Bike idles and runs great, but has issues with starting.

[larson7]

Hello all,

I've been utilizing the resources on the great site to work on a recently purchased 80 GS550.

I dipped the carbs and cleaned out all of the jets, the fuel tank, and installed a new petcock.

I seem to have issues starting and there are a few things that i think may cause this, i'd like a second opinion:

The new petcock does not have a knob to adjust, so I kept it on prime.

When I try and drain the bowls they don't stop flowing gas, this leads me to believe that the carbs may be flooded.

I was able to get it started a few times by blowing carb cleaner through the intake, but that doesn't seem to work anymore. I started to try to drain the bowls, but that seemed futile.

Once it is started though, it idles very well and stays at consistent RPMs. I took it for a test drive around the block and it runs REALLY well and pulls hard in the high rpm range, I really want to get this thing running consistent.

Thanks in advance!

[larson7]

One think I should mention, I did not set my floats. Would this cause my bike to not start?

[DanTheMan]

Is the petcock the one with a screwdriver slot? One direction is prime, the other is run. Whatever position it is currently in is obviously prime, turn it 90 degrees and it'll be in the run position and will stop flooding the carbs.

[DanTheMan]

One think I should mention, I did not set my floats. Would this cause my bike to not start?

If the float level is too high, yes it will prevent it from starting and running as the bowls will always be too full. Go over the whole job a second time, use the guide contained in this link: http://members.dslextreme.com/users/bikecliff/

[JJ]

One think I should mention, I did not set my floats. Would this cause my bike to not start?

You dipped and cleaned your carbs, but didn't check/set float heights? That is a pretty important step. Otherwise, your carbs may overflow. Sound familiar??

I suspect you took several other shortcuts, too. Take your time and do it right the first time, and it will be the only time you have to do it.

[Steve]

Is the petcock the one with a screwdriver slot? One direction is prime, the other is run. Whatever position it is currently in is obviously prime, turn it 45 degrees and it'll be in the run position and will stop flooding the carbs.

Actually, you need to turn it 90 degrees, not 45.

With the slot vertical, it is in the PRIme position. With the slot horizontal, it is in RUN. Please leave it in the RUN position.

The PRIme works a little differently on that petcock. It will not flow until it sees a 'puff' of vacuum, then will flow freely until the selector is moved to horizontal or it runs out of gas. THAT is why you think the carbs are flooded.

Just out of curiosity: how is it that you went through all the effort of dipping the carbs and cleaning out all the jets (did you replace all the o-rings?), and did NOT check the measurement on the floats? Right next to making sure everything is CLEAN, float height is more than "important", it is CRITICAL.

Once you get those issues sorted, you can go to the next task to get it running (and starting) right: valve adjustment.

.

[larson7]

I did follow the guide step by step, sans the float adjustment because I did not have my set of calipers handy that night. I know it was a critical step that I did not complete, i am just confirming before i tear it apart that this could be the issue.

Thanks for the help.

[A-train]

Welcome to the club! Steve is right - set that petcock to run, or horizontal (I have the same one) and dial everything in with your carbs.

Really good sign that it runs well once running.

Have fun!

[DanTheMan]

Actually, you need to turn it 90 degrees, not 45.

With the slot vertical, it is in the PRIme position. With the slot horizontal, it is in RUN. Please leave it in the RUN position.

The PRIme works a little differently on that petcock. It will not flow until it sees a 'puff' of vacuum, then will flow freely until the selector is moved to horizontal or it runs out of gas. THAT is why you think the carbs are flooded.

Just out of curiosity: how is it that you went through all the effort of dipping the carbs and cleaning out all the jets (did you replace all the o-rings?), and did NOT check the measurement on the floats? Right next to making sure everything is CLEAN, float height is more than "important", it is CRITICAL.

Once you get those issues sorted, you can go to the next task to get it running (and starting) right: valve adjustment.

.

OOPS! I fixed it.

[tkent02]

Calipers, a ruler, a piece of cardboard, book of matches, it's not critical what you use to measure it, it is critical that you use something.

[larson7]

Thanks for all the help guys, I'll go ahead and take them off and adjust the floats.

[chuck hahn]

Too LOW and it will be hard starting also. I set them in the middle of the stated range and dont have troubles there. Also, how far out you have the mixture screws is a factor. Too far in and it too lean and will be stubborn to start.

[850 Combat]

Another potential problem is insufficient voltage to the coils, causing too weak of a spark while the starter circuit is sucking up nearly all the electricity in the battery.

[jbird7262]

Just a chime in on that style of petcock, I have a 1980 GS750E and was wondering if that was a standard for that year, its a vacume operated verses gravity design, what do you guys think of these verses the gravity design, any reliability issues?. At least you don't have to remember to turn the valve off. :-)

[Killer2600]

Just a chime in on that style of petcock, I have a 1980 GS750E and was wondering if that was a standard for that year, its a vacume operated verses gravity design, what do you guys think of these verses the gravity design, any reliability issues?. At least you don't have to remember to turn the valve off. :-)

All our petcocks are vacuum operated. What you call gravity design is what everyone else calls a "manual" petcock. The downside to the leverless petcocks, the difference your actually speaking of, is the lack of a reserve position. Some never need this function so the difference between lever and leverless is minute, where as others rely on the "reserve" to save the day quite often.