top speed problem solved,jetting advise, and how it came about.

[3 or die]

Most of you know about the top speed problem I have had since I purchased my first waterpumper. At speds over 60mph I noticed my 250r holding back, like it needed more fule. I cleaned jets, changed plug with no progress. I did some reserch and got it corrected.

A stock 1985 250r uses a #142 main jet with the c-clip on main jet needel in the #2 notch. The air screw is screwed all the way in and backed out two turns.

Well when I dropped the bowel off my carb I found that it had a #150 jet in it, I was thinking wtf, its huge and still not enough, but I was sure that it was starving for more fule.Just in case I orderd a #142 jet and a #152 jet. I made sure main jet needel was in correct position, put in new jet, set air screw, and started it up. I could tell as soon as it started it was better.

My called my close friend mike ,who is also the local lawmen in my town. Folks she is running 73mph now, I am pleased. Problem solved.

QUESTION, why did she need such a big jet, does this mean it has been bored? Hope this thread stays alive long enouph to help sombody becouse it has had me baffeled. Mike my cop friend made a call to a new yamaha 450 owner, they are coming this weekend for a dragrace, i hope to get pics or a video for you all to see...Bill

[hrc200x]

So you have the 152 main jet in it now and it runs good?

[250sx]

hey now, don't go blowing it up! :eek: :nono:

That is a TRX carb, not a stock '85 250r carb. It's bigger than the stock '85 carb. More air=more fuel(?)

[3 or die]

yep, that was it.

[3 or die]

Now you tell me. Funny, I got one last quad to smoke on this trike and its time for the next one. But you better hurry, it has lots of fans now.

[Mr. Richard]

i am running a 170 main and a 160 in my 250's
:D :D :D

[Black Sheep]

"QUESTION, why did she need such a big jet,"


because HONDA always "underjets" there bikes/trikes/quads.

FYI...i run a between a 178 and 180 main in my 250. but, it is also a 39mm carb

[ange]

I'm running into this problem now on my T3. The only real mod is a Bassani pipe.
It will rev freely while in neutral, but if I actually ride it, it will bog out and not rev. It's good till about maybe half throttle.(but it's still not snappy, it doesn't accelerate all too fast)

How do I tell if it's a jet problem, or if it's not getting enough air?

The stock jet size on a 84/85 T3 is a 230.

Why is it so much bigger then your Honda's and Yami's?

[3 or die]

When my r did that the little c-clip on the main jet needel had broke off. It was sending all that air and only enouph fule for idel speed. Check that, while carb is off clean it real good, inspect float height, and instal a inline fuel filter. Let us know if that dont get it..

[ange]

I think I may have it figured out.

The carb was just rebuilt, so it's clean.

When I re-built it, I put the clip on the needle the same way it was when I took it out.

Reading through the manual, the clip wasn't in the right place, it was up too high. I moved it down, but have to wait till tomorrow to test it.

Hope it works.

[250sx]

if that doesn't fix it you may want to check your stator. my T3 would idle fine, but when you hit the gas it would start stumbling & missing as soon as it hit the powerband. Turns out the stator had gotten wet & went bad, but it still had enough spark to idle. :shrug:

[3 or die]

if your clip was stillon then thats not it. the main needel is only in use till approx half throttle, after that its all main jet, so if that needel was being pulled up then find somthing else. If you have another carb slap it on, easy way to eliminate that, and go to something else.

[ange]

so, ofcourse it didn't work.

So now, do I go up in jet size? or down? (down because I live at 6500ft above sea level...not as much oxygen up here)
Am I flooding it out? or is there not enough gas getting in?

It doesn't even rev quickly, or not as quickly as our T3 does back in NY. And I have no other carbs here to swap it out w/.

I dont know @#%#@ about tuning a carb, all our other bikes work fine w/out us having to mess w/ them.

[3 or die]

Question's

1. did it run ok at somtime, and it just started acting up?

2. are u sure the gas in the machine is ok?

3. not likely, but have u changed plug?



at this point I would not mess with jetting.

[3 or die]

This sounds like a main jet needle malfunction to me, it runs good, then when you open throttle it gives trouble. If you can find nothing wrong with the needle then ask dan(250sx) how to test stator. The t3 is know to have major stator problems, if u find out thats the problem use ron stator. It will end the problem for good

[ange]

Everything (except the stator is new).
Previous owner sold it because it was too fast for him (he lived near sea level). Said it was hard to start (thats because it was flooding due to the pet**** being messed, and a bad gasket in the carb)

I rebuilt the entire engine w/out even bothering w/ the previous owners problems. New top end, rebuilt carb, new clutch, new pet****.

I am leaning more towards it not getting enough air because of high altitude. The plug is new, but it is very oily and wet (not a complete burn), the silencer has a nice little drip off the back (not a complete burn).

I just bought the next size down jet (220). And I'll see if it makes any difference.

[3 or die]

pet**** wont make it flood, float controls how much fule in it