Are you a proud owner of a Doodlebug Mini Bike who’s experienced the frustration of a constantly stretching chain? If you’ve upgraded your Doodlebug with a more powerful engine like the popular 212cc Hemi Predator, you’re likely familiar with this common issue. The stock #35 chain often struggles to handle the increased power, leading to frequent adjustments, chain failures, and a less-than-ideal riding experience. Let’s dive into why this happens and explore effective upgrades to keep your Doodlebug mini bike running smoothly and reliably.
Understanding the Chain Stretch Issue on Doodlebug Mini Bikes
The original poster in our forum, TrailTamer, perfectly describes the problem: with a 212cc Predator swap on their Doodlebug and Racer mini bikes, the #35 chain stretches “like crazy.” Using even standard chain from Tractor Supply Co. (TSC), the chain becomes excessively loose quickly, requiring constant tension adjustments and frequent replacements – sometimes as often as every 3-5 tanks of gas. This not only becomes costly and time-consuming but also poses a safety risk if the chain snaps or jams while riding.
The core issue is that the #35 chain, while adequate for the stock Doodlebug engine, is simply not robust enough for the increased torque and power of a 212cc Predator engine. The higher stress causes the chain to elongate or “stretch” prematurely, leading to the problems TrailTamer and many other mini bike enthusiasts face.
Solution 1: Investing in High-Quality #35 Chain
Before jumping to sprocket swaps, consider upgrading to a premium #35 chain. As forum member chipper and others recommend, investing in a high-quality chain like the RLV Gold On Gold or EK chain can make a significant difference.
RLV Gold On Gold and EK Chains
These performance chains are designed to withstand higher stress and resist stretching. While they might be more expensive than standard chains available at local stores, the consensus in the mini bike community is that they are well worth the investment. Users like Daniel Coop swear by them, stating they are “the only chain I’ll use. Worth its cost.” FOMOGO, another experienced member, confirms that even high-quality chains will stretch slightly but “not enough to be concerned about. Or as much as cheap chain does.”
CarPlayLB further emphasizes the value of good chains, suggesting, “buy it right, buy it once!” They point out that the cost of constantly replacing cheap chains and potentially damaging sprockets due to chain failure can quickly outweigh the initial investment in a quality chain. OldMiniBikes.com is often cited as a reliable source for these premium chains and even chain breakers for easy maintenance.
Solution 2: Upgrading to #40 Chain and Sprocket
For a more robust solution, consider upgrading to a larger chain size, such as #40, #41, or #420. This involves swapping out your sprockets to match the new chain pitch. TrailTamer initially explored this route, asking about direct bolt-on #40 sprockets.
The Baja Warrior Sprocket Swap
In a clever and cost-effective move, TrailTamer discovered a solution using parts from a donor Baja Warrior mini bike. By drilling a new bolt pattern and swapping the clutch, they successfully installed a Baja Warrior sprocket on their Doodlebug. This allowed them to use a stronger, likely #40 or #41, chain.
This upgrade proved successful in eliminating the chain stretch issue and even provided an unexpected bonus: increased top speed. However, TrailTamer noted a decrease in low-end torque initially. This leads us to the next enhancement…
Solution 3: Torque Converter and Chain Upgrade Synergy
To regain the lost low-end torque and further enhance the Doodlebug’s performance, TrailTamer installed a torque converter. Combined with the sprocket and chain upgrade, and larger “snow hog” tires, the result was a significantly improved mini bike.
In a later update, TrailTamer enthusiastically reported: “Still running the same chain since day 1. Zero chain-related problem. I LOVE the combo. Hydraulic brake system, snow hog tires, torque converter, upsized chain. It’ll go anywhere…” This testimonial highlights the effectiveness of combining a chain upgrade with a torque converter for optimal Doodlebug performance and reliability, especially after an engine swap.
Alternative High-Performance Chain: JT Sprocket X1R2
For those seeking the ultimate in chain performance, TheDullCarbide recommends the JT Sprocket X1R2 chain. This is a high-end, X-ring chain known for its exceptional strength and durability. While it might be on the pricier side and require a bit more effort to break due to its robust construction, its hardened nature and superior grease retention make it a top choice for demanding mini bike applications.
Conclusion: Choose the Right Chain Solution for Your Doodlebug
Dealing with chain stretch on a Doodlebug mini bike, especially after an engine upgrade, is a common challenge. However, by understanding the cause and exploring upgrade options, you can significantly improve your mini bike’s reliability and performance.
Whether you opt for a high-quality #35 chain like RLV Gold On Gold or EK, upgrade to a larger chain size using a Baja Warrior sprocket (or similar), or invest in a top-tier chain like the JT Sprocket X1R2, addressing the chain issue is crucial. For the best overall performance and to recover any low-end torque lost from sprocket changes, consider adding a torque converter to your Doodlebug mini bike. By choosing the right solution, you’ll spend less time wrenching and more time enjoying the ride on your upgraded Doodlebug.
