Jump to content
Sign in to follow this  

TT FCR MX searched, searched, and now frustrated

Recommended Posts

Ok So I thought my jetting issues were over last week, when the bike seemed to be running ok. Thing is I was only taking it on short rides. Well I have so many issues right now, I am at my wits end. I have taken off my seat and fuel tank so many times I can't even look at it anymore. It all started when I purchased my TTFCRMX couple of weeks ago, it has never run well since day one. All the searching I did here and the jetting forum does not help me. Here are my mods....

3x3 exactly

TT FCR MX 160 main, 42pilot(currently) pilot air jet removed, merge fuel screw at 0-2 turns out, EMN needle 2nd clip, sea level, 70-85 degrees, 20%humidity, no vacuum leaks, intake boots tight

Yosh TRC full exhaust, spark arrestor removed

Uni Air filter

Ok since day one I have had this nagging studder while riding, 1/8-1/4 throttle opening steady throttle. Surging like running out of gas feel.

So I started with the stock recommended jetting specs. 160main, 45 pilot, 3rd clip on EMN needle.........

From that I got a really annoying studder. I tried moving the clip down one notch, got worse, went back up to second clip from top. A very slight change for the better.

Tried the EMR needle, no more studder, but really fat on the bottom and a hanging idel I could not get rid of.

Back to the EMN needle third clip, the 45 pilot was so rich I could turn in the fuel screw all the way and the bike still runs, poorly but it runs.

Now I put in a 42pilot with exactly the same results, I can turn the fuel screw all the way in and it still runs, just poorly.

Do I need to put in a 40 pilot jet? I also get alot of decel popping with throttle fully closed.👍 I also forgot to mention that the longer I ride the bike the worse it gets. Like after 5 miles.

Share this post


Link to post
Share on other sites

You are chasing your tail. You are doing multiple carb circuit changes at once, hence your frustration,

Pilot jet and fuel screw are for idle only. Once you have that right, leave it alone!!!!

I assume you did the main jet test and it is good, so no more changes to that either.

This now leaves youir with the needle. This changes everything from just off of idle to just below WOT.

There are two areas of the needle to understand. The straight diameter and the clip poistion with your two needles. The stright diamter, represented by the last letter of the needle affects throttle operation between just off of idle to about 1/3rd throttle. The EMN needle is slightly richer than the EMR. The EMR is a slightly larger diameter and therefore leaner. The clip position affects throttle operation from 1/3 to just under WOT. It also move the exact point at which the 1/3 spot is. Both The EMN and EMR are the same from about 1/3 throttle to just below WOT (same first two letters)

Being the studder went away with the EMR Needle at small throttle openings, your bike was running a little rich with the EMN and therefore the EMR is the correct needle.

Start your testing with this needle, clip position #3 (from the top/flat).

Share this post


Link to post
Share on other sites

you are 100% you removed the pilot air jet and not the main air jet?

the EMR is leaner than a EMN so it impossible for it to get "fatter on the bottom" with it.

if you are 100% sure on the pilot air jet do the following and report back.

turn the idle down as low as the bike will consistently stay running when doing the fuel screw tests.

install the EMR needle 3rd clip from the flat end.

put the 45 pilot jet back in your bike with the fuel screw at 2.25 turns.

Share this post


Link to post
Share on other sites
you are 100% you removed the pilot air jet and not the main air jet?

the EMR is leaner than a EMN so it impossible for it to get "fatter on the bottom" with it.

if you are 100% sure on the pilot air jet do the following and report back.

turn the idle down as low as the bike will consistently stay running when doing the fuel screw tests.

install the EMR needle 3rd clip from the flat end.

put the 45 pilot jet back in your bike with the fuel screw at 2.25 turns.

Will do right now, report back in about 45 min.

Share this post


Link to post
Share on other sites

Ok, I am reporting back on the results. Bike starts easy. The studdering is completely gone, but now it back fires like a gun fight with the throttle closed on decel, does not matter the RPM's. It does not seem like it has as much power. I started at 2 1/4 turns on the FC. I can turn it almost all the way in before it dies. It dies just when I fully close the screw. The idle is set very low. It seemed to idle ok after just riding easy and coming to a stop, but after hammering the throttle 2-4 gear and then coming to a stop, the idle drops super low and almost dies.

Share this post


Link to post
Share on other sites

needle straight diameter doesnt have any reall effect n power especially with the throttle wide open.

have you sealed all the pipe joints?

are you sure the o-ring is still intact?

Share this post


Link to post
Share on other sites
needle straight diameter doesnt have any reall effect n power especially with the throttle wide open.

have you sealed all the pipe joints?

are you sure the o-ring is still intact?

Yea, I check the o-ring like it's a compulsive thing. Still there. I don't have any exhaust leaks, no tears in intake boot.

Share this post


Link to post
Share on other sites

It runs pretty well now, except for the loud backfiring and crappy idle, I can live with a slightly hanging idle, the backfiring I can't. I have neighbors that already want me dead.👍

Share this post


Link to post
Share on other sites
...and to add, turn your idle speed up now to a normal idle speed. Lowering it is just to be a little more accurate with the fuel screw.

Yes, I just did that. I am in the garage right now. Seems ok for now. Opening the FC more did not get rid of the backfiring, so I just put it back where is ran the best 2 1/4 turns.

Share this post


Link to post
Share on other sites

the pop on decel is just a fact of life.trying to cure it via jetting will just make your bike run bad.

sealing the pipe joints will minimize it.

Share this post


Link to post
Share on other sites
the pop on decel is just a fact of life.trying to cure it via jetting will just make your bike run bad.

sealing the pipe joints will minimize it.

Ok Eddie, and William. Will do. what should I seal them with? I guess I am not used to that much backfiring, it didn't do it that much with the stock Mikuni with JD kit. Guess my neighbors will form a mulisha and stone my bike when I am not looking.👍

Share this post


Link to post
Share on other sites
the stock carb has a air cut valve.

you use permatex ultra copper on all the slip joints.let it cure 24 hours.

Thanks for the quick reply, will do.👍

Share this post


Link to post
Share on other sites

What I do to minimize teh decel pops is to either roll the throttle off gently or leave in a high gear and slow using the brakes. With some practice, you;ll be able to ride and keep a fairly low key. Having an open Yosh, you can learn to reduce the Db level simply with your wrist.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...