How do you ID "early" GL1000 cams?

[brianinpa]

20 years of aircraft maintenance taught me one thing. Engineers design them, college degrees flew, but high school diplomas fixed them and kept them in the air. :mrgreen:

 

[slabghost]

brianinpa » Thu Aug 17, 2017 8:57 pm[/url]":24xlkxpa]
20 years of aircraft maintenance taught me one thing. Engineers design them, college degrees flew, but high school diplomas fixed them and kept them in the air. :mrgreen:

Exactly! :BigGrin:

 

[canuckxxxx]

Old foggy, what do you mean by "You should also use a 371 advancer and remark the crank timing marks when using the early cams."?

 

[Old Fogey]

The ignition timing is different for the early 371 cams from the later 431 cams. The automatic advance/retard unit on the back of the left hand cylinder head gives different advance curves for each model. This is for the early model, the later one is stamped 431.

Likewise, the timing marks on the crankshaft are also different. The initial advance on the early model is 5 degrees BTDC, later is 10 degrees BTDC. It is relatively simple to use a small sharp chisel through the timing sight hole to remark the crank exactly half way between the T marks and the F marks. Do it for both sets of marks.

Ok, disclaimer time. Doing this resets everything to what Honda originally intended, apart from the carbs. I have never tried to run early cams with later type timing marks and/or timing unit. I suggest, if you have the patience for it, that you run the different combinations and see what difference it makes to performance and fuel consumption. If anyone has already done this, chime in now.

 

[slabghost]

Joe has been running the early cams in his bikes for many years. Using the timing each engine had to begin with. Has been running the Hooch bike on early cams and a very advanced ignition for 5 years I think. If you want stock performance keep everything stock. If you want to increase performance mix parts in a way that will do what you want.

 

[desertrefugee]

I am all ears. I have the early cams now in my possession and will soon be installing them in the '78. I'll order seals from Western probably this week. I'm in the camp that it's doubtful that any real substantive (seat of the pants) difference will be noted through changes in either initial advance or full advance.

But, I'm sure going to find out as the cams will be going in well before the Webers follow. I do appreciate Old Fogey's sage advice on marking the flywheel - and the photo distinguishing the early and later advance units. If it was a Chevy HEI, I'd just be shuffling weights and springs. You could probably do that here, too, if you had the patience.

 

[Old Fogey]

One combination I would avoid is the 371 advancer with the late timing marks. You would end up with WAY too much final advance.

 

[slabghost]

Going in to another gl1000 timing should pretty much be a non issue. Since timing can still be set by ear on those. If c5 ignition is used no mechanical timing advance is used. Having a little more advance spread should enhance performance.

 

[desertrefugee]

Old Fogey » Mon Aug 21, 2017 9:42 am[/url]":1v69exib]
One combination I would avoid is the 371 advancer with the late timing marks. You would end up with WAY too much final advance.

Noted!

 

[dan filipi]

More advance has always been a simple way to get a bump in power. How much more advance we talking about here, 10 degrees? At what RPM? Might be a welcome increase. Under load maybe get some ping maybe not.

 

[desertrefugee]

The saga continues. I happened onto an early 371 advancer unit, but it is lacking the advance cylinder itself. I'm assuming that these bits are completely interchangeable and mine will swap right over. I'm referring to the cylinder that either the electronic rotor or the points cam lob rides on.

I'm pretty sure it'll swap over fine. I'll probably take a shakedown run with just the cams before I swap this advancer (against OF's recommendation), but at least I have the unit and it's in decent shape - for ten bucks.

 

[Old Fogey]

Looks like the bronze bush is missing too. Actually, may be an Oylite bearing, not sure.

 

[desertrefugee]

Sheesh. I see that now. I imagine that will be a little more difficult to transfer over without damaging it. I seriously doubt if it will just slide right out without some serious persuasion. I will keep my eyes open for a better specimen. Thanks!

 

[Old Fogey]

Always check the bob weight pivots for wear, as these are not oiled. You can put a very light grease on them; anything heavy will alter the movement and hence the timing.

 

[canuckxxxx]

So this cam arrived today that I bought on EBay. Apparently it is '76 right side cam with rockers.

Just trying to confirm that is a hiperf early cam. There are no 3 digit numbers on it. Anything else I can check.

image

• canuckxxxx
• Oct 20, 2017

 

[joedrum]

That’s the ones ....no numbers

 

[Pony Ruiz]

where would the #'s be stamped if there were #'s? any pics outstanding?

 

[canuckxxxx]

Pony, I found an 1100 cam on Ebay with a picture that shows the part number on it. In this case it is "463".

picture showing part number on an 1100 cam

• canuckxxxx
• Oct 21, 2017