300ex hard start maybe new rev box?

[300exguy125]

my quad was running great and for christmas i got a big gun rev box then when i installed it it started right up like ussaully i didnt ride it around because it was crapy out side. the next day i went riding with my friends and i tried to start it but it wouldnt so i put it on the trailer and we went to ride still no start. this has happened before but it was really cold out and i had to warm it up in the garage for it to start i did the same but no luck then we pop started it and it ran its fine running no problems but it is hard to start is it my new rev box also i checked my spark plug and it was wet from trying to start i also checked the plug spark and it sparks nice blue im not sure please help me if you can
thanks
mark

[deathman53]

with alot of those rev boxes they are hard to start w/o a fully charged battery. Most of the rev boxes are cdi's off dirtbikes, as most are kick start, it takes a higher rpm to make a spark. Many of the 400ex rev boxes are nothing more than oem 99-05 xr250r or xr400 cdi boxes, some of them, you can see where the honda part numbers were scratched off. For the most part, the extra revs they give you, is where your motor stopped making power. A 300ex hits the rev limiter very quick, but in stock form its low rpm motor, its not a hi-rpm motor. Rev boxes are kinda like a roost boost or amp link, its a gimisk to sell you. For the majority of people, their motors aren't built for the extra revs.

[bwamos]

Originally posted by deathman53
with alot of those rev boxes they are hard to start w/o a fully charged battery. Most of the rev boxes are cdi's off dirtbikes, as most are kick start, it takes a higher rpm to make a spark. Many of the 400ex rev boxes are nothing more than oem 99-05 xr250r or xr400 cdi boxes, some of them, you can see where the honda part numbers were scratched off. For the most part, the extra revs they give you, is where your motor stopped making power. A 300ex hits the rev limiter very quick, but in stock form its low rpm motor, its not a hi-rpm motor. Rev boxes are kinda like a roost boost or amp link, its a gimisk to sell you. For the majority of people, their motors aren't built for the extra revs.

I agree that he needs to keep a battery tender on his battery to keep it a full charge.

I disagree that the boxes are a gimick.

Many have an timing advance, and increased rev limit. CDI advance is no more of a gimick than a timing advance key in a 400ex/450r, it does the same thing. The stock 300ex's rev limit is too low. It cuts out long before it's out of power (with an aftermarket exhaust, filter and cam). 6850 rpms. A stock 300ex can easily pull you to 7500-8000 rpms.

That being said.. I would prefer and run an 11:1 piston w/ a modified stock rev box (no advance).