Gl1200 cam differences- didn't know there was

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ekvh

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I was looking for 1200 specs the other day and came across this. I don't recall hearing they were different before. Can anyone confirm this??

From gl1200 gold wings.com

admin Wrote:Use a degree wheel to dial it in. I left mine stock.


Spend an afternoon on a chassis dyno and check the fuel/air mixture under full throttle and jet accordingly then go looking for your brother and his big bore Harley.

Vic if you milled your heads and put it back on the stock mark you automatically retarded your cams I wonder what your centerlines are now?? That may explain pulling all the way to 8k! BTW: do these things have rev limiters?? I've never hit mine.....

As far as specs go according to the honda manual I just got from Dave specs are as follows: 84 & 85, overlap: 20 deg, duration: 230 and centerline is 105. The 86 & 87 are: overlap 10 deg, duration 225 and centerline is 107.5. It looks like the intake and exhaust profiles are all the same except for late 1000's and 1100's which are spread apart. Also the 1000 has 38mm intakes vs 36mm for our 1200's so as long as the seat will take a 2mm grind job it looks like that'll work. I don't know yet what the base circles and rocker ratios are but when I get it apart and do some measuring I will know those. But the 84 & 85 have .010" more cam lobe lift this doesn't seem like much but with more duration and overlap every little bit helps!! I like the 107 centerline of the later cams and depending upon how that is done I may have some options (ie: did they use different pulleys or is it ground into the profile??) Anyway sorry to ramble on so long with all the boring stuff but I think I have a game plan now. Bounce this back if something doesn't make sense sometimes I get ahead of myself.......
 
I'm unaware of any differences in 1200 cams. Yes you can say the cams will be retarded if heads are shaved although it would be too little to notice. You'd have to plane a lot off the heads to achieve even one degree of retard. Which actually isn't as much as the acceptable variance as manufactured.
 
The difference in overlap is what caught my eye. Maybe the 84-85 models were tougher to keep a good idle, but more likely had issues meeting EPA standards. I would like to try the 20 degrees overlap in my hybrid. You give up some valve lift (1 mm), but double the overlap. Maybe I'm wrong as according to this article Honda went back to 10 degrees overlap.
 
yes ive known this ...i was thinking the 20 degree overlap was a european model....seems on a oldwing4 motor this would cause more spit and sputter ...being a boxer motor with 180 degree balance and CV carbs ....when honda went 6 cylinder im sure this help smooth low rpm running though the balance is off more ... but im sure this is why the high rpm is down on the sixes .....

the one thing i noticed when i ran with fstsix and his supercharge valk is his bike and hooch were instant on the throttle ....it was so fun watching him poor it on at a good spot in the road and be just feet away and watch that big valk go to work with frame wrenching power instantly....of course i tried to instantly respond with hooch witch also leaps instantly ..but the big valk was like it was shot out of a cannon .....hooch is the same way ..but a second cannon fire never catches the first one ..plus there no doubt the valk had some extra push on its high end or maybe better put a very long sweet spot ....im guessing if the big valk had more aggressive cam and valves there no telling what kind of torque that bike could deliver

gregs riding style matched mine ...like it insane to play with first gear thinking ...got to get good and strait and ready and rolling before hitting the throttle

it be interesting to know what the cam specs are for the big sixes and valves sizes ...as compared to the 1200s ....seems the valks are 6 cylinder 1200 design in there stock form ..but im guessing here some .....
 
The manual in the gallery says they had 20 of overlap. Now that you mention it, it was the old Trevor White article that claimed the European model had something different about the cams. I can't recall if it was the 20 of overlap or something else. I can't seem to locate his article anymore. Searching here led to MSGT's posts measuring them up. She had different findings as well..
 
