Moto Grand Prix
Main Motorcycle: 1973 Triumph TR7RV
Join Date: Oct 2013
Location: Pleasant Hill, CA USA
Other Motorcycle: 1964 Triumph Mountain Cub
Hi Happyfeet, I did what you are thinking about to very good results. I only had 12k original miles from new though. I've done this to a few motors all turned out good.
After you do tear down you can change your mind at any point.
Mark all tappets, push rods, valves. Do not remove pistons. Pad the rods to prevent nicks, damage. Tape up crank case mouth & pack with lint free rags to prevent dirt from falling in.
But for resealing of oil leaks. You must carefully evaluate motor before tear down, but if it really doesn't use oil now, it won't upon assembly unless you mess up rings.
A few thoughts. Very important do not remove rings!!! If you remove rings they will never seat again on used bore you have now. Do not worry about ring gap if it doesn't use oil. Just blow rings clean with compressed air & some carb cleaner. Only carb cleaner if you don't have compressor. Oil well wrist pin & rings, bore on assembly. I recommend using a ring compressor tool. They make it easy & prevent damaged rings. squirt lots of oil down into big end bearings. Remove carbon from piston tops & above top ring. No need to remove baked on oil from piston sides.
The valves always wear out of round. If you don't remove them, they will be exactly as before. If you remove them, they MUST be lapped using fine compound & suction cup. Don't start with course & go to fine. Just use fine only. The seats will be wide & conical. Don't worry. It won't cause a problem. You can measure stem clearance to guide. They can be very worn & still not use oil & seal fine. However they will tick/rattle like the valve adjustment is too loose. If tip of valve is worn from adjuster screw have them refinished at auto machine shop. Under no circumstances should the face be reground. Do NOT let the machine shop talk you into grinding face. Again only lap the face. Lap the valve until all pits are gone from valve face & seat. Assemble with lots of oil on stem. Make sure perfectly clean. Turn head up & fill the valve recess with solvent or gas. Look inside port with flash light & make sure no liquid is seeping through. NONE! If it seeps you either have dirt left behind or you need to lap more. Don't use drill or lapping machine. Do it by hand with suction cup tool. Keep head held such valve is vertical to prevent side loading while lapping. If valve stem is burred at keeper grooves or stem end, stone or file the burr off so valve doesn't scratch guide on removal.
If you determine guide clearance is too large, then you'll need guides, valves & seats cut with cutter or stone. Every Triumph valve I've tried to regrind face left margin too thin for best operation, so I just get new.
Worn/pitted adjuster screw tips can be refaced to a degree if not too bad. I use a lathe & emery cloth wrapped around a file. But you can put them in electric drill to spin them. Make sure to replicate the radius on end.
You will need torque wrenches & special tools to do this work. The sprocket socket must be deep socket or correct tool. I recommend 1/2 drive or 3/4 drive with 1/2 adapter. I have exact tool # if needed. I always torque the sprocket nut with torque wrench.
Purchase tappet block driver that replicates factory tool. I no longer heat cly or chill tappet block. Place the cyl on 4x6 on concrete floor. Use hammer about the weight of a large claw hammer. Using claw hammer is fine. Look at tool & tappet block. Notice block is not straight but angled slightly. Drive it at the angle that's correct. All O-rings should be viton. Make sure. Except the silicon one at bottom of push rod tube. If... your bike uses the silicon one. Later do not.
Deburr head bore & tappet block bore to prevent tearing O-rings. Even micro tears will leak. Deburr/smooth exterior of tappet block where push rod tube seal will slide over. Very important!
The set screw hole it tappet block is not close enough. Get a 3/4 square bar 12" long from hardware store. Take your square & find the straightest you can. Use it as straight edge. Of course a real straight edge is best, but this will work.
So installing tappet block is not hard. It will want to turn as you drive it. A firm wrist pressure is needed to keep it where you want. Never attempt to turn tappet block while it is stationary. It must be moving while driving to rotate.
Drive down to about 1/4 from home aligning by eye best you can. Then stop & measure with Vernier caliper or depth gauge using your square bar against tappet block ear measuring to spigots of each cyl. Use a marking pen & make an arrow on tappet block which way you want to rotate it. Then drive block down further rotating as you go. If you get home before it's square, no problem. Turn cyl over & drive slightly out while giving rotating pressure. Then back down turning as needed. You can zig zag like this several times only moving 1/16" inch or so. You'll very soon get the hang of it. The next tappet block will be much easier with this practice. Try for at least .003" max difference spigot to spigot.
Good alignment reduces tappet wear in my mine.
Resealing rocker shafts can be hard to get the o-ring in without tearing. I have a good special too to guide in ring. Many don't work well. Buy several spare rings. If you see even a trace of rubber peel off ring it will leak. Deburr & smooth bore in box so it doesn't catch, tear ring. A little smear of silicon on ring is not a bad idea in my mind.
When doing the rear sprocket look close at how deep the seal is. If you put seal too deep it can miss sealing surface on sprocket. Not deep enough & sprocket will rub side of seal. Feel how easy the sprocket turns now. When done it should feel the same or only just a slight more drag. If it feels tight at all something is not right! As was said put sealant on splines even with the o-ring. The o-ring & non oring sprockets are different. The o-ring type is chamfered. Don't use o-ring with non o-ring sprocket.
Pull the seal from inside main shaft with a bent wire hook. They usually come out easy. The rear sprocket seal can be really hard to pull out. I have a slide hammer seal puller, but don't damage the thin trans case in this area while pulling seal. After you remove sprocket the high gear will move in/out a lot. That is normal. The inner face of sprocket is the bearing side race so it should only have a trace of side movement once nut is torqued.
Overall your plan is very sound & straight forward. Doing in frame is how I've done it & works good. Don't scrimp on tools. If you need to force it apart because you don't have proper tool you are at great risk.
Remember you are not improving the motor in any way, just stopping leaks. It will be the way it was, but no more leaks. Suppose you had no leaks? We wouldn't even be discussing this. You'd just be riding it. You could cause damage during repairs by just taking it apart & putting together. So as long as you understand that you are good to go. So give every last part a good visual inspection or measure as you go. Make a parts list as you take motor apart. I'd recommend buying a 1" micrometer & 6" Vernier caliper if you don't have one. They are a must.