24
Aug
Chipped Symptom - The piston crown is chipped along the top ring groove. Is a guide for the most.
You can see the edge is rounded-over a sure sign the rings were catching in the exhaust port.
Two stroke piston failure chart. Failure then the crank must be replaced along with the main bearings and seals. Chipped Symptom - The piston crown is chipped along the top ring groove. Cause - Head gasket leak.
Reason - Coolant is drawn into the combustion chamber on the down-stroke of the piston. When the coolant hits the piston crown. 2 STROKE This bulletin is provided for technical reference and service related updates.
If you have any questions comments or do not wish to receive these e-mails please reply to this e-mail or call the Service Technical Support Group 800 478-1244. PISTON FAILURE DIAGNOSTICS BURNT - OUT BLOW HOLE Hole on top of piston THE PERFECT. Hole in the piston crown gasolinepetrol engine 40 Piston top land seizure due to the use of incorrect pistons diesel engine 42 Erosion on the piston top land and on the piston crown gasolinepetrol engine 44 Piston and piston ring fractures 46 Piston fracture in the piston pin boss 47.
Filter and washed the oil film off the piston skirt. 11-COMPOSITE FLAKING Most two-stroke cylinders used on motorcycles and snowmobiles have composite plated cylinders. The composite material is made of tiny silicon carbide particles.
The electro-plating process enables the silicon carbide particles to bond to the cylinder wall. A careful examination of the piston can help a mechanic trace the source of a mechanical or tuning problem. This technical article serves as a guide for the most common mechanical problems that plague engines.
1-PERFECT BROWN CROWN The crown of this piston shows an ideal carbon pattern. The transfer ports of this two-stroke engine are flowing. THE GUIDE TO PISTON PROBLEMS Examining a used piston can give mechanics helpful information on the condition of a two-stroke engine.
When engine failure occurs the piston is likely to take the brunt Of the damage. Careful examination Of the pis- ton Can help a mechanic trace source Of a mechani- cal or tuning problem. Is a guide for the most.
Piston failure chart Sitemap 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38. The piston above has been damaged by over-speeding. Look at the piston material between the ring-lands.
You can see a big chunk of it is missing and some has been squished thinner creating a super-wide ring-land. Look at the top ring bottom of photo. You can see the edge is rounded-over a sure sign the rings were catching in the exhaust port.
Normally the piston temperature is higher on the exhaust side so catastrophic problems will appear there first. There are several reasons for a failure like this here are the most common. Air-leak at the magneto side crankshaft seal too lean carb jetting too far advanced ignition timing or faulty igniter box too hot of a spark plug range too high of a compression ratio too low octane fuel.
Two stroke cycle Upward stroke of the piston Suction Compression When the piston moves upward it covers two of the ports the exhaust port and transfer port which are normally almost opposite to each other. This traps the charge of air- fuel mixture drawn already in to the cylinder. Further upward movement of the piston.
Cracks in the crown and crown bowl. Faulty or incorrect injection nozzle. Incorrect quantity of injected fuel.
Lack of piston cooling. Installation of pistons with incorrect bowl shape. Improvement in performance eg.
ProX pistons should be measured perpendicular to the wrist pin a quarter of the way up the piston skirt from the bottom. Subtract your piston size measurement from your bore size and you have your piston-to-cylinder clearance. ProX pistons come with a chart on the instruction sheet that shows the range your clearance should be in.
Besides this will translate over to failures that we experience in our bikes as well. That said this is a piston from a 2003 Arctic Cat Mod 800 motor. This piston has about 10 hours of run time.
Judging from what I could gather the culprits are either. 2 Improper warm up. 3 Too hot of spark plug heat range.
Carbon built up in combustion chamber or on piston crown. Poor quality fuel or incorrect pre-mix. Ignition timing not set properly.
Piston to cylinder clearance excessive. Cylinder or piston worn. Piston pin or piston pin holes worn.
Connecting rod small end clearance excessive. Check the under side of the piston for burnt black oil this would indicate that the piston crown is to hot and maybe cooling system or jetting related. There are plenty of other signs of problems indicated by the pistons condition these listed are most common.
Never reuse circlips and never use a punch and hammer to remove the wrist pin. Contents Advertisement 1 The role of compression2 Common causes of low compression21 Worn or damaged piston rings22 Loose or damaged parts23 Scored piston3 Diagnosing low compression The role of compression Having good compression is an essential component needed for any engine to. I tend to agree with stihl.
It makes me chuckle to think that guys are sure theyre smarter and more skilled than the engineers and techs who put these saws together. Sure if you know what youre doing you may make a saw perform a little better for special purposes. If you know what youre doing.
Most guys are doing good to change a cylinder and piston without causing a catastrophic failure. Although the included piston rings are matched for the specific piston and bore size the rings on the piston should always be checked on the ring end gap specifications. The ring gap should be around 04 to 05 of the piston diameter and can be measured by placing.
ProX two-stroke pistons are manufactured by the same OEM-suppliers to exact OE specs. They are available in A B C and D sizing for most applications. ProX pistons come with the piston rings pin and clips all in one box.
Complete top-end gasket kits can even be ordered under one part number. 2 Stroke Engine Troubleshooting - Spark But No Fuel As you read above this is assuming you have checked the basics you know gas is on gas in the tank choke is on. One quick check you can do is to pull the fuel line off your carburetor turn the gas on for a.
The piston returns to Position 1 comes to rest and the process repeats. Segment 4-4A-1 is called the suction event. This completes the basic reciprocating compression process.
One cycle around the P-V diagram represents one revolution of the crankshaft and two stroke lengths of the piston one from Position 1 to 3 and another from Position 3. Defense Against Two-Stroke Piston Ring Destruction. 2-stroke pistons have a very small feature that is unique to 2-strokes only.
Here Wiseco takes an in-depth look at what a locating pin is what its function is and why 4-strokes dont need it. Comparatively speaking four-stroke piston rings have it easy. In this episode Roland talks us through some potential piston problems that you may encounter on your 2 stroke motocross bike.