The high compression of the DR350 requires use of the manual decompression lever for the kick start model. Although some find it difficult to start the kick start models, they can start very easily when properly tuned and the decompression lever is used properly.
Starting procedure Edit
- If you have a stock vacuum operated petcock, set it initially to PRI. This will allow fuel to flow when into the carburetor bowl when the engine is not running. Failure to use the PRI setting might require many, many kicks to draw enough fuel to fill the carburetor bowl after the bike has been sitting for a few days. For simple ON/OFF petcocks, set to ON. Be aware of the RES(erve) position on the petcock. The bike will start and run just fine in the RES position but if you run out of fuel ...you're stuck as you have burned all the gasoline in the tank.
- If the engine is cold, apply full starting enrichment (choke). Partial enrichment can be used in some cases.
- A hot engine should not require any enrichment.
- On Dual Sport models turn the key switch to ON, disengage the engine stop stop switch. On dirt only models ignore this step as there is no key and the kill switch is a momentary button and defaults to a "run" mode.
- Depress the decompression lever and slowly kick the engine over until the decompression lever pops out
- Leave the throttle closed at all times
- Return the kick lever back to the top of stroke and apply a firm kick
- Once the engine starts, the stock vacuum petcock can be set to ON. This will allow fuel to flow only when the engine is running. NOTE: Dirt only models have manual petcocks with no "automatic" function like the vacuum petcock.
- Once the engine is running for a minute or so, you can try placing the enrichment knob in the second, or partial step. This will drop the RPM a bit and, providing the engine will idle, is a good position to let the engine warm up.
The 4-stroke engine on the DR is a "cold-blooded' motor requiring time to warm up before it will run at its best. It is important to bring the engine oil up to temperature before hard riding. Start the engine first then don your gear (helmet, boots, gloves etc) allowing both the engine and engine oil to warm to normal operating temperatures.
It is critical to use the decompression lever on every kick. Failure to do so can result in damage to the crankcase. Below is a picture of a cracked crankcase around the kickstart idler gear. Notice the damage to the inside of the housing as well. It is very likely the owner of this bike chose not to use the decompression lever. That being said, unless you have extremely developed leg muscles and the weight to overcome the high compression, you'll find it just about impossible to kick start this bike without using the decomp lever.
Starting difficulties Edit
Difficulties in starting are usually related to a dirty carburetor or improper idle fuel mixture. Stock vacuum petcocks are known to fail after many years and allow fuel to flow down the vacuum line. This leads to an excessively rich mixture causing the engine to run poorly, if at all. It can also allow large amounts of fuel to leak into the crank case and contaminating the engine oil. Gasoline will dilute motor oil which can lead to serious engine damage. Yamaha Raptor 660 ON/OFF/RESERVE petcocks are a usual replacement as they fit the stock fuel tank. The vacuum petcock page contains more information.
On dirt-only models it is important to remember to manually place the fuel petcock to the OFF position after shutting down the engine. With a hot engine the carb can heat soak; leaving the petcock ON can cause "flooding" or an excessive rich condition in the carb resulting in a hard restart.
A properly tuned engine will start with one or two kicks every time. If the engine does not start with a few kicks, something is wrong. It is best to solve the underlying starting problem rather than relentlessly kicking.