Honda Shadow Forums banner

Valve lift

2K views 11 replies 7 participants last post by  superspirit97 
#1 ·
Decided to post in technical as that is where all the gear heads are located.. Does anyone know what the lift is? Could get a really good ballpark but I do not have a cam sitting around.Goes to a discussion about "soft cams" and the 80s Honda cams.

Mark
 
#3 ·
I think Gypsy has had his motor apart and was looking at putting older pistons/ cams in his bike so may have some to measure?? a PM to him might help
 
#7 ·
I am not real knowledgeable on bike engine cam specs but can give an idea of the differences between and older 80's engine and a newer engine.
On the Japanese cars I worked on in the past 10 years or so, they have done a lot of changing to cams specs. They went to hydraulically, computer controlled, variable cam angles. They actually twist the cam in relation to the drive sprocket. That is to control emissions, economy and performance. I don't know if bikes have gotten that sophisticated, but I am pretty sure the old cams are not the same as a new model.
 
#8 ·
Older bikes have less restrictive motors thus are already about the best performing setup you're going to get. If you want more power, buy a larger bike and save your $$$ and time. BTW if the OP 1100 runs good etc. he would need purchase larger than 1300 cc to replace it power wise but he would gain better comfort.
 
#9 ·
The original question was for the valve lift and since these bikes use 0 lash tappets then I could use cam lift and I have the rocker ratio to calculate the valve lift. Still could use for a running "discussion" that I am having with one of the local shops.


Mark
 
#10 ·
#11 ·
Cam Lift

What is the issue your having? I have not gotten into the old 750 nor do I have a book on it. If they are like the 1100's it is next to impossible to calculate the lift because of the eccentric on the rocker arm shaft plus you have to put the head cover on that prevents you from doing a good measurement on it. If you have lifter height shimmed so there is no movement on the rocker arm shaft, then the calculation is close. For me, I made a follower that goes in the intake port and follows the valve movement and measure it with a dial micrometer. As I rotate the crankshaft with a degree dial on it, I can tell the lift and the timing of the camshafts. As most just use the rocker arm ratio for the specs but you will loose some thru the valve train.
 
#12 ·
Valve lift older 1100 87-96 vs 97 and up

Since I have some time on my hand and have both old,87-96 and new,97 and up, manuals I looked up the lobe height on the cams and noticed this> On the old ones on the specs it is listed at 1.4189 and 1.4267 and the in service limits it has it at 1.4437. I haven't measured a camshaft of the older one but many of the newer ones. On the newer ones the specs are the inline with service limits.
I can make an assumption. And as with any assumption it is assUme. The rocker ratio must be such that it allows more lift on the older models or what is called the base circle on the lobe is less or a combination of both in order to get the same lift. On the newer ones it is spec'd at 1.4969 to 1.5034. The service limit is 1.496. For the camshafts I have put in my bikes I use a 1.535 lobe height and take about .010" off the base circle giving on the cam an effective increase at using the before average of 1.500, Thus I would have an increase of .045 lift on the cam lobes.
The major factor is when you get lift on either intake or exhaust valves is how much clearance is there to the piston thru-out the rotation of the crankshaft. That is another whole topic that curtails the deck height of the piston, the relationship to the top of the piston to the top of the cylinder at TDC. On the newer ones the deck height on stock pistons is .100. That is gobs. I have run piston with .010 but choose to be on the safe side at .020 with concave,dished pistons. Never had a problem there.
The hindering factor on lift is the distance from bottom the valve stem keepers to the valve stem seal is what I have run into. That figure is .385 and can increase that by grinding the seat and valves to allow the stem to protrude higher giving that gap between the keeper and the stem seal to increase above .385.
Hope this helps.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top