perfect condition. OK to re-use, or must I replace with new? Thanks for the noob help.

[stopsign31]

Sorry for the double post -- what are the targets (maximums) for compression and CHT?