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Need Some Help Troubleshooting

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I have a 05 CRF450R and I am having a hard time figuring out why I can't get it started.

A little background to help with the prognosis: I was in an accident back in Aug. 08 with virtually no damage to the bike; but it hit the ground pretty hard. I'm told it landed on the back tire and then bounced to both tires and came to rest on it's right side (kick starter side).

Now; I can't get it to kick start for the life of me. I've gotten it to start by compression starting it a few times and then after it has been running for a little while I can kick start it.

It also backfires frequently when I'm trying to kick start it. Something that it did not used to do. It sounds like it wants to start but just doesn't do it.

The large lapse in time is also attributed to a cross country move that had my bike in storage for quite some time. Although, the problems began before putting it in storage.

I'm not mechanically inclined in the slightest. I can mimic things that I've watched others do as far as maintenance goes. Please use simple terms :thumbsup:

Any and all help will be greatly appreciated.

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Thanks for the tips.. I'll start there. Do I need to remove the carburetor completely or should I just remove the airbox inlet and use some carb cleaner?

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You need to take the carb completly apart clean everything,take out all jets clean them blow out with compressed air and maybe even use a peice of thin wire to run through the jets just to make sure they are clean. If it is too much make friends with someone who know how to work on a bike other wise its going to cost you a small fortune to take it to a dealer and even then I suggest find a local engine/suspension shop to get any work done.

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Thanks.. my neighbor happens to be a helicopter mechanic so he has some mechanical ability. I'll start off by looking at and cleaning the carb. I'll also check the valve clearances as recommended.

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Ok, so I took the carb all apart and cleaned it. (It didn't appear all that dirty or gummed up). However the hose clamp that seals the connection between the airbox and the carb was very loose. Though there still seemed to be a strong connection between the airbox and the carb.

When I checked the valves the left intake valve appeared to be tight. I couldn't get a .003 feeler gauge in, let alone the .005 that my book says it should be.

So, there's obviously an issue there, but could that one intake valve be causing the issues I'm having?

I appreciate all the advice so far. Please keep it coming.

I'm off to read how hard it is to swap out the shims.

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Ok, so I took the carb all apart and cleaned it. (It didn't appear all that dirty or gummed up). However the hose clamp that seals the connection between the airbox and the carb was very loose. Though there still seemed to be a strong connection between the airbox and the carb.

When I checked the valves the left intake valve appeared to be tight. I couldn't get a .003 feeler gauge in, let alone the .005 that my book says it should be.

So, there's obviously an issue there, but could that one intake valve be causing the issues I'm having?

I appreciate all the advice so far. Please keep it coming.

I'm off to read how hard it is to swap out the shims.

yes, I would be willing to bet that your intakes have somehow tightened up on you. it sucks but shimming is fairly easy, especially if you can do grade 3 math.

thousandths of an inch are not the best for doing valves IMO. maybe its just because im canadian, but I prefer to do it in MM... more accurate :ride: but if it calls for a .005, and you can barely get a .003.. that means the gap should be twice as big a what it is now, which means youve got a tight intake :thumbsup:

the hardest part, which still isnt too bad, is making sure youve got the correct timing when putting it back together.

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Thanks for the input...

I'm quite certain that there are plenty of expensive special tools that can make this job easier, however, any chance I can do this without purchasing said tools?

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Thanks for the input...

I'm quite certain that there are plenty of expensive special tools that can make this job easier, however, any chance I can do this without purchasing said tools?

I also have an 05 crf450r, and for a shim job all you need is:

feeler gauges - 5$

digital caliper, which are worth their weight in gold - 20$

8, 10, and 12 mm socket - 10$

allen wrench set - 10$

service manual - 30-50$ , PM me and ill hook you up with a free .PDF one :thumbsup:

and thats about it.. im sure you have half those tools laying in the garage anyways.

Edited by Santan9
caliper not caliper"s"

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Thanks for that information. I do have all of those tools laying around. I have a Clymers manual for the bike that has answered many questions as I work on the bike.

