CRF's Only Forums

hi,
I am having some issues starting my 2008 crf250r. To date i have rebuilt the top end, wiesco pistion, kibblewhite stainless valve kit, valves in spec, the bike has a akaprovic exhaust system and twin air filter also. The bike is hard to start both cold and hot but especialy when hot(sometimes will not start when hot)! I have a feeling that the bike is far too rich as there was a lot of carbon build up around the valves before the rebuild. I am considering rejetting the carb and am also looking into modifying the decompressor on the cam so the exhaust valves don't open for as long when turning over.

If anyone has any sugestions on the jetting or the decompressor mod i would appreciate any help i get.

Thanks.

when you replaced the valves were the valve seats professionally cut? has the bike been sitting without regular running?

Yes I sent the head to get the seats cut, the valves ares sitting fine. The bike was sitting for over a month before I could get a chance to reassemble it, if its is fuel you are thinking of, I drained the carb and it has got good fuel. this problem was there prior to the rebuild, the valves needed to be replaced and I hoped this would have solved the problem, but it is not much better!

if the valves are sealing, clearances correct, decomp mechanism functioning correctly, piston and rings installed correctly, there is proper spark then you have to look at the carb. sitting with fuel in the carb, even for a month or so can result in clogged jets. replace them just to eliminate this as the source of the issue. check your AP diaphragm and make sure it is not deteriorating. if you have removed the slide make sure the floating valve plate is installed in the correct orientation. the same for the floating valve plate seal.

ken

Thanks ken, ill check out the carb and see!

Hi,
I have cleaned the carb, wasn't bad but I gave it a good cleaning and the bike is still the same, hard to start, especially when hot, I'm looking at rejetting, any reccomendations would be appreciated as I am not too sure about jetting.

Thanks

jetting...JD Jetting Kit we offer. best jetting, plug and play.

ken

Thanks for the quick reply as usual Ken, ill b ordering one of the kits off you!

you're welcome. happy to help and thank you for the support.

Get CRFs fuel screw too since you will have the carb out. I did the JD kit and CRF screw and my bike rips

excellent suggestion!

I will get the fuel screw too, just wondering before i order the jd kit, does it include any pilot jets? Correct me if i am wrong but starting is down to the pilot jet i think, just want to be sure i get everything i need in one go!

Thanks.