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42 Posts
I have a 400ex and i would like to re-jet my engine to get the most out of my ride. As of now i have aftermarket exhaust and intake and was wondering if anyone knew if i should go stage 1 or 2 for the jet kit. thanks
want to re-jet engine
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7,526 Posts
You can call these guys and they can set you up.
Dynojet Jet Kits - Offering Motorcycle Jet Kits & ATV Jet Kits
Dynojet Jet Kits - Offering Motorcycle Jet Kits & ATV Jet Kits
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42 Posts
i was thinkin that maybe i should just go stage 2 right away because very soon i plan on putting in some kind of performanc piston and maybe a new cam so then it would all work together very good
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42 Posts
i figured that but when i am to install i figured i could just throw in the stage 2 right away and run that until i get more of my mods
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6,604 Posts
Stage 1 Jet Kits
Intended for motorcycles with a stock engine using the stock airbox, air filter and stock pipe. Stage 1 kits are fully adjustable to allow the use of a well designed aftermarket pipes and stock replacement air filters like K&N. Stage 1 kits are designed to improve throttle response and driveability and in most cases power increases of approximately 5% throughout the entire power range can be achieved. anchor point navigation
Stage 2 Jet Kits
Intended for motorcycles with a stock or mildly tuned engine using a well designed aftermarket pipe with a modified airbox and a stock replacement air filter. Stage 2 kits are designed for applications where individual filters cannot be installed and for applications where airbox modification improves the engine's performance. In most cases power increases of approximately 8% can be achieved.
Stage 3 Jet Kits
Intended for motorcycles with stock or mildly tuned engines using a well designed aftermarket pipe and individual air filters. In most cases power increases of 10-15% can be achieved. However driveability may be compromised particularly with short stroke, high rpm motors. On some modern engine and airbox designs, individual filters and proper jetting offer no performance improvement yet compromise driveability, in such cases stage 3 kits are not available.
Intended for motorcycles with a stock engine using the stock airbox, air filter and stock pipe. Stage 1 kits are fully adjustable to allow the use of a well designed aftermarket pipes and stock replacement air filters like K&N. Stage 1 kits are designed to improve throttle response and driveability and in most cases power increases of approximately 5% throughout the entire power range can be achieved. anchor point navigation
Stage 2 Jet Kits
Intended for motorcycles with a stock or mildly tuned engine using a well designed aftermarket pipe with a modified airbox and a stock replacement air filter. Stage 2 kits are designed for applications where individual filters cannot be installed and for applications where airbox modification improves the engine's performance. In most cases power increases of approximately 8% can be achieved.
Stage 3 Jet Kits
Intended for motorcycles with stock or mildly tuned engines using a well designed aftermarket pipe and individual air filters. In most cases power increases of 10-15% can be achieved. However driveability may be compromised particularly with short stroke, high rpm motors. On some modern engine and airbox designs, individual filters and proper jetting offer no performance improvement yet compromise driveability, in such cases stage 3 kits are not available.
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32 Posts
Gilby if you want the most out of your engine with all the mods you are planning on doing just throw away your stock carb, cause they are vacuum opereated, and get a FCR flat side that came off of a CRF250. The carb will fit with a little bit of tweaking but nothing serious. They are a 37mm carb and will be a great investment for your 400 that will add top end power and most of all more responsive. Any further questions just let me know and I will help in any way I can.
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42 Posts
ok. i will have to look for one of those carbs. i plan to re-jet before beginning any big engine mods so should i keep the carb in and re-jet and then wait to put the FCR flat side after i bore out the engine?
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18,211 Posts
Will this application work for my 250X? I could use the responsiveness when i change out my head.
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32 Posts
Red is correct and it doesnt matter but if you do make mods to your engine, to keep things less complicated, instead of doing all the changes it may be smart to keep the stock carb and get it running good and get all the bugs out before taking on the fcr carb change.
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32 Posts
TRX i dont c why not. The only thing that may be a bit hard is finding the right boot that goes between the carb and head? The fcr carbs have a bit bigger sized hole that goes on the head side of the carb and your stock boot from the 250 will not work. May have to get either a trx450 boot or so. I have a nephew with a 400ex and wants to put on a fcr so i will know more details on this in a few weeks or so.
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