The Automatic Cam Chain Tensioner (ACCT) in DRZ400 models has been a topic of discussion among riders for years. While later versions aimed to improve reliability, issues persist, not just in DRZ400s but across various Suzuki and other brands. Even without complete failure, ACCTs can apply excessive pressure on the chain, leading to premature wear. This is often exacerbated in riding conditions where chain slack can cause the ACCT to advance unnecessarily.
Many experienced DRZ400 owners recognize this limitation. They understand that while the stock ACCT may not catastrophically fail, it can still contribute to accelerated wear and potentially impact cam timing over time. This is why replacing the ACCT with a Manual Cam Chain Tensioner (MCCT) is a widely recommended upgrade across all DRZ400 model years.
Choosing an MCCT offers greater control and reliability. Several reputable brands offer MCCTs for the DRZ400, including Thumpertalk, APE, and Kreiger. These aftermarket tensioners allow for manual adjustment of the cam chain tension, providing a more precise and consistent approach compared to the automatic system. When selecting an MCCT, consider factors like price, design, and user reviews to find the best fit for your needs and budget.
Installing a Manual Cam Chain Tensioner on Your DRZ400
The installation process for an MCCT is straightforward, often compared to the simplicity of valve adjustments. If you’re comfortable with basic motorcycle maintenance, you can confidently perform this upgrade. Standard tools are all that’s required.
Before starting, ensure your DRZ400 is prepped by removing the seat, fuel tank, and valve cover.
Step 1: Set the Engine to Top Dead Center (TDC) on the Compression Stroke
Begin by removing the spark plug and the large and small access plugs on the left side cover of your engine. Rotate the engine in its normal direction of operation. Continue rotating until the camshaft lobes are positioned at approximately 10 o’clock and 2 o’clock, and the flywheel timing index line is centered within the sight window.
Note: While precise TDC is not absolutely critical, positioning the engine near TDC on the compression stroke, with valves closed and cam lobes at 10 & 2 o’clock, is essential. This precaution is to prevent potential cam rotation when tension is released from the chain. If the engine is not near TDC, releasing chain tension could allow the cams to rotate due to valve spring pressure, potentially causing the cam chain to skip a tooth on the sprocket and affecting cam timing.
Step 2: Access the ACCT
Locate the oil vapor recovery tank and loosen its bolt. Gently move the tank aside to gain clear access to the ACCT.
Step 3: Remove the Stock ACCT
Using the appropriate tool, remove the two hex head cap screws that secure the ACCT to the engine. Carefully detach the ACCT and the OEM gasket.
Step 4: Install the MCCT
Position the MCCT in place of the ACCT, reusing the original two hex head screws. Depending on the MCCT model, use the supplied O-ring or a new gasket for sealing.
Step 5: Initial MCCT Adjustment
Loosen the lock nut on the MCCT shaft and back it off, along with any O-ring if present, to maximize adjustment range.
Step 6: Adjusting the MCCT Shaft – Feeling for the Chain Cam Guide Touching Chain
This is a crucial step. Gently tighten the MCCT shaft by hand until you feel it just make contact with the cam chain guide. Finger tightness is sufficient at this stage; you are only ensuring contact, not applying tension yet. The key here is to feel when the Drz400 Chain Cam Guide Touching Chain occurs without forcing it.
Step 7: Fine-Tuning the Tension
Start your DRZ400 engine. Carefully and slowly back out the MCCT shaft until you begin to hear a distinct cam chain rattle. Once you hear the rattle, gradually tighten the MCCT shaft again, listening intently as the rattle diminishes.
Step 8: Finding the Sweet Spot – Just Enough Tension
Continue tightening the MCCT shaft only until the rattle completely disappears. Think of it like tuning an old radio dial – small adjustments are key. Once the rattle is gone, stop immediately. Do not overtighten. Avoid the temptation to add “just a little more” or another quarter turn for reassurance. Overtightening is detrimental and causes unnecessary wear.
Step 9: Secure the MCCT Setting
Once the rattle is eliminated, hold the MCCT shaft firmly in its position. Slide the O-ring (if applicable) up to the MCCT body. Tighten the lock nut securely against the body to lock the MCCT shaft in place and maintain the correct tension.
Step 10: Final Checks and Ride
Congratulations! Your MCCT installation is complete. Reassemble the components you removed (valve cover, fuel tank, seat). Typically, readjustment of the MCCT is rarely needed under normal riding conditions. However, significant engine work, chain stretch due to high mileage, or other major engine events might necessitate future adjustments. Resist the urge to periodically “adjust” the MCCT. If you find you need to tighten it further over time, it’s likely an indication of a worn or stretched cam chain requiring replacement.
By upgrading to an MCCT and correctly setting the drz400 chain cam guide touching chain tension, you enhance the long-term reliability and performance of your DRZ400’s engine, minimizing wear and ensuring optimal cam timing.
