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-   -   Newbie to K&B 3.5 O/B (https://www.rcuniverse.com/forum/speed-rc-nitro-boats-117/902216-newbie-k-b-3-5-o-b.html)

hebertjj 06-27-2003 01:47 AM

Newbie to K&B 3.5 O/B
I've just acquired an old, but unrun, 3.5 CC K&B outboard on a 38" tunnel hull boat of unknown make. It's unpainted, white ( ABS ?) plastic with molded in driver and engineer figures on each side. Any info on this boat and how to run a K&B 3.5 easily available?

It looks like the engine runs clockwise looking down on the spinner, is this correct? I guess just reverse the battery on my aircraft starter. It's also tight as all get out at TDC; I've oiled it with gun oil and un-gummed the carb barrel and turned it over by hand, but I'm not sure my starter will turn it over. Any ideas?

Can I run it on a test stand with a water bottle feed for cooling water on an IV type setup?

Thanks in advance for any info.


Ron Olson 06-29-2003 02:40 AM

Newbie to K&B 3.5 O/B
I am assuming that this is your first outboard. You are right, you do have to swap the wires around on your starter. K&B's are tight at the top and. They have a tapered bore on the sleeve. It will expand once thwe motor has warmed up. If you do have trouble cranking it over at first, loosen the glow plug a little but remember to tighten it back down once it is fired up. Adjust the high-speed needle to about 3-1/2 turns out from the bottom and then adjust it from there.
The biggest thing about the K&B outboards is that the drive dog is left-hand threaded. You will usually remove this to lube the flex cable.
You'll probably have more questions so keep them coming.
Another excellent site for outboard Lovers is www.intlwaters.com . I spend a lot of time in there. Some of the best OBers around hang out in there.

hebertjj 06-30-2003 08:35 PM

Newbie to K&B 3.5 O/B
So how about the test stand with the IV cooling water feed?

Ron Olson 07-01-2003 02:35 AM

Newbie to K&B 3.5 O/B
Sure, why not? Just don't rev the motor up too high while breaking it in. Run it slobbering rich the first few tanks then slowly start leaning it out.
I made an adapter that fits my garden hose. I used an ABS 3/4" threaded fitting, a small piece of 3/4" pipe and an end cap. I drilled a 1/8" hole in the cap and epoxied a piece of 1/8" brass tubing into place. I then ran a length of medium fuel tubing to the water inlet. You don't need much water, just barely crack the tap open. Bypass the water pickup so that the tubing doesn't get caught in the prop.

KB9STD 07-02-2003 01:37 AM

Newbie to K&B 3.5 O/B
The IV style water hook-up works fine.Just connect your tubing to the outlet, and let the water flow out of the "pick-up" tube toward the prop.Splashes water everywhere!
The problem with running a "Boat" motor on a stand is that it's almost impossible to tune the engine. Without the drag( Load) of the prop pushing the water,you can easily run it way too lean, and ruin the engine. It's also common to over-rev the engine, and break the connecting rod. Personally, I'd just take the boat to the lake and run it.The ABC construction of those engines needs very little "Breaking in". Just run it really rich for the first several tanks, and lean it out a little at a time( carefully watching for the sagging characteristic of overheating).You'lle need the practice at tuning the needle anyway.Unless it's "Slobbery" rich,you can't adjust it on the bank.You have to just guess (keeping on the rich side for safety) and see how at runs when you launch it.Then adjust, and try again.

drydock 07-04-2003 12:45 PM

Newbie to K&B 3.5 O/B
As far as cooling... U don't need much water. you can comfortably touch the head after running IV (2 Liter etc.) Also feel free to remove the prop! Don't overrev, and, not sure if it's true anymore, but some years ago K&B mentioned something about the need for water to lube lower bushing and never run out of the water. (Assume that statement to be near 100% ignored!)

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