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Gordon mods help!!!!!

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I tried the gordon's mods and so far my bike runs pretty crappy. It is a 02 xr400.

I started with putting in the 96 xr 400 spark arrestor which flows a ton of air and it is very loud. The bike didn't gain much power. I then put in a 58 pilot jet and a 160 main and the bike seemed to have maybe a little more top end and it ran pretty good.

But once I pulled the snorkel out of the air box it ran like crap. It bogs and doesn't start excelerating until really high rpm's. Could it be running lean now with the snorkel out??? Everything I read said that a 58/160 was a good way to go. There's no way this engine needs a 162-165 main and over a 60 pilot???

engine is bone stock with the uni filter.

elevation is about 700-800 feet.

Should I put the snorkel back on??

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I would not put the snorkel back in, but I would check for either an air leak or possibly some blockage still in the pilot circuit. I know that these bikes run well with a #58 pilot and #160 main because I have set up three XR4's with the same size jets.

I have read that "Baja Trail Rider" uses #165 mains in some of his stock Keihin's, but it should run fine on "Gordon's" recipe.

Don't give up on these jets... they DO work !:bonk:

Perc

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To add, you DO realize that each change requires you to retune the fuel screw. You can't make an airbox or exhaust change, drop in a different pilot and call it good.

There's also the needle clip position to think about.

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I checked the pilot jet when I put in the new 160 main, the pilot was perfectly fine. No leaks anywhere either. I think it was running super lean. I did adjust the fuel screw also today and all signs indicate very lean! There was a good amount of backfiring also.

I just put the snorkel back on and left the 58/160 in the carb and it runs much better now. I really think my bike needs like a 62-65 pilot and a 165 or higher main with that snorkel off to make it run good. Anyways it seems to have some more mid/top end power but I think I lost a little bit of low-end grunt and it kind of makes me think that maybe the stock exhaust is better. I love low end! I feel like I am riding a two stroke with this loud exhaust and higher end pull. It is all good though!:bonk: I will keep experimenting in the future with it but I have a feeling I may end up liking the bike in stock form best!!!!

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If the float level is low it will be lean at low speeds, I've found 1/2-1mm change in float level is about 1 turn on the mixture screw, or roughly 1 pilot jet size.

Also there are two very small low speed discharge ports in the floor of the venturi, one is the idle port and the other low speed transition to the needle. If one become even partially obstructed the bike will display lean symptoms.

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I can't believe that a #58 pilot is too small. As you open the adjustment screw, does it make any difference?

I can believe however that the pilot circuit may be partially clogged. Did you remove the adjustment screw and clean out all passages ?

Perc

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I have an 01 XR400, removed snorkel and replaced with a UNI, also, 4 1/4 inch holes in the baffle, I am in PHX, just over 1100 feet in elevation, but after the changes, for the most part the bike ran great and noticeably more power. I knew from research that I may have to change jetting and so on, so I ran the bike hard and got er real warmed up to check the plug. I did this and the plug looked fine ... nothing indicating rich or lean, this said, I now have consistent backfire at about 1/8th to 1/4 throttle, more so when its cold, but also hot, I was told a click or two up on the needle and adjust fuel screw to high idle after the bike is good an warm, I have yet to try it but you may not have to re jet.

my two cents ... I'll be trying tomorrow.

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Up your pilot jet with the snorkel removed. If you put the snorkel back on and it helped thats a pretty sure sign of being lean still.

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Trailryder, so if factory for that year was 62/162 with snorkel in, Maybe I should try like a 62-65 pilot and a 165 main with my snorkel out with the 96 spark arrestor to richen it up, and maybe set the needle one setting richer to get some more pull out of the old girl? I am sure that my 58/160 is super lean! Is it hard to find the correct jets when you get as high as a 65/165 as far as finding them and buying?

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Michigan400, yeah once I put the snorkel back in it ran fine. I need some big jets for her with that snorkel off. For now I am just enjoying my stock torque again, did you notice any torque loss when you did your mods?

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Trailryder, so if factory for that year was 62/162 with snorkel in, Maybe I should try like a 62-65 pilot and a 165 main with my snorkel out with the 96 spark arrestor to richen it up, and maybe set the needle one setting richer to get some more pull out of the old girl? I am sure that my 58/160 is super lean! Is it hard to find the correct jets when you get as high as a 65/165 as far as finding them and buying?

Make 1 change at a time. Start with uping the pilot 1 size and re tuning fuel screw.

162/62 on the older units was with the snorkel (different type though) pulled out.

I did loose bottom end untill I adjusted the jetting. But, I have a pumper carb so all I did was richen the fuel screw about another turn and I made the pump come on a touch sooner. Got it back and then some after that. I put the stock end back on afterwards for a comparison and it felt weak. Like someone stuffed a tater in the exhaust.

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Michigan400, yeah once I put the snorkel back in it ran much better. I need some big jets for her with that snorkel off. Maybe the 62/162 might due the trick. For now I am just enjoying my stock torque again, did you notice any torque loss when you did your mods?

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96-97 came jetted for "racing". Honda assumed you would pull the snorkel and the quiet core to lean out the overly rich stock jetting.

98-04 came jetted for "trail riding". Honda assumed you would leave it stock. CA bikes are even leaner in the jetting.

Pull the intake snorkel only. UniFilter added. No exhaust mods.

55 pilot and 155 main jet.

Gordon's Mods is simply going back to be closer to the 96-97 jetting. But every bike is different, air temp, altitude, humidity, riding conditions. 60 pilot and 162 main is a good start. Read my FAQ on the "Dreaded Bog" to learn how to check the pilot jet and fuel screw settings.

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Trailryder, Maybe I should try like a 62-65 pilot and a 165 main with my snorkel out with the 96 spark arrestor to richen it up, and maybe set the needle one setting richer

Like Kev said, factory jetted that year rich with the 162/62. So doing airbox and exhaust mods with that jetting, depending on elevation and weather, may be the ticket.

And like Mich said, make 1 change at a time. If you see a change in how the engine runs after having done more than 1 change at a time, you don't know what change it was that made the difference.

Jet and tune the pilot circuit/fuel screw, get it right. Then jet the main, get that right. Last, alter the needle clip position (if required). Stock clip position is 3rd from top.

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