GS450S- Mikuni BS34- Prime issue

[Guest]

Hey folks, forgive me if I missed this in another post, but.... picked up an 81 GS450S rebuilt the carbs had them back on and had the bike started and idling. Then noticed issue with high hanging idle above a quarter throttle, pulled carbs back off, found that breather hose to airbox had a massive tear in it, so i replaced it re-assembled and now no start. I have spark, but apparently no gas. Fuel petcock does not have "prime" setting; only RES and RUN. How do I prime these bad boys? I didn't remember having this issue the last time around. Any other suggestions if isn't the no fuel in the carbs are also certainly appreciated!

[tom203]

The 81 model should have 3 way petcock, but maybe you got the leverless 1980 petcock/tank. Does your petcock have a screwdriver slot in it ? Or how about a pic of it ?

[clark_sas]

Yes, it has screwdriver slot to the left of the petcock. I was able to rig up a series of hoses with a funnel, removed the tank and was able to get the gas in that way. However, now it will only start with full choke on and when choke is turned off, she stalls out. I imagine I need to play with the throttle adjustment screw to get her idling. Any other thoughts would also be appreciated. I will get some pics up her as soon as I can get a resizing program to change the size of the photos. At the moment they are too big to upload.

[clark_sas]

**correction, the screwdriver slot is to the right of the petcock...

[tom203]

Does your petcock look like this attached pic? This was used on lots of 1980 suzukis ( sadly). Had diferent mounting bolt spacing too.
As far as "rebuilt the carbs" stuff, did you follow the advice on here, or your own path? Unless all passages are thoroughly clean, the bike will resist starting easily and will idle and midrange poorly.

[Steve]

I will get some pics up her as soon as I can get a resizing program to change the size of the photos. At the moment they are too big to upload.

Irfanview is a great program for batch-resizing of photos. However, if you use Photobucket to host your photos, you can set your preferences to auto-resize anything you upload. I have mine set to "800 on the long side". Doing it that way is easy, as I don't have to have a bunch of different-sized photos around here, and trying to keep track of what is where. I just take my pictures, upload the few that I want to share, and it's done. You can see the size of that picture by clicking on any of the picture links in my signature.

By the way, you do know (hopefully) that if you host your pictures somewhere (Photobucket is just one of the places), you can copy and paste the IMG link for that photo in your message here and you can show up to 10 pictures per post, instead of the one at a time if you attach a picture through the forum.

.

[clark_sas]

Does your petcock look like this attached pic? This was used on lots of 1980 suzukis ( sadly). Had diferent mounting bolt spacing too.
As far as "rebuilt the carbs" stuff, did you follow the advice on here, or your own path? Unless all passages are thoroughly clean, the bike will resist starting easily and will idle and midrange poorly.

Yes, that is the petcock. yes, i did follow the advice found here when I initially cleaned them. My thought is that maybe they got gummed up over the past few months with the old gas I had in the tank prior to draining it...
Also, before the re-installation they I didnt have the idle problem, but I did find some issues with the fuel/air system: breather hose was replaced and the airbox filter was not in the proper position. I have fixed both of those issues and now it doesnt want to idle unless the choke is on full and that brings the rpm's way up...

[tom203]

With that style petcock, the "PR" is with screwdriver slot vertical, BUT you still have to crank engine a bit to get fuel to start flow. Avoid old gas- ethanol is bad news- the pilot circuit in these carbs is tiny and gets gummed up easily, causing difficulty at idle.

disconect fuel line to carbs in "PR" and crank it to ensure fuel is flowing.

[clark_sas]

Update: turns out petcock failed- opened it up to find diaphragm torn and circular disk under was broken into four pieces. Ordered a new petcock and will update once delivered and installed. Thanks to all for their advice, hopefully this won't be too long of road to riding!!

[clark_sas]

Irfanview is a great program for batch-resizing of photos. However, if you use Photobucket to host your photos, you can set your preferences to auto-resize anything you upload. I have mine set to "800 on the long side". Doing it that way is easy, as I don't have to have a bunch of different-sized photos around here, and trying to keep track of what is where. I just take my pictures, upload the few that I want to share, and it's done. You can see the size of that picture by clicking on any of the picture links in my signature.

By the way, you do know (hopefully) that if you host your pictures somewhere (Photobucket is just one of the places), you can copy and paste the IMG link for that photo in your message here and you can show up to 10 pictures per post, instead of the one at a time if you attach a picture through the forum.

.

Thank you, I am having trouble finding the time to research the proper way to post pics to an existing thread. I have registered for an account with Photobucket and will hopefully have time to figure it all out this weekend while I'm waiting for the new petcock to ship...