[hightower666]

Hi all,

Bought a '16 450X about a month ago, rode it 100 miles home without an issue, and then a week later went out greenlaning for the day without issues - ran a dream. Next outing a couple weeks later, fired up, I got 3 miles up the rode and it dropped power for second, then came back, another half a mile up the road it dropped power - I dipped the clutch and it just died. Sat at the side of the road, I just couldn't get it started again for 10 minutes. Tried again and got it going enough to get back home, as soon as I did, it died.

Thought carb must be clogged so took it out to clean, but it looked pretty good inside. While it was out I installed a thumb turn mixture screw as the other is a bugger to get to. Put them back in, nothing. Turns over, but shows no signs of going.

Checked the fuel, it's getting to the carb. Changed the spark plug, old one looked like it had been running rich. Checked spark, it's definitely firing. Put new one in, and nothing...

I'm about to start and look at the valves, but thought I'd post to see if anyone can suggest something silly I'm missing - can't believe it ran fine for a couple outings and then NOTHING! The hot start cable didn't seem the smoothest operation - could it be jammed causing low compression? I was going to order a new cable.

Any thoughts?

[hightower666]

Took the hotstart cable off, stuck solid - cant move it with pliers even. Got a plunger type of replacement coming Monday, hopefully this is the issue - does it sound like it could be?

[JimDirt]

Welcome to the site !!

Yes it very well could be , though I would also make absolutely sure the pilot jet is clear , as the hole is so small that even the slightest of debris will cause issues ...

You can either clean and reuse the current cable setup , by taking steel wool and cleaning and polishing the plunger , and cleaning out the hole with carb cleaner on a Q-Tip (spray the Q-Tip and swab it around in the hole till it comes out clean * may take several Q-Tips*) , or replace it with a pull knob (a choke knob will work also) , I prefer the lever on the bars , as when you stall the bike when its hot , or especially if you tip over , that lever sure makes it easier to start without missing a beat , just pull the lever and go , instead of fumbling around trying to find the plunger down by the frame , especially on a hot engine , when you are sitting on a side hill or something ...

Now would be a good time to remove the fuel screw and make sure the O-Ring is still intact , maybe even apply a slight bit of grease to it to keep it from sticking and drying out , before reinserting it and setting it ... the order should be spring ,washer ,O-Ring at the tip .... while you have things apart , it would not hurt to remove the valve cover and go ahead and check the valves , since you are most of the way there anyway , , that way you know what you have ....

Also if the bike came from a different elevation , it could also need to be re-jetted for your elevation ..

Jetting specs should be

Jetting Guide for Main Jet:(pilot 45) CRF450R/X

Fuel Screw start at 1-1/8 out

Sea level....165
2000 ft.......162
4000 ft.......160
6000 ft.......158
8000 ft.......155


Temperature/Elevation:
One main jet size (up/down) for every 2,000 feet or 25 degrees in temp .

[hightower666]

Thanks for such an insightful post! I’ve had the carb in bits (twice) and the jets are all immaculate. I’ll check the valves, but they wouldn’t just fall out of spec overnight surely, when the bike was operating fine.

The fuel screw is brand new (got the thumb turn mod as couldnt adjust the standard screw with the carb insitu), so the O-ring is good.

The hot start cable is snapped now - I smashed it pulling on it with pliers to see if I could move it. It didn’t budge a mm, so I’m really hoping this is the source of my woes. I’ve got a plunger type coming Monday so I’ll let you know - i wanted the lever off the bars anyways as I want a stubby clutch lever and was struggling to find them with hot start levers.

[JimDirt]

Yea , just figured since you just got it recently , and did not know the background on it , those would be the main interest in issues causing your symptoms , sometimes when someone sells a bike (not implying this was the case in your situation) , they will have the valves zeroing out , so they shim them just before the sale , that way when the new guy that has no idea about the bike comes along , it starts up great and then after a few rides , everything goes south ..... it happens a lot more than you think ...

