Jump to content

  • Do you own an ATV? Join our Forum!

    As a member, you can post in our forums, upload your photos and videos, use and contribute to our downloads, create your own member page, add your ATV events, and even start your own ATV club to host your own club forum and gallery.  Registration is fast and you can even login with social network accounts to sync your profiles and content.


1999 TRX300 Starting issue

Recommended Posts

Been slow in starting up, in the recent past it would start up in <1/2 second of the button press with a snap. Now it takes several seconds of cranking to get going. Once going runs as it always did. Replaced the plug no change. Battery is good.

Before I tear it apart and look things over was hoping others might have had the same experience and have a quick fix for me

Thanks in advance for any and all suggestions to get this old machine starting quickly again as it has for 20 years.  

Share this post

Link to post
Share on other sites

Probably needs a valve adjustment would be my guess.   You can check this by taking a simple compression test. I would also check the fuel delivery system. Maybe a little bit of dirt caught up in the needle where the float is. This could cause The gas from getting up into the intake port of the carb.  

You could have gotten some bad or dirty gas.

Hows the gas in the bike fresh ? Is the tank clean and maybe a fuel filter if you clean the carburetor. 

Last thing is make sure there are no leaks on the intake boot where the carburetor is mounted and make sure your vent hose on the gas cap is clear.   

Share this post

Link to post
Share on other sites

Might be a valve adjustment - don't believe its ever been done - Will try a compression and leak down test this afternoon

Always used fresh gas with NO alcohol - only thing is that it's 91 only way to get no alcohol around these parts 

Will also take a close look at the carb

Anyone know what the KV of the spark should be?  I have a Pico Scope with the pressure transducer for so can easily see the compression, spark amplitude, dwell, etc..  

Strange this starting issue happened almost overnight about a week ago - Guess it's time to get my hands dirty 

Share this post

Link to post
Share on other sites

My guess would be a fuel delivery issue that can be solved with a good carburetor cleaning and add a fuel filter as well.   But I’m sure a valve adjustment is long overdue.  

As far as spark goes if you can clearly see a good spark when you pull the plug and test it then you don’t usually need to dig deeper into that.  

Might as well double check your timing as well while your adjusting the valves. 

Share this post

Link to post
Share on other sites

Our 1990 Fourtrax 300 starts instantly in less than a full crank. But our 1985 250 cranked on and on but it would start quicker if we shook the machine. It ended up being a plugged screen in the sediment bowl on the bottom of the fuel shutoff valve. It wasn't getting a good fuel flow to the carburetor. 

  • Like 1

Share this post

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Similar Topics

    • By Brock Kincaid
      Ok so just picked up an 02 ds 650 and the guy said he couldn't get it to start. He had a shop put new shims in it and I had them checked and they were ok now things I've done is new plugs even though guy had just put new plugs in it.. got new carb 42mm just like the one that was on it.. bought new intake manifold because the one that was on it someone got way to tweaked out and ported the shit out of it excuse my language but yeah so installed new intake manifold and it just won't start like its not getting enough fuel.  Timing seems to be right it does fire every now and again but just barely.. did a compression test today and it was at 90psi.. i know thats low but don't know where I'm losing compression.. valves we at .06 and .07 when checked im lost ive tried everything I know and can't figure it out
    • By BuckBilly
      Good morning to all !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
      Let's see if we can make this a daily event.
    • By Brent Wright
      What's a good size to start a 10 year old on?
    • By ATVNetwork
      After an extended break between rounds along with a venue change to add to the mixture, the 2020 ATV Motocross National Championship Series, an AMA National Championship, continues to showcase some of the greatest battles the series has seen. With the season pushed further into the fall months and the cancellation of the Loretta Lynn’s round, Lake Sugar Tree in Axton Virginia would host the seventh round of racing.
      View the full article
    • By Dskip160
      Hey there! New guy here! So I bought an 87 250. I turn the key and it has ignition light. I press run and the engine turns over. Guy I bought it from said the carbs may need cleaning, I worked them good cleaned and blown out. I reinstalled the carb and still doing the same thing. It’s getting fuel, the battery is brand new and charged I’m lost here!( purchased a new carb on its way) anyone have any ideas

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Create New...