Jockey Journal Forum banner
1 - 18 of 18 Posts

·
Registered
Joined
·
234 Posts
Discussion Starter · #1 ·
Triumph 650 cams ... With cases split, new cam bushings in place and have been properly fitted in all ways and aligned, cam to bushing clearance is within spec, with the primary side laying on it's side and the cams in place sticking up into the air, ... Are the top ends of the cams supposed to wiggle back and forth a little bit?

Thanks in advance
 

·
Registered
Joined
·
3,691 Posts
yes they will move around a bit, usually the breather spring will keep the intake cam indexed to the timing side on 69 and earlier motors, but it's the cam gears that really keep the cams positioned.
 

·
Registered
Joined
·
234 Posts
Discussion Starter · #5 ·
yes they will move around a bit, usually the breather spring will keep the intake cam indexed to the timing side on 69 and earlier motors, but it's the cam gears that really keep the cams positioned.
Thanks. I'm referring to a side to side motion when I grab the top end of a cam and move it back and forth / left to right.
 

·
Registered
Joined
·
149 Posts
I am a novice at best when it comes to these motors, but I believe there will be just a slight amount of play. Kinda makes sense because it is only housed on one end at the moment and is just a slip fit in the cam bushing. Over the entire distance of the cam sticking up there is just bound to be some movement. I think you are good to go, but like I say, I am very new to these motors and doing a rebuild on a 650 bonny myself right now. Good luck.
 

·
Registered
Joined
·
3,691 Posts
the breather disk is in effect a PCV valve, it closes as the pistons go up (hopefully) creating a vacuum in the crankcase and opens as the pistons come down, the spring keeps the breather disk in place up against the exit hole. without the disk or the spring you will pump a lot of oil out of the crankcase breather tube.
the 1970 and later motors used the primary case as a breather area separating the oil from the air and venting the pressure at the top of the primary case.
the drawback to the later motors is the engine oil gets contaminated with clutch debris and todays oils don't work well with clutch discs
 

·
Registered
Joined
·
147 Posts
the breather disk is in effect a PCV valve, it closes as the pistons go up (hopefully) creating a vacuum in the crankcase and opens as the pistons come down, the spring keeps the breather disk in place up against the exit hole. without the disk or the spring you will pump a lot of oil out of the crankcase breather tube.
the 1970 and later motors used the primary case as a breather area separating the oil from the air and venting the pressure at the top of the primary case.
the drawback to the later motors is the engine oil gets contaminated with clutch debris and todays oils don't work well with clutch discs
What if you have a later motor like you mention and it has a belt drive . I heard that I could weld the vent holes on the primary side of the case and vent at the highest point of the engine... the rocker boxes or inspection caps.. is that correct?
 

·
Registered
Joined
·
243 Posts
DRPD66, you could,but it isn't the most efficient way,as the passages in the tappet blocks are the only way for the oil to return to the sump from the rocker boxes,oil trying to go down,air/pressure trying to go up. I've found using the cavity in the front of the motor(between front motor mount and crankcase) can be modified to use a one-way valve with good results.This is a proven method,I believe if you search you will find how/what/why about it. Jack
 

·
Registered
Joined
·
196 Posts
Bang on Jack Adams. As the lubrication depends quite a lot on gravity, and also negative pressure in the lower half of the crank cases, getting rid of the positive pressure caused by the downward stroke of the crankshaft, is the way to go (the pressure required to lubicate the top end, is provided by the pump/return pressure from the engine). The three holes that were in the lower section of the primary side of the case worked up to a point, but the downward pressure of the stroke, isn't really enough to force enough oil out, causing unwanted crankcase pressure.

I have a vent fitted to the timing cover (as was done "in the day") which allows excess pressure to dissipate through the timing side bearing (also keeps the lube up!). However, a lot are now putting a mod into the front frame mount as described. It works well, but is really good when a reed valve is installed, which creates the required negative pressure.

As far as wobble goes on the camshaft bushes, well, it's each to their own really. I'm very fortunate in that I have an original (Meriden) camshaft bush reamer, so I can replace the bushes in any engine I do, and I can line-ream the bushes in the two crankcase halves, so they exactly match the cams when the cases are bolted up. However, I have no problem with a bit of slop in original bushes, as the actual movement of the shafts, will not really make a lot of difference in their operation. What does make a difference, is tappet gap.

If the camshafts rattle a bit, two thou can make a difference at the tappet. Best bet is, put the cam wheels on, and feel if there is any movement once the idler wheel is in place. With a "dry" engine, if you can feel it, there's too much.

If, as deluxe72 is saying, there is lateral movement (along the length of the cam), then 1/16th is fine. The only normal load on a cam, is Bi-lateral, and as long as the bushes are good, then nothing will go bang.
 

·
Registered
Joined
·
3,691 Posts
What if you have a later motor like you mention and it has a belt drive . I heard that I could weld the vent holes on the primary side of the case and vent at the highest point of the engine... the rocker boxes or inspection caps.. is that correct?
it's easy to do, here is how I like to vent a belt drive T140...put a 69 and before crank seal in it and use the 3 Triumph patent plate rivets to plug the 3 small holes , that way it's reversible.
 
1 - 18 of 18 Posts
Top