Big Backfire wont Start

Came home from a ride approx 60km in bush, washed bike on the way home, now it won't start.

Drained carb and checked for water.

use air pressure to blow out all electrics to dry, removed magneto cover to see if it was dry and found oil(small amount, but checked on here and it is normal), no water or moisture. has fired about 4 times but does very loud gunshot type backfires.

Have checked many posts but cannot get definitive info.

This is the first issue I have had with the "wicked blue thing"

99 wr400 absolutely standard

This Might Sound Dumb But Have You Checked For Water In The Spark Plug Well :cry:

Something else you might want to check is the air filter. I had something similar happen to me and the filter got soaked with water.

Hmmm......... Did you take the carby off the bike? It sounds like water in the gas problem somewhere, either in your carb or in your gas. Drain the gas and clean the carb and might as well change your plug, maybe water somewhere caused it to foul.. I know, doubtful but you should try it...

Thanks for tips.

I will blow out spark plug well and try again and get new plug. I will have to get socket to fit as none of my existing XR tools will fit.

Thanks also Eruption, there was a small amount of water in air filter so i will clean it and start again.

Having ridden XR's and farm bikes, this thing is fantastic. I thought i was becoming a better rider until i realised it's mostly the bike.

I saw one post asking what WR stood for, maybe Woman Replacement?

Thanks again and thanks thumpertalk.

I had the same problem. Turned out to be water down the plug well. New plug and all was good.

thanks all who responded. new plug ( bit of a hassle to get in, had to cut plug spanner to fit it down well) put in new cr8e, started first kick. was water in well and old plug was slightly rusty.

am going in my first race this weekend on grasstrack. I know absolutely nothing about the process other than it will be like any other ride i go on, but with rules and results.

Thank you all very much, I only wish i knew more to be able to help others.

99WR 400 standard, new spark plug.

only blue will do.

Glad it was so simple. :cry:

ps -Bluebike, where are you? I'm in Sydney (Campbelltown).


I'm in Longford Tasmania, about 15 km south of Launceston.

Only had WR for about 5 months after long break from bikes. formerly had xr which resulted in busted discs in lower back. convinced wife that if I had more power it would be safer and got wr. WR is way more power and MUCH SAFER.

she even thinks that by me doing wheelies for miles is good because it doesnt run up k's with front wheel in the air and not turning and in turn can trade up to 426 or 450 and get more for my 400.Clever?

am going for first race this weekend on grasstrack. can't wait.

Mate, you are a genius!

I only bought my 426 a few months ago too. Had an RM before that, for only a few months aswell. That was my first dirt bike. Only other bike I've owned was a little ZZR250 about 10 years ago. I am/was a drummer and decided to sell my drums to buy a traily. Well, to convince the missus more acurately.

Loving it.

Good luck woth the racing.

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