I’m sure this is covered somewhere. I have the bike on the road after sitting for the winter (or so). Once it gets warmed up, after riding 10-15 minutes, the idle climbs. It idles at around 1,000 when cold and climbs to around 2-000+ after it warms up. If I feather the clutch in gear, it drops back down but after a few seconds starts to climb again. I assume that rules out a stuck advance mechanism. I have a Dyna III electronic ignition system. Suggestions? Thanks
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1976 R75/6 idle
- Thread starter cseltz
- Start date
ccolwell
Member
Ditto. I'd try tightening the hose clamps first; they want to be tighter than you (well, I) would expect. Then try spraying WD40 at the connections when it's idling high. Any change and that's your culprit.
stevenrankin
Active member
air box stuff
Make sure at least the two clamps between the carbs and head are tight and there are on leaks there. On the filter side of the carbs, it really won't make a big difference. St.
Make sure at least the two clamps between the carbs and head are tight and there are on leaks there. On the filter side of the carbs, it really won't make a big difference. St.
ebeeby
Member
Be careful about cranking down too much on the clamp at the lower end of the black plastic intake tube. The top clamp, and the clamp on either side of the carb as well as the clamp to the head intake nipple can be tightened because they bottom out against metal. The clamp at the lower end of the black plastic tube does not and can cause the plastic tube to produce a "fold" which will cause a leak.
At least, this is how it is on a R75/5. The later models IIRC were a little different. In any case, if there isn't a metal seat of some sort under a particular clamp, be careful about cranking it down too much.
At least, this is how it is on a R75/5. The later models IIRC were a little different. In any case, if there isn't a metal seat of some sort under a particular clamp, be careful about cranking it down too much.
stevenrankin
Active member
Carbs
One of the fun things about adjusting the carbs on an airhead is getting them adjusted in the golden zone of too hot or too cold. I mean, the bike has to be warmed up in order to adjust the mixture and idle. Yet, it can't be running standing still for too long or it will over heat. I put a big fan in front and that helps but still it can be touch and go.
As I have said many times, on an airhead, check the valve adjustment before doing anything with timing or carbs. Once the valves are adjusted, then points, if you have them, the advance system, if relevant and finally timing are to be adjusted. All of the timing and such depends upon the bike being in true idle, I mean the cables on the carbs have slack to let the carbs go into the idle position and the idle adjust screws are adjusted properly. Timing with the bike running can't be set properly if the bike is not idling.
Of course, timing can be set in static mode. Sorry, you would have to read Snowbum or someone else to tell how it is done, I have never done it myself.
Once the valves and timing are set and the carbs are in idle and the choke is fully off and working, then, the mixture and idle can be adjusted when the bike is warmed up. On my two bikes after carb rebuilds, the RT was easy to adjust with mixture and idle screws roughly where to set, I did a five mile ride, then fine tuned them. My RS took a bit more finagling and a couple of rides before I got them just right.
The key is to get the bike warmed up to the right level. The RT hit the right spot the first time and I made the adjustments and things were fine. The RS, the first time I rode it, adjusted the mixture and idle only to have the idle increase as the bike got ridden more for longer periods. After the second ride of a bit more distance, I was able to get things dialed in and the idle stays put, until the valves start to tighten up, then, things go out at idle.
I was told a long time ago, carbs stay in adjustment far longer than do valves yet, a lot of people fiddle with them first when idle changes rather than the valves. A long bit of written stuff here, hope it helps and doesn't bore you. Good Luck, St.
One of the fun things about adjusting the carbs on an airhead is getting them adjusted in the golden zone of too hot or too cold. I mean, the bike has to be warmed up in order to adjust the mixture and idle. Yet, it can't be running standing still for too long or it will over heat. I put a big fan in front and that helps but still it can be touch and go.
As I have said many times, on an airhead, check the valve adjustment before doing anything with timing or carbs. Once the valves are adjusted, then points, if you have them, the advance system, if relevant and finally timing are to be adjusted. All of the timing and such depends upon the bike being in true idle, I mean the cables on the carbs have slack to let the carbs go into the idle position and the idle adjust screws are adjusted properly. Timing with the bike running can't be set properly if the bike is not idling.
