1990 750 stalling issues (possibly electrical)

Hi guys been trolling the site for awhile since I've picked up this extra bike. Great machine in amazing visual condition with 12k on it. Refreshed and went over all of the connections in the harness. Replaced the r/r with a MOSFET unit from an r1 and it works great. New battery, carb service, and full exhaust and she runs absolutely great.... After an OEM new fuel pump and electric relay.


Buuuuut here's my dilemma. The bike goes well, runs perfect and has no issues, except when its over 90*F. The bike will cycle the fan a few times with no worries, then after a few more stops it'll lose power idle very rough and die out. However you just bump the starter and she fires right back to life like all is well. And will ride problem free for another 20/30 mins the. Repeat. Issue is only when. Its around 90* out. Anyone have any suggestions. I've done everything suggested in searches. Thanks a lot guys and gals. Sorry for spelling I did this on my phone at work *__*

-Vay

 

What is your idle speed setting? How many turns out are the mixture screws set? What size pilot jets?

 

Idle is right around 900-1100 but don't quote me. I doesn't sound high by any means while its running so I couldn't tell you. Had the carbs jetted by the guy who did the exhaust. I had the same problem before I put all the above listed items. All were maintenance/preventative with no change in the condition. Its my fathers bike I've been kinda getting going for him and this is the last hurdle. I'm a kawi guy and won't lie know nothing about the awesome v4 in this bike, but am willing to learn.

 

I just told him to get a viffer cause I heard they bare awesome bikes a stone reliable after you work the mior gremlins out. But its one thing after another

 

Only at first, then later it's just periodic r/r replacements...........

 

Glad I'm not the only one! .

You have any I dears to the issue I'm having with hot outside temps causing strange stalls? I'm about ready to surrender and take it to Honda...$$$$$$$$$$$ and that scares me.

 

Your idle speed may be a little too low.

Sounds like vapor lock of the fuel lines with high temperature, maybe the routing of the lines.

 

Okay, I was starting to think that as well. There is quite the bend in the supply line from the petcock to the pump that maybe is squishing with temperature... Any way to prevent that 90* bend in that location?

Also, how should the tank be vented (line wise &qty of places that vent) and is there any way to test the tanks vent abilities? Or clean its passages? Thanks again guys.

-vay

 

What is ideal idle speed?

 

If you intend to work on your bike or fix it, then you need to get a copy of the factory service manual and read it cover to cover. Do a search on this site or google to find a pdf version.

If you intend to take your bike to someone for service, then you need to get a copy of the factory service manual and read it cover to cover so you will know if they know what they are talking about or just blowing smoke up your ass.

 

Will do. Already been searching the site a lot before I joined. That's how I knew about the r/r swap and that these bikes wiring harnesses are junk. Was stumped and decided to join and ask for help. I was unaware that the service manual would have a troubleshooting area that would help solve my problem. But I'll give it a look.