Alan H wrote: ↑Tue Dec 24, 2024 7:35 am
Both the GS550 swing arms I have are 226mm wide at the frame end - including the dust/grease seals at each side.
Access to the GS550 swinger on the Earwig is dire, but I remember it went in without any issues. I have found out that K, M and A/B GT550 frames are very different, so I think you're in for some filing or grinding!
Your GS550 swingarm is similar to mine then. I have been cutting and filing quite a lot. It now fits perfectly to the frame. But I will have to add spacers to the top shock mounts, the exhaust and the crash bars. At the moment I am suffering from a virus, so progress has been put on hold. I’m not sure I would recommend this mod on a GT380; although it is possible it isn’t a direct fit. The width of everything is different, including the rear axle and the chain offset. As you can see in the pic below, after cutting off 10mm on each side of the pivot, there is very little clearance for the bearing cap, so I had to file away some of the blobby welds and file away some of the bearing cap.I will see this job to the end, I’ve too much invested in it to back out now. I will add more pics later.
Here is the new back wheel being cleaned up. It came out very well for something that old!
Alan H wrote: ↑Tue Dec 24, 2024 7:35 am
Both the GS550 swing arms I have are 226mm wide at the frame end - including the dust/grease seals at each side.
Access to the GS550 swinger on the Earwig is dire, but I remember it went in without any issues. I have found out that K, M and A/B GT550 frames are very different, so I think you're in for some filing or grinding!
Apologies for my lack of manners , I just realised I forgot to thank you for furnishing me with the measurements. It put my mind at rest knowing that I had got a standard GS550 part.
Thank you Alan. It’s much appreciated.
The rest was fairly straightforward, just fitting everything together and bleeding the brakes. But I also removed the exhaust wrap and modified the centre Higgspeed exhaust chamber to allow me to fit some slightly larger E-marked Giannelli silencers. What a difference to the sound it makes! It now sounds gorgeous, but civilised. My wife and I can now hold a conversation at 55mph. I’m not overly keen on the style of silencer, but it was all that was available.
The brakes are superb, the handling improved by the longer swingarm and the motor is running sweetly since the rebore and new Mitaka pistons. The only criticism I have is with regard to the fuel consumption. It only does 75 miles before reserve. Think I may need to do some rejetting before going to Switzerland in May.
I’m still running her in, so I don’t know if she is any faster since doing a little light porting work.
Oh and I also fitted these curiously coloured silicone carb stubs. They are the right length so I can fit the carbs on without them rubbing against the front sprocket cover housing.
It’s a pity they don’t do them in black, I know
P.S. I don’t recommend replacing the rear end on a GT380 with one from a GS550. Though it works great, it’s such a pain in the butt to do because nothing fits without modification. The GT380 sprockets are different, the sprocket carrier is different and the GS550 one required modification to make the front and rear sprockets line up. The swing-arm is wider therefore the exhausts needed moving. The rear axle, and everything on it, has to be from a GS550. The chain-guard mounting is different. The mudguard also may need modification to clear the brakepipe union. There are numerous things that didn’t line up. In short, it ain’t easy or cheap for a DIY mechanic to do.
Having said that, it has significantly reduced the necessary braking distance and improved the handling.
sportston wrote: ↑Sun Mar 23, 2025 11:19 am
Oh and I also fitted these curiously coloured silicone carb stubs. They are the right length so I can fit the carbs on without them rubbing against the front sprocket cover housing.
It’s a pity they don’t do them in black, I know
Fitting these orange silicone inlet stubs was a bad idea. They keep working loose. Instead I have purchased a set of genuine Suzuki GT550 items in the hopes they should fit better and last longer than the pattern parts did.
, I just realised I forgot to thank you for furnishing me with the measurements. It put my mind at rest knowing that I had got a standard GS550 part.
