Sign in to follow this  
Followers 0
ulumanati

07 450F WEIRD Starting Issues

15 posts in this topic

Picked up a used 07 450f from previous owner, and unfortunately dont know how many miles are on it. I live in Texas where the weather is currently in the low 100's daily. Just got valves checked and the middle intake valve was on the low side and mechanic adjusted accordingly.

When bike is cold (although outside temps are 100F), it fires up first or second kick with the hot start pulled in and NO choke. After riding hard for a while and bike is real hot, it suddenly stalls alot on me in the middle of holding clutch and turning slow, after that it takes approx 15-25 kicks to get started with or w/o hot start. What can be causing this? Valves just got checked about a month ago, and there is a red fuel mixture screw that may be aftermarket, but dunno if PO messed with it.

THanks for the help!!

Share this post


Link to post
Share on other sites

Start by finding out how far out the mixture screw is from being bottomed out. Using the marks that it most likely has on it, turn it in until it just stops and record the number of turns that takes. At that point, back the screw out 1 3/4 tuns and adjust the idle mixture:

http://www.thumperfaq.com/jetting.htm#PJ

See if that helps.

Share this post


Link to post
Share on other sites
Start by finding out how far out the mixture screw is from being bottomed out. Using the marks that it most likely has on it, turn it in until it just stops and record the number of turns that takes. At that point, back the screw out 1 3/4 tuns and adjust the idle mixture:

http://www.thumperfaq.com/jetting.htm#PJ

See if that helps.

Thanks for the help! Well I did what you suggested before my ride today, that little red screw was facing me showing a number 3, so I turned it in all the way then backed it out 1&3/4 turns which ended up at a 3 again. It seemed to start a bit better when hot with the hot start (3-4 kicks).

That article you sent me that read "Setting the Fuel Screw / Pilot Jet "by Ear" does that apply to turning that red screw with numbers while the bike is running and noticing how the idle is doing?

Oh ya and it seemed at one point when trying to kick start it, the lever got stuck and wouldn't budge, but then I moved the bike forward a bit and and the kickstarter released, and didn't happen at all again.. Any coincidence?

Share this post


Link to post
Share on other sites

How can I tell if that one instance of the kickstarter being stuck was from the cam chain jumping a tooth, or from me kicking the hell out of it in a frustrated attempt to get it started? I've been reading and am scared it might be a bigger problem than what I thought.

Share this post


Link to post
Share on other sites
...that little red screw was facing me showing a number 3, so I turned it in all the way then backed it out 1&3/4 turns which ended up at a 3 again. It seemed to start a bit better when hot with the hot start (3-4 kicks).

That article you sent me that read "Setting the Fuel Screw / Pilot Jet "by Ear" does that apply to turning that red screw with numbers while the bike is running and noticing how the idle is doing?

But you didn't count how many turns it took to turn it all the way in, so now you don't know where it was originally set, and thus, you don't know how much difference there was.

Yes, the article was about setting that screw, that's why I posted it.

How can I tell if that one instance of the kickstarter being stuck was from the cam chain jumping a tooth,

If it jumped a tooth, it would run badly, if at all. Read:

http://www.thumpertalk.com/forum/showthread.php?p=9110763#post9110763

Share this post


Link to post
Share on other sites
But you didn't count how many turns it took to turn it all the way in, so now you don't know where it was originally set, and thus, you don't know how much difference there was.

http://www.thumpertalk.com/forum/showthread.php?p=9110763#post9110763

Uh oh... If I remember correctly it was approx 2 turns in.. But if I didn't count correctly and now just have it set to the standard 1 3/4 turns out, what can I do to start all over?

Share this post


Link to post
Share on other sites
....what can I do to start all over?
Nothing. You'll have to go from where you are.

Share this post


Link to post
Share on other sites
Nothing. You'll have to go from where you are.

Okay so I tried following your advice. I turned on bike, set the idle on the high side.. But the weird thing is that, while turning in fuel screw just til the engine almost dies, it went all the way in to tight and never seemed like it was going to die. I turned it out quite a bit and tried gasing it an it would die out.

