Technical Q and A for classic motorcycle maintenance and repair.
Editor’s note: If you’re having trouble with that old Suzuki, BSA or BMW, Keith Fellenstein is your guy. From motorcycle tuning tips to detailed motorcycle engine repair, he can draw from a wealth of experience to help guide you to success. Send questions to: Keith’s Garage, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as the subject.
Q: I just started a total restoration of a Triumph Trident. The engine took on some water at some point, and I’m not sure if it is going to be worth the investment to rebuild it. My first question is, what size and type of wrench do I need to take off the cylinder? These are odd looking bolts. Also, the piston rings are fused to the cylinder walls. I have them soaking in penetrating oil, but so far I have not had any luck in freeing them up. — Jim T./via email
A: Those odd-looking nuts have 12 points and you need a box wrench to loosen them. A 13mm wrench works, but a 1/2-inch wrench fits better. Sometimes you have to grind down the thickness of the wrench to fit in the narrow space between the bottom fin and the nut. You may also have to grind down the circumference of the wrench for clearance between it and the cylinder base. For your seized engine, a 50/50 mix of ATF and acetone is reported to work well as a penetrating solvent. Applying heat cyclically can also help break things loose. If you’ve recently used the ATF/acetone mix, use a heat gun rather than a torch; a torch would be OK after the acetone evaporates. Don’t use MAP gas; it gets hot enough to melt aluminum. Propane should be safe if you keep the torch moving. Aluminum gives no warning; one second it looks fine and the next it’s melting. Alternating between hot and cold should create enough expansion differential that the rings will eventually break free of the cylinder walls. Applying a little torque to the crankshaft nut helps break it free, too. Remove the primary cover to access the crankshaft nut. Patience is your friend. MC