Engine wont rev up (video)

[jroy500]

Hi all! its my first post on this nice forum.. I dont speak english so please dont juge me :p  

So, my 250R wont rev up and its now out of my knowledge. Last time that I used it, It was working perfectly but I got out of gaz when I arrived home.. I leaved it parked 2 week, out door with some raining on it... : /    Now with fresh fuel mixed at 32:1 It bog and wont rev up and its getting worse and worse [video=youtube;t2WkBJB8k8U]https://www.youtube.com/watch?v=t2WkBJB8k8U[/video]

I installed brend new coil, cdi, sparkplug BR8ES, tried I used magneto and igniter. And it changed nothing, I cleaned carburator. Compression is 190psi...

Help me please I want listenned to my 250r rev up like before!


Sorry for my english!

[jroy500]

250r wont rev on load : http://youtu.be/RaSPGzjDN1o

[jroy500]

can it be my problem that reed valve? The motor start easily and idle all right..

[Pumashine]

can it be my problem that reed valve? The motor start easily and idle all right..[/COLOR]

You might have found part of the problem. When the reeds break you will loose all top end. Just speaking from experience. Welcome to the site.

[Jerry Hall]

can it be my problem that reed valve? The motor start easily and idle all right..

The reed petals need to be replaced, but it do not think this is the reason for the severe miss-firing.  The engine sounds very rich.  If the carb has the same jets as when it ran well in the past, I do not think it is a carburation problem unless fuel is running out of the vent hoses.

I would clean and re-oil the air filter if it has not already been done.

Does the muffler have a spark arrestor?  If so clean the screen if it has one and make sure none of the internals of the muffler are broken or in miss-alignment.


If it has a new Dynatech CDI borrow a Honda CDI from a friend and try it.  I have had a lot of problems with Dynateck CDIs.

If it has a new stator and flywheel from Ricky Stator (made in China), try another new or known good Honda ignition.

[jroy500]

its a cheap ebay no name CDI... : /  I just tried with my old cdi and it sound better, much more power on low rpm but still cut on top, I will order new OEM cdi and reed valve!
  My mufler is fmf, no spark arrestor and its all clean inside, cleaned air filter too

[jroy500]

Do you think its can be due to a wrong year CDI, I saw 86-87 have different timing of 2deg VS 88-89.. Its not the original motor in my quad, so I'm not sure about year... This Ebay CDI was a 88..

[Jerry Hall]

Do you think its can be due to a wrong year CDI, I saw 86-87 have different timing of 2deg VS 88-89.. Its not the original motor in my quad, so I'm not sure about year... This Ebay CDI was a 88..

An engine being out of time 2 degrees will not cause the running conditions like you are experiencing.  The timing would have to be advanced 40 degrees or so to cause the symptoms like you are having.

[jroy500]

ok perfect thank you

[Jerry Hall]

Remove the ignition cover, and dyechem the outside of the flywheel.

Make a short sharp pointer made out of 1/8" welding rod and bolt it to the engine case using one of the cover bolts.

Find Top dead center and scratch the dyechem with a scribe at the end of the pointer.  This is reference for the rest of your degree marks

I do not have a 250 R flywheel to measure the diameter at the moment but most of these flywheel diameter are such that a 1 degree spacing is about 0.9 mm to 1.0 mm on the outside of the flywheel.  

Mark the outside of the flywheel in about 2 degree spacing.

Hook up a strobe type timing light and run the engine.

I think the timing curve on the OEM CDI is fairly flat and is about 15 degrees at all RPM above 4000 RPM.  


If you timing is within plus or minus 4 degrees of 15 degrees, I do not think ignition timing is your problem.

Gap your spark plug at .018" to .020"

[jroy500]

turn like a charm now! new cdi installed, I will change reed valve next time but now it rev like i want and torc a lot!

Thank all!

[udontknowme]

all that time it was a china cdi   :congratulatory:

[udontknowme]

all that time it was a china cdi   :congratulatory:

[jroy500]

at first time it was the oem cdi, and china cdi after!  funny trouble lol