engine bogging on high speed
 

I have a kyosho gs21r engine that came with my landmax, which I bought used. When ever I give it full throttle on the straight it will bog out (lean out) I tried different needle setting and help from other people but the car does the same thing. I notice when I turn the flywheel with my hand the compression feel weak, so I decide to rebuild it. When I finish the compression feels strong. I decide to breakin the engine slowly, on my third tank I decide to open up the throttle on the straight and the car bog just like before I rebuild it. I examine the carburetor and didn't see any thing unusual, any advice will be greatly appreciated. Thank you.

PS
my high needle is set at 2 turn, with 20% fuel
and there is alot of smoke, and to start it I have to crimp the fuel line to starve the engine so it would start, but I was told the engine runs around 2 turn so I dont want to close it anymore.

engine bogging on high speed
 

I'm certainly no expert, concidering my last post, but might try leaning it out. I just had a similar prob., too rich. Don't listen to anyone who tells you this engine or that engine runs best at precisly X amount of turns. Impossible, they're all a little bit different. This can be a good starting point, but you must go through the procedure, to properly adjust the needles. Do you have the manual?
Do a search on needle valve adjustment.
--Rick

Tower hobbies says 2.5 turns out: http://www2.towerhobbies.com/cgi-bin...1&I=LXAVV3&P=7

OS says, for their engines, start at 2.5 and lean out for max performance, then adjust the idle mixture: http://www.osengines.com/manuals/21vz-r-manual.pdf

engine bogging on high speed
 

thanks for the links

engine bogging on high speed
 

An engine will never run best at a set number of turns. It can change as much as a 1/2 turn or more with weather. A specific setting is only a starting point. It sounds like you may have an air leak. An air leak may not be noticable until you go to full throttle so that may be why it you need to pinch the fuel line when you start it.

engine bogging on high speed
 

I feel I have a air leak in the carburetor, any idea on how to find it? I was debating a long time if I should buy the os .21rg or rebuild the kyosho gs21r that came with the landmax, considering that I would need new engine mounts for $15, header and pipe $75 and the engine $129 I decide to go with the rebuild for $60

engine bogging on high speed
 

On some engines, but not all, the idle mxture screw/needle will greatly affect the high-end mixture.
I've gone through this senario:
Top end perfect but bottom too rich-leaned low end <1/8 turn.
Now top end too lean but bottom just right.
Opened top end to 'just right' setting.
Now bottom too rich again.
Yadda, yadda, yadda.

Check all O-rings and take whatever steps necessary to seal them: i.e. slightly larger O-rings, fuel tubing, etc.
Also, make sure the carb body seals well against the crankcase. Sometimes a little blue RTV works wonders.

It may just take some tinkering to find that sweet spot.
Hotter plug? Cooler plug?...

engine bogging on high speed
 

GS 21R operating instructions say to start out at three turns out. That said, I run 15% Cool Power with a OS #8 and both needles 2.5 turns out. If the engine is cutting out and there is not a whole bunch of blue smoke, I would say you are running way too lean. Try my settings and give it a try. Remember, the GS 21R runs hotter than most and needs rich settings. ANd let it cool off before running again. Good luck.
Chris
Richmond, VA