I posted earlier about fuel not making it to my carbs. I replaced the 5/16" auto fuel lines with OEM fuel hoses and it fired right up :) . It's the first time it's run since I rejetted the carbs, so I know I probably have some tuning to do.
The mixture screws are 3 full turns out and I reset the idle since having the throttle cable unhooked from the carbs. The float height test put the fuel from the left carb slightly higher than the right (the right is at the proper level).
Now what's happening: Once the bike is warm the idle sometimes climbs to 3000-5000 rpms. If I'm in gear and riding (even very slowly) it acts fine, and it doesn't do it all the time. When it happens I'll adjust the idle right there on the throttle cable below the right grip, but when the idle is ready to come back down, it stalls. And it will come back down--usually after a minute or two.
Would that difference in the float height make this happen? Or at least indicate that the carbs are out of synch? Any ideas are welcomed.....I've been trying to get running for 7 weeks now!
I had a similar problem with an irratic idle and engine hesitation at around 4000 rpm. After a bit of searching I descovered that the spring seat was missing from the right cylinder jet needle. This allowed the jet needle to rise with the diaghram as the throttle was opened but without the spring seat the spring could not push it back down when the throttle was closed.
The spring is the only thing holding the seat in place so when the carb is disassembled the spring seat can easily fall on the floor as soon as the top cover is removed. You can easily check to see if this is what happened to you by removing the top covers (2 screws) from your carbs and look to see if the seats are in place.
Hope this helps. Good luck and ride safe.
I hear this can also be caused by the bike running lean. You might try putting on the choke and see how it affected the RPM to help diagnose the problem.
All of the carbs' parts are accounted for, so it's not a missing spring.
I adjusted the idle screw on the bottom of the carbs instead of solely on the throttle line, and I have it set to where everything sounds great on my driveway. I'll ride it to work tonight and report back once I get home.
As for the choke, I have to use the choke to start and it idles low at first until it warms up. Once the rpms climb to about 4000 I close the choke and it's happy. Now with the bike on the centerstand and in neutral, I can give it gas and rev all day long and it returns to 1200 quickly and smoothly just like it should.
If I apply the choke, it spikes briefly to about 2000 rpms and then crashes to about 800, chug-a-lugs and then stalls.
I'll see how it does on my trip to work and back and give you guys some more details tonight.
HAVE A GREAT 4TH!
Same thing happens with my bike, got really annoying the other day as I was stuch in a traffic jam and everytime I stopped it revved to three grand. I found by letting the clutch out just a little it would rev down where it should be but I don't want to sit letting my clutch slipping can't be good in the long term. I only find this happens when the bike is really warm, makes for frustrating sit on a busy highway in all of your gear when the heat is pouring off of the engine. I also tried to adjsut the idle at first but then it wouldn't idle well when cold.
Let us know when you figure out the cause.
dave
I was ready for work too early, so I decided to try something. When I put the carbs back in the bike I had reset my idle by adjusting the tension in the throttle cable where it connects to the carbs, and then made adjustments to the in-line screw up near the right grip. I had never messed with the idle screw that hangs down below the carbs.
I gave it a try, but several turns in either direction wouldn't make even the slightest change in the idle. Since the mixture srcews are set by tightening them down and then backing out, I did the same to the idle screw. Once it was cinched down (after what felt like 100 turns in) the rpms climbed, so I backed it out until the idle is where it should be (didn't count how many turns).
Now the bike runs like a champ with quick response to the throttle, no sputtering or stalling, and it idles as even as can be. Granted my ride to work is less than 20 miles round trip, but I was in holiday traffic coming home at 7pm and the bike did wonderfully in the stop and go (and it was 90 degrees here today!).
Could the fix really be this simple?
Yep, could be that simple if the problem was that it was sitting on the throttle cable instead of the idle stop. The throttle cable won't return very reliably to exactly the smae spot so the idle wanders. The idle screw stop is much more precise.
The high idle and sudden drop is usually caused by other things though. The main one is carb balance. If the carbs are not synched, the idle will hang high and then crash after awhile.
A vacuum leak will also cause it - leaving the little o-rings out when you put the carb tops back on; carb boots between the engine and carbs not sealing; the vacuum port covers on the carb tops missing or leaking; the carb top itself leaking; the vacuum line to the petcock leaking.
If the idle mixture is too rich (idle mixture screws too far out), or sometimes too lean, can cause it. 3 turns is usually a lot. 2 1/4 is more typical, but this isn't something you can just count the turns and have every carb set properly. My method of setting them is: get the engine warm, and idling at about 1000 rpm. Turn one screw in slowly from about 3 turns out. The idle revs should pick up as the mixture is leaned, and then fall off. you want to be 1/4 turn out from the point they start to fall off.
Re-set the idle speed, and do the other side. Repeat.
But you have to get vacuum leaks fixed, the carbs reasonably balanced, and the idle stop screw actually working. After getting the idle mixture set right, the carb balance should be re-checked.
I don't think I'm too far out on my mixture screws. I rejetted the carbs (pilot and main jets) so the extra turn out is compensation.
Like I said, I'll ride quite a bit more this weekend (got sat-mon off!) and I'll report back with the results.
Thanks for everyone that has responded!
Well, I rode about 140 miles today and everything was perfect. I closed the choke too early after first starting this morning. The rpms dipped, but once I went about another mile down the road it did just fine.
I've finished every project for my bike now! :thumb:
Congratulations! It must feel pretty good.
Be on the lookout for that nagging feeling that you really ... need ... to do ... just one more thing ... to that bike!