Crf250r starting problem`?

is it better to run premium unleaded (95octane) or unleaded (91 octane) in my bike as i am having trouble starting my bike i only done the valves, piston and rings not that long ago and the bike shop reckons that it could be the fuel any ideas

do a compression test first!(testers are inexpensive) If there is a problem with valves or rings seating it will show up. (since that was recently worked on)
If that comes out correct, check ign (good spark and timing) and then fuel...That is all there is!
Premium fuel is a must, the crf is a high performance motor and the higher octane you use, the better it will perform.

get a cr 250. They are better. The 95 octane would be the best for sure. Try cleaning your carborator. Also, those 4 strokes need valve adjustment and other adjustment that 2 strokes dont have.

One way is to use a process of elimination. Start by checking the valve clearances. When you are satisfied with that check the ignition. Particularly the spark plug, clean and gap or replace. The next thing is the carburetor. Once the the engine is warm adjust the idle air screw to spec.

There have not been any consumer Honda products built since lead was banned that require leaded gas. But good quality fuel is still a good idea, the higher the octane the better.

So once again 1)valves/compression 2) ignition/spark 3)carburetor/jetting.

92 or better. if its really hot out like in az where i go to ride sometimes ill use 92 cause its 110 out, but if you use to low of octane you will ruin your engine.

If you had the engine rebuilt not long ago I doubt very much that the octane is an issue unless you've gotten some bad gas or water in the fuel.
You don't state what model year you have, but I would recommend that you check the valve clearance. It should have been checked after 10 hours from the rebuild.
The valves most likely need to be shimmed. It is a very common issue with the Honda 4 strokes.
When I rebuilt mine I went with Stainless Steel valves/springs to avoid the problems inherent with the O.E.M. vavles (less stretch).
Here is a link to a site that can answer every and any question you have regarding your CRF:

http://crfsonly.com/forum/index.php

Not only will you find tips and "How to's" you can get specific answers from the members there.

Good luck with your R, it's a great bike!

95 octane. this will not cause a starting problem. i would bet that you have tight valves. you mentioned you had the valves done not that long ago. who did them. we went through a spell of trying to find a shop that could do them correct so we baught the stuff to do it ourselves (not cheep). also if they had just ben done did they tell you that the valves need readjusted after around 10 to 20 hrs. the valves will have a spell of seating after a valve job

your bike is made to run on 91 dude . duh ! 95 octane needs a higher heat to burn .so you would need to run a hotter plug. MAN WHAT DID YOU GET THE " SLOWSHOT " HAHAHAHA , HAHAAH IM JUST FKN WITH U