For the past few weeks I have been battling with the carbs on the XS750 I have been working on. I thought I would share my experience because I think it might be valuable to others who may encounter the same issues. I will post each step in a different post and include some pictures.
Something to note with all old bikes is you never know what the previous owners have done to them, even if you get a story about it from one of them. What I found with this bike was that the engine had been apart at some stage and a mild porting job carried out - whether professionally or not I don’t know, but there was obvious die grinder marks when peering down the intake runners. Or were they like this from the factory? I wouldn’t think so but not sure. There was also a few stripped threads here and there - one being the centre cylinders plug hole. This had a helicoil in there so seemed to be ok for now. Another issue was the stuffed carbs. I didn’t find out the full extent of the issue until I started trying to tune it.
The bike got a free-er flowing exhaust and pod filters installed, therefore requiring a carb retune, or at least a check anyway. When everything was put back on the bike it actually started pretty easy. So I warmed it up and did a carb sync - nothing seems to mess up any idea of where your jetting is at than if the carbs are out of sync. But the bike still wouldn't idle right. I wondered if the fact that the right carb was way out of sync had something to do with it. It turns out it would, but not in the way I thought. After fluffing around with the mixture screws a few times and achieving no obvious effect, I realised a closer inspection of the carbs would be needed.
Something to note with all old bikes is you never know what the previous owners have done to them, even if you get a story about it from one of them. What I found with this bike was that the engine had been apart at some stage and a mild porting job carried out - whether professionally or not I don’t know, but there was obvious die grinder marks when peering down the intake runners. Or were they like this from the factory? I wouldn’t think so but not sure. There was also a few stripped threads here and there - one being the centre cylinders plug hole. This had a helicoil in there so seemed to be ok for now. Another issue was the stuffed carbs. I didn’t find out the full extent of the issue until I started trying to tune it.
The bike got a free-er flowing exhaust and pod filters installed, therefore requiring a carb retune, or at least a check anyway. When everything was put back on the bike it actually started pretty easy. So I warmed it up and did a carb sync - nothing seems to mess up any idea of where your jetting is at than if the carbs are out of sync. But the bike still wouldn't idle right. I wondered if the fact that the right carb was way out of sync had something to do with it. It turns out it would, but not in the way I thought. After fluffing around with the mixture screws a few times and achieving no obvious effect, I realised a closer inspection of the carbs would be needed.