yes that what it said in the trever write article ....to bad that is gone ...it is what i used to build the hooch bike as basic info ...and it proved to be solid info through my build of hooch ....as the hooch bike lined right up with his info and opinions he made on crunching the numbers ....i basically used no other info from other sources except gearing info to finally arrive at the gearing i wanted ....seems you ended up in the same spot as me in gearing ...my bike became much safer with the taller gearing of the 1200 and 1500 final mods that are basically the same thing ...with the 1000 or 1100 gearing it was like riding an unbroken horse witch sent me flying over and down a cliff once...i was lucky i didnt get hurt worse than i did ...wish i could have finished the 1800 final swap ..i just about had it ...just wasnt meant to be ...i was within a whisker of having it ...before loosing my shop and parts and bikes except hooch ...that would have been a great achievement to me ...hooch could certainly handle the taller gearing of the 275 final 1800 gearing over the 1200 and 1500 283 gearing ...oh well i know i had it beat just needed wheel and front drive shaft mod ...
 
This is potentially a different mod for 1100 bikes which have rear ignition. Not sure how much that overlap would help, probably more low-midrange torque, which a lot of riders prefer. Sounds like the cams would drop right in. I wish I could find facts for sure on the 86-87 years. The manual in the gallery l should be correct and that is for 84 models.
 
Here are some differences noted in the 84-86 Honda service manual Maybe they will answer some of your questions.
IMG_2376.JPG

IMG_2377.JPG
 
hmmm this is saying 84-85 have 20degree overlap...and 86 on was cut to 10 degrees overlap ...like the earlier oldwing4s....as i said before im thinking with cv carbs the 20 degree overlap would cause more spit and sputter than 10 degree overlap..provoking the change back to 10 degree overlap ...but this is just opinion ....i remember working with Vs 1200 standard at the time hooch was just put together and running also ....i noticed the low end torque was not near as good as hooch at all ..at the time i was still trying to get the stock carbs to work on hooch...but at idle speed and slightly above hooch would throw rocks out back idling up the steep driveway...the 84 standard witch ran well spit and sputtered like most wings did that went up the steep driveway.....so im not thinking it adds low end torque if that bike had the 20degree overlap cam ..when i say Vs standard ran well it did ..i think it still runs great yrs later and is a great example of a nice running 1200 standard ....i ran it up close to 90mph once and it acted like it could do that all day long ...
 
Thanks Backlander. This confirms it from a newer manual. So the question is whether more overlap helps or hurts? It seems somewhere along the way I read that more overlap was desirable for forced induction. Googlesmoogling brings different views on what it does, but all agree it may send unburned fuel down the pipe at low rpm, which probably doesn't/didn't help emissions police. I'm thinking that at 2000rpm or more, it probably helps and of course it could be slanted ahead or behind to suit your desires. I think I have my spring plan. I will lose a mm of lift but double the overlap.

Unfortunately I sold my 85 heads and kept the 87 heads, so I'll need to pick some up, but just the cams are cheap.

Next question: how are they identified? Numbers on them? Anyone know? I'm 10,000 miles from mine right now.
 
Actually you can check your valve timing without taking much apart and without a degree wheel...I just did. The F1 mark on the flywheel is 10 degrees BTDC which is also when the intak valve is supposed to start opening on a '84 1200. So if you take the flywheel inspection plug out and rotate the engine via the stator bolt you can feel the #2 intake start to move if you have your finger on the rocker. For mine I could feel it move with about 3/8" before the F1 mark. That made sense because valve opening/closing specs are at 1mm valve lift.

So I now know that my valve timing is as per specs. BTW, I later set up my dial indicator on that valve and lift at F1 mark was about 1mm.

Brian
 
yep ...your good ...it will be interesting to see how the dft works on the 1200 stock motor ...on hooch the 1200 stock carbs didnt work at all ...they were the worse stock carbs tried on hooch ...1100s next and the early 1000s went the longest ..it like they were on a time limit to fail ....with the stock motor being able to run on stock carbs the dft dial in for 1100 ought to be close ..in my thinking
 
Joe, my newly rebuilt 1200 seems to run better on the DFT than the 1100 did. :good: With no changes from when it was on the 1100, it idles better cold and seems to have better throttle response. The small valves and intake ports of the 1200 heads are a close match for the runners on my intake manifold so I think that contributes to higher intake velocity.

