My 450R carb installation

[400exMO]

Originally posted by trx400 rider
ok so it will be ok to just tuck it out of the way

You will be fine

[trx400 rider]

ok cool.. and that leak jet you were all talking about do i need to get one or a new one.

[trx400 rider]

ok im confused again lol u told me to get a 50 and 52 pilot jet and when i was looking around some people were only useing 42 piolt and 155 main. and they are much more modded then mine. mine has a pro cricut pip k&n air filter and .50 borded over

[zrpilot]

Originally posted by trx400 rider
ok im confused again lol u told me to get a 50 and 52 pilot jet and when i was looking around some people were only useing 42 piolt and 155 main. and they are much more modded then mine. mine has a pro cricut pip k&n air filter and .50 borded over

I can't tell you WHAT EXACTLY will work with your quad, but I can help get you close.

[richards]

Originally posted by trx400 rider
ok im confused again lol u told me to get a 50 and 52 pilot jet and when i was looking around some people were only useing 42 piolt and 155 main. and they are much more modded then mine. mine has a pro cricut pip k&n air filter and .50 borded over

42 sounds small for the 450R carb on the 400ex. Also watch what you read on mains - the numbers are different for Keihin and Dynojet mains. For example, a Dynojet 155 is in between a Keihin 170 and 172 in terms of the size of the hole in the jet. It is confusing that they use different labeling schemes.

zrpilot's recommendations for you sound reasonable. My stock 400ex is running pretty good with a 48 pilot and a 172 Keihin main in a 450R carb. I just picked up a 50 pilot and will give that a try soon. It makes sense that your modded engine would likely need a slightly larger pilot and main.

And I will second the fact that nobody is going to be able to tell you exactly what will work. You will need to buy a handful of jets and try them along with different needle clip settings

[richards]

Originally posted by trx400 rider
its like a brake cable.i thought the hot start was the wire with and cap at the end

This brings up a good point that I have not seen mentioned yet (or maybe I missed it)... The 450R carb comes with a heater installed and there is no existing electrical connection for this on the 400ex. I just removed the heater, although you could leave it in place and just tuck the wires out of the way.

The heater is brass, located on the bottom of the carb next to the fuel screw, has a 12mm hex head on it, and 2 wires coming out leading to a 2 prong connector. You can just unscrew it and leave it off, the hole it leaves does not have any passages into the carb. It was put there to heat the carb to prevent ice from forming and I bet the 400ex does not have one since it is air cooled and the head runs hot enough to prevent carb icing.

[richards]

Originally posted by FlewByU352
so how much power really is there to be gained on a internally stock quad? i hear throttle response but that doesnt matter to me i have the choke plate removed and the timing advanced. Has anyone tried removing the choke plate in the R carb?

You are right, it is not really about power on a stock engine. I have just done mine so no extended test yet but I am looking for better throttle response, not much more power. I did not want to remove the choke from the stock carb, I do enough cold weather riding to make that impractical. The 450R design is better here, you get an enricher circuit without the choke plate so that is a plus. Basically my thinking is that I would like to have the carb upgrade first as it provides a good base for any future mods.

[exquad]

Im in the process of putting the 450r carb in and i know that i am supposed to use a 450r fuel line, but that fuel line is much bigger than the stock. My question is, the size of the fuel line needed on the carb is much bigger than the one needed on the fuel tank, which means the new fuel line would have to have one end big enough to fit the carb and the other end would have to be smaller to fit the fuel tank, what do i do?

[Snipe]

use the 400ex fuel line get one end wet with a bit of oil to cause it to expand and the oil acts as a lubricant. It will go on pretty easy after that.

[exquad]

Ok, also i have the 450r throttle cable and it doesnt seem to be working, it seems to be too short. By the time i get the throttle cable all set up on the carb there is absolutely no slack on the thumb throttle side, any suggestions?