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06 CRF250R Starting Problems... beating a dead horse here...

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So I did the cardinal sin and bought a used 06 CRF250R and the motor wasn't dead cold when I test rode it... I got impatient and it bit me.   :naughty:   With that, I got the bike home and took it for its first ride...kind of hard to start on a warm afternoon, but no big deal... then came the true effort of a cold morning.  What a nightmare to start (cold meaning California cold... 50-60's).  When I say nightmare, it will not start until i can feel the cylinder gets some warmth from repetitive kicking... easier if I use a heat gun.

 

I quickly took a look at the valves and all was OK.  within a .001 of spec on both intake and exhaust.  I then cleaned the carb and have rejetted (was too lean initially).  I then redid the top end.  Still a serious pain to start, so I did the decomp mod... still no go.

 

Once the bike is warmed up, it can start with only a few kicks (more than I'm used to coming off an EFI 450).  The bike runs great once its running as well.  The only issue is the cold start.  I have tried multiple routines mentioned on this forum to get the bike started and the one that works the best is a couple kicks with full throttle and then let off the throttle and kick... usually starts in less than 10 kicks or else I get a false start and have to repeat... 

 

The false start... I get what seams to be a start where the motor turns over about 10-12 times and I hear the compression release clacking with each rotation.  It almost sounds like it fires, but the cam rotation is too slow and the compression is not enough to give it a true fire... not sure that makes sense.  It just isn't the full loud fire of a typical start, almost like it is gurgling.  This happened before and after the decomp mod.  

 

Here is a highlight:

 - very good looking piston with ring gap and cylinder in spec

 - piston is high comp piston but I tried a new stock piston as well

 - Hot Cams stage 1 cam

 - Valves look very good and gaps are all within spec

 - just replaced valve seals and have new gaskets from teardown

 - carb is thoroughly cleaned with 40 pilot and 172 main... was a 38 pilot with 170 main, fuel screw is 2 turns

 

Any thoughts on this topic?  My big question is if anyone has ever had an issue with the decomp not releasing with a soft fire?  Is there something I can do to test the strength of the spark? Do any of the electrical tests on the stator or coil help with this?  I would not expect the electrical to change after warmed up, but anything I can  do to test the start issue is worth it.

Edited by MXwhit

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Have you tried adjusting the fuel screw? Assuming everything else is in spec, hard starting cold is a sign of a lean pilot circuit, try opening the fuel screw and retest.

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Ya, a 40 slow jet still seems kind of lean, on my 07 i run a 42 summer and 45 winter, and forget kicking it over with the throttle wide open, kick it through slowly a few times with the throttle closed, give it two-three quick pumps of the throttle, get the kickstarter just to the point you hear the decomp. click, let the kickstarter get to the very top of it's stroke, jump up a bit and fire your leg as fast as you can through the whole stroke of that starter. It should fire first time!

 

If it doesn't, do a leak down test to see if your losing any compression. A dealer can quickly test your stator and module output and coil. I didn't hear you say you tried a new plug?

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Have you tried adjusting the fuel screw? Assuming everything else is in spec, hard starting cold is a sign of a lean pilot circuit, try opening the fuel screw and retest.

I have ran it from 1 3/4 to 2 1/2 when I had the 38 pilot in there.  I will run it out to  2 1/2 with the new pilot and see if it makes difference.  Is there a way to validate the fuel screw inlet is clean?  I have hit every opening that I could find with brake cleaner.  I have not dropped the parts into chem dip (I use that as a last resort... especially when the top half of the carb is a pain to disassemble).

 

I will say that I have found the choke to be useless.  So the extra fuel comes from the couple of throttle twists prior to the kicks.  They are necessary to start, but don't seam to help the cold situation.

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I have ran it from 1 3/4 to 2 1/2 when I had the 38 pilot in there.  I will run it out to  2 1/2 with the new pilot and see if it makes difference.  Is there a way to validate the fuel screw inlet is clean?  I have hit every opening that I could find with brake cleaner.  I have not dropped the parts into chem dip (I use that as a last resort... especially when the top half of the carb is a pain to disassemble).

 

I will say that I have found the choke to be useless.  So the extra fuel comes from the couple of throttle twists prior to the kicks.  They are necessary to start, but don't seam to help the cold situation.

