What GL1200 Engine Modifications are out there?

[KB02]

While the end plan is to leave my '85 1200 I as stock looking as possible (it's going to be the wife's bike, and that's that way she wants it), I have been looking around for different engine mods I can do as a full rebuild is looking likely as I bring this thing back to life. I come from the Café Racer mindset when it comes to bikes, so I'm no stranger to engine modifications, BUT, I really can't seem to find much in my searches for ways to mod this engine. I can only imagine there is some untapped power n the 1200 block, so what have people done to bring it out?

Here is what I have found so far
- 1100 heads and 1000 cam swap. But this seems to include shaving the pistons and comes with overheating issues. Don't know if I really want to get that involved unless the power is really worth it.
- Does the Weber single carb conversion really do much for power? Or is it just ease of adjusting (one carb v. four)?
- Swapping in an '86 EFI set up seems possible, but I'd rather go a more mechanical route.

Aren't there simple Cam swaps that can be done? Maybe a regrind to lengthen lift and/or duration? Webcam doesn't seem to offer one, and neither does Megacycle. Anyone else out there have any luck?

 

[Steve83]

Joedrum is the 1200 modster here. He's got plenty of ideas, as well as experience.

 

[backlander]

Pretty much uncharted territory other than what you have already mentioned, the 1200 is in the correct form and gearing when it's brought up to par, the only thing I can think of to get more bang for your buck would be the new C5 ignition system for the 1200 that I think is in the works right now, which would make a race horse out of a plow mule.

 

[dan filipi]

I haven't heard of any overheating issues doing 1200/1000 cams.
Literally only 2-3 have done this mod so far.

I have not experienced that mod first hand but I have a single Weber with the C5 ignition.
This combination dramatically smooths low end torque but........coming from sport bikes/cafe racers, what performance increase are you after?

 

[ekvh]

I have one with 1000 heads. I haven't ridden a stock one to compare, but it is way better than a 1000. I blew a head gasket in a year, but it was with after markets, but I am pretty sure I just ran low of water. It runs fine right now. I think I have my 77 carbs dialed in pretty close. I would love to see what it could do in the quarter mile. Is it better? That's an opinion. The 1000 cams give it a different power curve, old school Honda. My guess is it makes more power but at higher rpm. Is that where you want it? Most people today, don't. They want it low or able to be reached quickly. The five who have written and reported about it have done it in a 1000 frame which changes the gearing drastically. I don't know if it would help in the 1200 platform. The 1200 carbs were pretty good. The cams were designed to give more oomph at the lower rpm, and the intake accommodates this at a cost of a little on the higher rpm. I don't know of any other mod to get more out of the 1200 outside of forced induction. Cyborg has a stock 1200 in a 1000 frame and he likes his. It makes the bike a six speed without a fifth gear.

 

[joedrum]

to me 1200 are the best motor to mod ..

 

[detdrbuzzard]

its your wifes bike, just getting it on the road would make her happy. you are putting in too much thought on this one, save the mods for your wing

 

[KB02]

detdrbuzzard » Mon Jul 07, 2014 8:04 pm[/url]":3ms0buqv]
its your wifes bike, just getting it on the road would make her happy. you are putting in too much thought on this one, save the mods for your wing

Yeah... That may say it best of all. :blush:

...coming from sport bikes/cafe racers, what performance increase are you after?

Well, on my '78 CB750, I bored it out from 736 to 849. Ported and polished the head. Total seal rings. Optical ignition. Custom 4 into 4 pipes. Custom air filter unit... and various other things. I am not planning on doing anything NEAR that extreme to the wing. We would like to get a side car to put on it and, while I know the stock engine will pull it fine, I just figured I would look around to see what options were out there to maybe make it better since I was going to have to do some work on the engine anyway. I was really shocked to find nearly nothing for these beasts. Not even a simple Cam upgrade...

Oh well. Like Detdrbuzzard said, get it on the road and make my wife happy. :good:

 

[83gl1200]

My 83 has 1200 block and 1100 heads, people tell me I will get higher rpms than a stock 1200 but mine isn't at riding stage yet. I just got it running with a vw carb, I think a single carb mod would be best in your case as it gives extra torque on the low end which makes much more sense than higher rpms for a sidecar rig, and easier maintenance.

While my bike isn't out of the driveway yet I can already tell the single carb switch was worth it. It sounds great, like a different beast from the stock 1100 carbs that were on it, and this is only a cheap single barrel 34pict3 like you'd find on a vw bug. I'd love to see what a well set up two barrel carb could do. Then again had cost not been an issue, I may have chosen the 86 sei fuel injection so there would be no carb maintenance ever.

C5 ignition seems too expensive to me for the average gl, but I hear neon coils or 1500 coils would make a nice difference for a lot less $.