Cafe Racer Forum banner
Cancel

GS550 Carb Vacuum line issues

5724 Views 4 Replies 3 Participants Last post by  hillsy, 
M
I have a GS550 with BS32SS mikuni carbs and I haven't been able to get a real answer from anyone as to why I'm having this issue or how to fix but maybe you guys can help here.

The bike had a leaky vacuum actuated petcock, so I decided to install a manual fuel valve and set the petcock to prime. I blocked the vacuum line that actuated the regular valve.

Now that I have everything back together, there are two lines that I have been told by some are supposed to go to the ground, to the airbox, to the other carb vent, etc,.

These lines are pretty peculiar though in a few ways:

1. the line on the left side of the carbs doesn't seem to do much of anything when blocked
2. the line on the right side makes the bike idle at around 4000rpm when blocked and slowly bog down and stall when open

What the hell are these lines for, why do they make this happen, and WHERE DO THEY CONNECT???
Reply
Save
Like
1 - 2 of 5 Posts
M
I'll grab some this weekend.

I'm not a carb expert but it seems like the engine runs immensely better when I have the float bowl breather on the right plugged. It revs really high but doesn't bog when throttled.

Can anyone explain why this happens? I know it's not my solution but I'm just curious.

I think I also have a vacuum leak somewhere in the main airbox from incorrect reassembly and this could be causing the problems.
Reply
Save
Like
1 - 2 of 5 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Cafe Racer Forum
A forum community dedicated to Cafe Racer style race bikes owners and enthusiasts. Come join the discussion about restoration, performance, racing, classifieds, troubleshooting, maintenance, and more!
Full Forum Listing
Explore Our Forums
General Bike Discussions Project Builds Technical Vintage Motorcycle Racing New Member Introductions
Top