Of course, timing can be set in static mode. Sorry, you would have to read Snowbum or someone else to tell how it is done, I have never done it myself.
Once the valves and timing are set and the carbs are in idle and the choke is fully off and working, then, the mixture and idle can be adjusted when the bike is warmed up. On my two bikes after carb rebuilds, the RT was easy to adjust with mixture and idle screws roughly where to set, I did a five mile ride, then fine tuned them. My RS took a bit more finagling and a couple of rides before I got them just right.
The key is to get the bike warmed up to the right level. The RT hit the right spot the first time and I made the adjustments and things were fine. The RS, the first time I rode it, adjusted the mixture and idle only to have the idle increase as the bike got ridden more for longer periods. After the second ride of a bit more distance, I was able to get things dialed in and the idle stays put, until the valves start to tighten up, then, things go out at idle.
I was told a long time ago, carbs stay in adjustment far longer than do valves yet, a lot of people fiddle with them first when idle changes rather than the valves. A long bit of written stuff here, hope it helps and doesn't bore you. Good Luck, St.
Thanks for the replies. I had the bike going pretty well and idling nicely before changing the air filter. Looking at the last work suggested that the removal and reinstall of the carbs was probably the culprit. If time is a factor in valve adjustment, I should look at that but if it is just mileage, I probably won’t live long enough to need that! I do notice that it takes a fair amount of time to really get the bike up to temperature. Can’t just ride around the block. Again, thanks for the help.
stevenrankin
Active member
Valves
Valves should be adjusted about every 15K miles. I hope you get to ride that many miles in your lifetime and many more. LOL. I have a Dyna system on my RS, it is nice because once I set the timing, it stays set. No points are a great thing!
Yep, one fo the first things to do after doing work and finding a problem is to recheck work. During the last work done on the bike were the carbs rebuilt or disassembled for any reason? The last time I rebuilt my carbs, I didn't realize I had forgotten a part in the reassembly. It had rolled off my workbench.
Enjoy the riding. St.
Valves should be adjusted about every 15K miles. I hope you get to ride that many miles in your lifetime and many more. LOL. I have a Dyna system on my RS, it is nice because once I set the timing, it stays set. No points are a great thing!
Yep, one fo the first things to do after doing work and finding a problem is to recheck work. During the last work done on the bike were the carbs rebuilt or disassembled for any reason? The last time I rebuilt my carbs, I didn't realize I had forgotten a part in the reassembly. It had rolled off my workbench.
Enjoy the riding. St.
ccolwell
Member
My airheads usually took a long time to warm up. The R100 took a half hour of riding in moderate temps.
stevenrankin
Active member
Warm up
My 84 RT will warm up quickly and if I ever have to adjust carbs, it is easy. MY 78RS on the other hand is very slow to warm up, is funny with the choke, starts great cold with full choke but has to be blipped all the time till fully warmed up to keep it running at an idle. On it, the chokes are correct, the cables correct, mixtures correct, yet, it is vastly different than my RT for the short period of time between a cold start and full warm up.
With the RT, I can ride a mile and it is warmed up fully. The RS, ten miles. Go figure? Maybe it is the extra 200cc needing more heat on the RS? or the 40mm versus 32mm carbs, need more? LOL, The mice just don't warm up as fast on the RS. St.
My 84 RT will warm up quickly and if I ever have to adjust carbs, it is easy. MY 78RS on the other hand is very slow to warm up, is funny with the choke, starts great cold with full choke but has to be blipped all the time till fully warmed up to keep it running at an idle. On it, the chokes are correct, the cables correct, mixtures correct, yet, it is vastly different than my RT for the short period of time between a cold start and full warm up.
With the RT, I can ride a mile and it is warmed up fully. The RS, ten miles. Go figure? Maybe it is the extra 200cc needing more heat on the RS? or the 40mm versus 32mm carbs, need more? LOL, The mice just don't warm up as fast on the RS. St.
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