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Moto CR 80 Two Stroke Tech Tips - Moto CR80 2-Stroke Break-In
Swedetech Moto - Honda CR80 Tech Tips |
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Recommendations for engine break-in and jetting, as well as what spark plugs and how much oil to use. Specifics about top-ends, reeds and other replacement parts.
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Engine Break-In |
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Start by increasing the main jet by one to two sizes from what you have determined to be the optimal jetting, taking weather, altitude and track size into consideration. Always warm-up the engine on the stand and do a walk around of the engine and kart... Check for loose bolts etc. See specifics below, regarding proper clutch adjustment, along with important tips about your cooling system and fuel pump. Break-in water temperature should be 135 to 140 degrees, with the normal running water temperature at around 125 degrees (RC20 recommended additive). You can take the temperature reading anywhere between the cylinder head outlet and the radiator. Out on the track, run at reduced lap times of 15% to 20% below normal (On a 30 second track, slow the pace by 4 to 5 seconds per lap). Towards the end of the break-in, gradually increase the pace by approximately 1 second per lap. Once you're up to speed, you don't have to come in and let it cool down... Just run it!
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Oil |
Please call us for recommendations on 2-stroke oil... Be prepared to advise us what race series that you are participating in and what the "spec oil" is for the series. Note: For most sprint racing applications, we recommend a 24:1 mix ratio. For the transmission, we recommend that you use 600ml of a brand-name 2-stroke gearbox oil if your engine is brand new or freshly rebuilt... Use 50ml less, for routine oil changes.
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Spark Plugs |
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Use any of the following NGK spark plugs...
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Top End |
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Use the following Honda CR80 piston and ring...
We recommend that the top-end be replaced, every 2 to 3 hours. Top-end kit includes; piston, ring, wristpin, circlips and upper rod bearing.
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Jetting - Mikuni 28mm Flatslide |
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Normal range of jets for a Mikuni 28mm flatslide carburetor...
Start with the needle set in the 3rd clip position from the top... Try the 2nd clip position from the top, for higher altitudes or bad weather conditions. And, try the 4th clip from the top, for low altitudes and exceptionally good weather conditions. Note: Even larger jets may be applicable for road racing applications.
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Reeds |
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Recommended replacement reeds...
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Clutch Adjustment |
Check to make sure that the clutch lever has 3/4-inch to 1-inch of play and that the clutch lever, cable and actuator arm retract properly. The clutch lever action should have a light and free feel to it. Make sure your cables have the nylon inner housing... Keep them straight and well lubricated. You should not need more than two fingers to engage the clutch.
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Cooling System |
There are two (2) spigots by the water pump. The spigot in the front is the one that connects to the bottom radiator outlet. The spigot to the rear connects to the inlet on the back of the cylinder head, utilizing an OEM hose... No other routing is correct.
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Fuel Pump |
Mount the dual outlet Mikuni "round" fuel pump as close to and preferably higher than the pulse fitting on the engine case. Using fairly stiff fuel line and utilizing the pump as a "T," route one line from the pump to the carburetor and a second line back to the tank.
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SwedeTech Racing Engines
10463 Grant Line Road - Suite #106
Elk Grove, CA 95624-4045
(20-minutes South of Sacramento and
20 to 30-minutes North of Lodi / Stockton)
916-714-3980 phone • 916-714-3981 fax