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Discussion Starter #1
So here's what I got, hope you guys can help. 97 400 4x4, just bought the bike as of now piston and rings fried, cooling circuit not working properly, carb completely clogged, fuel tank gummed and cooling fins covered in red clay dirt. Flooded out in a mud hole apparently.

What I've done, cleaned carb, flush tank, install inline filter. Complete top end rebuild, wired cooling fan to toggle, flushed oil cooler fins, cleaned motor and changed rectifier. The bike is strong as an ox but is not taching up the way it should in gear. VERY SLOW. Notice the fuel filter doesnt fill all the way up could this be a problem?
 

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ct90/vf1100c
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The TRX400 fuel system was designed to not have a fuel filter in the fuel line from the fuel tank to the carburetor. The only way to be sure is to check the flow of fuel through the line to where it would connect to the carburetor. there should be a constant flow of fuel. It should NOT dribble gas.
Did you check the gas cap for obstructions or the vent line connected to the top of the cap?
Also, going back to the top-end rebuild - did you get the timing correct? One tooth is enough to make it growl and provide massive torque with no top end rpm.
You should probably go back and check your timing.
 

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Discussion Starter #3
The TRX400 fuel system was designed to not have a fuel filter in the fuel line from the fuel tank to the carburetor. The only way to be sure is to check the flow of fuel through the line to where it would connect to the carburetor. there should be a constant flow of fuel. It should NOT dribble gas.
Did you check the gas cap for obstructions or the vent line connected to the top of the cap?
Also, going back to the top-end rebuild - did you get the timing correct? One tooth is enough to make it growl and provide massive torque with no top end rpm.
You should probably go back and check your timing.
 

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Discussion Starter #4
When I get home today will check vent line omit fuel filter and check the timing. Will update later.
 

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Discussion Starter #5
When I get home today will check vent line omit fuel filter and check the timing. Will update later.
So far had time to omit fuel filter and check vent line still no change on top end. Going to check valve clearance and timing when the rain stops.
 

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Discussion Starter #6
So far had time to omit fuel filter and check vent line still no change on top end. Going to check valve clearance and timing when the rain stops
 

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Discussion Starter #8
Yeah it's pretty quiet but has good flow from what I can tell through exaust. Timing is good check valve set and one was a little loose don't think that was enough to cut me that short on top end. Haven't been able to run it after valve tweak but will update. Note when I cleaned the carb it was def one of the worst I've dealt with as far as gum. I say I did a good cleaning, but think this could be a fuel issue?
 

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2020 520 rubicon foot shift
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It might be a good idea to check the carb again then, the main jet could've picked up a little piece of dirt, there's not much left to check.
 

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Discussion Starter #10

  1. It might be a good idea to check the carb again then, the main jet could've picked up a little piece of dirt, there's not much left to check.
    So another update no change by minor valve adjustment. Gonna get a chem dip kit for carb. What is the function of the big plunger diapraphram in the top of the carb?
 

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Discussion Starter #11


  1. So another update no change by minor valve adjustment. Gonna get a chem dip kit for carb. What is the function of the big plunger diapraphram in the top of the carb?
I ordered another carb for a little more than a dip kit will update in about a week.
 

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ct90/vf1100c
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What is the function of the big plunger diaphragm in the top of the carb?
Did you mean # 17?
Pressure differential between the air box and the air intake to the engine control it for fuel delivery to the engine using the needle, #3. Lots of porting in that carb.
#9 is the throttle enrichment valve/circuit. Since it is not a choke in the true sense of the word.
EDIT: #17 - It is called a 'piston valve' by Honda.
150373
 

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I ordered another carb for a little more than a dip kit will update in about a week.
if you bought a china carb off ebay or amazon ?, then you wasted your money !.
 

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Discussion Starter #14
I bought one from ebay but def not China made crap. Pretty quick to pass judgement there shadetree.
 

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I have bought some of that "China Made Crap" and you would be surprised how well it worked for the applications we bought them for. Especially when the Honda ones were"NLA".

Just sayin.....
 

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I bought one from ebay but def not China made crap. Pretty quick to pass judgement there shadetree.
and what was the price if you don't mind me asking ?, and can you post a pic of it please ?, once i see it ?, i'll pass judgement then ?, i also asked if it was china ?, i DID NOT CLAIM IT WAS !. SHESHH. where do you '' know it all's come from ?.
 

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I have bought some of that "China Made Crap" and you would be surprised how well it worked for the applications we bought them for. Especially when the Honda ones were"NLA".

Just sayin.....
china crap is a hit or miss..do enough of this like i have ? ( 29 years now )..and you will learn this :).
 

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Discussion Starter #18
and what was the price if you don't mind me asking ?, and can you post a pic of it please ?, once i see it ?, i'll pass judgement then ?, i also asked if it was china ?, i DID NOT CLAIM IT WAS !. SHESHH. where do you '' know it all's come from ?.
  1. In all respect shadetree I feel you were passing judgement on me not the carbs. I'm a newbie on this forum not to mechanics in general. I know you have read my post and are also aware I'm no dummie.. I do my research and buy quality items. And by the way your right sore fingers there are some parts from china that are better suited than us made. I appreciate what knowledge you guys have bestowed on me but shade tree do me a favor and kick me out I see nothing but people arguing and bickering over a forum that I thought was made for info and helping out your neighbor. Good luck with all your projects.
 

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Discussion Starter #19
Last update.... carb fixed all. Eric and sore fingers thanks for all your help. Again good luck to you guys on all your projects.
 
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