Oh and a last thing on the carb, it uses the stock needle on the third position.  I know this should have next to no impact on the start, but just for reference.

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Ya, a 40 slow jet still seems kind of lean, on my 07 i run a 42 summer and 45 winter, and forget kicking it over with the throttle wide open, kick it through slowly a few times with the throttle closed, give it two-three quick pumps of the throttle, get the kickstarter just to the point you hear the decomp. click, let the kickstarter get to the very top of it's stroke, jump up a bit and fire your leg as fast as you can through the whole stroke of that starter. It should fire first time!

 

If it doesn't, do a leak down test to see if your losing any compression. A dealer can quickly test your stator and module output and coil. I didn't hear you say you tried a new plug?

Thanks.  I have a 42 as a spare and can move to that next.  For the kick routine, I will try your method.  I usually feel it to TDC before kicking otherwise its a wasted kick.  I have noticed that the high comp piston likes a smooth but swifter kick than the stock piston.  I guess that makes sense.

As for the plug, I just tried a new plug last week and it didn't help either.  I was impatient and bought the plug at a local nationwide bike accessory store... won't do that again!  I think they were $15 more than the local Honda dealer on an already expensive plug.  Ouch!  

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Well I tried a couple things this morning.  I used your starting routine (couple soft kicks, 2-3 pumps of throttle, find TDC and then a hard kick) and it didn't fire, so I lined up and did a few more deliberate hard kicks and still nothing.  I then whacked at it 3-4 times continuously and it turned over for a second.  So i twisted the fuel screw to 2 1/4 and tried again.  Same thing but when it kicked over, it idled for a couple seconds and stopped.  So I went to 2 1/2 turns and repeated and this time it fired.

 

So I will try again tonight after work and see if the current fuel screw position with the procedure above will continue to act this way.  

 

I will say this is the first cold start that happened prior to me sweating profusely and stopping at least once i the process.  So this is a HUGE positive step!

 

Thanks.

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A huge positive step?  wow!   There has to be something wrong in the carb, like the air or fuel passage to the choke plugged?

 

Once they fire they should be on a nice fast idle.  Make sure you can hear the hot start valve snap closed in the carb.

Edited by bucket list

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A huge positive step?  wow!   There has to be something wrong in the carb, like the air or fuel passage to the choke plugged?

 

Once they fire they should be on a nice fast idle.  Make sure you can hear the hot start valve snap closed in the carb.

Well, I started the bike each day last week and had similar results except for Friday night.  Took forever again.  Then I went to the track Saturday for race practice and starting was easy and bike ran great.  Onto Sunday, race day, morning start was an absolute nightmare.  Had a few guys offer to help.  Finally got it started and needed a slight throttle turn to get it to fire (very, very slight).  Practice went fine and then was somewhat challenging to get started before moto 1 and then not bad for moto 2.  Once I warmed up the bio each time and went to the gate, it started in the first couple kicks at the gate.  Again, the bike ran fine in both motos (me, not so much... but learned twice that i can easily bump start when hot).

 

One big new learning is that I was getting a good amount of oil coming out the valve cover overflow.  I would read this as blow by... I replaced the main seal last week, so I know it is not oil crossing over at that point.  On Sunday I had to add a couple ounces of oil after each moto.  I'm big time not OK with a bike that does this, but can't figure how I would be getting blow by with brand new valve seals, piston, rings and ring gap at .030mm (within spec).  Im baffled.

 

I found the shop that had worked on the bike with a previous owner.  I am going to reach out to them this week and try to get a history.  I may get them to do a leak down test on it as well. After finding them Sunday, I realized I was within 10 minutes of their location all weekend (Doh!)

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Ya, leakdown test would be good. You may not have got a good ring seal with the new rings, cylinder surface just a bit out, a bit too smooth?

 

With the starting though, welcome to a carbed CRF250. I've had my 07 just over a year and I'm still learning to get it to start concistently warm. As I wrote earlier I've got my cold starting technic down so it's almost allways first kick, warm offtain one to two, but once in a while I'm ready to just push it down a cliff.

 

Some things I've learned. I never take half hearted stabs at the kickstarter, I always support the bike, either on a tree, stand or just something higher than the peg so that when I get that kickstarter in just the right position I jump up a little and fire my leg real quick through the full stroke of that lever. When hot , if it doesn't start with the one good kick i'll use the hot start, if it won't start in 3-4 good kicks, i just walk away, take a few min. to calm down, come back and it's usualy first kick again.

