In Denver, the high-altitude can make it especially hard to start a motorcycle when the temperature drops. The following suggestions might help you get your bike going when the going gets cold.
- If your bike is carbureted, sometimes blowing into each of the carb vent hoses will help "prime" carbs and make it easier to start
- If your motorcycle hasn't been started in a while, the carb bowls might have emptied. If applicable, turn the petcock to "Prime" and rock the bike from side-to-side, then return the petcock to "Run" before starting
- Sometimes covering the intake can help enrich the fuel while starting (this may take two people)
- If all else fails, you can try spraying starting fluid into the intake, but this can be dangerous. Be sure to follow the manufacturers recommendations if you go this route
Some motorcycles are considered "cold-blooded", meaning they are particularly difficult to start and idle poorly until they have warmed up. Proper maintenance and some adjustment, however, will usually remedy these issues. Be sure to check the following if your bike has consistent cold-starting problems:
- Make sure your choke (is applicable) is operating properly. Check the linkage and make sure it is not binding
- Check all intakes, particularly between the carbs and engine block; cold temperatures make these leaks particularly problematic. With the engine running, spray WD-40 around suspected leak areas and listen for a change in RPM - this indicates a leak
- Make sure your spark plugs are clean and are of the proper temperature range
- Clogged, or incorrectly adjusted carbs are a common cause of difficult cold starts. Thoroughly clean and dip carbs, replace all o-rings, and paying particular attention to the choke and idle circuits. Make sure the jetting is correctly set for this altitude and synchronized. Reference a Clymer or Haynes guide for proper procedure
When starting, always pull the clutch and front brake when starting your bike. This is especially important in the cold as the viscous oil can cause your bike to jump even with the clutch held in. Be sure your bike is properly maintained for the winter. Use an appropriate grade of oil for weather conditions and make sure the battery is charged; this will prevent battery damage and make your bike easier to start.
For more information on winter riding, see: Denver winter riding: an alternative to winter storage.