Purging

[Bobbuff]

Good Afternoon Everyone,
I broke down and decided to take my Sportster 1800 to the shop to see why my starboard motor is purging. The mechanic pulled the plugs and told me that I have one plug that appears to be getting fuel and was a little wet and the other was completely dry and looked brand new. He stated that what was happening was that I had a whole in the diaphragm on my carb and that was the reason why it was purging. When I asked why I only had one plug getting wet he stated the same problem. He did all of this without even starting it or putting it under load. My question is does this sound right to you guys??? I am getting ready to pull the carb and rebuild it and just want to make sure that this is the problem. I asked if he did a compression test and he said it came back with 120 psi on both cylinders. I thought I read somewhere that it was suppose to be 140 but not sure he told me this was fine.

Also, I successfully just pulled the jet pumps off my boat for the first time and found it to be rather easy. I will be posting picks of the wear rings and impellers in just a few minutes. The spacing I think is a little to much but since this is the first time I have ever looked inside one of these I just want to make sure I am right in thinking that. I am having major cavitation problems and I know that the wear rings are the first starting point.

 

[howie099]

120 is pretty low on a compression check. Should be in the 140's. On my Sporster 1800 the internal filter on both the carb was pretty plugged and caused some surging when accelerating real fast. I put new rubbers in since it was never apart since 1998. Your wear rings are pretty much gone you are supossed to have black rubber all over were you see white.

 

[Bobbuff]

Thanks for the reply, Why is it do you think my compression is so low???? And after re-inspecting my wear rings and looking at what you said I literally have none left. There is very little black anywhere and mostly white. It is hard to explain but I was thinking the white part was the wear ring and that was what I had to take out. From what you are saying is basically I just need to scrape the blacks stuff off and put new ones in.

 

[howie099]

The rest of the wear ring needs to be removed. It like a big sleeve. I would compression check the engine yourself to verify. The SBT wear rings all white with no rubber coating. The OEM's are rubber coating over a fiberglass base.

 

[docster]

my sportster 1800 has 145-150 psi on all 4 cylinders, so yes yours is a bit low.

 

[speedster98]

The edges of your impeller look pretty rough too. That will cause some of your cavitation issues. Search the forums for how to fix this yourself, if I recall right you can file it.