Bogs down after 20 min on Freeway

[caryetch]

I am the very proud owner of an 85 fj1100.  I ride the bike as a daily in-town commuter only.  Mostly because when I take the bike on the freeway at normal speeds (60-80) for 20-30 miles (sometimes less), the engine suddenly bogs down drastically.  It gets to the point where it will not respond to throttle and wants to die and will if I don't crank the choke.   If I crank the choke, the engine will stay running with lots of throttle although very intermittently and with little power.  If the bike dies, its almost impossible to get started again.  I did replace the regulator at one point a couple years back because the battery would frequently die.  I believe this is not the problem now.  I suspect overheating of some sort tied to the fuel delivery, but it happens in almost all weather (even in winter - I live in Reno/Tahoe area) and in very short rides of continuous throttle at mid RPM - 6-7 or so. 

Any ideas or experience with this behavior?   Many thanks.

cheers,
Cary

[simi_ed]

This sounds like the gas tank cap is not venting, creating a vapor lock and starving the engine for fuel.  Try opening the gas cap to see if that allows you to restart the engine.  A search should find the info on removing the flapper in the gas cap, causing your vapor lock condition.

[Klavdy]

G'Day mate,
yeah, like Ed said, could be gas cap venting issues, could also be:

• Dirty Fuel Filter
• Old Fuel Lines Collapsing

I can't remember if your model has a fuel filter or a screen but it sounds similar to what's happened to me when the fuel filter was clogged.
Bike would splutter, die, then ten, twenty minutes later, enough fuel would trickle through the cloggage (note, nice new word)to start back up again.

Really does sound like there is a restriction in the fuel delivery.

[rktmanfj]

>> trickle through the cloggage (note, nice new word)<<

Yeah, but once again, the Ozzie spelling is all wrong... should be clogage.         

Randy T
Indy

[Klavdy]

>> trickle through the cloggage (note, nice new word)<<

Yeah, but once again, the Ozzie spelling is all wrong... should be clogage.         

Randy T
Indy

Must be the Dutch influence.

Dirk Hartog & Abel Tasman have a lot to answer for.

[rktmanfj]

Must be the Dutch influence.

Dirk Hartog & Abel Tasman have a lot to answer for.

Heh, could be...     

Cary, have you been using a tank bag for the commute?

Randy T
Indy

[Klavdy]

Convict scum, Irish rebels and Scot gits.

[caryetch]

Must be the Dutch influence.

Dirk Hartog & Abel Tasman have a lot to answer for.

Heh, could be...     

Cary, have you been using a tank bag for the commute?

Randy T
Indy

Thanks for the replies.   I do have a tank bag but don't use it - I have the soft bag on the rear and that suffices.  I will try and test the vapor lock theory.  I will take it out in the morning and get it to the point where its doing its 'thing' and open the cap and see if it starts and runs normally again.  Now that you mention it, I have heard sucking sounds coming from the cap at times so hopefully that's the solution.   I would be thrilled if it was!

As for the fuel delivery, I will also check the fuel lines for any (obvious) blockage and replace the fuel filter. 

Thanks again for the help.  I'll post an update with any progress (or lack of)...

Cary

[FeralJuggernaut]

On the fJ1100s....    there is a vacuum tube that drives the petcock.    If you set it to prime and get past the 20 minute mark, it could be a crack in the vac tubing just as it over heats or collapses on itself too. 

[Mark Olson]

plus one on tank flapper. 

gravity feed fuel will cause the problem, a full tank of gas will act normal and as the fuel gets to 1/3 full a 80mph run will cause a vapor lock and starve carbs.