suspect cracked head

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I had my RH4 head rebuilt with new valve guides, seals, and valves. One of the exhausts needed to be made because the guide had loosened up so bad. After installing the rebuilt head same problem as mentioned- so much oil in the cylinder it fouls the plug. Is the dye test commonly used in machine shops?
 
Dye check is common anyplace that does NDT. You can buy the kit and do it yourself. It's relatively simple and inexpensive. Not magic...just a matter of following instructions. I've done a lot on tube and pressure vessels prior to x-ray or sheerwave & pre-shake n bake.
 
Sorry I haven,t been responding but I had a death in the family. Back to suspect cracked head. I think I have found the problem. I removed the head again and on inspection I found the cylinder that was smoking had the exhaust port and guide soaked in oil. I removed the valve and found that the valve guide was worn kind of egg shaped. No cracks visible and all other valve ports were free of oil. I,am replacing the valve guides and installing new valves on the exhaust side. I,ll keep you posted of the results when I put it back together. Thanks for your comments. Jack
 
hershey said:
I am replacing the valve guides and installing new valves on the exhaust side. I,ll keep you posted of the results when I put it back together. Thanks for your comments. Jack
Click to expand...

In that case the guide to bore interference fit would be critical.
For what they cost a set, 4 new Kibblewhite valves and guides would have it done and dusted.
 
If they do coded work they shall most certainly have a QC dept. capable & equipped to do so. You really need to get it checked out so you can sleep easy.
 
I think I have found what is causing the smoking in the left cylinder. I preheated the head to 200 degrees to remove the old guides. I removed the right side first and it was a very tight fit and took a lot of force to get it out. however on the left side ( smoking cylinder ) the guide came out with some resistance at 200 degrees but not near as much as the other guide. So I,am thinking at normal running temp that the guide is a looser fit and the oil is passing between the guide and head and running into the cylinder. I miked the OD on both guides and they both miked the same . Does anybody know what the normal running temp would be for the head ? I,am looking to install an oversize guide . What would be a recommended oversize guide .001 .002 ?? Thanks Jack
 
Normal head temp is between 4 and 5 hundred F. in the area of the exhaust guides. 600 is not unheard of.
I install new bronze guides with the head at 375 F.
Guides in an RH4 should be fit at .001 to .0015 interference at room temp. You can go up to .002 on the exhaust side only.
More than that will crack the head, so you have to be careful with an RH4.

I would never install iron guides in an RH4 head. The difference in expansion makes it difficult to avoid problems. If they are tight enough to prevent leaks when they are hot then they may crack the head. Jim
 
Thanks Jim I,ll go by your advice ! I read in the service manual that the guide should be between .001 and .0015 bigger. I,ll have to measure the ID of the guide port and see if it is within specs. If it is a little oversize I,ll try and find a guide that is a little bigger than the stock guide. My guides both measured .626 OD . Could I go with a .628 OD guide if the guide bore is say a half thousand too big and be okay ? Thanks Jack
 
If the guide is a bit too big just chuck it in a drill and use some emery paper and work it down a bit. A bolt through the center with a nut will let you chuck it in a small drill. 320 grit will take it off pretty fast.
Of course if the hole is rough or scored you will be better off honing the hole to the oversize.
Kibblewhite has guides in .002 OS and bigger.
 
jbruney said:
Dye check is common anyplace that does NDT. You can buy the kit and do it yourself. It's relatively simple and inexpensive. Not magic...just a matter of following instructions. I've done a lot on tube and pressure vessels prior to x-ray or sheerwave & pre-shake n bake.
Click to expand...
Only Dyes that are NOT magnetic will work in alloys- I hope I have cleared that up!
 
And it definitely should be dye checked. If the head has been cleaned or blasted there is very little chance that a crack would be visible to the naked eye. It is not an expensive procedure.
 
I purchased a kit for around $80.00 delivered, nice kit that I used on my crankshaft to make sure it didn't have cracks. Not having used something like this before I first tried it on a crank that i had with a known crack. It was just to see what I was looking for on the one I was testing. Easy to use and really will find cracks that you can't see. This kit was the red dye type made by Dynaflux, little bit of peace of mind.
 
There's water based & the old hydro carbon based. I've never used the water type. Dynaflux is the brand I've always used also. Excellent stuff. Now the magnetic qualities I don't know squat on that with aluminum alloys, but have on occasion slapped the stuff to aluminum. An RH4 head and the composition …. I'd venture some more research since a man in good standing has raised a question making another look worthwhile because my experience is in the ferrous & chromium alloys and such. Gotta go.
 
Problem solved !! I replaced both exhaust valve guides with oversize ( .002 ) guides and new valves. reassembled the motor fired it up and went for a nice ride and no smoking at all and runs strong and smooth. Like I said earlier I new the person who owned the bike almost from new and it always smoked some from the left cylinder. I suspect that the left guide bore was bored a little oversize from the factory causing the guide to leak oil into the cylinder. Anyway problem is solved so thanks to everyone for the tips and comments. Later Jack
 
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