CR500/KX500 Fuel Primer

mtn-doo · Aug 23, 2014

Hey guys,

These are a great aid in adding fuel to those big cases to help for a quick start when cold. That big case needs fuel to reach a decent AFR to light. This is a push/pull Mikuni primer. Installed in the main fuel line. The primer port is a small brass nipple tapped into the back of the Carb. Three pumps on a cold engine and it jumps to life. This primer with the compression release makes this Service KX500 a breeze to start. Be sure to shorten the thread reach on the nipple for a flush, clean finish on the inside of the carb.

portgrinder · Aug 24, 2014

looks like you need a new carb boot randy!

nice setup though. primer helps big time. i made a backet to put it up on the triple clamp by my egts

found a nice larger fuel tank too. few min w a heat gun and you can mold it to clear the head

summitboy · Aug 24, 2014

Are those 1/2 to 1/8 to 1/2 brass fittings ? My primer came with plastic T's etc and id like to change em. Also thats a 1/8npt nipple you used in the Smarty ?

mtn-doo · Aug 24, 2014

portgrinder said:
looks like you need a new carb boot randy!

nice setup though. primer helps big time. i made a backet to put it up on the triple clamp by my egts

found a nice larger fuel tank too. few min w a heat gun and you can mold it to clear the head

Sharp eye Joel,...

That boot is toasted for sure.

mtn-doo · Aug 24, 2014

summitboy said:
Are those 1/2 to 1/8 to 1/2 brass fittings ? My primer came with plastic T's etc and id like to change em. Also thats a 1/8npt nipple you used in the Smarty ?

It's 1/4 X 28 nf. The Brass fitting came as a interference fitting. I threaded it 1/4, 28 then drilled and tapped the Carb accordingly. Here are a couple more finished pic's. The short primer lines seem to push a lot of fuel quick. Seems to work really well. I fabbed the hanger from a ski-doo suspension bracket and mounted it to the head stay. Knob on the right, kick side, and fuel side on the left close to the fuel lines and carb. Short lines and super clean.

eskimojoe77 · Aug 25, 2014

Back on a 500?

Mtn-Doo are you going to be back on a 500 stroker for the 2014-15 season? Curious what your next ride is.

wwillf01 · Aug 27, 2014

mtn-doo said:
Hey guys,

These are a great aid in adding fuel to those big cases to help for a quick start when cold. That big case needs fuel to reach a decent AFR to light. This is a push/pull Mikuni primer. Installed in the main fuel line. The primer port is a small brass nipple tapped into the back of the Carb. Three pumps on a cold engine and it jumps to life. This primer with the compression release makes this Service KX500 a breeze to start. Be sure to shorten the thread reach on the nipple for a flush, clean finish on the inside of the carb.

Is there an alternative... Or is it just a ton if kicks?

Sent from my iPad using Tapatalk HD

mtn-doo · Aug 28, 2014

A spray bottle of fuel and access to the intake, or, what we used to do, lay it on it's side until fuel is running everywhere, stand it up and start kicking. That was the original method in the 80"s. A primer is a good fix.

wwillf01 · Nov 2, 2014

mtn-doo said:
Hey guys,

These are a great aid in adding fuel to those big cases to help for a quick start when cold. That big case needs fuel to reach a decent AFR to light. This is a push/pull Mikuni primer. Installed in the main fuel line. The primer port is a small brass nipple tapped into the back of the Carb. Three pumps on a cold engine and it jumps to life. This primer with the compression release makes this Service KX500 a breeze to start. Be sure to shorten the thread reach on the nipple for a flush, clean finish on the inside of the carb.

So with the primer do you need to pull the choke? This just came in for my cr500

Pbeaud01 · Nov 16, 2014

Can you buy this kit or is it just get your self the pieces and make one? Also what larger tank can you run. I'm currently building a 2012 kx500af and need all the input I can get.

wwillf01 · Nov 16, 2014

You can order the mikuni parts then you drill it into the carb... mtn-doo shows you in is kx500 thread

portgrinder · Nov 16, 2014

the primer usually comes w some hose. you'll need a T somewhere to draw the fuel in.

the brass nipple on the carb is a 10/32 tap size that i used. lots of room on the back of the kehin to tap it in. 1/8in tubing

IMS makes a 3 gal tank for that bike. i got one from SH. if i remember right i had some shenanigans getting the fuel petcock to fit though. i think i had to make a gasket and oblong a bolt hole on the petcock. then i think the fuel line bend was too tight, so my fuel line loops around the head and then over to the valve on the frame. it helps though because you have some more slack when you take the tank off. its meant for a 250F as well, so you need to heat it up and make some clearance for a few things underneith. off the top of my head, the coolant hose going to the rad on the other side, the coil, and the plug all needed some more clearance. not too much work with a heatgun and some patience.

adamd1979 · Nov 16, 2014

Thinking about doing one of these. Would it have the same result if I were to tap into the top of my rad valve inlet? Just engine side of the rubber boot. This way it wouldn't interfere with my carb jacket and would be one less thing to disconnect when removing the carb.

the gman · Nov 16, 2014

I am installing this on my 500 and my 300. I am going to install it BEFORE the slide. I know, I know, in the intake stream would be better but if it ever comes loose I worry about a lean condition. Hold the throttle wide open and stroke the motor and gas will get there without the worry of running lean. Just my thought on it....garry

preclatton · Nov 18, 2014

I've always just tipped the bike on its side to fill the bowl and it starts easily. That is with a PWK carb. However, I am looking into a smart carb for this year (CR 500). Will this method still work for a smart carb? OR do you need the primer. I don't like the idea of drilling a hole in a $675 carb and may have second thoughts if they are harder to start than with a convenional carb.

summitboy · Nov 18, 2014

I found if i tipped the bike over 3 times with cycling the motor over 3-4 times it will almost start 1st kick when cold. Took a while to figure it out. Primer would get rid of the hassle i think. I wish the Smarty had a way bigger choke circuit.

adamd1979 · Nov 22, 2014

Just finished installing the primer with the smart carb. It started hard before when it was cold, but after a few pumps of the primer, it fired up fist kick. Way worth the $25 and a few hours of work.

M5- · Nov 22, 2014

I just got a primer for my Cr500. BTW that's a good idea with the hose on the decomp I think I might do that maybe help keep it from getting snagged on something.

M5

Mofood · Nov 27, 2014

Where is everyone sourcing their primers/kits? So far only able to find primer plunger on ebay. Thanks in advance!

Btw Newb here..glad to have these resources

the gman · Nov 27, 2014

Farts unlimited has one for 24.95....820005. It is a choke elimination kit and you use the one brass fitting and thread it. I threaded the fitting into the carb boot right before the carb on the top side and with the angle of the boot slanted to the carb the squirt runs right down the carb body and under the slide. This setup is working for me but was warned it has not worked for others. IF your boot is angled away from the carb this way won't work. Hopes this helps....garry

CR500/KX500 Fuel Primer

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