Starting issues

[desdave]

08 WR450. All the usual mods. Has consistantly started and run great. Until....last ride I got some backfiring while e starting cold. Once warmed up it started fine the rest of the day. Yesterday I got the same thing only it seemed to be worse. Finally had to kick start it (first start of the day) and it started and ran fine. Any thoughts? Again, it run as great as ever, just a cold start issue. I'm thinking plug or possibly battery getting weak (still has the original battery )

[William1]

Check the valve clearences

[desdave]

Good point. I just had them set a couple of months ago (very minor adjust required), and it kick starts and run great. Gonna change the plug first. I've only changed it once and then I found it to be heavily rusted due to water intrusion thru the plug well drain hole. If that doesn't do it then I'll verify that the battery isn't getting weak. The fact that it kicks and run fine would tend to eliminate cdi, valve I would think.

[desdave]

So I left the battery on a charger all day and after reinstalling, the bike fires right up cold with no backfiring etc and turns over faster than seems usual. I'm thinking the battery was a little low from sitting, and when cranking it was not adequately powering the cdi. Anyway, all is well now.

[climaxx dirtbikes]

I recently bought my 07 450 brand new but obviously the battery has been sitting a while. Starts decent but not immediately. Do you think its the battery? How many volts when starting should I have and when at idle? How much does running the bike actually charge the battery?