Engine Mods/ Yeah the go fast ones!!!!

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G

ggillman

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Ok Dudes,

I will list the things I do, I got some links to the pros also to post, So chime in with what ya got here!!!!

Here is what I do,

Reshaped head button, enlarged dish shape, get with Tim D. for details, he is a sharp cookie on these.

Chamfered inlet tract on crank toward front, basic cleanup and remove burrs and such, not polished, just nice SHARP edges.

Replace the stock rod with a RPM unit if you plan to run a pipe, or porting mods, its just good insurance fer 28 bucks.

Here is a biggie if your engine has any hours on it, do the blow through test, get with Grim for details, ANY leaking replace the bearings. Also new gaskets while your at it and replace the o ring on the carb mount. Lube the O ring push down hard and tighten cinch bolt.

As far as porting and timing, this page is good ta get ya goin: http://rcboat.com/exhaust.htm

and this one http://rcboat.com/timing.htm Just go a little at a time till you get the results ya want, dont GONZO it out. Document what yer doin as far as props pipe and needle settings as you go.

Or if ya get stuck on sumpin, here are the PROS:

[email protected] Power Surge Products

[email protected] Skip at Big Dog Engines

[email protected] Mark Hopper

[email protected] Jerry Dunlap

[email protected] Joe Monahan

[email protected] Rod Geragthy

Next!!!! my fingers are tired,

Gene ;D
 
where can you get a RPM rod for a CMB .21LS? i've been looking around and cant seem to find one.
 
Yep, I got mine at Randys Hobby Shop,

Rpm rods for OPS, K@B, Picco, Rossi,

No listings for CMB :-

Gene
 
there is a guy named Brad Christy that hangs around in rcboat.coms listbot that makes titanium rods for about any engine. I don't have his e-mail address though, I'll have to look it up.
 
I hear talk about tapering the sleeve and skirting the piston. Anybody have details on doing this. I think I understand tapering the bottom of the sleeve but how much and how sharp of an edge do you leave?

-MikeP
 
What the tapering of the sleave does is allows fuel to enter the ports eaiser, there is no set angle on this,
 
i accidentally GONZO'D it tonite :eek: ...........i hope it runs at all. end mills are so much fun i cant control myself. i really dont know what happened other than my measurements were just plain wrong.
 
thanks Ron........i found it there. ;D any of you guys tried one of his rods?
Click to expand...
;D Yes I am running one of brads titan rods in my Mac 21 and there quality is first rate, a little pricey at $75.00 but as they say speed is not cheep and in the case of his rods you DO get what you pay for. 8) Scott
 
Hi Guy's

If you want to find some extra power have a look at the cranks in Nova Rossi engines - the turbo ported ones. Allows increased fuel flow without shrouding from the rod. Every edge is round - not square or sharp - two strokes cannot stand anything that looses charge velocity. Likewise the rods are very thin and knife like, although still very strong. Common usage in cars but not widely used in boats is 'turbo' glowplugs. Don't know why as they really make a difference to performance. Also Novas (and derivatives) have some of the most exotic porting seen - you have to check out a 12 port sleeve to see what I mean. Yeah I'm a fan of the Novas although there are a bunch of good 21s around at the moment.

cheers

GT 8)
 
in my hawk rigger i run an o.s. rz-m .21. it has a notoriously oversized carb. when i ran the engine stock there seemed to be no difference in power between 3/4 throttle and full throttle. one day i got an itch after doing some reading online about modding glow engines and ended up tearing down the engine and polishing everything i could reach......the interior of the crank, transfer and boost ports (which were also ported a little), carb inlet, barrel and neck, knife edged the rod, put a "turbo" cut on the face of the crank, and opened the intake port on the crank without changing the timing (a lot of extra metal around the opening). these basic tune ups made a heck of a difference. when i tested the boat it could now use the last 1/4 of the throttle opening....it seemed to kick into the next gear. this winter i plan on getting more advanced and playing around with timings. all this i did with a dremel and a few different bits. pretty basic but well worth it
 

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