My 400 scr quit yesterday.
While driving approx 2/3 throttle engine began to
bog down as if it was running out fuel.
Shut down checked fuel (fine) and it would not restart.
Temp lite and fan came on then went off after a couple minutes. Lite was not on while running.
My dealer had just previously changed low speed jet to cure a mild low end bog ater pipe installation.
Checked spark plug seems okay and has spark.
Seems to be getting fuel,just won't start,backfires after turning over for an extended time.
Was running extemely well prior to this,very fast with no low end bog. Easily lift wheels and accelerate like crazy.
Any suggestions before I take to my dealer would be appreciated.

Thanks

 

Don't want to get you upset but it sounds like a blown top end. Usually a bike runs great, better than normal prior to blowing a piston. The bike is getting plenty of air but just enough fuel to keep running. There isn't enough fuel left over to help cool the engine. This power rich condition exists until the bike gets too hot and the piston seizes. Remove your spark plug and put your thumb over the hole, try starting the bike and as it cranks if it doesn't blow your thumb off the hole than you have lost compression and will probally need a rebuild. I had almost exactly what you described happen to me while riding last year.

 

Thanks wolp,tried the thumb thing and itapears to have lots of compression.(Whew!!!)
The motor didn't seem tobe running a lot faster prior to quiting ,but a lot smoother and no longer had the low end bog as before rejetting.
Any other comments welcome.

 

I would guess the same as wolp. You need to be a little more scientific. Get a compression gauge and do a compression check, also I would look for very small spots of aluminum on the plug. if you have aluminum on the plug don't bother with the compression check because it defineately blew up!

 

You can also look at the end of your silencer to see if it is dry with alum. particals at the exit. What did your plug look like? This is exactly what happend when mine blew. Was jetted way too lean because Aaen screwed me with there recomendations.

jad 2000 Scambler 400

 

My blaster seemed to have compression after it blew up. I even got it running afterwards, just knocked.

Before you do more damage to it, you should just take it apart and check it out.

Also, when it blew it was running great, then it sounded like it was just in too high of a gear and running out of a power, and it just stopped

 

A buddy of mine had that same problem once just after he got gas in it from the local gas station. Try draining the gas and adding some high octane fuel. She wouldn't start so we drained his added some higher octane fuel and there she goes same machine (400 Scr).

 

Did you unscrew the nut on the bottom of the float bowl under the main jet to see if there is fuel in the bowl? Maybe the jets got clogged (had that happen once with a piece of gasket) or maybe the floats got stuck?