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2005 CRF450 needs valves?

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Hey guys,

In the next few weeks, I will be working on my riding buddies 2005 CRF450 that does not start. The last time it was able to run, he wound up draining the battery, and then tried to kick start it for about 10 minutes unsuccessfully. I ride a 2001 WR426 so I am pretty good at kick-starting a bike, and eventually got the CRF to start after about 5 more minutes. Once the bike was started, it ran and started OK for the rest of the day. Now the bike does not start at all. This was roughly 18 months ago, luckily he has his 2001 CR250 to ride ever since. Time to work on the bike has been at a minimum for him, and has not been a priority.

If I remember correctly, there were some years that the valves were somewhat problematic and a lot of guys went to the Kibble-White (sp?) valves. In the next few weeks I will be tearing the bike down a bit to see what the problem really is. For those of you with experience with this bike what would you check, and what was typically problematic with this model year.

He suspects that the chain tensioner went bad and the timing skipped a tooth.

Assuming that the bike needs new valves, cam chain and other goodies, are there any aftermarket brands that are a significant improvement over OEM? I did my WR last year with new cam chain, valve seals etc, and I am assuming the process on the CRF is roughly the same.

I appreciate any and all help you guys might have, and I am sure my friend will too if I can get the CRF running again. Thanks.

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more than likely the non starting is caused by the intake valves being worn and zeroed out. Check clearances and do a leak down test.

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First off the R doesnt have an Estart. Kick start only.

So what bike is this???

Second, have you done any routine checks on the bike? leak down test? check the spark and plug? cleaned the carb?

No one on this board can do the checks for you. So its up to you to find out WHY it wont start.

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Must be an X, cuz the R doesnt have an Estart.

JJ is right. Youve gotta do the checks and tell us what you find. Could be a simple carb clean, could need intake valves. Sounds like it needs a battery either way though.

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Haha, I guess it must be an X. Sorry about that, not my bike :bonk:.

As far as doing the standard checks like plugs, clean carb etc., I will do that as well but I highly doubt it is the problem. The non-starting was an issue that got worse during the last season it was ridden. It was put away after running all day, never to start again the following spring. I assume it will be something mechanical, or out of clearance that finally got worn enough to cause the problem. I don't know this bike, and the idiosyncrasies of Honda's in particular so that is why I asked. I will be doing the work in a few weeks and just want to make sure I am prepared and have my homework done.

Any actual answers to the questions I asked regarding the pecularities of the CRF450 and things to look out for, besides the standard things like clearances, plugs, cam chain stretch etc.

Thanks for the help so far, maybe I'll go post this in the correct forum. :smirk:

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again, it is the same no matter what brand of bike 2stroke or 4 stroke:

ignition

compression

fuel

"it got progressively worst"

well since this friend doesnt wrench on his bikes start at ground zero. Check the spark, measure valves, clean the carb. clean the filter, inspect the oil. The only thing unique to the honda is the twin drains on the motor - 1 for the crank, the other for the tranny. Other than that, same as the green, blue or yellow bikes. they even use the same FCR carbs.

Dont want to sound short, but you are asking questions no one can answer but you when you get into the bike. Sure you can throw new valves in the motor, new piston crank and clutch. But is that the problem? dont know. Tear into it and you will figure out what needs to be done.

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If you're looking for a place to start, Id start with the intake valve lash. Check that. Its probably zero. Needs to be .006".

If you can bump start the bike its the intake valves for sure. I can explain why...but it really doesnt matter.

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If you're looking for a place to start, Id start with the intake valve lash. Check that. Its probably zero. Needs to be .006".

If you can bump start the bike its the intake valves for sure. I can explain why...but it really doesnt matter.

Thanks for the reply. That is the kind of info I am looking for. I'd like to have a laundry-list going for anything non-standard, or specific to the 450. I don't even have the manual to look through right now, and won't until I have the bike.

I'm not asking for folks to diagnose for me, but to inform me of anything unique to the 450 that may be a common failure point that could reduce the amount of guessing game time. Were OEM cam chains crap, did they have a bad run of tensioners in 2005, the auto-decomp was a known problem etc. I know that Hondas had some valve problems in the past, and I guess was hoping for "that's exactly what mine did. I bet its the valves. I'd definitely recommend checking A, B and C, and if bad replace with brand X valves."

