Engine miss when hot

[MrMAX1985]

My intermittent problem has reared it's ugly head again. When it gets hot and I am driving around town it wants to stutter/miss at idle and when letting out clutch from idle. It acts like maybe some sort of heat sink issue is going on. I have attached a video of it at idle. Checking battery voltage at idle it is at 13.6-13.7. Throwing this out there to see if anyone has had this issue. If I take it out on the highway for a while the issue goes away until I get in town again. I went thru the carbs this last winter and they are synced. Apparently the file is to big to load.

 

[MrMAX1985]

I got it shortened up to load
View attachment 1000001842.mp4

 

[CaptainKyle]

How old are your spark plug wires and caps ?

 

[MrMAX1985]

Original, took them apart this winter and did not see anything wrong visually.

 

[CaptainKyle]

Original, took them apart this winter and did not see anything wrong visually.
[/QUOi would put some new NGK caps on it and wires before i done anything. TE]

 

[MrMAX1985]

Where would I source them from? Would you know part#s? Thanks

 

[CaptainKyle]

Where would I source them from? Would you know part#s? Thanks

https://www.ebay.com/itm/1860487371...HoR8m61RbS&var=&widget_ver=artemis&media=COPY

 

[CaptainKyle]

You can put 7mm spark plug wire in the search on ebay or Amazon You only need about 4 feet of copper core wire.that will give you some extra in case of an error

 

[MrMAX1985]

Well I replaced my plug caps and wires and took for a ride yesterday. Still have same issue, noticed if I hold throttle steady at 2500-3000 rpms while cruising with no load on engine (flat level road) it will start to miss/stumble. If I jump up a gear (at the same speed) the stumble goes away (rpms 2200-2500). If I put the choke enrichener on a little bit I can feel the stumble quit somewhat. All of this happens when the engine and ambient temps are hotter. Anything above 3000 rpms I have 0 issues. Completely stumped at this time.

 

[Fire-medic]

I'm not saying it is the cause, but any stumble at lower engine RPM's I attribute to dirty/plugged pilot jets. You need to ensure that the gas tank is shiny-bright clean on the inside bottom and sides. Cleaning your pilot jets and carb passages, preferably by an ultrasonic bath (hardened deposits in the jets may need to be poked-out with a stiff piece of wire smaller than the hole) is what most of us have success with. If your tank has been internally-coated with some liner product, it may not appear to be shiny-bright.

 

[brian hicks]

Here in the UK we have some stuff called REDEX which you put in the tank and it cleans the fuel system. That would be the first thing I would try. Also carefully inspect your ignition coils for cracks. Have you put meters on the carbs to check they are all in sync? Mine ticked over much better after I did that.

 

[MrMAX1985]

I was thinking that the carbs were the issue also so I had pulled them off last fall and went thru them completely including the ultrasonic bath. The fuel tank is absolutely clean on the inside and I had replaced the fuel filter with OEM at that time. There was nothing that I could see for debris in the old one. I have drained the carbs a couple of times since and found nothing in the float bowls. What has me stumped is when the weather and engine temp is cool I have no issues. The carbs were synced using th Digi Sync tool and have been rechecked.

 

[brian hicks]

I was thinking that the carbs were the issue also so I had pulled them off last fall and went thru them completely including the ultrasonic bath. The fuel tank is absolutely clean on the inside and I had replaced the fuel filter with OEM at that time. There was nothing that I could see for debris in the old one. I have drained the carbs a couple of times since and found nothing in the float bowls. What has me stumped is when the weather and engine temp is cool I have no issues. The carbs were synced using th Digi Sync tool and have been rechecked.

Recently I was ticking over at 1000rpm waiting at the lights with a hot engine when it suddenly stopped. I quickly restarted and it's never done it since. No idea why.