Jonsered 670 Champ Chainsaw (Owner’s Guide)
The Jonsered 670 Champ is a legacy, roughly 67 cm³, air-cooled two-stroke saw. Before using or buying one, confirm its identity and serial details, then match the bar, chain, and sprocket by their markings. Use the correct manual for fuel, setup, and service. Treat safety, parts condition, and dealer support as essential, not optional.
Would you rather buy a saw that is sound but needs careful checks, or pay extra for a “professional” label that tells you little about its condition? With a used 670 Champ, the answer depends on the machine in front of you. Age, repairs, and replacement parts can matter more than the name on the cover.
Identify the 670 Champ before ordering parts
The 670 Champ is a legacy professional saw with an air-cooled, single-cylinder, two-stroke engine and about 67 cm³ of displacement. That identifies its general class, not every detail of your machine. Production differences and later repairs can change what parts fit, so use the saw’s identification and matching manual as your starting point.
Check the saw and its serial details
Look for the model and serial markings on the saw itself, then compare them with any paperwork and the correct owner’s or service manual. Do not rely on a seller’s description or a generic online serial-number chart alone. Serial formats and available records can vary by production period and market, and a number by itself may not confirm a saw’s complete history.
I treat the serial as one clue, not a certificate of condition or origin. Check that the markings appear consistent and unaltered, and ask a Jonsered-capable dealer or qualified repair shop to help confirm the model and parts when records are unclear. For a used purchase, also compare the nameplate and casing details with documented examples; mismatched parts may reflect normal repairs, but they deserve questions.
| Check | What to look for | Why it matters |
|---|---|---|
| Model and serial markings | Clear, consistent identification on the saw | Helps find the right manual and parts |
| Manual | Model and production details that match | Procedures and specifications may differ |
| Seller’s claims | Receipts, service notes, and clear photos | Supports, but does not prove, condition or origin |
| Replacement parts | Bar, chain, sprocket, carburetor, and ignition markings | Repairs can change the original setup |
Set up the saw and prepare for safe work
A safe setup means the saw, cutting attachment, protective gear, and work area are all ready before the engine starts. On an older machine, do not assume the factory parts remain in place. Confirm the actual bar and chain configuration, check safety controls, and stop if a damaged or mismatched part cannot be identified.
Match the bar, chain, and sprocket
The bar mount is the shape and size of the fitting that connects the guide bar to the saw. Before installing a cutting attachment, match the mount pattern, chain pitch, chain gauge, drive-link count, and sprocket pitch. Read the markings on the bar and chain, and confirm the sprocket is compatible. Do not choose a chain or bar from engine size alone.
Set chain tension by the manual for that setup. The chain should fit the bar correctly and move as directed by the manual; do not run a loose, damaged, or mismatched chain. Chain depth gauges, sometimes called rakers, control how much wood each cutter takes. Set them to the chain maker’s specification with the correct gauge, not a guessed universal measurement.
Inspect protective equipment and controls
Wear chainsaw-rated leg protection, a helmet with eye and face protection, hearing protection, gloves, and protective boots. Before starting, inspect the chain brake, throttle lockout, stop switch, chain catcher, fasteners, chain tension, and bar lubrication system. Keep bystanders out of the work area and plan an escape route before cutting.
The chain brake helps stop chain movement in certain situations, but it cannot prevent every injury. Check it as the manual directs and do not use the saw if it fails or if a required safety part is missing or damaged. Apply relevant ANSI Z133 and OSHA 1910.266 requirements when the work falls under those standards.
Fuel, starting, and basic operating checks
The 670 Champ uses a two-stroke engine, so its fuel must be mixed with the specified two-stroke oil. The correct ratio and starting sequence depend on the matching manual and oil instructions. Never assume a ratio from a newer saw, and never put straight gasoline in a two-stroke engine.
Mix fuel and check lubrication
Use fresh gasoline mixed with quality oil made for air-cooled two-stroke engines, at the ratio stated in the correct manual and oil label. Label the mix so it cannot be confused with straight fuel. Avoid stale or contaminated fuel. If you cannot confirm the correct ratio for this saw, pause and find the applicable manual rather than guessing.
Fill the bar-oil reservoir with dedicated chainsaw bar-and-chain lubricant suited to the working temperature. Do not use engine oil as a substitute, and do not operate with an empty reservoir. Check oil delivery using the safe method described in the manual. If oil is not reaching the chain, stop and diagnose the cause before cutting.
Start and check idle behavior
Start on stable ground with the chain brake applied, following the manual’s cold- or warm-start steps. Once the saw runs, check that the stop switch works and that the chain stays still at idle. If the chain moves at idle, stop the engine and have the idle setting or clutch checked before using the saw.
Do not adjust the carburetor by copying generic screw-turn instructions or an RPM number from another model. Exact settings and speed limits belong to the serial-specific service procedure. Incorrect adjustment, especially a lean high-speed setting, can damage the engine.
Cut safely and recognize kickback risks
The right cutting method depends on the wood, the saw’s condition, and the operator’s training. Keep two hands on the saw, stand firmly, and stay aware of the bar nose. Use this machine for work you can control; a large engine does not make a difficult cut safe.
