Hard to start when motor warm; BUT only if parked for just the right amount of time.

ett · Oct 27, 2023

I am rather certain this topic has been discussed a fair amount on here.
But my searching has not been able to find relevant threads.

I've encountered a few instances of my NT being very hard to start, with a warm motor; IF the ambient temp and time parked is just right.
Hence I've only encountered it on hot summer days, when filling up at a gas station, AND I happen to take a short break to eat/drink some refreshments.
I never had a problem when only filling up with gas. It only occurs if I take the few extra minutes to eat and drink something.
And does not happen consistently.

During the 6k miles I rode this Summer. And with the dozen or so fill-ups; which also included taking a break to eat and drink; I did during that 6k miles. I think it only happened 3 or maybe 4 times.
And on those few times it did happen. I spent a worrisome half minute or so cranking the motor to start, and the "Check Engine" light will stay on.
To turn off the "Check Engine" light, I simply turn off the motor and restart it without issue.

I seem to recall reading threads about this happening to others.
But I am 50/50 on remembering if this hard-to-start-on-warm-motor situation was just the nature of the NT's design or if it meant some sensor is giving warnings of future failure.

Any links to possibly related threads, would be GREATLY appreciated.

Thanks;
--ET

Woodaddict · Oct 27, 2023

it has happened on both my NT's. 2 things, has the recall spark plug caps been done, and / or the little black box inside right side case - goes bad or malfunctions sometimes mostly when hot. neither of these things i have replaced on either my 2 nt's. can't remember what that thing is called................but it senses the crank postition

rc_heli_nut · Oct 27, 2023

Crank position sensor, there's plenty of threads on this issue in the archives. Honda PN is
30300-MEW-921

When you search the item on Partzilla, it will be labeled a pulse generator, underneath the RH engine case side cover. The "crank position sensor" term derives from the automotive world.

ARKNT · Oct 27, 2023

Agree possible crank position sensor. When you stop, the cooling system also stops and the engine heat builds up. The thoughts are that this excess heat makes the coil faults show up. It may or may not show a code.
The intermittent things can be tricky to troubleshoot.

Arknt

cliffh · Oct 27, 2023

Yep, almost certainly the crank position sensor. I just replaced mine last month. Exact same symptoms. Search this sensor and you will find lots of hints on replacing it. In my opinion....a piece of cake if you can get the muffler off.

Cliff

DirtFlier · Oct 28, 2023

To verify you can read the stored codes in the bike's computer.

mikesim · Oct 28, 2023

I have always been hesitant to give a seat of the pants diagnosis, but this problem has occurred numerous times to many on the forum and as far as I know, the cause and the cure has been the crankshaft position sensor or pulse generator as Honda calls it.

Mike

rc_heli_nut · Oct 28, 2023

Just to help out the person who started this post, "ett", those of you that have replaced the crank position sensor, did it always fix the problem? Inquiring minds want to know.

I don't own my NT anymore, and mine never exhibited this problem.

cliffh · Oct 29, 2023

It solved my problem.

I tried to post the link, but I'm having trouble. If you search "computer codes" though, you will find how to read the codes stored in the computer. If the code you get is for the crank position sensor....then yes, it needs replaced. The problem will only get worse. All it will take to read the code is a short piece of wire and a few minutes of your time. Just search "How to read and reset MIL".

Cliff

mikesim · Oct 29, 2023

It fixed my problem as well..... (driveability, smartasses!

).... I lived with the issue for quite some time as it was very infrequent. Once I isolated the problem, I carried a spare sensor with me just in case it failed on one of my long safaris. In spite of the number of folks on the forum who have dealt with the dodgey sensor, I can't recall anyone who had the sensor fail and leave them dead in the water. My bike always fired up and ran great after a cool down, YMMV.

Mike

ett · Oct 29, 2023

AWESOME replies ! Thanks everyone !

Charlie U · Oct 29, 2023

I just replaced mine. Took me longer to remove the plastic body panels than to change out the sensor. Tip: When removing the exhaust pipes where they slip on here’s what I did. I sprayed some penetrating oil on the joints and had someone hold the muffler while I used my Bosch Bulldog Hammer drill power chisel in chisel mode and off it came.

ett · Oct 30, 2023

Thanks again for all the helpful replies !