Brian
 
When I was having trouble with my 77 carbs on the hybrid, I installed a set of 85, 1200 carbs and elbows. They seemed to be excellent. I figured the big openings at the head wouldn't be good, but it ran great. I'm talking about the small 1200 runners dropping into the larger openings of the heads, about 1/4" larger. They seemed to run fine though. I proceeded to cannibalism and swapped them with a mixture of v65 carbs, which now leak. I kind of wish I still had a set to compare with the 77's and a single.

Good to hear yours run well with the 20 degree overlap cams. I read up on the internet more last night, and as usual, it's full of conflicting info, with the exception of poorer idle low rpm issues. By naturally aspirated racing overlap 20 degrees is nothing. I find some who say the overlap should increase bottom end torque, below 5k, but increase upper end horsepower.
 
Bumpity bump. Staring online at the rocker arms, it looks like the 1200 arms had a higher ratio, meaning the valves would have opened more. It may be just an optical illusion, but comparing the two, it looks like it to me.
 

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So here's something newly old or oldly new:

I've been digging around and can't get out of my head two early articles introducing the 1200 stating it has more lift.

The other piece that points to the 1200 having more lift is the springs which were identical to 1000/1100 springs in length and spring pressure. But that may have just been a manufacturing decision based on economics- they already had them on hand, but it also intimates that they at capable of more lift.

The shop manual only gives cam lift, not valve lift.

Interesting to me are early articles claiming more valve lift.
From : https://www.moto2s.com/m_news.asp?id=13043
"Both bore and stroke of the base engine were upped to produce an extra 97cc while compression was dropped slightly and camshaft lift increased. These alterations, allied to smaller intake valves, significantly improved gas-flow velocity, and the whole deal meant more grunt in the low and mid-ranges."

Also from https://www.motorcyclespecs.co.za/model/ ... e%2085.htm
IMG_1073.JPG


If you can't read my blurry copy it says the 1200 had more radical valve timing and more "valve lift."

So what does this mean to my application? Nothing. But it appears there's more to the 1200's power than cc's and speed of intake charge. Any other times this subject has been discussed that I've seen, people point to the cams and say the 1200 had less lift. It does. The 1200 rocker arms are buried under the hydraulics so their not seen easily to compare. With these early articles about the 1200, which probably was information straight from Honda, there must be something to it.
IMG_1068.PNG
I've measured the above pics six ways from Sunday and I keep coming up a minimum of 1.25:1 to as high as 1.4:1.

I measure from the approximate contact points to the center of the rocker journal.

I think this is what was sought after a few years back by MSGT-R

So, the hybrid builds are bringing a little more volume to the game, but I won't be surprised if the cam lift is a complete wash. Not saying it's better or worse, but we need more facts.
 
reading all the info you posted ...its more a sales pitch than specs id say ...1200 carbs are the smallest of all oldwings carbs made there simply not 32mm at the slides like the 75-77 carbs are ...the carb and the valve are on the suction side of things and yes you will get more speed of flow here but with less volume ...but this was never the problem of the so so low end torque on oldwings ...it was always the cv carbs and there late acting operation ...being the worse at low motor speed ....many have put on SCC car carbs and felt the increased low end torque as the biggest plus ...anyway if there any extra lift id say it from the rocker and extra lift over what ...1100 cams ..78-79 1000 cams or 75-77 1000 cams ..there all different ...i personally have used all the cams in the same motor ...there no doubt in my mind that the early 75-77 cams are the ones the oldwing motor likes the best .....in my opinion ..it is also my opinion the oldwing motor likes strait carbs over CV carbs ...even more so than the cam differences ...

any hooched out 1200 with strait carb will blow away anything honda did with the oldwing motor big time .....plain and simple
 
[url=https://classicgoldwings.com/forum/viewtopic.php?p=186467#p186467:bj8e6gde said:
slabghost » Today, 6:43 pm[/url]":bj8e6gde]
Makes me wonder just how far the hydraulic lifters push.
The hydraulics in the 1200 don't work to push on the rocker or valve in any way. They simply take up the space that adjustable tappets would do by rotating a concentric shaft the rocker arm is on. Ingenious design.
 
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