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Crf450r decompression problems

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I just bought a 03 crf450r that just had the valves done, the bike is hard to start with heeps of compression, so i thake off the head cover an check the gaps valve they are pretty tight but there is a gap, i checked that the timing is spot on with stick frm a stick welder down the spark plug hole, timing is spot on, now i look a the decompresser gap and it is huge so i loosen the nut an tighten the gap to the spec the book tells me, i put the cover back on an try an start it, but it has no compression then an wont start. So i make the gap a bit bigger at a time trial an erro, but i find a happy medium an can start the bike, but its still hard to start. Shoul i clean the carb ?

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I just bought a 03 crf450r that just had the valves done, the bike is hard to start with heeps of compression,

so i thake off the head cover an check the valve gaps are within spec.

I checked that the timing is spot on with stick frm a stick welder down the spark plug hole, and the inspection hole on the left hand side (fly wheel) timing is spot on,

now i look a the decompresser gap and it is huge so i loosen the nut an tighten the gap to the spec the book tells me, i put the cover back on an try an start it, but it has no compression then an wont start. I take the cover off an make the gap bigger till it has some compression the i can start it but still hard to start.

Should i clean the carb?(been sitting)

Edited by Shauno450

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Yeah, your valves are either within spec or not, theres no "pretty tight but there is a gap"

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Your method of checking TDC is no good. You have to line up the arrow and dot in the inspection hole on right side of engine, then make sure the lines on cam gear are lined up. I had the same bike, same issue, timing was one tooth off seemed like it had too much compression... It never hurts to clean the carb you should do that aswell.

Edited by Mx Factory USA

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Must use timing mark for TDC

You can adjust the decomp on that year by just adjusting it for the least amount of compression you can stand, which shouldn't be enough to be restrictive

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I'm not sure if you're adjusting the decompression gap with a feeler guage, or just "winging it". The decompression gap needs to be correct. If to close, the decompression pin will bump (open) the exhaust valves too much, inturn releasing too much compression and a no start condition. Too wide a gap, and the decompression pin will not bump (open) the exhasut valves enough, inturn not releasing enough compression and making it difficult to kick it over. I'm not saying you have to use a feeler gauge, but if you're not well seasoned with the 450, you may try that first.

Also, take a look at the decompression mechanism on the side of the camshaft. Make sure the counterweight swings freely, and that the actual decompression pin is in place and not bent or damaged.

P.S. There's been a few times that I swore I had the cam/crank timing perfect, just later to have egg on my face. lol

Edited by WALKINGWOUNDED

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Oh i checked that inspection cap on the right side of the bike and it looked like it was off by a tooth, but i wasnt sure. Is it an easy job, is this all i have to do

Loosen cam chain tensioner

Take cam sprocket off

Move it a tooth

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Oh i checked that inspection cap on the right side of the bike and it looked like it was off by a tooth, but i wasnt sure. Is it an easy job, is this all i have to do

Loosen cam chain tensioner

Take cam sprocket off

Move it a tooth

What?? Don't mess with the cam timing!!

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Like I said line up the dot and arrow in the inspection hole. Then go to cam sprocket, the cam sprocket lines should be aligned with the arrows/line on the cam holder. If timing is a tooth off which it probably is, remove cam chain tensioner, remove sprocket bolts, pull sprocket off and turn it one tooth in the direction needed. Triple check timing marks always with tension on cam chain.

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Check timing using the ign. Side (shifter) check the sticky at the top of forum , it illustrates the correct procedure

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Like I said line up the dot and arrow in the inspection hole. Then go to cam sprocket, the cam sprocket lines should be aligned with the arrows/line on the cam holder. If timing is a tooth off which it probably is, remove cam chain tensioner, remove sprocket bolts, pull sprocket off and turn it one tooth in the direction needed. Triple check timing marks always with tension on cam chain.
This couldn't be any more wrong... you do NOT remove the cam sprocket, or gear, from the camshaft, EVER!! And don't remove any gear attachment bolts!!!

You simply need to undo the chain tension and skip the chain over the cam gear, so you're rotating the entire cam/gear assembly how ever many teeth you need to in order to get the cam timing correct with TDC.

Don't use the marks on the right side as your final info, it is rough at best. Pull that top little plug on the left hand side and look for the TDC marks on the flywheel, the 2nd one is true TDC, flywheel rotates counterclockwise when viewed from the left. They line up with a mark on the case casting where the plug sits. Yes, this is a VERY easy chore.

Edited by Eddie8v

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This couldn't be any more wrong... you do NOT remove the cam sprocket, or gear, from the camshaft, EVER!! And don't remove any gear attachment bolts!!!

You simply need to undo the chain tension and skip the chain over the cam gear, so you're rotating the entire cam/gear assembly how ever many teeth you need to in order to get the cam timing correct with TDC.

I couldnt be anymore wrong?? Thats a little exaggerated. I dont know what kind of condition your cam chains are in but if you have a chain within service limits you will never be able to get enough slack the move the camshaft with the gear still on. Motion pro makes a tool for removing the cam gear when doing timing but guess they are wrong too..

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To jump the chain on the cam sprocket a tooth or two in either direction all you need to do is loosen and remove the four (4) cam tower bolts, remove the tower with its two (2) bearing locating devices, lift the cam slightly, slide the left-side cam bearing waaay to the left (this gives you the chain slack you need) then raise the right side/drop the left side of the cam a bit and then you're able to move the chain a link or too over the sprocket with the slack you've gained. Do this while at TDC on the compression stroke, of course, and you have to release/remove the chain tensioner.

