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need help!!! kjs with Mikuni TM40

P901 Single carb intake, FLAASH Cams, Super Charger, NOS.......
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need help!!! kjs with Mikuni TM40

PostAuthor: Thrash47 » Sun Aug 06, 2017 1:27 am

before i start, i have an 87 xv700 and just installed the KJS composite with Mikuni TM40 and I cant get the bike to start. I wants to, but just pops thru the carb. The main jet I have is 152.5, have not taken the bowl off to look at pilot, but by all i have seen it should be a 20.
I got this setup second hand, but it is brand new and never was installed on a bike. I let everything sit as per instructions and I know I have spark, and fuel, so I'm looking for a little guidence here. Also just adjusted valves and they were way too tight. many thank!

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Re: need help!!! kjs with Mikuni TM40

PostAuthor: bstig60 » Sun Aug 06, 2017 6:48 pm

If you have both a strong spark and fuel, and good compression, the engine will start. Something tells me you are not getting enough fuel. Are you sure the float level is correct and that you have fuel in the bowl? I am not terribly familiar with the TM40, but assuming the former is correct, adjust the pilot screw out 3 turns and try starting the bike again. If that doesn't work, try spraying some starting fluid directly into the intake and see if the engine fires. If it doesn't fire with the starting fluid, you may have a spark problem. Install new Autolite AP63 Platinum plugs and try again.
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Re: need help!!! kjs with Mikuni TM40

PostAuthor: Thrash47 » Mon Aug 07, 2017 2:09 am

Thanks for your imput. I have good spark, and seems as though I have plenty of fuel, there is fuel pooling in the intake! I just ordered an intake from Adam Smith, because this KJS intake looks like crap! It's very rough inside( composite ) and the paper gaskets did not line up with the intake runner holes, had a slight bit of the gasket blocking the bottom portion of the port. Plus, not sure that the float level is set right?? All I know is I'm pretty frustrated. Any other suggestions are welcome.

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Re: need help!!! kjs with Mikuni TM40

PostAuthor: billygee » Wed Aug 09, 2017 12:27 am

Do you know what model Virago that KJS came from? If it came off a 1000 or 1100, the float needle and seat are likely set up for the 1000/1100 and not the 700/750 due to the former's fuel pump.

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Re: need help!!! kjs with Mikuni TM40

PostAuthor: Thrash47 » Sat Aug 12, 2017 1:34 am

it was set up for a 750

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Re: need help!!! kjs with Mikuni TM40

PostAuthor: billygee » Sat Aug 12, 2017 10:21 pm

Thrash47 wrote:it was set up for a 750


Ok, you have the 152.5 main and 17.5 pilot with the 3.0 float needle and seat. Your bike should start up easily with that if installed properly.

if you are finding a pool of gas in the intake, it's because your accelerator pump is squirting raw gas directly into the intake and it pools there every time you twist the throttle and the bike doesn't start. That can lead to flooding your cylinders and fouling the plugs. Do NOT twist the throttle to start the bike. Only crack it open a touch if warm or use the choke if cold.

Now there is a problem I find with many that install the KJS or Adam's intake themselves is that they DO NOT FOLLOW INSTRUCTIONS. When they don't follow the instructions for using the Ultra Black RTV, it creates all kinds of massive vacuum leaks. You must put an even layer of RTV on both mating surfaces, put the intake on barely finger tight and LEAVE IT FOR AN HOUR. After an hour, tighten the bolts down as usual, clean any excess RTV with a damp cloth and leave the bike the hell alone for the next 12 hours so the RTV can fully cure. Then you should have no problem starting it if all else is good.

Most seem to be too impatient to wait for the RTV to cure and try to start the bike right away. Well, the RTV is still ultra soft and not fully cured, so the engine vacuum is gonna pull that RTV in and leave gaps where the air can leak into the intakes.

Make sure you either plug that vacuum nipple on the rubber carb flange or connect it to your petcock if you have a vacuum operated petcock.

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Re: need help!!! kjs with Mikuni TM40

PostAuthor: Thrash47 » Sun Aug 20, 2017 8:48 pm

That is correct, but I'm pretty deliberate when i follow instructions, and I did this time to the T. I let the RTV set and did not try to start the bike until the next evening. I ordered an intake from Adam

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