Yamaha XT350 Knocking - Blown Engine (?)

[JohnRaven.exe]

Hey guys, I was out ridin my brothers Yamaha XT350 the other day, and I knew it needed an oil change, but my brother showed up and took off on it, so I was like...ok, I guess it will be fine for a few more minutes of riding. (It was sitting all winter, and I put about 30 miles on it about a month ago...and maybe another 4-5 this past saturday)

So when he came back we could hear the engine knocking with that chattering/clicking noise. We put some oil in it (some racing oil) and let it cool down for an hour or so (It was REALLY hot) So after we let it cool down a bit I took off with it. I wasnt pushing it all at, just kinda strolling along. So when I came back to the house, I did noticed the knocking/clicking started to sound better. My brother says the engine is blown and is going to eventually lose power and die.

#1 How many miles should I be able to put on it before I need to change the oil?

#2 Is this engine totally blown and worthless now?

#3 How can I ATLEAST make it last longer if there is serious damage?

#4 How much would it cost to completely rebuild the engine?

I'm still a real novice, so any help would be VERY helpful.

Thanks :)

 

[Ol'89r]

I did noticed the knocking/clicking started to sound better. My brother says the engine is blown and is going to eventually lose power and die.

#1 How many miles should I be able to put on it before I need to change the oil?

#2 Is this engine totally blown and worthless now?

#3 How can I ATLEAST make it last longer if there is serious damage?

#4 How much would it cost to completely rebuild the engine?

I'm still a real novice, so any help would be VERY helpful.

Thanks :)

1. For the price of a quart of oil and the damage that can be done by not changing the oil, you can't change it too often.

2.If it is still running, the engine is not blown in the true sense of the word.

3. If it has serious damage you can't make it last longer. Chances are, it only needs the cam chain adjusted or a valve adjustment. Purchase a service manual. It will show you how to do these things and if you have to dissemble the engine it will show you how to do that too.

4. That's something you can't tell until you disassemble the engine and evaluate the damage.

Just my $ .02

Ol'89r

 

[QKENUF4U]

im with OL89r on this one. start with the simple things first before thinking the worst.
1. change oil/filter
2. get a manual
3. check valve clearance
4. pull the timing chain tensioner and make sure its working correclty
good luck

 

[rmc_olderthandirt]

You said that the oil needed to be changed, and you also said that you put oil in it when your bother came back. Was it out of oil when your brother took off?

Riding on old oil is not likely to cause an immediate problem. It is more of a long term wear issue, change the oil regularly and the engine will last longer.

If it was out of oil then the damage occurs very quickly.


If the rod is knocking and you continue to ride it you will increase the damage.
If you stop now and rebuild there is a good chance that the rod and crank will be okay, perhaps requiring a minor grinding. If you keep going you will pound the crank out of round to the point that it can't be reground to fix it and you will need a new crank.

If the rod breaks (common occurance shortly after the knocking starts) the damage to the case will likely be so bad that the engine will be worthless.

If you continue to ride on it I doubt that it will slowly lose power and die. It will suddenly break; WHAM!!!! and never run again.

 

[Ol'89r]

If you stop now and rebuild there is a good chance that the rod and crank will be okay, perhaps requiring a minor grinding. If you keep going you will pound the crank out of round to the point that it can't be reground to fix it and you will need a new crank.
QUOTE]

rmc_olderthandirt.

FYI, the engine in question uses a replaceable crank pin and continuous needle bearing on the big end. The rod and crankpin assembly can be replaced and journal grinding is not necessary.

Just my $ .02

 

[JohnRaven.exe]

Hey guys, thanks for all the replys.... Its much appreciated.

I don't know if it was completely out of oil when my brother took off, but I didnt put anything in it before he did...so I guess it was empty(?).

In about 10 days or so... I'll be bringing down to my home town for a check-up at a motorcycle shop. I guess all I can do is pray for the best :)

I'll let you all know how everything turns out! Thanks again!