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XR400 starting procedure

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I've just acquired a 1998 Xr400. The guy I bought it from said to start it:-

 

  • pull the manual decomp lever
  • kick it 3 times
  • drop the lever
  • kick again and it will start

 

and mostly that works, however the user manual doesn't suggest using the manual decomp level unless its flooded.

 

What have people found is the best way of starting ?

 

 

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Learn to use the forums search function. You'll get a quicker answer to your questions without having to wait on someone to answer your post.

 

The manual decomp is not just for clearing a flooded engine. It works great for priming the system by pulling in a fuel/air mix BEFORE you give it an actual starting kick. I like to go more than 3 times tho. DO NOT wick the throttle when starting. The stock carb doesn't respond to that.

 

Be sure you're not running too low of an idle speed.

 

Always bring the engine to TDC and start your kick from there.

 

For cold starting the engine for the first time of the day or after its sat awhile and cooled off, use full choke.

 

Learn to listen to your engine for what it needs. If you're kicking with full choke and it pops like its wanting to start, then nothing after that, put choke to half and kick again. Alternate back and forth between full and half choke as needed.

 

If it's still harder to start than you think should be normal, the most common causes are valve clearances that are too tight and need to be adjusted and/or the fuel screw passage and/or pilot jet is dirty/partially plugged up. If your bike sits as little as 2 weeks without being started, with fuel left in the float bowl from its last run, I suggest not even trying to start it until you've drained and flush the bowl. Fuel in the bowl goes stale faster than that in the tank and it also can start to varnish up the tiny passages in the carb.

 

And like George says, proper jetting for your elevation and mods is key.

Edited by Trailryder42
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Learn to use the forums search function. You'll get a quicker answer to your questions without having to wait on someone to answer your post.

 

The manual decomp is not just for clearing a flooded engine. It works great for priming the system by pulling in a fuel/air mix BEFORE you give it an actual starting kick. I like to go more than 3 times tho. DO NOT wick the throttle when starting. The stock carb doesn't respond to that.

 

Be sure you're not running too low of an idle speed.

 

Always bring the engine to TDC and start your kick from there.

 

For cold starting the engine for the first time of the day or after its sat awhile and cooled off, use full choke.

 

Learn to listen to your engine for what it needs. If you're kicking with full choke and it pops like its wanting to start, then nothing after that, put choke to half and kick again. Alternate back and forth between full and half choke as needed.

 

If it's still harder to start than you think should be normal, the most common causes are valve clearances that are too tight and need to be adjusted and/or the fuel screw passage and/or pilot jet is dirty/partially plugged up. If your bike sits as little as 2 weeks without being started, with fuel left in the float bowl from its last run, I suggest not even trying to start it until you've drained and flush the bowl. Fuel in the bowl goes stale faster than that in the tank and it also can start to varnish up the tiny passages in the carb.

 

And like George says, proper jetting for your elevation and mods is key.

 

i jetted my xr400 98 to 130 and 52 - thats what the shop said.

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i jetted my xr400 98 to 130 and 52 - thats what the shop said.

 

 

What kind of info about your bikes specific setup ( intake, exhaust, elevation, current jetting) did you exchange with the shop before they gave you that answer?

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I have pretty much narrowed down the starting procedure to a few simple steps.

First prime it three times, then put the choke to full on,

The pull in the manual decompression lever and kick it, on the way back up find tdc and just kick it hard, once it fires up put the choke to half on or i just turn it all the way off.

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What kind of info about your bikes specific setup ( intake, exhaust, elevation, current jetting) did you exchange with the shop before they gave you that answer?

 

its stock and im at 7200 feet - this is not recommended 

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I have pretty much narrowed down the starting procedure to a few simple steps.

First prime it three times, then put the choke to full on,

The pull in the manual decompression lever and kick it, on the way back up find tdc and just kick it hard, once it fires up put the choke to half on or i just turn it all the way off.

 

"First prime it three times"? You mean by twisting the throttle? That does nothing if you are still running the stock carb, as it is not a pumper.

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its stock and im at 7200 feet - this is not recommended 

 

The guys at the shop just looked up the stock jetting and applied the correction factor from the manual to account for your elevation and temperature. That's how they came up with 130. If they'd have done the same thing for the pilot jet, they would have come up with 45.

 

For a completely stock bike, no air box filter mods, snorkle removal, exhaust mods, you might be fine, I don't know. Honda jetted the main lean after '97. It came stock with a 142. Then apply a .92 correction factor. That is how they came up with 130. Not by any real riding or jetting experience for your bike and elevation. You'll just have to ride it and see how it runs. Check your plug periodically for signs of running lean.

 

I'm guessing your bike is newer than '97.

 

If the bike still has the stock 52 pilot in it, that's going to be too rich for 7200'. Learn to tune the fuel screw. Its state of tune will tell you whether the pilot jet size is right or not.

Edited by Trailryder42

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Someone told me once that the first few kicks are a waste of time because they set the fuel air mixture up correctly for the third kick, so they told me to kick it over lightly two times (all my xr decomp levers have been removed) and on the third kick set it up for tdc and jump on it. For cold start, full choke no gas, for hot start no choke, and a smidgen of throttle. That seems to work for me and my xr350 and my xr4

Edited by Undercover Poe

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Hi,

I'm on board with the proper jetting comments.  Mine was a serious pain to start...  tried every combination recommended, but usually had to resort to using starting spray.  Once it was warmed up it was better, but stop for lunch, let it cool down, grab the spray.

 

I finally rebuilt the carb because I was convinced that it must be gummed up and surely a good cleaning would do the trick.  I knew that the previous owner did some upgrades including a high rev kit and a white bros exhaust.  During the carb rebuild I also found that he put in a bigger main jet, but left the stock pilot jet.  So, all that time I was trying to start the bike and idle with a pilot jet that was way too small.  Put the proper jet in (had to guess, but anything would have made an improvement).  After putting everything back together, it started on the second kick and idled without having to keep blipping the throttle.

 

I removed the decomp lever.  I still use the kicker to get the engine to TDC before giving it a good starting kick.  But now it starts on the first or second kick and I don't have to mess with the idle RPM wheel any more.

 

Doug

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