If I can't get the feeler guage under the cam now, how will I determine what size shim to put in? Am I going to have to make an educated guess and then put it all back together and see how the clearance sits?

Thanks for all the valuable info. It's been a very educational week.

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Thanks for that information. I do have all of those tools laying around. I have a Clymers manual for the bike that has answered many questions as I work on the bike.

If I can't get the feeler guage under the cam now, how will I determine what size shim to put in? Am I going to have to make an educated guess and then put it all back together and see how the clearance sits?

Thanks for all the valuable info. It's been a very educational week.

if you cant get the feeler gauge under the cam then you need to use a smaller feeler gauge, until you get one that does fit. hopefully theyre not closed right up and there is at least a small gap in there.. the set I have has about 30 different sizes, ranging from .01mm to like 1mm, just like this: http://www.diseno-art.com/images_2/feeler_gauge.jpg

also, it really helps to bend the last inch or so of the gauge, it makes it WAYY easier to get under the cam.

but yeah, use a smaller feeler gauge until you find out which one will fit, but when you go one size bigger it wont fit.. thats where you stop measuring and start doing math.

the intakes should be 0.16+/-0.03mm., I generally like to have it in the middle of that range, plus a little looser because you know theyre going to tighten up in the future, so I like to set mine to 0.18mm if possible.

so lets say you measured a .10mm as one of your intakes.. it is too tight, approx .08mm too tight.

you then take that shim out, measure it, lets say its a 1.80. youre going to need a smaller shim, .08mm smaller to be exact. I know in the hot cam shim kit they go in increments of .05 so you would have to install a 1.75 shim. that would bring your clearance to .15, but im sure you already know this part :thumbsup:

sorry if the metric measurements confuse you... standard measurements confuse the hell outta me!!

but youre right though, sometimes (rarely) you just need to make an educated guess as to what shim to put in (might want to start by measuring your current shim, with the digital caliper, and using one thats .10mm smaller) then re torquing the cam assembly down to proper torque (page 251 in the clymer manual if I remember correctly :ride:), then re measuring clearances. taking it apart again , do the math, put proper shim in, put together and enjoy your bike that now starts first kick every time :lol:

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also, while youre in there, you should check your decompressor clearance for the hell of it. Im sure it will be fine but you never know, especially if you adjust your exhaust shims.

the procedure, specs are on page 79-81 in the clymer if I remember correctly (you can tell Ive done this a few times eh...)

also. in the clymer manual, it tells you to make your decompression arm clearance as .35mm. THAT IS WRONG!!! .35 is too big of a gap. cross those numbers out and write down .28mm instead. trust me on this one, clymer is wrong and im right!!!! you can set it as .35 if you want, and roll the engine over via kickstart by your hand while the cylinder head cover is off, but the cam is torqued down, and see if the little lobe is activating the decompression arm enough to open the exhaust valve a little bit.

I set it as .35mm and it caused me LOTS of headache, then set it to .28 as many on TT recommended and it started first kick!

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wow that was a lot of information. I appreciate all the advice. I will be reading through my Clymer's manual tonight and I will probably start working on it tomorrow after work. I'm not really sure what decompression arm clearance is, but I will learn and check it accordingly.

Thanks again for everything... stay tuned for when I need further advice. It's only a matter of time.

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wow that was a lot of information. I appreciate all the advice. I will be reading through my Clymer's manual tonight and I will probably start working on it tomorrow after work. I'm not really sure what decompression arm clearance is, but I will learn and check it accordingly.

Thanks again for everything... stay tuned for when I need further advice. It's only a matter of time.

decompression arm is on page 79-81 I believe if your manual is anywhere near the same as mine. if not just go to the index in the back and look up "decompressor"

good luck, feel free to ask for any questions, I check back here every few hours (I need a job!!) so im always around to help.

I should also mention that the decompressor arm is the last thing you want to adjust, after youve done the exhaust shims, because the decompressor clearance will change as you change the exhaust shims.

