.12-.15 Carbs.

[MikeP]

I would like to get some thoughts on .12-.15 carbs. I have a pretty good collection of them now and have noticed that they are all 5mm or 5.5mm inside bore. This is IFMAR leagal 5.5mm max.

Would bigger bore suit the boaters needs?

I found a really nice 6.0mm rotory carb that is stock on the .15 Sirio. Fits the .12's just fine.

I would like to try and enlarge the bore size on one of the 5.5mm OS carbs. Has anybody ever tried that?

-MikeP

 

[Saugling]

Some years ago I had a Tamiya TG10 car and I enlarged the bore size of the .12 engines carb to 6mm. After this modification I noticed that the engine had a bit more power and made some more rpms. ;D

I only did it because I was curious...the carbs intake was 6mm in diamater, the outlet also...only the diameter of the rotatory part of the carb was about 5mm. ???

But be warned, this mod runined one expensive cobalt-drill >

 

[MikeP]

Interesting, maybe some kind of a stone would work on the barrel to grind and polish it to 6.0 or 6.5.

-MikeP

 

[GTR]

Hi Guy's

You can definately enlarge the carb bores - I have seen them at 7mm that still work. OS carb barrels - and a lot of others are hardened - you can get around this by heat treating them (annealling) boring and then rehardening. Or you can machine one out of brass.

Have fun

GT ;D

 

[ClayGlover]

has anyone seen a performance difference between rotary and slide carbs in boats? ???

 

[nitrotoys]

I have used the 10 ER carb from OS.

seems to be a good carb.

 

[ClayGlover]

those small OS carbs are interesting. it's us$54@tower. i'll pick up a shot-out OS .12 on ebay just to try that carb. although it may take a little work to fit ... hmmm

OS 10E-R

Outer Mounting Diameter: 0.39" (10mm)

Inner Throat Diameter: .031" (8mm)!!!

i've settled on the novarossi/rex/mugen MT-12 standard crankshaft and plug with rotary carb. as far as i know it's the first rear exhaust .12 that came out and a lot of car guys swear by them. being a NR based rear-exhaust engine, the price is excellent. here's the cheapest i've come across that have it in stock. $149-

Mugen MT-12 source

Mugen MT-12 specs

after a lot of research, it has the features, quality, and price i'm looking for. i wanted to go with an engine that i haven't heard of anyone using yet in a boat just to try something different

 

[CySlyde]

sounds interesting... is there really thaat much performance boost from a .15 to a .12? maybe a better question would be where is there a good guide to nitro (marine) engines.