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Discussion Starter · #1 ·
I have had a problem with starting ever since I rebuilt the top end. And I think I have traced it down to the carb. Whenever you hit the key the motor turns over almost a full revolution and then the starter stalls. It will eventually get past it after hitting the key a time or two and start. I thought it was battery, cables or something electrical. I also adjusted the valves. They were a little loose.

Today I was lowering the idle speed to help it shift better. And for some reason I killed the motor by putting my hand over the air intake instead of using the key. I went to restart it and the motor spun over free like it used to. I refired and killed it this way 2-3 more times and it worked like a charm. I killed it with the key and it did the stall during the first revolution.

My question to the carb/tuning experts is what is causing this and what can I do to fix it? Its an 04 stock motor. I do believe it is running rich after looking at the plug.
 

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Discussion Starter · #4 ·
@dbestduner: Everything is stock internal. Carb is stock but jets and settings are unknown. I bought it used and haven't messed with it.

@canucklehead: I have thought of that but didn't want to pull the head cover until I made sure everything else is right.

I don't understand why it turns over fine when I killed it by covering the air intake. Could the carb be dumping excess fuel into the combustion chamber and raising the compression just enough to slow/stop it. I double checked my lines to and from the fuel pump and everything is correct.
 

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If the decomp mechanism isnt working right, you will have issues with turning over the engine.........
 

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Discussion Starter · #7 ·
@ Albanate and Willykiller: I agree with both and all that suggest the decompression mechanism. But what I don't understand is why does it not do it if I kill the motor by covering the air intake on the air box. Does killing it that way change the way the decompression mechanism works? I'm not trying to be an ass about this, just trying to figure out why killing it by covering the air intake hole makes a difference. I just want to rule out the carb. I know the timing is on there was a (factory?) white mark on the chain and on the cam sprocket that lined up when the bottom mark was lined up. I did remove the cam with sprocket attached but I could not figure out how to get it back on that way so I remove the sprocket and reinstalled it. i made sure the cam and sprocket went back together in the same orientation and the decompression mechanism moved freely before I put the cover on. That doesn't mean everything is perfect but it runs pretty good. I'm gonna read up on carb settings and maybe pull the carb and check and clean everything.
 

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The only reason I could think it might start 'better' when you kill it by covering the intake, is that there it runs 'rich' for a few seconds, and there is still fumes in the cylinder that ignite quicker. This might mask the issue?

Try killing it with the intake, let it sit overnight, and see if it still fires up right away.

The fact that the decomp mechanism 'moved freely' before you put the cover on means nothing. If you don't install it EXACTLY like in the manual, it's installed wrong. The 'white mark' on the chain and sprocket means nothing either... the little dots on the sprocket and the way the cam is aligned is a VERY specific procedure.

The carb isn't the problem - I can almost 100% guarantee that. The fact that the starter can't get past the compression stroke means the decomp setup is installed wrong, or your cam is out of time.

Sorry dude - you can dink with the carb all day... that's not where your problem lies! :(
 

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Discussion Starter · #10 ·
@canuckle head: That does make sense about the fumes in the cylinder. I will definitely try what you said about letting it sit overnight. The white mark was just coincedence, I did line up the marks like the manual says to. I didn't find the top dot until I removed the bolt and plate on the cam sprocket. Depending on the weather this weekend I may pull the head cover and recheck the timing and decomp mech.
 

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It may just have to do with where the motor comes to rest in reference to cycle, but I cant be for sure.

Nate
I'm with Nate on this one. It is common for modified Rhino engines to be hard to start (cranking rotation), especially if they have a stock or small cam with little valve overlap.
 

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Discussion Starter · #13 ·
Update: Had a day off and the weather wasn't horrible. I pulled the head cover (pain in the butt) and lined up the marks and found my problem. It turns out I am an idiot. My cam timing was a tooth off and I missed the part in the manual about lining up the dot on the decompression hub in the cam. It was 180 out. I think my timing issue has to do with a stretched timing chain. I counted the turns on the tensioner I'm just over 3 turns out. I found this out by trying to re-time the cam and had to do it over 3 times before I was sure it was right and the decomp mechanism was right. Fired it right up like it should. Thanks for all the replies and patience with me.
 
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