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New To Me......CRF450

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Posted by: PGHRam---------------------

Ok, I just switched to a CRF450 from a CR250. It's a bit tricky to start. Any tricks you guys have? I'm used to just kicking it till it starts. Cold start is easy on the 450.
Also, any tips on how to ride this thing? What's different? I had to feather the clutch on the 2 stroke sometimes on the hills.

I'm excited about the switch. My buddies......not so much.


Posted by: Chili---------------------

So the only trouble you have is starting it hot? If so are you using the hot start? I know when we switched I had a hard time starting my kids 250F at first, had to remember big full kicks and not that rapid fire rabbit kicks that will light up a 2 stroke.

You'll likely forget this thing has a clutch very quickly with as little as you'll need it. A very fast Vet rider here gave me some advice when I got my first 450 when he said just remember if it sounds like a tractor your making power, In other words no need to be banging it off the rev limiter.


Posted by: PGHRam---------------------

The kid I bought it from had no problem starting it at all. Started for him every time. He said on the hot start to hold the hot start in with the throttle wide open and kick it 6 times. Then let go, hold the hot start in, no gas and kick it. Worked for him, but not me. Maybe I just need to learn. Until then, when I stop, I'll be facing down hill

Does this sound right?


Posted by: jb_dallas---------------------

I dont own a CRF450, but I have never heard of opening up the throttle while kicking any bike...especially an MX 4 stroke. You had better hope it doesnt kick back. I have heard of guys spraining ankles or worse when a big bore kicks. I have a nice tear in my boots as proof. On my YZ400F, if I even prime the throttle more than twice, it is flooded. You are pouring fuel into the engine when you hold the throttle open and kick 6 times. The YZ400 has a reputation for being an engine that is hard to start, but I dont have issues starting it. I never hold the throttle open at all when I start the bike, hot or cold. When its hot, kick it without the hot start..if that doesnt work, pull the hot start and kick...dont hold the throttle...repeat.


Posted by: Matt90GT---------------------

first off, you should never use ANY throttle to start the bike. If you have to use throttle, you have a jetting issue.

The hot start is ONLY for when the motor is hot and floods. Ie you crash or stall

The choke is what is used when the bike is cold, just like any 2 stroke or other gas engine.

pull the choke, twist the throttle 2-3 times, take your hand off the throttle and in neutral kick the bike. full kicks all the way through. should light of in 2-3 kicks. If not, you need to clean the pilot jet out.

When the bike is warm, should just kick no throttle no hot start. If the motor is still HOT like just turned off, then use the hot start, no throttle.


Posted by: Chili---------------------

Quote:
Originally Posted by PGHRam
The kid I bought it from had no problem starting it at all. Started for him every time. He said on the hot start to hold the hot start in with the throttle wide open and kick it 6 times. Then let go, hold the hot start in, no gas and kick it. Worked for him, but not me. Maybe I just need to learn. Until then, when I stop, I'll be facing down hill

Does this sound right?


I would not expect to have to follow that procedure if you simply stop riding and then restart. That is the procedure most use when they crash the bike and flood it while it's very hot. Wide Open throttle with 5 slow kicks to clear the flooded fuel and then grab the hot start and it should light up.


Posted by: PGHRam---------------------

I had the bike out tonight to try this. It started on the first kick when cold. Had the choke out and kicked it in sandles. Went for a ride around the neihborhood and came back and shut the bike off. Couldn't get it started again no matter what I did. I tried the hot start with no throttle and I tried wide open throttle with 6 kicks.
Should I have it looked at?

Thanks


Posted by: 1989kx250---------------------

i have an 04 crf450r and mine did the same thing, i could get it to start after it was hot only if i kicked it FOREVER. probably enough time for it to cool. my mechanic told me that it was a valve train problem. i checked the valves and they were too tight. i cant remember if it was intake or exhaust... but one set of the four were too tight. my bike starts fine now all the time. hope this helps.


Posted by: PGHRam---------------------

Thanks.

Can anyone give me the specs on the valves? Or a link to start reading on how to adjust them? I know I can do this myself, but don't want to F it up.

Thanks again.


