Starter recoils are one of those chainsaw features that have a notorious reputation. In fact, the phrase ‘if it isn’t broke, don’t fix it’ applies here perfectly.
However, City & Guilds Unit 201 Chainsaw Maintenance requires the candidate to demonstrate knowledge and skill to check and maintain this component. This can be a help when things go wrong either on-site with a broken cord or more involved problems develop with the tensioning spring and cord canister.
On our training courses, we mainly use a demo set of recoils from Stihl MS261, Husqvarna 550XP and also a Jonsered. This avoids the need to remove the fixings so much, and this can lead to deterioration in the casting threads and screw heads. Interestingly, Husqvarna has changed to a Torx type from an Allen key - both can also be removed with a flat head screwdriver, but this is our last resort.
The starter recoil components comprise the:
- Housing or cowl housing acts as a guard to the flywheel and allows air for cooling to enter
- Spring in a case provides the recoil power to the cord
- Canister or pulley contains the cord when stored
- Flywheel, the engagement mechanism delivers starting rotation to the flywheel but retracts when the engine is running
- Cowl sometimes concentrates airflow
- Fixing screws hold the housing to the engine unit
Wear over time affects the pull cord. This is easy to check at the pull toggle end but more tricky where it is located in the plastic canister, as the starter housing needs to be removed and the tension released for this to be thoroughly examined.
Damage can occur through various errors in the use and importantly in bad maintenance:
- Multiple pulls where the engine fires and recoils can break or bend the pins mounted on the cord canister, these engage in the palls that turn the flywheel but retract.
- Not using the decompression feature can also make starting less straightforward
- Incorrect maintenance by over tensioning the spring leading to early breakage or failure
- Failure to locate the housing can damage pins when they engage with the flywheel at an angle
Visual inspection without removal will often provide early warning of impending cord failure. This is quick and straightforward to do and will not result in any of the errors above around spring over tension.
Cleaning of the air intake can also be performed with it in situ. For a more thorough job, removal is better, and a strip down - thorough clean ideal. This can be done by removing the four (usually) fixing screws and gently lifting or sliding the starter housing free.
Basic de-tension & re-tension as per the NPTC Assessment is a matter of:
- Pulling some cord out
- Hold the canister with a thumb
- Lift the cord free of the canister and gently allow the spring tension to release the canister then turns without re-stacking the cord
If the cord is worn, then a new piece can be inserted of the correct diameter and length. It’s best to heat the seal using a hot knife (or similar) and pull any stopper knots very tight ensuring they are flat in the canister. Remember to feed it through the housing exit hole and collar before fitting to the toggle. The recoil can be re-tensioned as described below.
Canister release is achieved by removing an R clip (Stihl), circlip (Husqvarna) or screw. Be careful to pull it out gently to avoid bringing the spring with it on older machines. Newer models tend to have the spring safely contained in a plastic cassette; this makes handling and replacement uncomplicated.
The spring cassette securing screws can be removed, and the spring lifted out. Most likely it'll be broken, so this is an excellent opportunity to thoroughly clean the housing now it's free of all other parts. Refit the new cassette and then gently locate the cord pulley to engage with the spring end and refit the fixing to hold it in position.
Fit a new cord as described above and you’re ready for re-tensioning.
To re-tension, hold the cord out at 90 degrees to the pulley and turn it clockwise 5-6 times. Each turn is winding the spring below up more, so if this is overdone, then starting the machine can easily break the spring, so check for over tension by attempting to add a half-turn or so. If the spring binds, then it’s likely a turn needs to be removed to achieve correct spring tension. Under tension, the drop will be noticeable.
Now it’s time to refit to the engine unit; the housing can sometimes sit proud of the engine unit, pulling the starter solves this by moving the engagement pins along rather than crushing them by tightening the fixing screws before this step is completed.