Starts cold, runs, hard time restarting when warm.

[hondabeat]

I had the exact same problem. My honda would not start when warm and it sucked at the gas station. Check your ignition timing and crank seals and that should do it. I checked my timing by sticking a small fluorescent tube over the magneto and connecting one end to the ignition coil and other end to ground. Then i cranked it over and checked the light flicked and shone on the "F" mark as it passed the index mark on the motor. If the timings bad, you may need another key for the spline that the magneto is held on by. If the timing is good, check your crank seals.

[Wheelman-111]

Greetings:

1: Vapor lock? Did you remove a bunch of heat shields when you did the mods?

If so the warm engine can and often does evaporate the fuel out of the bowl quite rapidly, leading to a reluctant re-start. If you swap to clear fuel lines, you can sometimes see the bubbles that form as the heat emanating from the warm engine does its thing.

2: Bystarter cover? Removing that allows the bystarter to cool too quickly when AC current is interrupted. (It's activated by temperature, either self-generated or radiant...) If it cools before the engine, the plunger withdraws and applies enrichment to the mixture when the still-warm engine doesn't need it. Check plug right after non-start to confirm. Wet?

3: I always start these trouble-shooting adventures on a fresh spark plug.

[jsun3thousand]

what is your plug gapped at?what plug are you using? how many turns out do you have the air fuel screw?

plug NGK 4632, not sure of the gap, two turns out.

I had the exact same problem. My honda would not start when warm and it sucked at the gas station. Check your ignition timing and crank seals and that should do it. I checked my timing by sticking a small fluorescent tube over the magneto and connecting one end to the ignition coil and other end to ground. Then i cranked it over and checked the light flicked and shone on the "F" mark as it passed the index mark on the motor. If the timings bad, you may need another key for the spline that the magneto is held on by. If the timing is good, check your crank seals.

I don't know how to do either of those.

Greetings:

1: Vapor lock? Did you remove a bunch of heat shields when you did the mods?

If so the warm engine can and often does evaporate the fuel out of the bowl quite rapidly, leading to a reluctant re-start. If you swap to clear fuel lines, you can sometimes see the bubbles that form as the heat emanating from the warm engine does its thing.

2: Bystarter cover? Removing that allows the bystarter to cool too quickly when AC current is interrupted. (It's activated by temperature, either self-generated or radiant...) If it cools before the engine, the plunger withdraws and applies enrichment to the mixture when the still-warm engine doesn't need it. Check plug right after non-start to confirm. Wet?

3: I always start these trouble-shooting adventures on a fresh spark plug.

1: I didn't remove anything that I am aware of. The bottom of the carb does not get warm. Not sure if this answers what you are asking.

2: The bystarter is covered. The plug is not wet. Even after reinstalling the plug or another plug the problem still occurs.

3: I have more plugs on the way and a uni filter.

The engine doesn't have to run long, a minute or more, for the restart problem to occur. I added a quarter of tank of gas to the remaining half tank I had left mixed at 30:1. It sounds so close to firing it is annoying. If I give it any throttle when trying the restart, it sounds like it does not want to fire.

[bakaracer]

so your running a bpr6hsa? check the gap and make sure it between .024-.028 . i like the .025 gap myself. what jet are you running?

[jsun3thousand]

Yes. I have two of them. I'm using the jet taz sent with the 44 bbk. This problem started after I installed the kit.

[bakaracer]

what jet number is on the jet?

[gfisher99]

I just installed the 44mm BBK from Taz and I do not have the warm start issue. I am using the stock airbox (with new OEM filter) for now (UNI on the way) with 3 holes in the lid that were made using a grinder wheel from a dremel. They are roughly 3/4" in size. Still running quite rich as I am getting a lot of smoke and pokey throttle off the line. Temps running about 260-280.

[catsailor]

i have bbk installed and get a minor warm start issue that is usually solved with a couple of turns of the throtle. I found that once i turned my idle up a bit, the problem lessened.

[jsun3thousand]

The jet # is 90. It started up today and I shut it down 30 seconds later and it wouldn't restart. I'm going to have the battery tested today.

[gfisher99]

If your battery is good enough to start it cold, it should be ok warm. There is a thread on here that tells you how to test your own battery using just a simple volt meter.

I just went out and tested mine to make sure. Started it up, let it idle for 2 minutes (its raining here or I would have taken it for a spin), then shut it down. It started right up without throttle. As the previous poster said, you may want to increase your idle speed. It should be set to where its just under the RPM to start turning the rear wheel when its on the stand.

You said you have a UNI filter on the way.. How is your airbox set up now? Holes in the lid? Pure stock?

[jsun3thousand]

I did the idle thing. The air box is running without the lid right now. Once the environment of the engine changes after it is warm makes it difficult to start. I think it is too rich to start. I have been all over the internet trying to figure this out. It is a mystery to everyone that can't start a warm engine because it goes against most people's understandings of how an engine works.

[Wheelman-111]

Greetings:

Just a wild hunch - check your reeds?

[gfisher99]

Wouldn't runnng no cover on the airbox suggest it would run very lean? You said the plug isnt wet when you take it out. If you were running too rich, I believe your plug would be wet. Someone may correct me, but I think thats how it goes...

[JohnRobHolmes]

I'm an idiot, CDI doesn't have a condenser generally. I've been working on points systems lately and need to get my head into the future.

[Bear45-70]

Wouldn't runnng no cover on the airbox suggest it would run very lean? You said the plug isnt wet when you take it out. If you were running too rich, I believe your plug would be wet. Someone may correct me, but I think thats how it goes...

I too would suspect this as the issue. Install the cover and see if it start when warm.