71 R75/5 dies when warmed up

[cvhd94]

Yes, I did get new non resistor plugs and wires, and new coils as well. Just tested and got about 19,300 ohms.

Yeah it’s a new paper filter, not K&N. It’s definitely clean and clear, blocked one end and blew on the other just to see if there was any resistance at all and it felt like there wasn’t even a filter there, so I don’t think that’s it.

 

[cvhd94]

Well, I don’t want to speak too soon, but I think I made some good progress again!

Took both carbs off again, and completely disassembled them for a fourth time, cleaned and blew out every passage and jet, and put it all back together. I installed a one step leaner needle jet and main jet while I was at it as well. Then put the carbs back on the bike and fired it up. It did still start without choke, but I did run it earlier in the evening.

But it ran great, no more mush at the low end when starting to apply throttle, and when it settled right back into an idle without acting like it was going to die. I was elated and wanted to take it for a spin to see if it was just a fluke.

I turned on my headlight and started backing out of the garage, when I looked forward again I saw smoke pouring from the headlight. I guess you can’t win them all. After quickly turning off the bike, disconnecting the battery and inspecting the damage and cursing the PO’s shoddy botch job that he called wiring. I made sure to insulate anything that got singed and put the headlight cover back on because damn it I was going for a ride, lights or not.

It ran great, I didn’t go very far, or for very long on account of not annoying my neighbors at 9:30pm. So I made it back to the garage and let it idle some more, turned it off, turned it back on. Then did it again to celebrate.

Will try my luck again tomorrow, fingers crossed it wasn’t a Guinness induced fever dream.

 

[kinterridge]

Great news on getting it running on the fuel side of things. If your harness is bad in the headlight, I recommend checking all the wiring and grounds. If the harness is beyond repair, Britts and Beemers Motorwerks makes harnesses up through /5 bikes. (He used to supply to Bench Mark Works their harnesses.)

 

[stevenrankin]

Considering

Well, you had a large list of stuff you did and for sure karma will stick a finger in and mess up one item on the list. But as you find, rechecking things and not giving up works in the end. Maybe in this case the needles were just in the wrong place.

As for the smoking headlight, yeah, if I recall, some of the early /5 bikes didn't have fuses which led to bad things. I am saying a prayer to the god of wiring things are minor in your case.

Kit, thanks for the link to Brits and Beemers, I know my shop owner friend will be interested. So far the only place we have found harnesses has been from EME and to be honest I don't know if they sell /5 harnesses or not. It is always good to have a second source.

Enjoy the riding. St.

 

[44006]

"Things I have done:

.......Fuel - Rebuilt both carbs (cleaned/blew out all passageways, all new o rings, new idle jet, float needle, float, diaphragm and needle, and new gaskets)....."

71 R75/5 does not have large diameter push down spring on top of carb slide
Slide must drop by gravity with freefall and click when hits bottom
There are new diaphragms out there that are too stiff to work without pushdown spring
Impossible to tune bike if slides do not fall freely and sharply to bottom when throttle closed

Run bike without air tubs and confirm slides fall completely every time you blip throttle
Stiff diaphragm will hold slide up when you stop warm and not fall till bike cools

Will drive you nuts!

I did not read every post so forgive me if I missed something

 

[stevenrankin]

Again, don't forget to make sure your valves are adjusted. Tight valves can cause poor idle or stalling as well as poor performance. St,