I'm a typical weekend, DIY mechanic without extensive training and without extensive knowledge of what exactly to check within the engine (besides fuel flow, air flow, spark, compression and proper jetting) unless it is laid out within the repair manual. I just like to have all my t's crossed and i's dotted before I tear into a project, especially when it is not my own equipment and/or something that is unfamiliar to me being a Yamaha rider at the present.

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Just start with the valve lash. Actually just start with trying to bump start the bike.

Drop the bowl screw and clean the pilot jet since its been sitting. Undoubtedly its clogged at this point.

At that point start pushing!! Second gear, dump the clutch....it'll probably run. And run well too.

The cam chains are fine. The later cam chain adjusters were ok. Shouldn't be an issue. If it ran fine, then started to get crappy to start, its the intake valves leaking. The reason it'll bump start like that is your spinning the engine fast enough to disengage the decompressor and the engine will have enough compression then to fire up. With the intakes leaking and the decompressor, too much leaks out for it to start with the kicker or the Estart.

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I would bet the carb is plugged up, bike is neglected maintenance, airfilter is dirty and you need to check the valves to make sure they are in spec.

Gosh, have you even turned a wrench yet?

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I would bet the carb is plugged up, bike is neglected maintenance, airfilter is dirty and you need to check the valves to make sure they are in spec.

Gosh, have you even turned a wrench yet?

Did you even read my first post, or any other posts?

In my first post from Tuesday 1/3/12:

In the next few weeks, I will be working on my riding buddies 2005 CRF450 that does not start...luckily he has his 2001 CR250 to ride ever since. Time to work on the bike has been at a minimum for him, and has not been a priority.

Next post from 1/4/12:

I will be doing the work in a few weeks and just want to make sure I am prepared and have my homework done.

Post from 1/5/12:

I don't even have the manual to look through right now, and won't until I have the bike.

His bikes are not neglected maintenance either. Considering he still has a 2001 CR250, and the 2005 CRF450 he knows how to wrench, and keep things in top condition. His bikes are meticulously maintained and you could probably eat off the rear tire. The whole issue was that during the summer where the starting got to be tougher, he had another kid, work had been kicking his butt, home projects etc, and just hasn't had the time to make working on his bike a priority. Life has gotten in the way for quite a while. He would like to have both bikes running, so he can choose which to ride based on the trail, or have a backup for whatever reasons. If he didn't have the 2s to ride he would already have had the bike fixed. He doesn't trust the shop around his house, and knows how well I take care of my WR and thought I could check things out for him.

Asking for advice on what are common failure points for a specific model year should not have to turn into a flame war. JJ, if you don't take the time to read what I have posted, and then form a constructive response, just don't bother responding at all.

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damn bro, i dont think you are gonna get much help from the guys here on the "r" forum. there is an extensive base of knowledge for these bikes on this forum with shawn and jj and a few others but questions and answers can be taken differently when typed out versus spoken face to face. jjrace was just giving you solid advice on where to start, not giving you any attitude or starting a flame war. my two cents says to get a manual and follow the advice jj and shawn have given. they have never steered me wrong. happy new year!

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All the advice given, although rudely, is totally valid.

'Neglected maintence' refers to leaving gas in the carb, not adjusting valves, not replacing timing chains and tensioners.

All CRF motors come with Titanium coated intake valves that come UN-LAPPED from the factory. They have a short life span, and when time to replace them you have several options. Kibblewhite is one of them.

The suggestions were made to keep you from getting ahead of yourself, because most bike that wont start don't need valve work, or have skipped a timing chain. They have a clogged pilot jet that needs to be replaced, or a left intake valve that is sinking into the head, and needs to be shimmed.

Good luck.

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pooley i like your post i also have a 450 honda that used to run awsome then one day it needed a bump start, once warm i could kick it once and be gone. i know dam well its the intake valves.i just ride my other bikes lol but now its winteri need to get em all in shape. the crf450,s are famos for needing intake valves THE END

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Like they all ready said. First check valves , .006 intake , .011 xe. then see if it will start. If not carb , and so on. You just have to start soom place.

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If motorcycle has been sitting for 18 months as indicated: 1 Drain all fuel from tank and carb and replace with 93+ octane pump gas. 2 Remove and clean carb. 3 Make sure pilot circuit is completely clean!!!!!!(If any doubt replace pilot with new)4 Attempt to start ( choke on, 3-4 pulls on throttle(accel pump), zero throttle, press magic button. If it won't hit after that more than likely you need a top end check and service(at least intake valves). If it will start but not run properly try a richer pilot jet before you go to extremes.

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