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06 CRF 250R not wont start

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OK I guess I will jump in and join the CRF 250R Non start club.

Here it is:

2006 CRF 250R

Have checked, double and triple checked the following

1.timing... TDC...punch mark on gear lined up, both marks on cam gear line up and notch in housing (treaded area) on flywheel cover are inside marks on flywheel

2. Shimmed valves (several times) all good

3. compression (w/decom working) +/- 60 psi.. jumps to 30 on initial kick then climbs to around 60 in increments of 10 psi or so per kick

4. New plug. and getting great blue spark. (And Honda and NGK are certainly proud of those bastards)

5. Rebuilt carb. 42 pilot and have tried 170 and 175 on main.. needle 3rd position

6. Verified that hot start was closing and not hanging open which could lean out

7. Have tried all the different starting techniques that I have read on several forums to no avail. 

8. Fresh 93 white amoco fuel

9. Tried different air/idle screw positions. From 1/2 to 2 turns

10.Tried everything except a little C4 or dynamite.

 

When bought bike started great. First kick. Then just one day outta the blue it starting not wanting to start. Was strange because you could kick you ass off and nothing. Then others just walk out and kick and would start first kick. No choke. Just crack throttle about a 1/8 to 1/4 turn and she would fire right up. So I thought as while I was tearing down I might as well install Hot Cam, My son wanted a little more bottom and mid range.

After installing cam and shimming valves it cranked on 2nd or 3rd kick. Again 1/8 to 1/4 throttle with no choke. This worked well for days then went out one morning and bike had reverted back to the same starting problems. 

 

At times after pumping and kicking plug will be nice and wet. Other times it will be bone dry. If I place my hand on back of carb with boot off it will fire and try and start. Take off and nothing.

Sounds like its starving for fuel. But where?

Gonna check intake boot, o-rings on hot start and choke next.

 

Any ideas before I reserve my spot on a 100 story building ledge with the rest of you.

thanks for any suggestions, 

Thank you Federal Government and EPA for trying to eliminate the 2 stroke. 

Give me a 2 stroke any day!!

 

 

 

 

 

 

 

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I have shimmed several times just to rule things out. I try and little tight and then a little loose just to see if it helps. Just trying different combination of tolorences I hate that the shims only come in ,05mm increments. I like to do things to the gnats ass. 

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Have you ensured the pilot circuit isnt blocked somehow? I have to twist the throttle twice before I start mine, so the ap squirts a little, but if I try with the throttle open at all its a no go. They all start different but between that and it starting with no choke something might be off somewhere, just a thought because mine wont start without the choke ever unless its warmed up. How many turns out is your fuel screw?

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I have been thru carb several times. Gonna go thru once again. I have tried anywhere from 1/2 to 2 turns on fuel screw. I try in 1/4 turn increments.

They are strange temperamental creatures for sure. 

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and notch in housing (treaded area) on flywheel cover are inside marks on flywheel

 

 

See below.

Edited by mossman77

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When you say "are inside marks on flywheel", do you mean the pointer on the case is pointing between the flywheel markings?  If so, your timing is off.

 

Also, the stock pilot is a #45, so I would swap out the #42 and set your fuel screw to 2 turns to start out with.  Also, replace your floating valve seal, check your float level, and be sure your float needle isn't sticking.  You didn't soak your carb when you cleaned it did you?

Edited by mossman77

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Just a thought. What is the function of the floating valve in the carb??? Could worn o ring of clog be the culprit?

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mossman77

What I meant was. On the flywheel side of the bike. The threaded boss for the flywheel plug is grooved or notched. When I check timing that groove is somewhere in between the two punchmarks on the flywheel it self. 

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Im just guessing, hopefully someome will correct me or maybe validate, but I think it stops it from pulling air in while the throttle is closed but allows it out in some cases, maintaining the proper vacuum or something. Fyi Yamaha sells that seal seperately so you dont have to buy the whole float valve.

Also I dont have my manual here but I think the pilot is a 40 stock, all I could find when I googled were other thumpertalk threads but thats what they said too, I dont want to say for sure based on that. Either way I agree go back to stock settings and start from there if you're sure its clean.

Orings or clogs could definitely be the issue too, if you soaked it or sprayed carb cleaner indiscriminately you would have dried out the rubber.

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mossman77

What I meant was. On the flywheel side of the bike. The threaded boss for the flywheel plug is grooved or notched. When I check timing that groove is somewhere in between the two punchmarks on the flywheel it self.

Im pretty sure it should line up with the second mark, cant check now but theres a good thread called "timing your crf" or something similar on here that will explain it.

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Yeah it sux that Honda makes you buy the whole plate for just the damn seal.

Its it a seal or just an o-ring? Hummmm 

It doesnt slide or move. Wonder if there is a work around. Little Hondabond maybe. 

Anyone ever tried that. 

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Yeah it sux that Honda makes you buy the whole plate for just the damn seal.

Its it a seal or just an o-ring? Hummmm 

It doesnt slide or move. Wonder if there is a work around. Little Hondabond maybe. 

Anyone ever tried that.

 

CRFsOnly.com sells just the seal for about $15.  I realized this after I bought the OEM seal/plate for $80.

 

I believe the seal simply keeps air from passing by the slide.  It is shaped in such a way that it has a spring effect to it so it keeps the plate pressed against the carb for an air tight seal.  I'm assuming this is necessitated by of the flat-slide carb design.

 

I stand corrected...the stock pilot for the 2006 is a #40, and the stock main is a #172.  Stock pilot screw setting is 1-3/4 turns.

Edited by mossman77

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Regarding the timing, the marking on the case should line up with the second tick mark (when counting clockwise) on the flywheel.  If you're in between, your chain is likely off by a tooth.  However, it may be that the crank punch mark isn't actually lined up perfectly.  It's hard to get it lined up because it can look off based on the angle at which you are viewing it.  I've heard it's better to use the flywheel marking to set the timing.  The manual for my bike says to use the crank, but the 450R manual I just looked at says to use the flywheel.  I think maybe Honda doesn't want people to get confused by which of the two markings to use, so they tell you to use the crank marking.  I guess they figure 250cc owners don't know any better and 450cc owners do.  No clue.  As long as the second tick mark lines up with the index mark on the case and the cam markings line up, you should be good.  BTW, the crank marks should also line up, but as I alluded to, it's easier to line up the flywheel markings.

Edited by mossman77

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