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flanneltooth
03-22-2012, 10:04 PM
Hello,
I'm a bit a of a newbie to motorcycles so bare with me. I recently got a 1976 triumph bonneville. It turns over fine and runs great. but today i ran into a problem. The bike is having trouble staying on when i'm idling. I have to rev it to keep it on. I also notice too when I was in 5th gear with the clutch in coming to a stop the engine turns off too. What are somethings I should look at/try to fix this problem?

starwolf
03-23-2012, 7:07 AM
It sounds as if possibly your idle adjust screw needs to be adjusted a bit. If its normal idle is say 800 RPM but the idle adjust is set so that it idles at 500RPM it may not be enough to keep it at idle/running. I would suspect this is also why the engine cuts off with the clutch pulled in, in 5th gear. Try fiddling with your idle adjuster to get the idle RPMs up a bit,(don't go crazy and make it idle at 2,000RPM or some other craziness) If its not in the idle adjuster, it may be other things like clogged jets, dirty/clogged fuel filters,etc. You might also try down shifting while coming to a stop, and putting it in neutral at the light vs, just pulling the clutch in in 5th ,holding the clutch in through the light, and hitting first when the light changes.

Torch
03-23-2012, 8:30 AM
Hello,
I'm a bit a of a newbie to motorcycles so bare with me. I recently got a 1976 triumph bonneville. It turns over fine and runs great. but today i ran into a problem. The bike is having trouble staying on when i'm idling. I have to rev it to keep it on. I also notice too when I was in 5th gear with the clutch in coming to a stop the engine turns off too. What are somethings I should look at/try to fix this problem?

do a search about "cleaning pilot circuits"...

flanneltooth
03-23-2012, 10:14 AM
Thanks Starwolf and torch. I'll give those things a try and tell ya how it went when im done. Cheers!

flanneltooth
03-23-2012, 6:22 PM
It sounds as if possibly your idle adjust screw needs to be adjusted a bit. If its normal idle is say 800 RPM but the idle adjust is set so that it idles at 500RPM it may not be enough to keep it at idle/running. I would suspect this is also why the engine cuts off with the clutch pulled in, in 5th gear. Try fiddling with your idle adjuster to get the idle RPMs up a bit,(don't go crazy and make it idle at 2,000RPM or some other craziness) If its not in the idle adjuster, it may be other things like clogged jets, dirty/clogged fuel filters,etc. You might also try down shifting while coming to a stop, and putting it in neutral at the light vs, just pulling the clutch in in 5th ,holding the clutch in through the light, and hitting first when the light changes.

Thanks for the detailed explanation!:killerjob:
I adjusted the idle adjuster and the ol bike is idling perfect again.

Trevor04
03-24-2012, 11:20 AM
hey guys i figured it was better for me to ask a similar question in this thread rather than start a new one. i got my bike timed at 38 deg btdc . on the right side of the bike ( the timing side) and then adjusted my idle and i can idle fine it just seems like the right side is working harder or more consistently than the left side. i tried timing the left side and i got it close but i couldnt get it exactly on the 38 deg mark. im not sure what to do. ive tried adjusting one cylinder at a time by taking a spark plug off. i know i have the timing right, at least on the timing side. but i can definatly tell a difference in back pressure coming out of the pipes, and it just seems like the left is not quite right were it should be. i can also tell when i accelerate. it doesnt bog down but it just sounds like the right side is the only one doing the work.

TRUMPNUT
03-24-2012, 12:51 PM
hey guys i figured it was better for me to ask a similar question in this thread rather than start a new one. i got my bike timed at 38 deg btdc . on the right side of the bike ( the timing side) and then adjusted my idle and i can idle fine it just seems like the right side is working harder or more consistently than the left side. i tried timing the left side and i got it close but i couldnt get it exactly on the 38 deg mark. im not sure what to do. ive tried adjusting one cylinder at a time by taking a spark plug off. i know i have the timing right, at least on the timing side. but i can definatly tell a difference in back pressure coming out of the pipes, and it just seems like the left is not quite right were it should be. i can also tell when i accelerate. it doesnt bog down but it just sounds like the right side is the only one doing the work.

