Intro and Valve Guide Swap question

[Shakey]

Quick intro - I'm based in the UK and have has my '79 SE for a dozen years or more. It has been in the shed for the past five but I have finally got round to rebuilding it. I have been offloading some other projects to fund an ambitious project...
277 rephase, 750 big bore kit (both Heiden Tuning), Pamco ign, PMA conversion using VF500 stator and reg/rec plus RD350 rotor all spliced with a Rick page adapter plate, fzr600r monoshock, s/a, rear wheel, matching fzr front end (all sitting in the garage waiting patiently).
So, to the issue at hand - I have broken the engine down ready to ship parts to Heiden and have been checking over the cylinder head. There is a tiny bit of play in each of the exhaust valves (between valve stem and valve guide with springs removed). I have a spare head from an old spare engine which has no play in any of the valves, but the head is in overall worse condition (could be salvagable...).
If I bake each head to remove the exhaust valve guides, swap them over so I get the good ones in the good head, will they still need reaming? Will I have to recut valve seats to match (I'll be lapping valves anyway)? Should i use the valves (cleaned up) from the spare head too?
Any thoughts would be most welcome

 

[retiredgentleman]

Have you read the Yamaha Service manual? www.biker.net has the service manual. A dial indicator is used to measure the valve guide side clearance.

 

[Shakey]

Yes I saw that. Don't have access to a dial gauge so was hoping to do the swap if it isn't going to cause big headaches...

 

[5twins]

Usually, you do have the seats cut when you install guides. A new guide (or different used guide) may not align quite the same as the old one. I guess all you can do is try it. Install the used guides and see if the valves will lap in and seal. If not, then get the seats cut. I would use the valves that were in the used guides originally, not the ones currently in your worn guides.

I just swapped a used valve from an SR500 into a Virago 1100 (to replace a bent one) and it worked fine with just a hand lapping.

 

[retiredgentleman]

When doing any engine re-build work, there is a need for micrometers, dial indicators, snap gauges, vernier calipers etc. If you are spending a lot of money on up-grading the engine, it would be wise to accurately measure the engine internal parts, otherwise the final results may or may not turn out how you planned.

 

[Shakey]

sounds promising, thanks 5twins. What bent the valve on the Virago - broken camcain?

 

[Shakey]

Wise words retiredgentleman - duly noted!

 

[5twins]

I don't know what bent that Virago valve. Nothing was broken inside. The bike had been sitting for several years. I worked on it with the owner's son (who is taking it), not the owner, so I didn't get the full story. I don't know for sure if it ran like crap (on one cylinder) several years ago and that's why he parked it or if the valve hung up and got bent when we fired it up this summer.

 

[Purplezinger]

When doing any engine re-build work, there is a need for micrometers, dial indicators, snap gauges, vernier calipers etc. If you are spending a lot of money on up-grading the engine, it would be wise to accurately measure the engine internal parts, otherwise the final results may or may not turn out how you planned.

Wise words from retiredgentleman, I would add: learn to read and use the tools.