Bent valve, now what?

[poorman9]

This is the next chapter of an on going saga titled "You Will Never Enjoy Owning a Motorcycle"...you can read the previous chapters here, here and here.

Basically the bikes never ran for longer than 10 seconds, and most recently wouldn't do anything at all. So the last thing I did was get a new set of carbs from the junk yard. I put them on, kicked it over and it felt like it wanted to go. Kicked it again and started hearing this metal on metal klanking sound. It also had been leaking some oil so I tore my top end apart again. I think the oil leak was caused by loose head nuts, but the klanking turned out to be a stuck valve. I tapped the valve spring, pulled out the valve and the shits all bent up!

So obviously I'm gonna be donating another $20 to the charity of Mike's XS, for a new exhaust valve but is there anything else I should replace? I looked around for collateral damage but everything else seemed fine. What would cause this to happen?


Thanks for the on-going support during these trials and tribulations.

Poorman9

 

[oldbiker]

hi you could check your guides,,,, regards oldbiker

 

[Tomterrific]

An engine that sets gets corrosion and the oil bleeds off. The valves are dry and a start or a kick will sometimes have a valve sticking in the guide so the piston comes up and kisses it. If the spark plugs are pulled and oil squirted into the cylinder, then the engine is turned to spray teh excess out the plug hole, the valve probably would not have stuck. Too bad you didn't know this. A darn shame.

Tom

 

[poorman9]

hi you could check your guides,,,, regards oldbiker

Here's the springs and the guides

Too bad you didn't know this.

So to recap, any time I leave the bike sitting for a while, it's a good idea to pull the spark plugs and squirt some oil down the holes? Your right I had no idea.

 

[xscessivecompulsive]

I had the same thing happen to me after rebuilding my top end, my guess is my engine was running way to lean which caused it to happen! But then again thats only a guess! And if you cant find stock exhaust valves, dont put in the stainless valves from Mikes! They are complete garbage!! I took my head to Baisley Performance on Interstate and Killingsworth and had them install Kibblewhite valves and guides and havent had a problem! They are a little spendy but well worth the money! And it might not be a bad idea to run your head over to Baisleys and have them check it out! They are straight shooters and the best in the business!

XsC

 

[poorman9]

Hey nice to see somebody else from Portland here. How much did the new valves end up costing you? I don't have too much extra cash, but I definitely wouldn't getting somebody else to take a look at my engine while it's out of the bike.

 

[Eire Taylor]

none of the parts in that pic are your guides, the guide is the part in the head in which the valve slides!

Check and make sure it didnt get cracked etc, the bend on the valve is not too bad so id say it should be ok!

 

[xscessivecompulsive]

I think for both valves and new guides I think it was around 120, or right in that area! And if you cant find a stock valve, I have an extra stainless exhaust valve you could have if you wanted it! I just heard mixed reviews on those valves which is why I switched them out after install and went with the Kiblewhites!

XsC

 

[poorman9]

Yeah $120 more than I'd have to spend and this damn nice weather is really making me want to ride. I just read a few bad things about the stainless valves too, although free is a nice price. I'll think about it, but either way thanks for the offer.

 

[poorman9]

none of the parts in that pic are your guides, the guide is the part in the head in which the valve slides!

Check and make sure it didnt get cracked etc, the bend on the valve is not too bad so id say it should be ok!

Ooops

It looks fine to me...but I can't tell a guide from a keeper, so what do i know.

 

[xscessivecompulsive]

Yeah $120 more than I'd have to spend and this damn nice weather is really making me want to ride. I just read a few bad things about the stainless valves too, although free is a nice price. I'll think about it, but either way thanks for the offer.

Ya man, lemme know if I can help out in anyway! And I hear ya about this weather! Theres still tons of riding time left though! Im hoping that since we had such a shitty spring that the fall will be nice!! And fall riding in the NW cant be beat!! Best of luck to you!!

XsC

 

[bikerjack]

had a bent exhaust valve too. cleaned the guides, the heads. got every bit of carbon out of them. bright light, magnifying glass and found no cracks, pits, etc. i bought an exhaust valve with its collets here from one of our members for 10 bucks and im set

 

[grizld1]

poorman9, the factory manual at www.biker.net gives the procedure for valve guide inspection. With springs removed, you shim the valve up in the head so that it clears the seat by 10 mm., set a dial indicator against the valve edge, and check how far the valve can rock in the guide, then set up 90* from your first inspection point and check the rock on that axis. Tolerances are given in the manual--download the engine section and the appendix (it's free) and look it up. Check the clearance when you have a new valve in hand.

If stem-to-guide clearance is too wide the valve guide seal won't hold, and erratic contact at the valve seat can also occur. Be sure to check the clearance before you have the seat ground and the new valve lapped. A new guide changes the valve position slightly, so the seat must be ground to fit; you don't want to grind the seat twice.

 

[Tomterrific]

Valve guides can oval either from many miles or an over rev floats the valves and the piston barely ticks the edge. The engine keeps running with the almost imperceptable bent valve.

I used to rebuild old equiptment engines and I could feel a bad/worn guide by wiggling the valve side to side and fore and aft. My Norton had ovaled intake guides from over revs and I could feel it so I replaced the guides.

Since the engine didn't run with the bent valve and the guide did not crack, my guess is the guides are useful so go ahead with new valves unless you find a reason to pull the guides.

What I said about squirting engine oil into the SP hole dealt with those bikes that had set in a field for a long time. IOW, any suspect bike you try to get running again, The best time for everyone to squirt oil is before the bike is stored so it is as fresh as possible when taken out of storage.

Tom

 

[Purplezinger]

poorman9, you better damn well learn the difference between the valve guides, the valves, the retainers and the keepers and all the other engine parts and procedures or you will waste tons of money correcting your own mistakes.

 

[poorman9]

I'll get right on learning all engine parts and procedures.

Thanks for that.