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over heating, lost some power, what's up?

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I have an 06 450X that I purchased new out of the crate about six months ago and now I noticed it is backfiring louder, has overheating problems and it has lost the 'edge' on its power. This is what has happened in sequence since I bought it:

1. As soon as I got the bike home after buying it I removed the radiator louvres (fins) and installed a radiator guard. I also installed a plastic Hyde racing skid plate.

2. The first breakin ride was at Ocotillo Wells, I rode the bike for an hour at slow speed 25MPH) with no problems until I was T boned by a rhino. Dislocated knee, bike was fine with the exception of a small dent on top of the radiator, the small fins were unaffected.

3. 3 months later my knee is repaired and I ride again in Dove Springs. We got to 6000 feet and run into a little snow which slows us down, my radiator immediately starts boiling and I smell coolant. I let it cool and go home.

4. I then added a wetting agent to the coolant to help with the cooling. Once again I experience the same overheating problems on other rides in soft sand trails or when riding slow with my 8 year old boy on hard pack. My buddy also mentions he can hear my bike backfiring, which I thought was normal. I also had to refill the overflow tank with Honda Coolant after two other rides, per the instructions in the Honda Owners Manual. The radiators themselves have always maintained fluids.

4. After reading that the 450X runs lean to meet CA emmissions, I took it to my bike shop to have it rejetted from a 45 to a 50. I chose not to modify the airbox or exhaust as it ran fine as stock with the exception of the overheating. After getting the bike back I noticed that the bike is now backfiring significantly louder and the power of the bike when I get a little speed up is sluggish nearly bogging. No more power all the way through the power ban and no more fun! I get on a single track with my son for a few minutes and the bike also boils again...aaagh!

5. I send the bike back to the shop and they called me today and said the radiator has good flow, the cap pressure is fine but the pressure in the radiators is building up too quickly. They suspect a leaking head gasket or cracked cylinder....what?!!!

It's a new bike, I'm 38 years old, I ride like a grandma and over maintain it! How could this be? Any thoughts would greatly be appreciated?

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You are still too lean on the main jet. You can re-jet yourself it is really easy get yourself a book and do it to it. I run a stock idle jet, a 165 main needle in the 3rd pos. with a #65 leak. If you have not changed the main you got a 145 in there. This is most likely why you are running so hot. If it is actually an afterfire (backfires come out of the carb and afterfires come out of the pipe) you are talking about that comes from a lean condition( and also maybe an exhuast leak), and since it became worse after having the shop enrichen your idle I would bet you have an intake leak. You need to re-check your carb. where it ataches to the cyclinder. There is a huge amount of info. in the stickies at the top of forum that covers jetting. Skoot seems to have a sweet set up with the needle he uses an NVCS I think search a little and you will find everything you need to know about your bike in this forum. You also may want to think about blocking your smog that will also cause poping on decel no matter how well you are jetted, and get your airbox cut up if you havent already.:thumbsup:

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Eddie Sisneros from the jetting forum just dynoed my '08 450x at 6,000 feet, and the 158 main I was using was 16 to1 A/F mixture still with a Hotcam and opened up airbbox. The 162 main hit the sweet spot at wide open throttle. My 45 pilot at 2 full turns out was correct. A sniffer is great!

KK is exactly right with the lean diagnosis making the heat.

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10-4 never thought about the head gasket that could be another prob. fo sho especially if you got the bike real hot.

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Mine used to overheat until I rejetted it. If it overheats or boils frequently, it just needs rejetting. Its too lean. When I got that through my thick skull and had it jetted propewrly, it totally solved the boiling and hasn't overheated since.

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I doubt you have a cracked cylinder but, depending on how hot you got the engine, you could have warped the head which would cause head gasket failure.

You say they rejetted from a 45 to a 50 so I'm assuming you're talking about the pilot jet. I don't know why they would install a 50 pilot and no other jetting. Never heard of anyone using a 50 pilot on these bikes. 45 is standard and usually doesn't need to be changed.

You need to cut the airbox, remove the screen, do a baffle-ectomy and rejet properly. These engines need to breath. All corked up and stock they run hot and crappy.

You can use the Skoot method or JD jetting. Your choice. Can't go wrong with either. Skoot should be along shortly to elaborate or you can do a search.

As far as backfiring is concerned, you need to remove the smog equipment or disable it. Backfiring will not go away till this is done. Skoot has a good method of disabling the smog equipment. Good luck.

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They gave you a 50 pilot!? And only a pilot jet!? I'm no expert but i would think the first step would be a bigger main jet... Put a 165/168 in there with a NCVS needle and see what happens. I've boiled my bike over a few times from idling and nothing happened.

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Well i suggest you never ask that honda shop for any jetting tips ever again. The pilot is the only jet that is close to being spot on. And at 6000' you need a 42 pilot. 50 is way way too rich. As stated the NCVS needle is the way to go, 3rd pos. Order through your honda shop part # NCVS 16233-MEN-671, its an option needle out of an 04 450r. You can put your stock needle back in, it might be a tad rich, but still ok and alot better than the 50. Fuel screw 2 turns out and a 165 main jet. You also need to block off your smog pump with JB weld, and open your airbox. At that elevation you need all the air you can get. I have pics of almost everything if you need. Let me know. Or search NCVS and you should find all the info you need. Good luck.

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Thats exactly what i was thinking skoot, he needs a 42 pilot not a 50! I cant believe they put a 50 in there for riding in cali

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Sounds like a head gasket or maybe an intake leak. If there is no coolant in the engine oil or oil in the coolant it is probably an air leak. Are you blowing coolant out the exhaust?