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Thanks.  One of the guys that help me get it started yesterday used to own an '07.  He got it started.  He found that it needed just a touch of throttle... basically leaning on the throttle was enough.  Turning it a quarter turn was way too much.  

 

I also talked to the shop that worked on the motor and it looks like the motor has had work since he touched it (he doesn't do hi-comp pistons in his builds).  He told me to check the tranny level even though i replaced the main seal.  He said the balancer seal can also cause a problem with oil crossing over.  I'll do that and next would be a leak down.

 

As to your question about the cylinder bore, I did a hone to it before I put in the new piston.  It has a good 45 degree crosshatch.

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I have heard it's critical the grit of the hone and how clean you get the surface after.

When i drain my two oil's after every couple of rides, i always measure exactly how much comes out of each.

 

These bike seem to have personalitys of their own, i enjoy the bike so much, it;s worth a little inconvience. Good luck with yours and your racing.

Edited by bucket list

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Just for a small update on this one.  I checked the tranny oil after getting home from racing last and the level was right at bolt for the test, so I am not losing any to cross over.  So I am still falling back to blow by.  I did not pull the top end again as I haven't ordered any parts.  So I went back to the starting issue and checked the valves yet again.  One intake was off now .05mm and an exhaust was off ~.03mm.  So I got that squared away.  After getting her back together, I was able to use the starting method with a touch of throttle and the bike started in less than 20 kicks.  it had sat for a while, but it is in the 80s outside, so a tougher test.  I am going to order a new set of gaskets/rings, re hone the cylinder and give it one more try.  

With all this hassle and continuing to be strung along on my new bike, I picked up a '12 450.   Knowing the previous owner and that its injected, should mean better luck.  I think I am about out of the woods with the 250 motor, so time to get rid of it.  

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I have worked on engines and have discovered rings installed upside down, this can make an engine use oil, somthing to look for if you tear into it. I would do a leakdown test first, good luck.

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Also a Nikasil plated cylinder has a very hard surface and all it needs is a good cleaning to remove any glaze and carbon.   The service manager at my local Honda dealer said they use a ball hone because it is fast, and he approved of my method of using  Scotchbrite with soap and water.

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I have worked on engines and have discovered rings installed upside down, this can make an engine use oil, somthing to look for if you tear into it. I would do a leakdown test first, good luck.

 

 

I have seen this as well.  and actually forgot to check when i was first putting it together.  Luckily I remembered before I put the head nuts on.  Of course, the top ring was correct when I pulled it apart... Oh well.  Better safe than sorry.  

I ordered up the new rings and gaskets.  I will try the scotch brite and soapy water and see how it looks.  I use a stone hone and get it to where I can see a good crosshatch, then rebuild.  I think my break in was a little less than stellar on the bike.  I works for me on a number of bikes that I have rebuilt, but this one seems to be a rather finicky bike.

One question off the topic of starting, is there a place that the oil pump could get clogged even with the screen and oil filter?  My breather tube got too close to the pipe and it burned a hole in it on break in.  I replaced it, but concerned something got sucked in through the tube to the oil system.  I'm just hunting for any culprit.  It just still baffles me that blow by could be bad enough for my compression to be low and affecting starting.  Even a poorly setrin on the cylinder may allow for a little smoke out the pipe, but next to no affect on compression (from what I've seen).

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I have seen this as well. and actually forgot to check when i was first putting it together. Luckily I remembered before I put the head nuts on. Of course, the top ring was correct when I pulled it apart... Oh well. Better safe than sorry.

I ordered up the new rings and gaskets. I will try the scotch brite and soapy water and see how it looks. I use a stone hone and get it to where I can see a good crosshatch, then rebuild. I think my break in was a little less than stellar on the bike. I works for me on a number of bikes that I have rebuilt, but this one seems to be a rather finicky bike.

One question off the topic of starting, is there a place that the oil pump could get clogged even with the screen and oil filter? My breather tube got too close to the pipe and it burned a hole in it on break in. I replaced it, but concerned something got sucked in through the tube to the oil system. I'm just hunting for any culprit. It just still baffles me that blow by could be bad enough for my compression to be low and affecting starting. Even a poorly setrin on the cylinder may allow for a little smoke out the pipe, but next to no affect on compression (from what I've seen).