Posted by: IndyMX---------------------

.006 in on the intake valves with the piston at top dead center on the intake stroke.

Open the site hole on the clutch cover, line up the dot on the gear with the triangle on the outside of the hole, then open the site hole on the ignition cover, verify that the notch in the hole is lined up with the mark on the flywheel. Then make sure the mark on the cam gear is lined up with the mark on the cam holder. Then make sure that the intake lobes are facing to the rear of the bike. And measure.

If you can't get a .006 thru, you are too tight. So you know, you measure from the front of the cam, between the lobes of the cam and the buckets.

It's more likely that the intakes are tight, and the exhaust are fine. If they're not too bad you may get away with shimming them. However, once you shim, the next time they tighten up, prepare to spend some cash getting a valve job. Shim too many times and you will also be buying a new piston, head, and cylinder. And whatever else the dropped valve trashes.

When I had my valves in perfect spec, the bike was easy as could be to start, hot or cold.

Now that they have tightened up again, you have to pull it with a truck to get it started.

I'll not be riding it until I can put new valves in.

Also, save yourself a lot of headache, get a service manual. Worth ever penny.


Posted by: PGHRam---------------------

That doesn't sound too hard. I was thinking I had to take all the plastics off, drain the gas and coolant, and have hours of work ahead of me.
I'm going to call around today to see who has a manual for my bike. Hopefully I don't have to buy it off of ebay.

Thanks for all the help. I'm sure I will have a ton of other questions.

On a side note, Man.....I love the sound of a 4 stroke. Deep and mean and not that rin tin tin sound. Kinda like my 68 GTO


Posted by: jb_dallas---------------------

Buy a Clymer manual like Indy said and check your valve clearance. If you continue to kick that bike in sandals, you will regret it one day.


Posted by: IndyMX---------------------

You don't have to drain the gas, but you will have to remove the tank.

I'd also take off the shrouds for easier access..


Posted by: PGHRam---------------------

I don't kick it in sandles all the time. Just that once. My point is that it starts cold very easy, but will not start hot at all.

I may be able to do this tonight. Hope so.

Thanks


Posted by: PGHRam---------------------

Ok, I checked the valves. Both were .10
It started cold again with no problems. Then I tried to kick it hot. I had 1 sputter that sounded like it may start, but nothing. Then I caught it in gear. Had it running for maybe 2 minutes until a back fire. I can feel a puff of air on my leg when it back fires if that has anything to do with it? Then I couldn't catch it in gear.
That's where I quit for the night.

Any suggestions?

Thanks


Posted by: IndyMX---------------------

.10??

Seriously?


Posted by: PGHRam---------------------

Maybe I meant .010
Sorry


Posted by: IndyMX---------------------

Errr.. The spec is .0063 plus or minus .0012in

So they are a bit loose. You should get the appropriate shims to tighten them up a bit.

So, now you know the spec, the measured clearance, now you just need to know the current shim thickness and someone on here can give you the shim size you need to replace with.

So, if you don't have one already, you're going to need a quality micrometer to measure the shims.. Make sure you mix them up when you take them out, they could be different thicknesses.


Posted by: PGHRam---------------------

Do you think this is what's causing the bike not to start? I don't have a manual yet so I can't work on it. I'm thinking about dropping it off at the shop to have them check the valves.

What do you think I should do?

Thanks.


Posted by: IndyMX---------------------

If the valves aren't opening enough, yeah, that could be a problem.. Although I've never heard of loose valves causing a hard start, I suppose it's possible.


Posted by: PGHRam---------------------

Took it to the shop tonight. The guy was able to start it cold and hot with no problems. I was able to as well. Looks like I just need to learn how to start this thing.


Posted by: derek145---------------------

my neighbors just recently boughta crf450r and if u turn the gas on and choke and pump the throttle 3 times it starts first or second kick every single time


Posted by: youngnbald---------------------

I have the '03 CRF450R and can back the method derek145 stated. People say not to touch the throttle on a four stroke, but when the engine is cold 3-5 twist of the throttle gets the engine started within 3 kicks. Once warm, I never struggle to restart it. If jetted correctly this should be true.



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