Thanks for all the great information guys. I just got back from Bishop (had to ride my wife's quad) so my apologies for the delay in responding. I'm going to call the shop tomorrow and tell them to open the air box and lose the baffle. I'll ask them a few questions about the jetting and report back what they say. I was trying to keep the baffle in to keep the bike from being obnoxious but it seems there is way more benefit to removing it.

In regards to the coolant, that's a negative, no coolant coming from the exhaust that I noticed and the coolant looked uncontaminated with oil. I did not check the oil before taking it into the shop. Does the fast build up of pressure in the radiator indicate a head gasket?

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Ya I would say it is pretty likely. How fast is it?

I just got off the phone with the shop and now they are saying the head gasket seems to be okay. They said the coolant looked contaminated because it was forming carbon dioxide bubbles possible as a result of an additive I added. After changing the coolant they say it was not heating up as fast. I did add a wetting agent in there but that was only recently in an effort to control the over heating. I had the overheating problems before putting the additive in so their contamination idea from my additive does not seem plausible.

They think the jetting is fine after they rode it....

To fix the backfiring, which got louder after they rejetted it last time, they blocked off the emmissions equipment..sounds like a band-aid to another problem personally.

So what gets me is that they are putting the overheating and loss of power down to bad coolant. Sounds odd.

My plan is to pick it up on Friday. I'm pulling their 50 jet out and will try rejetting myself (thanks skoot!). I'm also going to open the air box and either remove the exhaust baffle or put an aftermarket exhaust on.

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Well i suggest you never ask that honda shop for any jetting tips ever again. The pilot is the only jet that is close to being spot on. And at 6000' you need a 42 pilot. 50 is way way too rich. As stated the NCVS needle is the way to go, 3rd pos. Order through your honda shop part # NCVS 16233-MEN-671, its an option needle out of an 04 450r. You can put your stock needle back in, it might be a tad rich, but still ok and alot better than the 50. Fuel screw 2 turns out and a 165 main jet. You also need to block off your smog pump with JB weld, and open your airbox. At that elevation you need all the air you can get. I have pics of almost everything if you need. Let me know. Or search NCVS and you should find all the info you need. Good luck.

Skoot, what pipe do you have and do you have a picture of your modified air box so I know how to open it up? Thanks

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Stock pipe with baffle removed,

Airbox

Top

450X001.jpg

450X002.jpg

Right side

DSCF0223.jpg

Looking through the left side at the right side

DSCF0224.jpg

I used this knife

DSCF0227.jpg

Heated the knife up with a lighter and the airbox with a hair dryer. This makes cutting alot easier.

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Thanks for the pictures skoot they are great. I was surprised at how much you opened the air box up. Your bike looks well looked after. It looks like you have a little CRF70 there as well. My boy rides the same bike. Have you modified the 70 at all?

I spoke with the shop again today and they said they used a sniffer/leak test and the gasket is definently tight. They took my coolant out and replaced it with water and water wetter. They said the pressures have gone back to normal and it is not over heating now. They still believe my coolant was bad and the reason for the overheating.

With regard to the jetting they say their jetting (50 pilot to replace the stock 45) is best for my bike with the air box and pipe unmodified. They say if I uncorked it they would change the main jett and use a different recipe. I asked about uncorking the bike and they suggest riding it first to see if I can repeat the heating problem under the same conditions as before.

With regards to the loss in power they said it's altitude and me not knowing how to adjust the fuel screw properly. They are going to give me a lesson on it tomorrow.

I will test it like it is but ultimately I intend to uncork it and put in the right jetting.

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I still dont think they know crap about jetting an X. A 50 pilot is too rich even for a 20* day at sea level. A 48 is the max i would go and i think that is a little too rich.

At 6000' which is not very high, your bike should not be losing any power what so ever, and a 50 pilot is way too rich for that altitude, even with a stock airbox and exhaust. The stock exhaust actually flows pretty good. I ride from 3000' to 7000' all the time with out making a fuel screw adjustment. Alot of people do. I have been to 9500' without any loss in power or a fuel screw adjustment. The fuel screw is for off idle and determining a pilot jet size. The main jet must be changed no matter what. A 165 is probably about perfect.

Open the airbox, Get the NCVS needle put it in the 3rd position. Ask them to trade that 50 for a 42 pilot. Keep your 45 just in case. Fuel screw at 2 turns out, 165 main jet, and never worry about it again.

The lil bike is actually an 03 CRF50. It is gone now. I got it for like $500 and basically just turned it. Kinda wish i would have kept it now. Im gonna have to buy another one here in about a year.

Oh yeah here is how to determine the correct pilot. There lessons are not needed. :thumbsup:

With the bike warm and idling turn the fuel screw in till the idle drops/misses. Then go back out till the idle peaks/smooths.

This should happen between 1 and 2.5 turns.

If you end up at less than 1 turn you need a smaller pilot jet. More than 2.5 you need a bigger pilot jet.

Choose the appropriate size and retest.

I guarantee with the a 48 or 50 pilot in you are going to find no adjustment in your fuel screw.

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I still dont think they know crap about jetting an X. A 50 pilot is too rich even for a 20* day at sea level. A 48 is the max i would go and i think that is a little too rich.

I guarantee with the a 48 or 50 pilot in you are going to find no adjustment in your fuel screw.

Yep. I agree. I don't think they know what they're doing either. I run a 48 pilot, BUT, I have a highly modified engine (cam, porting, hi comp piston) my airbox is opened up and I have a full aftermarket exhaust. After all that, my pilot circuit needed richened up and I'm still only at 48.

Find a new shop or better yet, do all the work yourself. With the help of this forum and others like it, you'll be able to make your bike perform better than any shop can, and you'll save yourself a bunch of money in shop fees.

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