R5 Right Cylinder Intake Pop When Hot

[bhdaug]

Well guys, this one has me stumped. I recently went through my '72 R5 and did a top end, fitted JL chambers, electronic ignition and new coils. I put about 400 miles on it after the work was done without any issues (other than setting the jetting in the beginning.) About a week ago, once the bike got hot it will pop out of the carb on the right cylinder while taking off (below 3 or 4k rpm.) The longer it is ran like this the higher the rpm it will need to stay running. I almost was left stranded today because it would just pop and bog with any throttle input. The bike starts first kick and runs perfect until about 20 miles into the ride and this problem starts. Any help or guidance would be appreciated because I feel I am flying blind and going through and checking components without making any progress.

[Striker1423]

Three questions from me. ( FYI, I have issues with my bike too and others are much more knowledgeable than me, but)

Are you positive the carbs are clean?
What electronic ignition did you install?
Did you pressure test the motor?

Sounds to me like backfire which leads me to either a clogged jet causing lean running, a severe timing issue (i.e. something moved from where you set it), or you have an air leak. My 90 Kawasaki ran like crap but I only used the timing mark and got it as close as possible. This was before I had the correct tools mind you. 

[bhdaug]

Yes, I just went through the carbs to make sure everything was good there. I am running a dynatek ignition. The motor didn't do so great on a pressure test and led me to change out the crank seals. Now it holds pressure as it should.

[Jspooner]

Could be a bad coil. Switch your coils and see if the problem follows. You don't need to physically switch them just switch the wiring under the tank and then switch the plug wires at the plugs.

[SUPERTUNE]

Check charging system also, weak system and or weak battery will cause issues.
Chuck

[bhdaug]

I will switch the coils tonight. I suspected the battery was low as the problem occurred more when the turn signal was on. As soon as it would be turned off it would stop popping and when it was flipped on it would begin again. I charged it when I got home and it still popped. Either the coil had not cooled down yet or the 1 year old battery is bad.

[SUPERTUNE]

I like a Yamaha Zuma AGM battery...MY OPINION!! 
I still don't like cheap alarm batteries, even though a lot use them.
I want bolts for terminal hookups and AGM for long life against vibration our RD's make.

Chuck

[quocle603]

I had bad coils and it would "pop" when it was hot because bad coils tend to run worst when they are hot.

[bhdaug]

Switched coils yesterday and it did the same thing on the opposite cylinder. Ordered coils and an AGM battery. Hopefully after this I can start logging some miles on this thing.

[m in sc]

make sure the double female connector in the harness to power the coils is in good shape and making a tight contact. 

[Jspooner]

Switched coils yesterday and it did the same thing on the opposite cylinder. Ordered coils and an AGM battery. Hopefully after this I can start logging some miles on this thing.

Glad to hear you figured it out.

[m in sc]

indeed 

[quocle603]

Cover the soldered connections with silicone or electric tape on the coils.

[bhdaug]

Alright, got everything hooked up and now I can't even get it to start. It will pop out of the intake or exhaust of either cylinder once every few kicks. Everything is wired how the last coils were and it will not even try to start. Took it apart several times to make sure I did it correctly and even switched the positives to the coils around to make sure I just didn't have them on the wrong cylinders. There wasn't any difference.

[Barrie]

If this is a points machine you want to switch the negatives to the coils , not the positives