If you ran the bike in the dirt with a hole in the breather tube you were sucking in dirty air directly through the intake tract, right into and past the intake valves, into the cylinder/rings, and then out the exhaust... Edited by Eddie8v

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I have seen this as well.  and actually forgot to check when i was first putting it together.  Luckily I remembered before I put the head nuts on.  Of course, the top ring was correct when I pulled it apart... Oh well.  Better safe than sorry.  

I ordered up the new rings and gaskets.  I will try the scotch brite and soapy water and see how it looks.  I use a stone hone and get it to where I can see a good crosshatch, then rebuild.  I think my break in was a little less than stellar on the bike.  I works for me on a number of bikes that I have rebuilt, but this one seems to be a rather finicky bike.

One question off the topic of starting, is there a place that the oil pump could get clogged even with the screen and oil filter?  My breather tube got too close to the pipe and it burned a hole in it on break in.  I replaced it, but concerned something got sucked in through the tube to the oil system.  I'm just hunting for any culprit.  It just still baffles me that blow by could be bad enough for my compression to be low and affecting starting.  Even a poorly setrin on the cylinder may allow for a little smoke out the pipe, but next to no affect on compression (from what I've seen).

 

Nikasil plating is very hard and the bores are for all practical purposes for life.  You do not cut fresh cross hatch in a Nikasil plated bore, but the cross hatch needs to be cleaned so the grooves can hold oil, you also don't want to knock down the ridges of the cross hatch with a hone. That is why shops use a ball or brush hone with an appropriate abrasive.  The good news is I doubt a cheap hone would be hard enough to cut the Nikasil, if you have any doubts take the cylinder to the service department of a Honda dealer and ask them to check it, there are a lot of Honda motors with Nikasil bores and the dealer service departments have the knowledge to do it correctly and most will help a DIYer fix his bike. My local Honda Service manager has 20 years in service and the parts manager has raced and rebuilt CRFs for a decade, they have alway been very helpful.

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If you ran the bike in the dirt with a hole in the breather tube you were sucking in dirty air directly through the intake tract, right into and past the intake valves, into the cylinder/rings, and then out the exhaust...

Agreed.  I am trying to recall if I rode the bike this way or if it was only in the garage on the stand.  I just can't remember when I found it.  I think it was after break in on the stand.  Either way, I am putting in fresh rings just in case anything happened.  I have already replaced the valve seals and the main seal after this happened and I change the oil immediately after break in.

 

Nikasil plating is very hard and the bores are for all practical purposes for life.  You do not cut fresh cross hatch in a Nikasil plated bore, but the cross hatch needs to be cleaned so the grooves can hold oil, you also don't want to knock down the ridges of the cross hatch with a hone. That is why shops use a ball or brush hone with an appropriate abrasive.  The good news is I doubt a cheap hone would be hard enough to cut the Nikasil, if you have any doubts take the cylinder to the service department of a Honda dealer and ask them to check it, there are a lot of Honda motors with Nikasil bores and the dealer service departments have the knowledge to do it correctly and most will help a DIYer fix his bike. My local Honda Service manager has 20 years in service and the parts manager has raced and rebuilt CRFs for a decade, they have alway been very helpful.

Thanks for this info.  I have have reached out the the shop that did the work and clarified some of the details and from a ring gap and cylinder bore measurement perspective all looks good.  I did not realize the stone hone will not affect the nikasil.  I have seen that it cleans to a good crosshatch, but if it isn't affecting the nikasil, then I may just be cleaning the "polish". I will do the scotch bright trick and see how she looks.  

Edited by MXwhit

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The important thing is a clean shiny silver bore, no yellow or brown tint. I don't recommend using a hone just lots of elbow grease, or have a dealer de glaze the bore with their hone and knowledge.

The term hone comes from the rebore and prep process used on iron and steel bores, the plated aluminum cylinders on our newer cars and bikes are not the same and only need to be cleaned and deglazed.  There is absolutely nothing in the Honda Owner's or Service manuals about honing the cylinder, only checking the dimensions.

https://www.youtube.com/watch?v=vaFp8aYkHNA

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