Bucking and felling
Bucking means cutting a felled tree or log into shorter sections. Before each cut, assess whether the wood is under tension or compression, could roll, or might trap the bar. Plan your stance and escape path, and do not force the chain through a binding cut.
Felling requires training, a sound tree assessment, planned cuts, and control of the fall direction. A hinge is the wood left between the cuts to guide the tree; its condition and size matter. If you are not trained or the tree, wind, or surroundings make the fall uncertain, leave the job to a qualified professional.
Kickback is a rapid movement of the saw that can occur when the upper part of the bar nose contacts wood or another object. Keep that area clear and in view, use compatible low-kickback equipment where appropriate, and maintain a working chain brake. Never cut above shoulder height.
Maintain, sharpen, and store the saw
Regular care helps reveal faults before they become failures. Follow the correct service manual for cleaning, inspection, adjustments, and fastener values. Because a legacy saw may have replacement components, identify the parts fitted to your machine before using a sharpening guide or ordering service parts.
Clean and inspect after use
With the engine stopped and cool, clean debris from the air filter, cooling fins, and starter area as directed by the manual. Inspect the bar groove, oil holes, rails, sprocket, chain links, and brake. If a part is damaged or showing abnormal wear, find the cause and correct it before returning the saw to work.
Sharpen the chain to the chain maker’s specified file size, angles, and depth-gauge setting for that exact chain. Keep cutters even and depth gauges consistent. A dull or poorly filed chain can create more heat and vibration, increase engine load, and make control harder.
Use the right service procedure
Carburetor tuning should follow the serial-specific service procedure, with a reliable tachometer and any required safety controls. Do not tune by ear, use generic RPM targets, or turn screws by a recipe meant for another saw. Use the service manual for fastener torque values as well; generic figures are not a safe substitute for clutch, flywheel, bar, or engine fasteners.
For seasonal storage, follow the manual’s fuel-system instructions. After use, let the saw cool, clean and inspect it, and cover the chain. Keep the saw and fuel away from ignition sources. Before returning it to service, inspect fuel lines, the filter, carburetor condition, and any purge parts fitted to the saw.
Used-saw inspection scenarios and buying decision
A used saw should be judged by its identity, parts compatibility, safety systems, engine behavior, and service options. These checks are more useful than relying on a “pro” label or a seller’s claim that the saw is ready to work. The scenarios below are inspection examples, not reports of specific individual sales.
Scenario: the saw runs, but its setup is unclear
A saw that starts and idles may still have an incorrect bar, chain, or sprocket. Read the markings and verify every fitment point before buying or cutting. If the bar and chain cannot be identified, budget for a correct, matched setup and ask a qualified shop to confirm compatibility.
Scenario: the serial or service history is uncertain
If the serial is missing, altered, or hard to read, treat the machine’s identity and parts history as unresolved. Ask a dealer or repair shop to inspect it before you commit. A receipt or service note can help, but it does not replace an inspection of the saw’s condition and safety features.
| Finding | Practical next step |
|---|---|
| Identification and parts match, safety checks pass | Confirm service needs and dealer support |
| Parts are present but markings are unclear | Have a qualified shop identify the setup |
| Chain brake, stop switch, or catcher is faulty | Do not operate until repaired and checked |
| Fuel ratio or tuning details are unknown | Find the correct manual; do not guess |
| Seller will not allow a careful inspection | Consider walking away |
Before buying, ask who can service the saw and obtain compatible parts. Dealer access matters for an older machine because diagnosis and parts identification can take more work than on a current model. A sound platform with a clear service path is a better choice than an attractive price paired with unknown repairs.
Conclusion and FAQ
The 670 Champ can be a capable legacy saw, but its age and configuration call for careful checks. Confirm the model, use the matching manual, identify the parts already fitted, and verify safety systems before cutting. If fuel, tuning, or component fit is uncertain, stop and get qualified help rather than relying on a generic specification.
Is the Jonsered 670 Champ a professional saw?
It is a roughly 67 cm³ legacy saw in the professional class. The label does not prove that a used example is safe or in good condition.
What fuel mix does a 670 Champ use?
Use the ratio stated in the correct manual and the oil maker’s instructions. Do not assume a ratio or run straight gasoline.
What bar length fits the 670 Champ?
Bar length depends on the saw’s setup and intended work. Confirm the mount and approved configuration in the matching manual.
Can I choose a chain by model name alone?
No. Match pitch, gauge, drive-link count, and sprocket pitch, and confirm the bar mount.
How do I decode its serial number?
Use the serial with model-specific records or ask a knowledgeable dealer. Do not assume one online chart covers every production period or market.
Should the chain move at idle?
No. The chain must remain stationary at idle. Stop using the saw if it moves and have it checked.
Can I tune the carburetor by ear?
No. Follow the correct service procedure and use the required tools and safety controls. Generic settings can damage the engine.
What oil goes in the bar reservoir?
Use dedicated bar-and-chain lubricant suited to the conditions. Do not substitute engine oil or run the saw with an empty reservoir.
How should I sharpen its chain?
Identify the chain first, then follow its manufacturer’s file size, angles, and depth-gauge setting.
What should I do if the chain brake fails?
Do not operate the saw. Have the brake repaired and checked before returning the machine to service.
(This article was written by one of our staff writers, Elliott Fowler. Visit our Meet the Team page.)
