Topic: '71 CB750 K2 dying while riding

[sullivad1618]

Need some ideas folks. Riding home on my 1971 k2 today when it died. Took a couple minutes of trying but it started again, only to die again a few minutes later. This happened twice more, every time it would take a couple mi utes of trying before it would start. the last time when coasting to a stop I tried giving it a little gas, and it started again, but was herky jerky like fuel was intermittent. First time it happened was while clutch was pulled in, downshifting to stop at a light. Other times were while cruising along at between 40 and 50. Any ideas on where to start? I have a brand new petcock, new plugs, did the timing and synced the carbs about two months ago.

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[Pielz]

If it's dying like it's running out of gas, it could be that the tank is getting a vacuum and the gas isn't able to flow? I've been having issues with that but on my k7. Petcock on, but it spitters and dies. I just have to crack the gas cap and then tighten it again.

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[calj737]

Check to insure fuel line routing to carbs doesn’t have a loop in it causing an air bubble to intercede with flow as well.

[Pielz]

Yeah that's a good point. Being gravity fed, the fuel lines shouldn't be travelling uphill at any point.

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[Duke McDukiedook]

Fuel cap vent blocked? Do you have inline fuel filters?

[BenelliSEI]

Checked the petcock screen/ filter is clean and clear?

[PeWe]

+3 on fuel cap vent. I had a tank with rusty blocked vent. Bike ran well for almost 10 minutes, then starvation.  Open fuel cap and see if it start when it dies

[ekpent]

 Just out of curiosity how long have you been riding the bike and it seems this is an issue that has just recently cropped up ? Make sure you check the temperatures with a wet rag or something of the exhaust headpipes the next time it fizzles out to make sure you are hitting on all 4 and if not you can isolate which ones may not be as hot as the others. That could lead to help in more troubleshooting like a set of points crapping out or one bad carb,which carb or other carbs not getting fuel, etc. etc..
  On a side note a K2 750 is a 1972 and a 1971 is a K1.

[Menno]

Maxbe try this:
Start your bike.
Let it idle.
Pul the negative wire from your battery.
If your bike stalls it is not charging properly.

[calj737]

Maxbe try this:
Start your bike.
Let it idle.
Pul the negative wire from your battery.
If your bike stalls it is not charging properly.

Completely irrelevant to the symptoms. If his bike were not charging properly, it would not restart after dying because the battery would have been drained.

[sullivad1618]

Just out of curiosity how long have you been riding the bike and it seems this is an issue that has just recently cropped up ? Make sure you check the temperatures with a wet rag or something of the exhaust headpipes the next time it fizzles out to make sure you are hitting on all 4 and if not you can isolate which ones may not be as hot as the others. That could lead to help in more troubleshooting like a set of points crapping out or one bad carb,which carb or other carbs not getting fuel, etc. etc..
  On a side note a K2 750 is a 1972 and a 1971 is a K1.

Its been running fine for a while, about 3 months with no issues. Good idea, thanks for the advice. It is a 71 k2, they started making k2 november of 71.

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[Maraakate]

It may be the condensor.  Some times they get will read out okay on a tester but once they are heated up (after 5-10 minutes of solid riding) then they cut out and cause issues.