Bike runs the dies after 5 mins

[Frush87]

Hey so i was riding my bike yo denver from houston as i was shifting gears it felt like a gear sliped out or was partially engaged cause as i kept on the throttle the bike would not go past 40mph and died shortly after this so i pushed the bike of the road and tried to start it and it would not run i then waited for about an hour and started it and it ran great for all of 5 mins.. so i thought it may be a carb issue and upon further inspection of the carbs i could not find any faults but since i have the carbs arpt now i notice they could use a good cleaning and figured with winter coming why not just try and over haul the entire bike while all the white stuff is on the ground. but i would be very thankful for any help trouble shooting the main issue

[tarzan]

Will it run longer with the gas cap open?Maybe a plugged cap vent.

[jetmechmarty]

Will it run longer with the gas cap open?Maybe a plugged cap vent.

+1. I've been through the same issue.

[WMarshy]

You might want to resolve your problem first before taking everything apart otherwise you'll never find the problem if you introduced another...

[motoman]

Hey so i was riding my bike yo denver from houston as i was shifting gears it felt like a gear sliped out or was partially engaged cause as i kept on the throttle the bike would not go past 40mph and died shortly after this so i pushed the bike of the road and tried to start it and it would not run i then waited for about an hour and started it and it ran great for all of 5 mins.. so i thought it may be a carb issue and upon further inspection of the carbs i could not find any faults but since i have the carbs arpt now i notice they could use a good cleaning and figured with winter coming why not just try and over haul the entire bike while all the white stuff is on the ground. but i would be very thankful for any help trouble shooting the main issue

More likely a primary or secondary ignition issue than a fueling issue. Would help to know year and model as there is differences ignition wise.

[natemoen]

You might want to resolve your problem first before taking everything apart otherwise you'll never find the problem if you introduced another...

+1!!!!! Figure out the problem before you potentially cause other problems!!!

[devilschld]

this sounds like something i may have just went thourgh. so trust me when i say check wires going to PICKUP COILS for a break

[DGXSER]

Being the every day normal human, I am naturally drawn to the quickest simplest solution. So, I would try the gas cap first. Does sound like it is running short on fuel, but an air locked tank will not let fuel out since air can not get in. As suggested, run it with the gas cap open, if it improves you know the cause. If not, then move on to the ignition items like pick-up coils. Just my 2c worth.

[devilschld]

Being the every day normal human, I am naturally drawn to the quickest simplest solution. So, I would try the gas cap first. Does sound like it is running short on fuel, but an air locked tank will not let fuel out since air can not get in. As suggested, run it with the gas cap open, if it improves you know the cause. If not, then move on to the ignition items like pick-up coils. Just my 2c worth.

only reason i suggested what i did is cause it sounded real simial to what i was going through. that morning when i was riding from the turn i was giving her all she had and she did the same thing. but i called it spitting and sputtering.

[DGXSER]

I am not sugesting I think your wrong, may well be the pick-up coils. Just saying that running it with the gas cap open is a very simple thing to try first.

I have found that fixing anything complicated and electro-mechanical like these bikes is a process of eliminating what it is not till you find what it is. Rule out the simplest things first, then move on to the tougher ones.

[James England]

Rule out the simplest things first, then move on to the tougher ones.

Absolutely. Also, only do one thing at a time.....resist any temptation to remove the coils, the pickups, the carbs etc all in one go. Just go one step at a time and see if it cures the problems and, as DGXSER has said, it makes sense to start with the simple things. In general, carb issues are at the more complicated end of the spectrum because it involves gasoline, lots of little parts that need cleaning, airways/fuelways than need checking etc and it's messy. So, if I were you, I would start with the fuel cap, then check plugs, ignition leads, coils, pickup coils, vacuum advance (if fitted) and, if all that lot doesn't nail the problem, then start on the carbs, fuel lines, fuel filters etc etc.

You may find, as many people have, that it's as simple as a blocked fuel cap, or a pickup lead.

Re-reading your post, it seems you have thew carbs off already, so I suppose you should clean them thoroughly now that they are off the bike!

[Frush87]

Absolutely. Also, only do one thing at a time.....resist any temptation to remove the coils, the pickups, the carbs etc all in one go. Just go one step at a time and see if it cures the problems and, as DGXSER has said, it makes sense to start with the simple things. In general, carb issues are at the more complicated end of the spectrum because it involves gasoline, lots of little parts that need cleaning, airways/fuelways than need checking etc and it's messy. So, if I were you, I would start with the fuel cap, then check plugs, ignition leads, coils, pickup coils, vacuum advance (if fitted) and, if all that lot doesn't nail the problem, then start on the carbs, fuel lines, fuel filters etc etc.

You may find, as many people have, that it's as simple as a blocked fuel cap, or a pickup lead.

Re-reading your post, it seems you have thew carbs off already, so I suppose you should clean them thoroughly now that they are off the bike!

I will have to try that with the gas cap and then ill check the coils ya i already got the carbs out and just got all the new carb parts in today my carbs were pretty dirty so kinda happy i am cleaning them hmmm thoo next hard part will be to sync them lol i feel like an idiot now for jumping like that

[TopCatGr58]

Hey Frush,

As I probably stated when you registered, these machines are YEAR and MODEL specific and tech info is directly related. IF we don't know the whole picture, then we can't give the correct advice. I just viewed your profile, and you posted your serial # of your bike, a 3H3 model, which is a 79 SF Special...which is NOT listed in your signature.

But knowing this info then provides us with more fuel supply related info....that your bike originally came with an OCTOPUS vacuum controlled valve fuel assembly. As you stated, waiting a few minutes, and then the bike will run again for 5 minutes...a bit longer than the time it take to empty the carb float bowls when running. IF the OCTY is misbehaving, then it can also restrict the fuel flow to the carbs. Cause can be a cracked vacuum hose that goes from the Octy to the #2 carb boot sync port. Or the Octy vac. valve diaphragm has gotten stuck so it doesn't open much so it only allows a small amount of fuel flow.

SO....yes, the gas cap vent may be clogged, but that's not the only possible fuel delivery problem....now that we know that you have a Special...provided you still have the OEM Octy valve assembly. IF the open gas cap doesn't solve the 5 minute stall problem, then turn the petcocks to PRIME, which bypasses the Octy's vac. control and feeds the bowls directly. IF the 5 minute stall is solved after this, then you can then say that the Octy is at fault, and the solution can be to either just remove it and remember to turn your petcocks to OFF when you park, or spend the $ to rebuild the Octy, or just replace the vac. hose...depending on what you find wrong with it!

If these fuel delivery diagnostics don't solve the 5 minute stall, then I would say look for other faults as mentioned... ie. ignition.

Would be good to edit your profile/signature to add that it's a 79 SF Special.

T.C.

[slow mo]

this sounds like something i may have just went thourgh. so trust me when i say check wires going to PICKUP COILS for a break

GOOD advice buddy !! ride safe ,,slow mo!