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Old 06-15-2009, 01:43 PM   #16
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OS manual doesn't specify, and the manual doesn't exist on their website.
Your engine comes with the same carb as .18, and its manual shows the carb's factory settings.

http://manuals.hobbico.com/osm/18tm-...evo-manual.pdf

Low speed / metering needle: Flush
Mid speed / mixture screw: Flush, then 1/2 turn in.

It doesn't list main needle settings, but I imagine that 3 turns out from gently fully closed is close on this carb as well -- if it's too lean, it will be obvious. I'd just richen it up until it bogs and dial in that high speed first, then adjust the factory settings of the low speed and mid range as needed, staying away from the midrange needle unless it bogs hard on midrange to high speed transition.
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Old 06-17-2009, 03:04 PM   #17
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Everything is siliconed and sealed with new hoses, and an airtight exhaust gasket. Same problem. While playing with it on the bench it went through an entire tank and there is no oil coming from the front bearing as far as I can tell...

It still wants to overheat even though oil and smoke are coming out the pipe all the time. Like the tuning bible says an overly rich low speed can cause a high idle to appear normal and load the crankcase with fuel, causing a gradual increase in engine temp until overheat. With that in mind, I lean out the low speed, close in the idle a bit to get it under control and it wants to be around 250C or hotter, just idling, while smoking away.

Any high throttle and the engine begins to overheat badly. Still lots of power, fuel, fuel pressure, and richness.

What can I try next?
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Old 06-17-2009, 08:45 PM   #18
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Everything is siliconed and sealed with new hoses, and an airtight exhaust gasket. Same problem. While playing with it on the bench it went through an entire tank and there is no oil coming from the front bearing as far as I can tell...

It still wants to overheat even though oil and smoke are coming out the pipe all the time. Like the tuning bible says an overly rich low speed can cause a high idle to appear normal and load the crankcase with fuel, causing a gradual increase in engine temp until overheat. With that in mind, I lean out the low speed, close in the idle a bit to get it under control and it wants to be around 250C or hotter, just idling, while smoking away.

Any high throttle and the engine begins to overheat badly. Still lots of power, fuel, fuel pressure, and richness.

What can I try next?
Survey says; an infrared thermo-gun says sensors are out to lunch. 290 = 230, 320 = 250... Nothing is overheating, but it still stalls going over most jumps and on every rollover.
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Old 06-17-2009, 09:14 PM   #19
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Try these old tricks. Pull out your high speed and low speed needles and coat the o rings with some AE Green Slime. This will seal any air leaks in the needle o rings and if any gets down in the needles it will get washed away by the fuel and cause no harm. Also, try running a longer fuel line from the exhaust to the tank or you can add a fuel filter. These 2 mods will equalize the pressure to the tank and make the engine run more consistantly. As far as the engine stalling when turned over, run longer a fuel line from the tank to the engine. This will give you more time when upside down. I would also put a new tank in there. You would be suprised how many engine tuning problems are solved with a new tank, lol.
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Old 06-18-2009, 05:10 AM   #20
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Yeah, look for bubbles in the fuel line.
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Old 06-18-2009, 10:54 PM   #21
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It's an immediate stall, not from gradually running out of fuel when overturned. When it hits something or gets jarred, it just dies, otherwise runs great, and not hot. If the slipper clutch is tight, and the engine is at a high enough RPM for the clutch to be fully engaged, could a sudden drop in tire speed actually stall it out, or do you think it is something else? It is instantaneous, not even a second.
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Old 06-19-2009, 08:22 AM   #22
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It's an immediate stall, not from gradually running out of fuel when overturned. When it hits something or gets jarred, it just dies, otherwise runs great, and not hot. If the slipper clutch is tight, and the engine is at a high enough RPM for the clutch to be fully engaged, could a sudden drop in tire speed actually stall it out, or do you think it is something else? It is instantaneous, not even a second.
Yeah -- dragging clutch shoes can certainly cause that.
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Old 06-19-2009, 09:19 AM   #23
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I'm thinking a wacked out cluch or tired o-rings on the carb. More than likely the cluch.
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