After work today; went to local Honda dealer and ordered a crank sensor. Will probably arrive in a day or two. And It actually cost about $10 less than mail-ordering it.
BUT no idea how long till I actually install it.
Since it really hasn't been problem for me, it been mentioned that no one has ever reported as being stranded by the sensor completely failing, and I bet the never-ever-before-removed exhaust will be a bit of a PITA to remove from my NT.
I would not be surprised if I try to install it this weekend and if the exhaust does not come off easily; that I probably throw new sensor on shelf until the original one in NT completely fails a couple years down the road.

ARKNT · Oct 30, 2023

ett you will also need sealant for the cover if you don't already have some on hand. It doesn't use a gasket, just sealant.

Arknt

mikesim · Oct 31, 2023

I think I mentioned this on another thread but the most commonly available sealant is Permatex Motoseal Gray available at most parts stores.

Mike

cliffh · Oct 31, 2023

I seem to have been the only person who had real difficulty removing the muffler. Maybe yours won't be difficult. It will come off, but .....
Once you do get the side cover off the motor, the replacement is a piece of cake.

Cliff

mikesim · Oct 31, 2023

Cliff, I've heard of others that had difficulty in removing the muffler. It seems that you have to hold your tongue just right

and use the right combination of expletives to get it off.

Mike

rc_heli_nut · Oct 31, 2023

mikesim said:
Cliff, I've heard of others that had difficulty in removing the muffler. It seems that you have to hold your tongue just right and use the right combination of expletives to get it off.

Mike

This is exactly why I always removed the RH saddlebag assembly for rear tire changes. I just knew what a PITA removing the muffler would be, i had no desire to dive into the big book of swear words

Obviously for the pulse generator it has to come off, may I suggest rotating and/or twisting the end of the muffler in a circle, whilst pulling it backwards? It should slowly walk off the front pipes. I always hated exhaust work as a tech, but this method worked for me to remove mufflers, resonators, etc., along with plenty of PB Blaster.

Are the 2 pinch clamps welded to the muffler? If not loosen them fully and slide them up the front pipes, the idea here is to take as much tension as possible off the clamped area of the muffler. Or take the clamp bolts out all the way and open the clamps up a bit, with some snap ring pliers.

Never had the muffler off my NT, just throwing some ideas out there. The ears you save may be belong to your kids

cliffh · Oct 31, 2023

rc_heli_nut said:
(snip)
Obviously for the pulse generator it has to come off, may I suggest rotating and/or twisting the end of the muffler in a circle, whilst pulling it backwards? It should slowly walk off the front pipes. I always hated exhaust work as a tech, but this method worked for me to remove mufflers, resonators, etc., along with plenty of PB Blaster.

Are the 2 pinch clamps welded to the muffler? If not loosen them fully and slide them up the front pipes, the idea here is to take as much tension as possible off the clamped area of the muffler. Or take the clamp bolts out all the way and open the clamps up a bit, with some snap ring pliers.

Never had the muffler off my NT, just throwing some ideas out there. The ears you save may be belong to your kids

You cannot twist the muffler to remove because BOTH header pipes go into the front of the muffler, that's the problem. The pinch clamps are not welded and can be loosened and slid up the header pipes out of the way easily. I used a combination of penetrating oil, heat from a torch, prying the slit part of the mufflers apart, and hammering carefully on the header end of the muffler using a large screw driver and a hammer.

If needed, the front header pipe can be removed easily from the front head to help. The rear header pipe would be a very difficult job I would think. I didn't try.

Fortunately, when I reinstalled the muffler, it slide right on easily almost all the way. Then I put a small piece of a 2x4 on the exhaust end of the muffler and tapped on it to slide the muffler the last 1/4". It went on very easy,.

Someone else mentioned an air hammer on the front end of the muffler. That might work well if you are careful to not damage the muffler.

Cliff

DirtFlier · Nov 1, 2023

"This is exactly why I always removed the RH saddlebag assembly for rear tire changes. I just knew what a PITA removing the muffler would be, i had no desire to dive into the big book of swear words

"....RC Heli Nut

Glad to find another NT rider who uses the same method as me to remove the rear wheel! The first time I did a rear tire swap, I did it by removing the muffler but it was still a lot of aggravation because of things I COULD NOT see, such as the caliper bracket and how it fits into the swingarm...plus I had to work on my back. With the RH saddlebag lid & body removed, everything is in front of you for easy access! At least for me, it's about 100% easy this way.