And yea , I understand about the levers , as that is what I prefer , is short ones , at least on my 20 R , though my X still has the original levers (unbent) from when I got it new .... and for trail riding where you work the clutch a lot more , I prefer the longer lever , just to keep your hand/fingers from getting fatigued from tight single track or technical sections where you are constantly on the clutch , it allows you to be a bit smoother on the clutch with the longer lever , but slid in so the tip is closer to the middle of the grip .... But yea , not much for aftermarket allowing the use of the Hot Start lever

So yea , good on going over the carb and everything ... that at least eliminates those items from the checklist .... so yea , hopefully the Hot Start plunger was the issue and you will be good to go after this .... keep updating if you find other issues , or if that does solve the issue , and as long as you are jetted as the chart I posted shows , or close to it , you should be good on that ....

[hightower666]

It's got a 145 which I think is stock on this year.

[hightower666]

UPDATE!

Plunger hot start came yesterday and I couldn’t get it started still. But I think the fuel screw was about 1 1/2 turns when the manual says 1/8 - so guessing I’d flooded it. Just tried again with a freshly charged battery and and engine that isn’t flooded, (and a fuel screw at 1 1/8) and it fired with choke and no throttle, as should be expected.

I gave it a couple minutes and it was ticking over nicely about 2000 rpm with the choke still. Had a ride up the road, literally 200 yards, got to the junction, dipped the clutch and it died. Couldnt get it going, so pushed it home. Got home, fired it up, sat ticking over no problem again. I leant the bike over slightly to turn it around and go out again and it stalled. Float bowl in carb set right though, and there’s plenty fuel in there when i turned off the tank and drained the bowl.

Is this starting to sound like valves? I’ve flattened the battery again trying this morning, so that’s back in charge, but I’ve ordered some feeler gauges in preparation for checking the valves.

[JimDirt]

It could be valves , but the leaning over sounds more like a fuel issue .... Have you checked the vent line to the gas cap . make sure it is clear ??? , it could be that the line is blocked and when the air gets blocked out of the tank and it can't vent it will stop the fuel flow ....

It could also be a electrical issue , with the CDI/ECM getting hot and breaking down ... coil could do the same as could the stator ....

Basically you need fuel/air , compression and spark to run , the issue is in one of those things .... so you need to eliminate each as the culprit ....

Fuel/Air : Tank venting air and Flowing fuel ,Fuel valve or Float Level/Needle-Seat , Internal blockage , Carb Vent Line clogged

Compression: Rings , Valves , Head Gasket (when you check the valves this will tell you , if they are below 0.004 on Intake that is the issue , if they are , the Intakes are toast , the Exhaust usually will outlast the Intakes by a longshot but they should not be below 0.008... , I would highly recommend Stainless Intakes , I have had Stainless in my 06 X since 06 and have not had to adjust the valves yet) ...

Spark: Plug ,Coil ,CDI/ECU , Stator , Loose Connection

[hightower666]

Fuel cap vent line fine (although when I refitted the fuel tank last time it had a bunch of straw like gunk in the line - didn't make a difference removing it). Carb vent line seems fine too.

I couldn't get it started again when I tried last night, and the Haynes manual says after all the things I've checked, the valves are next on the list. I've got some feeler gauges coming Thursday, and if the valves are out I feel like I should kick off with the dealer I bought the bike from because surely they don't drop out of spec over night.

I wonder if they've known about it, and had the bike running rich to make up for a lower compression, hence why the old spark was black. Although I don't know if that's even possible to hide a valve issue, so could be way off the mark.

I'll update when the gauges come. I'm also going to get a lend of a compression tester off a friend. I love a good head scratcher, it's just annoying I can't ride my new toy!

