Gl1200 cam differences- didn't know there was

[ekvh]

Sales pitch? I've heard your perpetual sales pitch, Joe. Glad you feel that way. I'm just presenting facts as can be known. Just sit back and watch if you like. I really don't think you're reading what's being said.

The valve curtain area ( the area around the valve that is open and through which all gas must flow ) if you go by the cam info only is

36mm intake v x Pi x 5.8 mm 1200 cam lobe = 656 mm sq

36 mm intake v x pi x 7.08mm cam lobe of 77 = 823 mm sq

38mm intake v x pi x 7.08mm 77 cam lobe = 845 mm sq

The differences between what people think are the 1200 values are hugely different than I think it could be. If this were true, I don't care how much faster that charge is, there's no way it will flow near what the 1000 heads flow. 25% is just too much to made for by anything except a blower. I could be wrong, but the 1200 heads had to have more lift.
I need to find out how much actual valve lift there is on a 75-77 head and on a 1200 head.

Nothing in this thread about carbs. Everything affects everything, but I'm trying to focus on cams in this thread.

 

[dan filipi]

Very interesting info Eric.

 

[joedrum]

gee eric my comment was about what was said ...a lot was just wrong ...your post was great ...it had everything to look at ....the rockers was a good pic ...but it lacks the adjuster on the 1000 ...with that in play the rockers look dam near the same ....i personally put the 75-77 cams in the 1200 heads and the intake valve would hit ....meaning the smaller 1200 intake valve made no difference ....thats because the duration of the 75-77 cams and the fact that the 1200 motor piston top out higher ...the 78-79 cams did not hit in the 1200 motor ..but what was the point ....these cams are milder than 1200 cams ...so i didnt use them at all ....

as for squish area in combustion chamber ..that is also lacking in real world ....the centralize squish area is basically a flatter piston top and maybe slight different milling in the head ...the volume is dam near the same ...you and skypilot both went to milling the heads over the supposed drop in compression ..the read said 1200 lost compression with 1200 heads opposite of what you guys were thinking ..that the 1100-1000 heads would lose compression on 1200 motors ..i can tell you that hooch has more compression not less ...why cause the piston tops out more than the 1000 or the 1100 motor and has longer stroke ...

as for what was said about the carbs ...this is all proven here ..the read makes it out that the carbs are bigger at 32mm and that simply not true ...honda was always good at measuring something in a different spot to make for good reading for a sales ..i dont blame them ..they build to sale them ....

the only thing here that might get some real world difference is putting a 84-85 1200 cams in 1000 or 1100 heads with there greater overlap and more flow capability of the earlier heads ..me and V talk this ...

you can think what you want about my opinion on things but i can tell you im rather sound with results ...the hooch bike is proof im no fool....you dont have to be a paper tiger to know to do something or know it plain and simple ...as it stands ive got the only hooched out bike that has proven its fast and proven is a reliable road bike ...regardless of my lack of paperwork backing ....backyard tech no joke my bike runs like it has a supercharger on it ...

here at classic one of our best traits is to weed out the BS out there on oldwings ...and classic has done this at a high level ...i read all the info out there and i gave my opinion .... we all do ...including you wasnt trying to poo poo this thread ...just strait up talk from me .. opcorn:

 

[ekvh]

I'm merely looking at the cam differences and the possibility of the 1200 early cams working better in a different situ. I've read several posts here back several years. Nobody said the 1200 cams were different and most said they're all the same. Everyone who I have read also said the valve lift was less on the 1200 and then used cam lobe height as evidence. Backlander brought some data and in a different forum Dave stated it. eBay sales mostly sell 1200 cams as 84-87. It is likely that there are a few 1200's floating around with different cams side-to-side. I suspect that could what was happening with Dan's 205 lbs compression anomaly. So hopefully this post gets info out to everyone that there is a difference.

No one has come forward with how much actual valve lift there is on a 1200. It would be nice to know. It's pretty safe to say the lift of the 1000/1100's because they all used the same rockers. The 1200 stock hasn't been investigated and I think it would great to know.

My head shaving was my own choice. It had nothing to do with what Steve said about compression losses. As I recall, you said it wouldn't work and that I shaved too much. Whatever Steve and I did, had to result in compression bump which is good for power.

Honda did use some slick wording on the 32mm carbs in that they had 32mm on the plenum side, but had a much smaller throttle plate. They called them bigger than earlier carbs. They were smaller, but once air passed through the venturi, the 1200 carbs kept the same smooth bore all the way to the head. On the flip side the 75-83 carbs had big openings and a bigger throttle plate, however they had a venturi that necked down to create the speed but then almost as fast as the fuel air mix went through the Venturi they opened back up. To me, they may have slowed it back down right there. It creates a smaller passage, then opened up to 32mm again all the way down, so the charge was sped up during the venturi but slowed back down right after the Venturi. The 1200's were basically the same and may have flowed better and faster because they eliminated this.

I have no problem with what you say about single carbs, but it seems almost all of your posts come back to that as the final solution to a myriad of problems. Some people may prefer the smooth nature of the four carb arrangement. It probably can't give the same burst of power as a non-CV carb, but there are dangers to having too much throttle available at the wrong time.

 

[Ansimp]

+1 on the smooth transition of power with CV etc style carbs. I enlarged ( on the advice of my motorcycle mechanic mate) the air pass holes on the plungers/needle hats on some CBR carbs and they jump to full revs without much progression. I though my CBRs already reved quickly enough and my mods are more suited to all out racing. I also managed to lose 1/5 of my cruise range with my carb mods. :doh: