Kuma

My Feedback: (1)

I think my $18 GS 21B01 is finally giving in. It seems to have good compression and runs great with 1-2 pulls to start up when cold with a solid idle (can sit there forever without needing to blip throttle), but after a tank of running the car on the track or behind my backyard in the mountains the engine becomes easier to stall with a weaker idle and when it dies it gets difficult to restart. The compresison feels milder and when I plug the exhaust to prime the motor, it doesn't suck the fuel through and I'd have to blow through the preasure hose to push the fuel into the carb. Also when I disassembed this motor the night I received it, I noticed it has 2 head shims (not sure how thick they are) and I run 20% nitro/16% oil- would it be safe to take one shim off to see how it responds? I've replaced fuel lines, glow plug (McCoy #8 & #9), used a freshly charged glow starter, cleaned air filter.

Any ideas? I guess this is a sign of needing a rebuild, I knew $18 wouldn't last long.

Aerobirdbrain

Take out one head shim in order to raise the compression. Next turn the high speed needle all the way in, then turn it out 3 1/2 turns. Also, cheack the fuel line for clogs, then cheak the gas tank for cracks by submerging it in water, holding the fuel line shut in one hand and blowing through the pressure line. If bubbles come from anywhere (the lid might pop up due to air presure)then you know that you have an air leak and that would make tuning the engine a real pain in the arse. After that cheak the backplate and under the carb for air leaks by tightening the screws on the backplate and loosening the pinch bolt on the carb(or whatever holds the thing in place), putting pressure on the carb body, and then tightening it back up. By doing this you ensure that there are no air leaks IN the engine. If all else fails, then simply rebuild it.

Kuma

My Feedback: (1)

ICK, now the head screws are on so tight, it broke the tip off my hex and the broken piece is still stuck in the screw head, time to find stronger hexes. Wonder if running the motor to warm temps will help loosen it, doubt it.

jsswcks

running for a few minutes wll help but recomend getting some craftmen allen wrenches so if they break sears replaces them with no hassles forever!

packfan88

My Feedback: (2)

you can try just heating it with a hair dryer.

how much fuel did you get through that motor?

maybe you can send it out to those guy on ebay who resize the sleeve. i think its only $20 and then you would be at $38...if it last a gallon id say you got your moneys worth........well that is unless your the type who puts in a gallon a day

wanna buy a brand spanking new never seen fuel gs .21? email me [email protected] for check the parts for sale here at rcu.

Kuma

My Feedback: (1)

Managed to get the screw out with a drill set, replaced it, took out a head shim. P/S seems still to be in good shape and has more compression now witht he removed shim, and fires up quicker- but I also added an EFRA 9886 pipe too. The $18 is still paying off!

Not sure how much fuel has been run through this motor but when I got it, I've done maybe 1/4 gallon so far.

Aerobirdbrain

Told ya about that head shim. Now you know how to tune yer compression. Keep one ring in though so that the piston doesn't start slapping the top of the head.