Fitting 550 exhaust to 650 motor/head

[Suzuki_Don]

Of course, with all the extra torque you'll be getting as well as power your bike will pull great from 1st to 6th anyway!

Thanks Wally, it all makes sense now. I am not really interested in splitting the cases to change cogs as I have just finished rebuilding the bottom end and don't really want to go in there again for a long time.

[waterman]

Great writeup with pics Don, just have a couple questions. Which brand pipe are you fitting up? This way if we want to fit a pipe to a 650, we may know which brand to look for. Secondly, what did the stock 650 exhaust gaskets look like? I am trying to remember what size the Vesrah gaskets were that I installed, it seemed to me that that covered about the same amount of the exhaust port as your "solution" gaskets. I am not sure whether I have some left, if so I will get some measurements to put here for documentation.

Great work on the bushings and I need to give a thanks for your brake plate mod for the Kawasaki twin pots, I made a set for my 650 that look nearly identical. I am still trying to get lines figured out and then I should be ready to go. I can't wait to see finished pictures and more importantly, ride reports.

[Suzuki_Don]

Great writeup with pics Don, just have a couple questions. Which brand pipe are you fitting up? This way if we want to fit a pipe to a 650, we may know which brand to look for. Secondly, what did the stock 650 exhaust gaskets look like? I am trying to remember what size the Vesrah gaskets were that I installed, it seemed to me that that covered about the same amount of the exhaust port as your "solution" gaskets. I am not sure whether I have some left, if so I will get some measurements to put here for documentation.

Great work on the bushings and I need to give a thanks for your brake plate mod for the Kawasaki twin pots, I made a set for my 650 that look nearly identical. I am still trying to get lines figured out and then I should be ready to go. I can't wait to see finished pictures and more importantly, ride reports.

Ed,
First Point: it doesn't matter which pipe from a 550 you are fitting as the 550 has smaller ports than the 650 by quite a large amount. So any 550 pipe will require the sleeve and different gaskets. The OD on all the 8 valve 550 header pipes will be the same.

Your Second Point: As far as the 650 gaskets are concerned the OD of the GSXR gaskets and the GS650 gaskets are the same obviously because their OD has to fit inside the diameter of the port and this is 42mm. It is the ID of the GS650 gasket that causes the problem, it's ID is 35mm and the 550 pipe having a smaller diameter slips inside this gasket and will eventually bear on the aluminium port when tightened by the exhaust flange. NOTE: Pics below with measurements. The GS650 gasket ID is 35mm but the GSXR gasket is 28.5mm = 6.5mm difference.



ABOVE: GS650 Standard Exhaust Gasket. OD 42mm and ID 35mm.



ABOVE: The GSXR gasket, OD 42mm and ID 28.5mm.



This picture shows the GS650 gasket overlayed over the GSXR gasket. The part of the copper GSXR gasket that can be seen inside the original GS650 gasket is the part that the 550 header pipe bears on. Therefore protecting the 650 port from damage.



ABOVE: Both gaskets side by side. Both gaskets have the same OD = 42mm, but the difference in the ID of each gasket is obvious.

Yes the bushings turned out OK didn't they. It's good to have a machinist friend that owes you a favour isn't it.

Glad your project is progressing well and sounds like you nearly have the front brakes sorted out.

I DO NOT SELL the front brake bracket that I designed and developed. It is FREE to anyone that would like a copy of the CAD drawing to make a set for themselves. A few people have said it looks better than the larger bracket available that mounts on the outside of the forks.

[waterman]

Thanks for the explanation, in previous posts it had been mentioned that a 550 pipe would work with 650 head using 2 exhaust gaskets.

For fun I went to garage and checked the size on two exhaust gaskets that I had on the shelf. My 650 vesrah gaskets are 42 mm outer and 34 mm inner and my vesrah 550 are 36 and 29 respectively. Not sure if you are familiar with the vesrah gaskets, they look like some sort of metal wrapped around paper and then rolled into a circle. Think of metal wrapped toilet paper still on a roll, sliced thinly.

How thick is the new gsxr/rf gasket that you used, it seems rather thin compared to the stock 650?

[Suzuki_Don]

How thick is the new gsxr/rf gasket that you used, it seems rather thin compared to the stock 650?

Yes the GSXR gasket is thinner than the GS650 gasket, but will still seal alright. It's measurement is just under 3mm.

[Suzuki_Don]

With the added power of your conversion this isn't as desirable / necessary as for the standard 550 but you could end up having either a very high first gear or revving out too easily in 6th, depending on what sprockets you fit.

Wally I have just fitted a new H/D 530 "X" ring chain with sprockets. I have gone with a 16 tooth front sprocket and the standard 50 tooth rear. This is about the equivalent of dropping 3 teeth on the rear. It gives a slightly lower 1st gear for good takeoff than the 650 LOW gear and still gives a top of around 130mph.