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Super Hard Starting

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Hey I know there are lots of forums of hard starting CRF250R bikes. I'm just stumped when it comes to my bike. I'll get into details. 

 

I just rebuilt it. It started hard before the rebuild and still starts hard. I can start it but it takes a very long time and only starts when I crack the throttle while a really hard kick, even after it has run for a while. 

 

Things I have checked:

 

Timing, is dead on.

Valve clearance, within spec.

Carb, cleaned and jetted for my conditions.

Spark, Good. 

Fuel, seems good. Not sure how to check really. 

Kill Switch isn't cutting it off. 

 

If anyone knows something that might work I would appreciate it so much. 

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Just because the valves are in spec doesn't mean they are seating properly. Do a compression and leak down test

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Hi to far out on the fuel screw makes for hard starting somthing to try for you pull the hotstart for 2 seconds before you hit the kill switch then try to refire your bike if it starts up better you need to go in on your fuel screw

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@Red Dirt Ryan gas is fresh

 

@yeomans555 that sounds like a good idea to me I'll see if I can get that done. 

 

@martin truszkowski I will have to look into that as well

 

Thanks guys

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 I can start it but it takes a very long time and only starts when I crack the throttle while a really hard kick, even after it has run for a while. 

 

     Try turning your idle up. I've had that happen when I replaced a carb on a bike before. Other stuff, make sure all the parts of the fuel screw are there: oring, washer, and spring. Make sure the tip of the fuel screw isn't funky. You might mention your pilot jet and fuel screw setting.

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     Try turning your idle up. I've had that happen when I replaced a carb on a bike before. Other stuff, make sure all the parts of the fuel screw are there: oring, washer, and spring. Make sure the tip of the fuel screw isn't funky. You might mention your pilot jet and fuel screw setting.

As far as all that goes I think its alright. We set everything to what it should be then played with the screw a bit while it was running just to see if we could get it better. 

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sounds like its to rich on the pilot circuit since you have the crack the throttle. Put the carb back to oem specs or something someone recommends on here. Start there and see what happens. Give the carb another good cleaning and check the float height as well. How about the air filter is it clean? And is it not over oiled?

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im having the same exact problems now. if I figure out wats wrong with my bike ill get back to you and let u know. let me know if u figure out wat was wrong with urs thanks

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Like I said the carb is set to standard specs which is correct for my elevation and temp, and it got 3 good cleanings already. I don't know exactly how to check float height. The book was somewhat confusing on that. 

 

@elivingston I'll definitely let you know if I get it going. 

 

One thing I'm curious about, I have a brand new head and valves. Shouldn't they fit perfect because they are new or is cutting required regardless?

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Not sure what it was about the 08 and 09 bikes but some of them just didn't start.

You could have everything perfect in them but they just didn't like to start.

I would not recommend a 08 or 09 to  anyone for that reason. Most were ok but there were some that just sucked.

We were unlucky enough to own an 09.

I'll do mechanical repairs on them but I won't take on any starting issues on them.

 

Search this forum for posts from Charlie C.

He doesn't seem to be here all that much lately.  

He had some good info with regard to the carb'd bikes. 

If I recall correctly even he had some that just couldn't be made right.

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ya I also have brand new valves and guides and seats. my friend has the same bike and the same exact problem. idk wat it is but definitely lmk if u get it figured out

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Pilot jet plugged? I've heard it is undersized and that the PJ from the 450 can help starting issues.

I looked at a '08 last week, super clean everywhere, low hours, valves were in spec but wouldn't start. When it finally did the owner said it required an overly lengthy time at full choke or it would stumble and die. Needless to say I walked.

GL bro!

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So I got the bike back yesterday. Starts consistently now. Usually 4 kicks which is awesome compared to what it was. Now it won't idle without the choke. I'm going to try a 45 pilot jet and see if that works.

So the reason for not starting. The slot for the decompressor in the cam was worn and the decompressor could wiggle and possibly cause to much decompression. Without the decompressor in it starts good.

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So I got the bike back yesterday. Starts consistently now. Usually 4 kicks which is awesome compared to what it was. Now it won't idle without the choke. I'm going to try a 45 pilot jet and see if that works.

So the reason for not starting. The slot for the decompressor in the cam was worn and the decompressor could wiggle and possibly cause to much decompression. Without the decompressor in it starts good.

 

If its not idling turn up the idle before messing with the jetting

We tried removing the decompression mech when we had a 09 and I was afraid something was gonna break when kicking it over because there was so much compression.

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If its not idling turn up the idle before messing with the jetting

We tried removing the decompression mech when we had a 09 and I was afraid something was gonna break when kicking it over because there was so much compression.

The idle screw isn't the issue, that I know. You just have to kick it from the right spot so you don't break your leg haha. 

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check the carb.. clean it, adjust it. if not look for fuel restrictions, fuel filter, bad hoses. if not check timing, valve clearances

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Sorry for not updating in a long time. I ended up dropping a valve after about an hour of riding after the rebuild. This bike is cursed. Anyway I got a new head assembly from fastheads.com and a wiseco high comp piston. Should have it all together next week sometime. I bought some other jets to so I'm hoping that gives it better response and idling. 

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