Loosening the cam sprocket bolts is only necessary to properly degree-in a camshaft if there are slotted cam gear attachment holes and even then you're not fully removing the gear from the cam. Most don't need to degree in the cam or have the knowledge, and specific tools, to do so. Newer-model cam gears are an interference press-fit onto the camshaft with no bolts whatsoever used for retention.

Are you telling me that every time you install or remove your camshaft you remove the cam gear from it? I can understand how you might not have known, but that is, 100%, not necessary.

Edited by Eddie8v

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That doesn't make it "right", bud, kind of like removing my front wheel so I can remove the rear. Can't teach a stubborn old dog new tricks, I guess. If I had an older bike like you, I wouldn't even consider loosening/removing cam bolts to re-time the cam, just takes too long and creates more room for mistake and eventual failure. Once you get a newer CRF you'll have to adopt my method as there are no bolts at all. There's more than 1 way to make a pie, I guess.

I'll stick with my method, worked fine since 2002...
Edited by Eddie8v

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That doesn't make it "right", bud, kind of like removing my front wheel so I can remove the rear. Can't teach a stubborn old dog new tricks, I guess. If I had an older bike like you, I wouldn't even consider loosening/removing cam bolts to re-time the cam, just takes too long and creates more room for mistake and eventual failure. Once you get a newer CRF you'll have to adopt my method as there are no bolts at all. There's more than 1 way to make a pie, I guess.

Lol I don't understand what your trying to tell me. I don't own a crf but have been a honda tech for many years and I own a shop. I've rebuilt thousands of crfs, my method never gave me a problem and I find it easier than your way. I don't care what your method is but if it works for you go for it. Take your pissing match somewhere else, your not gods mechanical gift to earth becauae you retimed a couple of your crfs. I'll stick with my method because its worked since hondas first 450s.

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I have time more than a few bikes, myself. Sorry for trying to teach you the proper way.

And after working on "thousands of CRFs" you obviously haven't worked on a single 2009-2013 CRF450R, or any year CRF250R, because they don't have any cam gear bolts and you need to remove the cam just to change an intake valve shim. As such, I think you're fibbing about working on thousands of CRFS because NOT working on a single CRF that doesn't have the cam gear bolts would be next to impossible because those aforementioned CRF are some of the most popular bikes around.

You're giving out bad info and I don't want a young kid popping off his pressed-on timing gear because you think removing the gear is required just to change some valve shims, for instance. Please don't take it personally, but taking a 20min job and turning it into an hour-long ordeal and involving threadlocker just seems silly to me.

Lol I don't understand what your trying to tell me. I don't own a crf but have been a honda tech for many years and I own a shop. I've rebuilt thousands of crfs, my method never gave me a problem and I find it easier than your way. I don't care what your method is but if it works for you go for it. Take your pissing match somewhere else, your not gods mechanical gift to earth becauae you retimed a couple of your crfs. I'll stick with my method because its worked since hondas first 450s.

Edited by Eddie8v

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To jump the chain on the cam sprocket a tooth or two in either direction all you need to do is loosen and remove the four (4) cam tower bolts, remove the tower with its two (2) bearing locating devices, lift the cam slightly, slide the left-side cam bearing waaay to the left (this gives you the chain slack you need) then raise the right side/drop the left side of the cam a bit and then you're able to move the chain a link or too over the sprocket with the slack you've gained. Do this while at TDC on the compression stroke, of course, and you have to release/remove the chain tensioner.

Loosening the cam sprocket bolts is only necessary to properly degree-in a camshaft if there are slotted cam gear attachment holes and even then you're not fully removing the gear from the cam. Most don't need to degree in the cam or have the knowledge, and specific tools, to do so. Newer-model cam gears are an interference press-fit onto the camshaft with no bolts whatsoever used for retention.

Are you telling me that every time you install or remove your camshaft you remove the cam gear from it? I can understand how you might not have known, but that is, 100%, not necessary.

Uh, let's see here. Your way requires the removal of 4 bolts that thread into the head, putting unnecessary wear on the fragile threaded aluminum holes in the head. You then have to pull the cam tower up, start to slide the camshaft out and angle everything just the right way to slip the gear on the chain.

...or you could leave all that junk in place, break out the hex-wrench, take out the two cam sprocket bolts, fix the timing, put two little drops of loctite on the cam bolts and reinstall them. Taking a quarter of the time with far less hassle.

No one competent enough to adjust their timing is going to be stupid enough to try and pry off the later pressed-on timing gears if they read instructions saying to "remove the cam sprocket bolts"

Edited by Lead Head

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Says the guy who's obviously never done it the proper way before... it takes less time to undo the 4 bolts and manipulate the cam around as you don't have to dork around with preventing anything from turning. And the tower bolt threads are coated in oil before assembly, unless you're forgetting to do that on the bikes you work on, so you're not gonna wear out any threads at the low torque spec' with oiled threads.

What will you do on a newer EFI 450 bike? You guys are killing me. How do you adjust the intake shims when you assemble a new engine? Pop the cam gear off until you get it right? Makes no sense to undo cam bolts to shim your valves or adjust the cam timing, just plain laziness.

Do you guys send the EFI CRF450R motors, and all CRF250R motors, out for someone else to work on when valvetrain work is needed? What do you do about the pressed-on cam gear?

Edited by Eddie8v

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