Cylinder Repair for 2-Stroke Top Ends

We offer an all-inclusive package deal to service a 2-stroke top end components like the cylinder, head, and powervalve system on applicable models.

We offer 4 types of repairs;

1) Honing of plated cylinders to clean-up minor seizures $20
2) Boring and honing to the next oversized piston for cast-iron sleeved cylinders $50
3) Replating with nickel silicon-carbide composite plating to stock size and up to 2mm oversize $275
4) Repairs to a big bore cylinder that we originally prepared by Forward Motion since 1990 $150

Here is a list of what each package includes and some helpful notes.

1) Diamond honing for plated and iron-lined cylinder with port chamfering and solvent-flushing, and bore measurements. Also we offer slightly oversized piston kits (example A,B,C,D,) like Pro-X and Vertex cast aluminum piston kits. Our prices are on par with Motorsports mail-order prices. $20 plus parts

2) For cast-iron sleeved cylinders we will bore, hone, chamfer the ports, relieve the exhaust bridge, machine the cylinder base or top for flatness, clearance the exhaust valves, and clean the cylinder. We have piston brands available like Wiseco, Pro-X, JE, Wossner, and Vertex and you can supply a piston kit that you already bought, but theres no free trade-ups if you bought the wrong size. We also have gasket kits like Cometic, Moose Racing, and K&S. $50 plus parts

3) If you're looking for a comprehensive top end repair to original or oversizes up to 2mm/.080inch we offer an all-inclusive service to repair the cylinder and reset the port heights to comply with AMA/NMA stock classes, maximum oversize for the class. We'll also re-machine the cylinder head for flatness, clean-up scarring from broken rings and pins (within reason) and set the compression ratio for fuel type choices, compliment aftermarket accessories, or for high altitude riding like in the Rockies and Sierra Madre mountain ranges (plus 5,000ft). We'll also clean and service the powervalves (on applicable models) and assemble the system with moly-paste (factory recommended lubricant) and re-time the system so you can just install the piston and slide the top end assembly on the cases. We have piston brands available like Wiseco, Pro-X, JE, Wossner, and Vertex and you can supply a piston kit that you already bought, but theres no free trade-ups if you bought the wrong size. We also have gasket kits like Cometic, Moose Racing, and K&S. This package comes with a 1-year warranty and free diamond honing for the life of the cylinder. $275 plus parts

4) If you bought a big bore kit from us in the past 21 years that we've offered our kits, you can get it repaired for a special price of only $150 which demonstrates our commitment to the lifetime support of our products and services. This all-inclusive package includes service to the powervalves and head too. And you don't need to disassemble or clean the cylinder first, we have all the EPA compliant cleaning and recycling equipment for the Greenest consciences. However you should pack the top end in a plastic bag because if the oil leaks out and stains the box it may be scrutinized and opened by the freight company and delayed in shipment. $150 plus parts

APPLICATION CHART

All 2-stroke cylinders for motorcycles including:
Aprilla
GasGas
Honda
Husqvarna
Kawasaki
KTM
Pavesi
Suzuki
Rotax
TM
Yamaha

FAQs on 2-Stroke Cylinder Repairs

If the piston breaks can I just powerwash the crankcase and change the oil to get out the broken pieces?
The crankcase on 2-stroke engines is sealed so draining the transmission oil won't help. Most likely the metal particles will contaminate the bottom end to the extreme that you'll need to rebuild the bottom end with a new crankshaft, bearings, and seals. We offer that service and it averages $500 parts and labor. Additionally you'll need to powerwash the exhaust pipe (not silencer) because metal may be trapped in there and re-enter the cylinder once you restart the freshly rebuilt engine.

If I send my old piston with the cylinder can you tell me what the original failure was caused from and recommend repairs to keep it from happening again?
Yes, we recommend that you send any and all damaged parts, especially if you've had repeated failures. Also you should check out the tech article (PDF format) from Eric's book titled Piston Diagnostic Guide (on our home page). We'll diagnose your mechanical problem and recommend action solutions.

My bike has an aftermarket sleeve and now the coolant blows out the vent hose from the radiator. Why does this happen and what can be done to fix it?
Cast-iron sleeves are installed with an interference thermal fitting method. The sleeve is chilled in a freezer and the cylinder is heated in an oven and the sleeve in quickly installed in the cylinder where it expands and locks into place. Good sleeving companies install the cylinder in a press and hold the sleeve down until it cools to room temperature and the machine the top of the cylinder flat. On your cylinder the sleeve is squeezing upwards out of the bore, which allows combustion gas pressure to escape into the cylinder's water-jackets. The excess pressure blows-out past the radiator cap. The only was to fix it is to machine the top of the cylinder and that machine-op is included in the $50 package for cylinder boring/honing.

I just had my cylinder plated by US Chrome for a 2mm oversize and now my bike is slower than before and pings like crazy in the upper mid range. What's wrong and how can I fix it?
Plating companies are not engine builders! They don't have people with the knowledge to do the job right. When a cylinder is over-bored there are many other factors to consider like head and crankcase clearance to the piston, compression ratio, and port heights. Just boring the cylinder 2mm oversize and installing the stock head and powervalves effectively raises the compression ratio to dangerous levels which limits the top end power and makes the powerband flatten-out lower in the rpm range and causes detonation. Additionally the powervalves may contact the piston. We can usually fix a top end like that for about $100.

HOW TO GET STARTED

Just CLICK & PRINT a copy of the Service Order Form and follow the directions on packaging your parts for shipping. All the options are listed for services, powerband choices, fuel types, spare parts, shipping methods, and payment options. Click here for the service order form.

ALL INTERNATIONAL ORDERS GET OUR RUSH SERVICE FOR FREE!