Thanks for the suggestions everyone. It looks like I'm going to be looking for another motor to swap and will start scanning CL, ebay, and salvages. But, since I will have to take out the old motor first, I might as well attempt a rebuild on it anyways, right? I mean, once the old motor is out, will I be able to do anything with it or sell it for anything? If I won't be able to do anything with the old motor, then at the very least I think I may as well take out the cylinders to see how bad the damage is and if it can be rebuilt. Next time I have a free weekend I'll try and take the motor out. Until then I'll be reading up on rebuilding this motor. I'll keep the group posted.
- Matt On Friday, April 20, 2012 10:44:30 PM UTC-4, Matthew Webb wrote: > > Hi my name is Matt. I'm new to the group and I recently got my first > bike, a 1992 CB750 with 3,800 miles for $1,800. It was always garage kept > and in very good condition. > > I had had the bike for only about 2 months but had put almost 2,000 miles > on it already. At the time I was getting home from work in the dark and > the cold and kept putting off my first bike maintenance until a weekend > when I could do some work in the daylight. I made a big rookie mistake and > ran my bike dry and the engine locked up when I stopped at a traffic > light. The low oil indicator light had turned on that morning but I was > hurrying to a meeting and thought I would be able to make it before things > got serious. > > I got my bike back to my house, and a few weeks later poured some oil over > the top of the engine, manually turned the engine, and then was able to get > it to start with no problem. However, the engine didn't seem to respond > right. So I looked into the top more and found some pretty serious > scouring on the exhaust camshafts, exhaust camshaft holders, and > crankcase. It also looks like some of the rubber stuff on the defoaming > chamber covers melted, but I'm not sure. The rest of the top end looked > completely fine, even the intake camshaft. See > pictures<https://plus.google.com/photos/118089145265544102347/albums/5733673720992831665?authkey=CKH1v53yteGPnAE>for > details but be warned, they are depressing. > > I am worried that pieces of metal may have gotten into the bottom of the > engine and wrecked more havoc. I'm also wondering if there may be more > damage than I've seen from when my engine locked up. Does anyone know what > damage is typical when you run your engine dry? Is it likely the entire > engine will need to be replaced? > > I have searched past messages but have not found much. Possibly because I > don't know what is best to search for. I've done a lot of other reading so > far and have some ideas but wanted to run it by the group first. > > To me it looks like I have a few options: > > 1) Sell the bike as is on CL for parts to someone who knows what they are > doing > 2) Purchase replacement parts for the damaged components and replace > them. With a quick search I have found these on ebay: cylinder > head<http://www.ebay.com/itm/CYLINDER-HEAD-CB750-NIGHTHAWK-91-93-92-1991-1992-1993-VALVE-TOP-END-ENGINE-MOTOR-/140691166315?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item20c1d8d46b> > , another cylinder > head<http://www.ebay.com/itm/Honda-CB750-SC-Nighthawk-Good-Used-Original-Engine-Cylinder-Head-1992-BDK-/150711279313?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item2317179ed1>, > > camshafts.<http://www.ebay.com/itm/Honda-CB750-SC-Nighthawk-Good-Used-Original-Engine-Cam-Camshaft-Pair-1992-BDK-/400261036787?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item5d316abaf3> > > I don't have much experience working with engines but I do have a Clymer > manual. The camshafts and holders look easy to replace but the body of the > crankcase is also damaged where the camshafts sit. Would it be possible to > have a shop re-machine it so that I wouldn't need to replace it? > 3) Take it to a shop, have them replace the parts and open the bottom of > the engine to look for more damage. > 4) Purchase another CB750 and use my first one as a parts bike. Also part > out my first one on ebay since the rest of the bike is in excellent > condition. > > Any suggestions would be appreciated, thanks. > > - Matt > > > -- You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. To view this discussion on the web visit https://groups.google.com/d/msg/nighthawk_lovers/-/rJ5N2GyyYkMJ. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/nighthawk_lovers?hl=en.
