Ever since I modified my endcap with a 2" pipe my machine has been really hard to start. Then today I can't get it to start at all. It is getting gas and spark but it won't even fire (not even with starting fluid). The only mods are the endcap and a UNI stock replacement filter. I tried adjusting the air/fuel screw but didn't seem to do anything. I just pulled the valve cover over to check the valves and they are all tighter than spec. I am going to adjust them but could this be why it won't start? Could backpressure be an issue? Thanks for the help in advance.

 

Put the plug caps back on.... [img]i/expressions/face-icon-small-happy.gif[/img]

Uhmm... sounds like another issue.
Modifying the pipe wouldn't keep it from starting.
Nor would a filter mod..... UNLESS the carb got choked up with filter material

quick story;
I washed my CRF450 with the filter out... but stuffed a couple paper towels into the airbox. Well.... when I tried to start it... it sucked the papertowels up into the carb intake. It kinda started... then choaked out (after a second or two). And wouldn't even light up with starting fluid.... soon after (in the shower) is when I realized what I had done. Removed the new clean filter, the paper towels and wha-la! BRRRRRRrrrrroooom!

So ... check the obvious again. You might be surprised. [img]i/expressions/face-icon-small-wink.gif[/img]

(someday I should tell ya about the oil change to my F350... and not spilling any oil on my driveway! Now that's a funny story)

 

try a new set of plugs

 

Sandman430 has a good point, your plugs could be fouled.

 

Now seriously....?!

A fouled plug may give you trouble... but two at the same time?

Can ANYONE on here tell me they've fouled two at a time?!
If so... then there's more to the problem than just a fouled plug!

And....
How could one fouled plug KEEP the bike from running?! If one is still good.... then the bike should at least fire. And he said he checked spark... so we know it's not a BAD plug or plugs.... Or did ya'all miss that? Fouled plugs don't really "spark"....

Maybe all my 2stroke years of plug fouling is nonsense.... but enlighten me if I'm wrong here on the "fouled plug" keeping a bike from running at all. Especially when there's two!!

 

First make sure you have gas in the tank,petcock on,and the Kill switch on the Handle bars turn to "on". Next make sure you have a FULLY charged battery. Then turn the key, pull the choke all the way out. and give it NO throttle. It it still doessnt start, then use the BUTT end of a screw driver to peck on the bottom of the carb. Your flaot my be stuck closed or something. Try it again. If your getting Spark and gas, and your Battery is fully charged , and you have made sure the Kill switch is on. Thier is no reason why it should start.





BIgger.

 

I put new plugs in, and tapped the bowl on the carb and it still wouldn't start. Took the bowl off and checked the float and everything and everything seemed to be fine. I am going to order some new shims for the valves next week. Hopefully that is the problem. Either way they need to be adjusted.

 

o and for whoever wondered who could screw up two plugs at once I HAVE!
after my last oil change it wouldnt start and i had fouled out BOTH ngk plugs....!

 

yeah i had both plugs go bad thought it wasn't possible and this was when the machine was two weeks old. two new plugs and bam not problems since

 

dhughes. You didn't say whether you re-jetted when you modified your endcap. You need a big jump in jetting when you let it breath. This would make it hard to start without the choke. Then, if you rode it that lean, you could have burned the valves. I hope that's not what the problem is.