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Santan9 - you wrote to check my decompressor clearance and that it would probably be fine, but then you said to change what the book says to .28mm, so I'm assuming it's not going to be .28mm and I should adjust it to be .28mm?

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Santan9 - you wrote to check my decompressor clearance and that it would probably be fine, but then you said to change what the book says to .28mm, so I'm assuming it's not going to be .28mm and I should adjust it to be .28mm?

first thing to check is the intake valve clearances.

well if you have no problems with it/with starting the bike when hot, then I would leave the decompressor alone. but it would be nice to remember/have written down in the future just in case.

I had set mine to .35, like the clymer manual said.. and my bike wouldnt start when hot, it would start first kick when cold, but not when hot. it would jumpstart just fine when ho though. and sometimes the kickstart would lock up and throw my leg off it. I think what was happening is that .35mm gap was too big, so it wasnt actually decompressing.

I then posted on TT and several people told me that their actual OEM manual (not the POS clymer) says to set it as .28mm, not .35mm

so I set mine as .28mm and voila! starts first kick every time, hot or cold. im glad it was such a simple fix.

I think it might have something to do with what size of a exhaust shim you are using though, im not 100% sure.

it also says in my manual that having the wrong decompression clearance could damage the valves etc.. I didnt want that happening.

maybe youre having the same problem as me? it wont start because its not decompressioning the engine properly? the intakes we fine, and it still wouldnt start, it was very frustrating... turns out it was the decompressor gap that was too big.

if the cylinder head cover is off, give the engine a few revolutions slowly with the kickstart with your hand, and keep an eye on the decompression pin on the cam. watch when it activates the decompression arm, and look to see if its actually opening the right exhaust valve a little bit, or if its not. your decompression gap could be a little too big and not decompression, thats why your bike might be hard to start. just something to consider.

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and someone correct me if im wrong, because I could be. but for the decompressor arm clearance, you cant really have the gap too tight, but you can have it too loose? is there a downside to having the decompressor gap set as, lets say .20mm?? its just going to open the exhaust valve that much more..no? I dont see any problems in that but ya never know.

but you definitely dont the decompressor gap to be too big, otherwise it wont even open the exhaust valve, and thats where problems begin. right guys?

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Thanks for the clarification. I'll check it soon and keep you posted. The problem you were having sounds similar, only my bike isn't starting cold (but jump starts) and starts when it's hot. The only valve I've noticed out of tolerance is the left intake.

thanks again.

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Thanks for the clarification. I'll check it soon and keep you posted. The problem you were having sounds similar, only my bike isn't starting cold (but jump starts) and starts when it's hot. The only valve I've noticed out of tolerance is the left intake.

thanks again.

how much out of tolerance is it.. that could be the problem depending on how much its tightened up.

have you put in a new spark plug just for the hell of it?

what you described might also be piston rings, the reason it starts when hot is because stuff starts to expand, creating a better seal than when it was cold. when its cold, the metal is small and doesnt create that good of a seal. that was the problem with our last 2 stroke, old school quad. turns out the piston ring was worn out from running too lean. it hard a hard time starting cold, but when everything got hot and expanded it would start a lot easier. I could be wrong though, hopefully someone else chimes in. im learning a lot by helping you guys :banana:

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Ok, so it's a been a while and I've had a lot of distractions. I've been working when I can and I've come to another question. I was following the directions step by step in the Clymer's manual and I had to turn the camshaft to expose both of the screws holding the upper timing gear on. After it said to rest the gear on the chain guides if you're just adjusting the shims, it said you need to have the engine at TDC when you take off the camshaft holder assembly.

How am I supposed to make sure the engine is at TDC when I've already taken off the upper timing gear and I've removed the automatic timing chain adjuster?

Is it really not that imperative that the engine is at TDC when removing the camshaft holder assembly? I figure if I mark the holes on the holder and the upper timing chain gear, I should be able to put it back on exactly as it was before.

Any help is appreciated as usual!

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