4 into 1 Fitment

[Guest]

The bike: 1979 GS750 (EN, i think).

Towards the end of the year last year, I bought an RC Performance Products 4-1 exhaust from the classifieds here. We couldn't find a part number, so I just took the chance and bought it. The pipe fits the head...no problem there. I have all the bits necessary to tighten down/clamp/etc.

The flanges are too big, though. What I mean is that the spacing between the holes for the bolts is too big by about 1/2". Does anyone know if flanges like these can be purchased anywhere? My google-fu is failing me this week.

Here's a quick photo:



Thanks in advance—

Don

[Dave8338]

Do the pipes fit in the heads exhaust ports? The reason I ask, is that there doesn't appear to be 1/2" of available material to remove, even if you found a retaining collar to fit the head studs?

[mrbill5491]

That pipe might be for the 16 valve head. I have a RC on mine.

[saucebox]

The pipe fits in the ports very well, actually. The downtubes are a little long, but other than that, everything lines up...other than the collar, of course. Drilling them out was my first thought as well, but there is definitely not enough material.

I think Mr Bill is correct about the 16V head. I'll cross my fingers that someone knows of a way to make it work, but suspect that before too long I'll have to put it right back on the classifieds here.

[slayer61]

What size do you want them to be? I've got some spares in the shop that were too small for my 1100. Let me know what size you need and if they fit.. they're yours for postage. Paul

[Suzuki_Don]

The pipe fits in the ports very well, actually. The downtubes are a little long, but other than that, everything lines up...other than the collar, of course. Drilling them out was my first thought as well, but there is definitely not enough material.

I think Mr Bill is correct about the 16V head. I'll cross my fingers that someone knows of a way to make it work, but suspect that before too long I'll have to put it right back on the classifieds here.

You can make them up yourself if you can be bothered, it has been done before and will almost cost nothing. Or you could obtain a section of 1/4" plate and have the 4 x large holes cut by an oxy operator and then drill the smaller holes and shape each collar with a small angle grinder and finish them off with a bastard.

As I say it can be done -- some effort required though.

[saucebox]

What size do you want them to be? I've got some spares in the shop that were too small for my 1100. Let me know what size you need and if they fit.. they're yours for postage. Paul

I may take you up on that. I'll measure everything tomorrow and see what's needed. Either way, thanks is due.

[saucebox]

You can make them up yourself if you can be bothered, it has been done before and will almost cost nothing. Or you could obtain a section of 1/4" plate and have the 4 x large holes cut by an oxy operator and then drill the smaller holes and shape each collar with a small angle grinder and finish them off with a bastard.

As I say it can be done -- some effort required though.

I just checked. The only bastard I could find out in the garage is the idiot that stands in front of the toolbox wonderin' what the hell he's got himself into this time...

I might be able to make them as well. I've got plenty of spare plate steel. It'd be a challenge to see if the bastard could make 4 reasonably close copies, though.

Don

[Suzuki_Don]

I just checked. The only bastard I could find out in the garage is the idiot that stands in front of the toolbox wonderin' what the hell he's got himself into this time...

I might be able to make them as well. I've got plenty of spare plate steel. It'd be a challenge to see if the bastard could make 4 reasonably close copies, though.

Don

This is the bastard I was talking about -- not you Don.



They really rip the metal away and then you can smooth it all up with a 2nd Cut file.

Good luck.

[slayer61]

The flanges I have will accommodate a 38.5 (1 1/2") pipe. Inside of mounting holes measures 48mm and outside measures 70mm. Let me know if these will work for you. Paul

[saucebox]

Finally had the chance to check/measure.

The mounting holes on the flanges pictured above are 57mm on the inside, and 75mm on the outside.
The holes on the head itself are 55mm on the inside, and 67mm on the outside.

I don't your flanges will work. I really appreciate you checking, though. Looks like I'll have to make some (unless I see that GP Werks is doing another run in stainless...)

[slayer61]

Finally had the chance to check/measure.

The mounting holes on the flanges pictured above are 57mm on the inside, and 75mm on the outside.
The holes on the head itself are 55mm on the inside, and 67mm on the outside.

I don't your flanges will work. I really appreciate you checking, though. Looks like I'll have to make some (unless I see that GP Werks is doing another run in stainless...)

Maybe I'm not quite getting it... your numbers (55 inside and 67 outside) will seem to work with my flanges (48 inside ((closer than yours)) and 70 outside ((wider than yours))

[saucebox]

Hah, it could very well be me that doesn't get it. I'll take you up on your offer and send a PM over with my information.

And thanks again. You're really throwing me a bone here—

Don

[slayer61]

Don,
Your flanges are on their way via USPS. PM about to be sent. Good luck, Paul