So with high idle and fuel screw about 1 3/4 turns out, I tried kick starting it and scared the hell out of my gf! It popped real loud and she said it shot "fire" out the exhaust. The more I turned it IN, the more it popped /when starting. So I left it at 1 4/5 turns out and called it a day.. How can I tell what to set the idle back down to again? Just til its above dying out after starting?

Share this post


Link to post
Share on other sites

Quite often when someone states that turning the pilot screw all the way in makes no difference, they simply have the idle too high during the adjustment.

As to how to set it, as long as it's fast enough to stay running under most circumstances, it's fine. Check both the hot and cold star plungers to be sure they are sealed correctly and that they close.

Share this post


Link to post
Share on other sites
Quite often when someone states that turning the pilot screw all the way in makes no difference, they simply have the idle too high during the adjustment.

As to how to set it, as long as it's fast enough to stay running under most circumstances, it's fine. Check both the hot and cold star plungers to be sure they are sealed correctly and that they close.

Okay thanks! I left it for now at the nominal 1 3/4 turns out and a steady idle.

After setting it to this the bike starts within 3 kicks with the hot start pulled in right now, which is good compared to 5-15 kicks before. But by having it on the INCORRECT fuel screw setting and riding, can I damage anything? Or will I just notice that the bike doesn't run like it should? .. What can I look for while riding to see if its decent enough or not?

It still popped loud once when starting it up, but not the other 3x

Share this post


Link to post
Share on other sites

After setting it to this the bike starts within 3 kicks with the hot start pulled in right now, which is good compared to 5-15 kicks before.

No real damage to worry about other than some extra combustion chamber deposits.

How hot is the bike when it starts as you posted in the quote above?

Share this post


Link to post
Share on other sites
No real damage to worry about other than some extra combustion chamber deposits.

How hot is the bike when it starts as you posted in the quote above?

Well that's the weird thing! If I am barely pulling the bike out of the garage for the first time of the day and want to fire it up, it starts withing 3 kicks with the hot start even though the bike is supposed to be "cold". But I guess my garage in 100F weather here in Texas doesn't exactly keep it cold. The problem was it flaming out on me during a ride and then being a pain in the @$$ to fire it up while its really hot, with or without the hot start.

In the previous post I was referring to bike just being idling for couple minutes and then turned off, then turning it back on with the hot start. So I'm guessing not too hot

Share this post


Link to post
Share on other sites
The problem was it flaming out on me during a ride and then being a pain in the @$$ to fire it up while its really hot, with or without the hot start.

Let me ask you this, then: when it "flames out", does this frequently happen in situations where the throttle is opened or the bike is under a moderate load and then the throttle is suddenly closed?

Share this post


Link to post
Share on other sites
Let me ask you this, then: when it "flames out", does this frequently happen in situations where the throttle is opened or the bike is under a moderate load and then the throttle is suddenly closed?

Well it doesn't happen if I am on the throttle and accelerating or closing it suddenly.. It only happens when I'm out riding and slowing down, I pull in clutch and as soon as I come to a stop or sometimes even just slowing down it flames out. Every time it has stalled, has been with the clutch in and at slow speeds.

This is not all the time, but it does happen at least once or twice every ride. Then after that, sometimes I pull in hot start and it kicks right up, and other times it takes 30 kicks.. At times I get so frustrated I just wait it out to try starting it again

Share this post


Link to post
Share on other sites

All of this is adding up to a too rich idle. Whereas a lean idle tends to "hang" a little and idle down slowly, it also resists stalling for the same reason. If one goes too rich, it first tends to drop to an idle suddenly to the extent that it will idle down below the actual adjusted idle speed, then come back up to it. Go richer, and it just simply stalls. Often a bike that rich will slowly loose idle speed as it idles, to the point where it just quits eventually, and, oddly, you can actually get a really rich idle to hang at a higher RPM because it feeds the engine too much fuel. At that level, the idle is too dirty down where it's set, but cleans up some at higher speeds and wants to stay there.

Also, the fact that you can close the pilot off and not have it at least stumble points to a too rich pilot, or a carb that's letting fuel in from another source.

What size is the pilot now?

Also, you might check the float level setting and be sure the float needle holds.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0