How to tell if a valve is bent

I recently took on a new project and ended up taking the head off the engine. I found some majorly crusty intake and exhaust valves. I cleaned 1 and 2 pistons valves up and tried to put them back in the head. The exhaust valves fit in perfect, but the intake didn't. I noticed that they wont rotate quite right when I push them all the way in and are hard as hell to get out of the head. There is also some space that I can see that is left between the head and the intake valve. Visually it looks ok, but I would be happy to snap a pic for everyone to see. It seems like all the intakes are bent and the exhausts are fine. Any advice or does anyone know how much new valves are?

Yeah they're bent all right, makes sense too since the intakes are usually the ones that hit the pistons. Dennis kirk has vesrah valves for about 27$. Make sure the cam timing is on and also see if the sprockets for the cams have been/are slotted. Someone may have been "playing" with the timing and BAM! If you are in question (still) as of the valve to piston clearance when u re-assemble, Put a piece of solder down the cylinder and curve it so it fits into the valve pocket on the piston. Youll feel it hit. Then turn the engine over by hand to squish the solder. Pull out the smashed solder and measure and compare to spec. Maybe a round of ape springs would help for future over rev. That is likely what happened anyway. When you get new valves, consider new guides and seals if needed. Youll be glad you did.

Thanks for the reply. Out of curiousity, could this be a far out reason why I might have thought I needed new rings? As I got some RPMs I would sometimes get blue smoke and or oil comming out of the crank case breather? I was anticipating having to get new rings, but thing will go much better if I have to buy the new valves but not the rings. Can I visually tell if I need new rings? The compression test didnt tell me to much because of the open valves. So this definately sounds like bent valves to you? I just found it odd that I don't get free play all the way around. Right now I am looking more towards replaceing the valves and seals.

ALso do I have to have these valves ground, or can I get away with lapping the new valves?

If you are getting all new valves I would think having the seats newly cut would match them up better.

RomSpaceKnight wrote:

If you are getting all new valves I would think having the seats newly cut would match them up better.

what Rom said,but id also have the guides checked also as long as you are doing the valves.is there any ridge in the cylinders?the rings are are kind of a crap shoot,i hate to have to do something twice so i personally would check the bores if they are in spec id toss some rings in there while its apart.if the bores are too far gone you can toss it back together and try and put it off for a while or have it bored,your call.

Totally off topic, but I see you are a Ghost in the Shell anime fan from your avatar, Neotrion. Groovy.

Actually, the Denniskirk OUTLET store may have some valves real cheap for your bike. You can get their number from Denniskirk.com customer service. They were selling valves for about $3 a couple months ago on eBay and they didn't sell well. Their outlet store isn't really connected with the main business and you have to call (no internet).

Once you get the valves, stick them in the guides. Rock the valves to see how they feel in the guides. If they don't have excessive play, the guides will work OK and you can then MEASURE the stem length using a digital caliper. Most digital calipers have an arm that comes out while the jaws open and the arm is for measureing depth.

If the valve stem length is within spec, lap them and check for the seal. If they are too long, take them to a good machine shop and have them grind the valves. They have a tool that spins the valves against a grinder to make sure the ends are flat. You can't hardly do this grinding them yourself. Make sure you have the length you want them to grind them to as they won't know.

To check valve seal, use some machinsts dye. You can buy this at any autoparts store. You coat the valve seat and set the valve in place WITHOUT spinning it. Pull the valve out and if there are gaps in the dye that transfers, re-lap or have the seats recut if the gaps are excessive. Normally, when you can use the old guides, you don't need to recut as the old guides drop the new valves in the same wear circle as the old valves were in. If you use new guides, this isn't the case and you generally need to recut the seats. Three cutting stones are used and a bike machine shop should ALWAYS be used as car places will want to whack too much material and you will end up with no valve clearance and new seats will be needed.