Motorcycle Forum banner

Just bought 94 zxr750 engine blew up on me. Where should I start diagnosing.

1462 Views 10 Replies 6 Participants Last post by  Unkle Krusty
Welp I done did it now. I bought a 94 zxr750 last night and not even 15 minutes after I bought it the engine blew up. Was on expressway at 55mph then I feel/hear boom between my legs and entire bike instantly cuts off, pull over to the side of E way and I'm leaking heavy oil... before you guys bash me I checked the bike out last week and made sure every thing was fine the guy even let me test ride on expressway and was hitting 150mph easy, and thought everything was gravy, yea yea I know I should have gotten a mechanic to inspect it before hand so please save that cause I already know... I got stranded 50 miles from home (I drove a car and had my buddy with me to drive my car back while I'm on bike) then once my engine blew I called the guy up cursing a storm and knowing there's nothing I can do I call my cousin with a pick up and load it there...Bike is at my house and got the battery on a charger for right now and gonna hack off the fairings to see where I could be leaking oil. (I tried putting a screwdriver in starter solenoid and it's cranking) but I have no oil to really start it up and nothing no lights when I put key in..... any help on where I should start to figure out what happened ??? Any help is appreciated
1 - 11 of 11 Posts
No clue, sorry. But I am interested in what you find.
Can't help either but I do wonder if you didn't cause this problem yourself with this so called 150mph run. Doubt you did that but thats all together different. Still may have caused it doing something the bike/engine might never have done previously. Do hope you can get it back operational without too much extra expense.
I feel/hear boom between my legs...
Well, some people pay good money for that feeling... :devil:

Sorry, but it sounds pretty catastrophic. Until you get the fairings off to see the actual damage, there's not much point in speculating...
  • Like
Reactions: 1
Can't help either but I do wonder if you didn't cause this problem yourself with this so called 150mph run. Doubt you did that but thats all together different. Still may have caused it doing something the bike/engine might never have done previously. Do hope you can get it back operational without too much extra expense.
Of course, there's really no way to know if the bike's been to 150mph twenty thousand times before, either... in which case, I doubt anything the new owner did created the problem.
Can't help either but I do wonder if you didn't cause this problem yourself with this so called 150mph run. Doubt you did that but thats all together different. Still may have caused it doing something the bike/engine might never have done previously. Do hope you can get it back operational without too much extra expense.
Of course, there's really no way to know if the bike's been to 150mph twenty thousand times before, either... in which case, I doubt anything the new owner did created the problem.

Yea I did the 150mph run last week but yesterday when I bought it I didn't even dog the engine once the motor blew at 55mph 4-5 k rpm in 4 gear. I'm guessing the guy straight up murdered the engine in the last week when he knew I was gonna buy it
Can't help either but I do wonder if you didn't cause this problem yourself with this so called 150mph run. Doubt you did that but thats all together different. Still may have caused it doing something the bike/engine might never have done previously. Do hope you can get it back operational without too much extra expense.
Of course, there's really no way to know if the bike's been to 150mph twenty thousand times before, either... in which case, I doubt anything the new owner did created the problem.
Yea it's been too cold this morning to look at it really good. But I'm not sure if I sent a piston through the block cause wouldn't have my rear wheel locked up instantly if something seized up?
Of course, there's really no way to know if the bike's been to 150mph twenty thousand times before, either... in which case, I doubt anything the new owner did created the problem.
You are absolutely correct. I just go by that other saying, the straw that broke the camels back, so I do wonder. If it did it before it should be able to do it again. But drag strip cars blow otherwise perfectly good engines all the time with that one more run thing. Not anyone fault. Just happens. I wasn't trying to blame. Was just my out front wondering.
Of course, there's really no way to know if the bike's been to 150mph twenty thousand times before, either... in which case, I doubt anything the new owner did created the problem.
You are absolutely correct. I just go by that other saying, the straw that broke the camels back, so I do wonder. If it did it before it should be able to do it again. But drag strip cars blow otherwise perfectly good engines all the time with that one more run thing. Not anyone fault. Just happens. I wasn't trying to blame. Was just my out front wondering.
Yea I know what you mean. I did my highway pull last week then just to see it's limits and did the speed limit after. Yesterday when I bought it I didn't even dog on the engine once. It blew at 55mph/4-5k rpm in either 3rd-4th gear.

But if I would have thrown a rod and shot a piston straight up. Wouldn't that make the rear wheel lock up?
Yea I know what you mean. I did my highway pull last week then just to see it's limits and did the speed limit after. Yesterday when I bought it I didn't even dog on the engine once. It blew at 55mph/4-5k rpm in either 3rd-4th gear.

But if I would have thrown a rod and shot a piston straight up. Wouldn't that make the rear wheel lock up?
I have never blown an engine. How I've managed not to is beyond me cause I've done some stupid stuff. So I honestly can't answer. What you say sounds logical but I'd speculate every case is different. If parts stay out of the way and don't jam the works then no. But if the wedge in other moving parts then yes. I did see a V8 poke a hole in the oil pan and that engine had to be shut don't. It was still running. Is that rare? I don't know but somehow doubt it. I just haven't been around blown engines enough to know one way or the other.
I am going to gloss over the fact that you test rode someone else's bike at high speed.
Now we need to interpret what you mean by blew. If it is leaking or blowing oil, then the crank is building pressure and forcing the oil out.
You should not be trying to start a " blown " engine with a starter motor. Otherwise you are contradicting yourself.
You do need to remove the spark plugs and turn the motor slowly by hand.
Fill the oil first. You may need to check the valve gear.

The crank goes round and round, the pistons go up and down, the cam or cams go around and open and close the valves. Check all those thing. And the timing chain. If most things appear okay, check the compression.

With the back wheel off the ground check the gearbox.
If you thru a rod, the back wheel would stop turning. If a valve broke there would have been a lot of exciting noises.

Bon chance. UK
  • Like
Reactions: 1
1 - 11 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top