Is this a early points plate ( pre68) If so you can only time one side then the other side you must adjust your gap to get the timing right . Also you didn't give much info on your set up . Is it a twin carb or single ? are you running a ET ign.? Have you already check for air leaks and valve clearances ?

Trevor04
03-24-2012, 1:19 PM
its a 71' t120r. 2 carbs, no battery with points and sparx capacitor. where should i check for air leaks.

TRUMPNUT
03-24-2012, 3:58 PM
A 71 you should be able to adjust the timing for each set of points seperatly . Make sure both carbs are set up the same . Set the idles to match vacuum off throttle ( freeplay in cables ) with the throttle stop screws . Then set the cables tension while on throttle ( about 2 grand or so )so the vacuum matches . Check for air leaks at the carb flange and the manifold gaskets . Also if you have a weak stator then you can have idle issues without a battery . If you can turn off you lights do so and see if it idles better . Also make sure you spark is strong . It should jump 1/4 and be bright blue .

Trevor04
03-24-2012, 7:08 PM
i should point out that its not just at idle, so let me make sure i have this right. Loosen the throttle cables. use the throttle stop screws(both sides the exact same) to get it to idle then set up the cables so it idles at 2grand. i dont think its just an idle problem, it does it if lights are on or off. i will do some messing around with it . thanks

Torch
03-25-2012, 2:44 PM
if it "pops" when you rev it from idle then it's most likely the pilot cricuits are still plugged,
we sell a pilot jet cleaning tool for $9.00 plus envelope shipping. it works great I'll post a video of the cleaning process.

Trevor04
03-25-2012, 9:10 PM
the left side does seem to pop but its all the time not just when i open up the throttle. when it pops its very sporadic and inconsistent. in the glenns manual i have it says to losen the pillar bolts and adjust the entire point plate to adjust the right side , then to time the left side just adjust the one side to get it timed , not the entire plate. this is what i did. i got the right side lined up correctly and got the left side as close as i could but it would not adjust enough to get the marks to line up. could i re time it and move the entire point plate so that the left side would be timed right and then just adjust the right side by itself. i think that there would be enough adjustment to get the both sides to time up correctly.

Torch
03-25-2012, 10:18 PM
a lean mixture (from a clogged pilot circuit) and a little off timing is a recipe for a holed piston.The popping is caused by the piston firing to soon, this could be timing only, but 90% of the time it's caused by too lean of mixture.
If you finally get tired of messing with individual points timing you might think about putting an electronic ignition in there.

When it comes to the carb, the pilot ckt. is 90% of the idle mixture and when the throttle is opened it is still 30% of the mixture. No mater how many times you spray carb cleaner in the holes it doesn't usually un-clog the pilot jet itself. you need to run a #78 drill bit (so small it's hard to tell it's a drill bit) or a guitar string through the jet to un-clog it.
It can be reached through the air adjuster screw going back all the way to the other side of the carb. when it's clean you should be able to spray carb cleaner in to the jet and have it come out in the bowl.

Trevor04
03-27-2012, 11:28 AM
i used a guitar string and cleaned out the jet. it seemed to make it run alittle better but that side still seems to be off alittle. i started messing with the points and started the bike. immediately i could see that the right side contact points where opening about the correct amount and the left side ( the side thats not running great) was barely opening at all. so i opened it up to match the right side. the pop is gone but its still doesnt sound the same as the right side or run the same. and also now there is a slight hesitation when i start to open up the throttle. :banghead: would i be able to run the electronic ignition with the same set up i have now. Podtronics rec/ reg- sparx capacitor. i appreciate your guys help. i feel like im getting closer to figuring it out.

Torch
03-27-2012, 4:19 PM
yes you can , as long as you have a good alternator all you need to do is put a Pazon ignition in there and that will be the end of your ignition problems.

Trevor04
03-29-2012, 6:25 PM
i getting close to giving up and paying someone who knows more than me to get this thing running correctly. i did a compression test and both sides where equal. i got both sides timed correctly. it seems to be alittle better but the left side still seems to be off. any other suggestions.

Trevor04
03-31-2012, 10:19 AM
i figured it out. and it was an easy 5 min fix, the left side carb the clip that goes on the needle was in the top groove not the middle so it was running extremely rich. i put it in the middle groove and she runs amazing.