[JimDirt]

Usually when a Dealer gets a trade in , they may adjust the valves , or take the prior owners word that it runs good , and just wash it , fire it up , and if it runs , then they just re-sell the bike , but if the valves are toast , you can literally adjust them , and within a couple hours they will be closed up again , that is the sign of needing valves ... basically when you need to start adjusting them period , then they are closing up and will eventually (it varies greatly) close up and you will run out of shim sizes ... once you get to needing a 1.20 shim , you are done and there is no adjustment left , so depending on what actual shim is in there , is going to tell you where you are at , but anything under 2.0 is bad news , so once the valves start to move and are in need of adjusting , it is only a matter of time before they are done , so you need to prepare for either replacing the valves and have someone cut the seats , or have a shop do it (someone that does these bikes not just a regular automotive shop , as they don't have the correct tools , nor know how far you can cut the seats before you ruin the head)

The way these valve systems are designed , the stem sticking out is what determines the shim needed under the bucket or at the rocker , once the valve face wears , it goes deeper into the seat and wears the seat in the head as well as the valve face , so what happens is the stem will now stick out farther , and there is less room for a shim , till you get to the 1.20 , then no more shims are available and your valve lash is at zero , which means the valve will slightly hang open and you will not be able to start it without compression , but the valve being worn prevents that ... plus the fact the valve face is now becoming so thin , that it can literally snap off and suck the valve , which then hits the piston and/or cylinder wall , then you have a whole new set of issues and things to replace ...

So yea , usually dealers just flip them and don't spend much time , if any , on maintenance , as that takes away from the profit margin ....

You can download a Owners Manual direct from Honda , as that would be much better than the Clymer one , the Clymer manuals are kind of generic and don't have the stuff that even the Owners Manual has , or better yet , if you plan on keeping the bike for a while , get a Factory Service Manual , they are about $60.00 (you can get one here) https://www.crfsonly.com/catalog/produc ... ts_id/3226 , as it will cover the entire electrical system , engine , suspension and anything else that can possibly go wrong with the bike ,,, but the Owners Manual will cover the valves , rebuilds , and suspension as well ...

Link to Honda Owners Manual PDF download : Just click on Year 2016, Segment/Off Road , Category / Trail , Model /450X , then download the manual and you have it on your PC and/or Phone all the time for reference
https://powersports.honda.com/downloads/owners-manuals

[hightower666]

Valves all within spec - 0.11 both on the exhausts (bang on), 0.005 on left intake and 0.006 on right. What next? I’m thinking it’s time to get the multimeter out

[JimDirt]

Yea , it is starting to sound like a stator or ICM/CDI issue , the coil could be breaking down when it gets warm , then works when it cools off , but stator and ICM/CDI can do the same , so yea , testing is in order , however you can't really "test" the ICM/CDI , basically what you can do is check voltage or resistance on the connections , then when it goes wonky , test again and see if the reading are the same or not present or different ... everything else can be tested ...

But yea , sometimes you have to eliminate the obvious items first , since they are checking out ... you are now looking at electrical .... sometimes these things are just a guessing game , since the symptoms , mimic other issues ... which is why you eliminate each item before going to the next .... electrical , is now "next"

[LoisWright]

Took the hotstart cable off, stuck solid - cant move it with pliers even. Got a plunger type of replacement coming Monday, hopefully this is the issue - does it sound like it could be?


Look into a starter solenoid. Not a bike guy but sounds similar to the issue with a boat motor.

[hightower666]

Can someone give me the idiots guide of how to undo these bloody electrical connectors?

[hightower666]

Hi all, I’m not one of those that goes missing without giving an update (I hate when you stumble on someone with the same symptoms then they disappear without saying what fixed it) - I just haven’t had an update to give until today.

I gave the bike to a local mechanic to look at, told him everything I tried, and how the symptoms developed etc. Turned out to be something really simple, but I think I’d just lost my patience with it so didn’t try (although sure I posted here that I think that was the issue).

Anyway, water in the electrical connectors. Mechanic pulled them, saw evidence of water, sprayed some water repellent stuff on and put it all back together. Dropped the bike off a couple hours ago, fired up straight away.

So if anyone has similar symptoms to me, check your connectors. I saw another forum post with similar symptoms and the same solution. I need to be careful washing it in future.

Thanks for everyone’s help - cant wait to give it a spin after I take it for an MOT.