250R Is Running Awful

[PYF]

Hi, I just rebuild my 250r with a brand new piston, rebored cylinder, cranks bearings and some tranny gears.

I also had my head shaved and my cylinder midly ported.

Breaking it in at 32:1 Amsoil Dominator (Damn it's rich :eek2: )

The quad is running AWFUL, in fact, a lot slower than when it got dissambled. The engine was rebuilt professionnally so it's out of the question.

So there is 2 choices left...it's either a electrical problem or carburetion problem.

Here are my mods and carbs adjustements on the stock carb:

1988 TRX250R
.050 Over Wiseco Piston
FMF Pipe
Mild Porting
Shaved Head
Boyesen Reed Valves


175 Main Jet
58 Pilot Jet
3rd position clip on needle
2 turns out on airscrew (IIRC)

The quad just bogs and cut on top end. Strangely, IF I go WOT on neutral, It will rev to the moon (A lot faster and a little higher than before btw :devil

It just don't seems to run good while in gear...Whatever Main jet I use, It will only make it worse or stay the same. It just won't rev high in speed. On top of that there is hesitation at 1/4 throttle like it's bogging (Probably the needle adjustement though, it was there before the rebuild).

Here are what I think it could be, just add what you think...

- Incorrect Float Level (Could explain that whatever I do, It won't rev high)
- Faulty electrical system component (Coil, CDI box)
- Completely off carb adjustements

I know you can't jet a carb online, but I'm just giving you an idea of the setup I'm running. I'm really depressed since I've just put a lot of cash in my engine and it's running a lot shitter than when I tore it apart.

THE WORST PART OF THE DAY WAS WHEN I WAS GOING TO MEET SOME FRIENDS IN THE FIELD ROLLING IN 2ND SPEED SLOWLY THE STREETS TO GO MEET THEM AND I MET SOME POLICE. OFFICER HERE ARE REAL FU**** SO IT WAS BETTER TO TURN AROUND. SO I TURN AROUND STILL GOING SLOWLY AND THE QUAD STARTS TO BOG TO DEATH AND NOT HAVING ANY POWER ANYMORE. I TRY TO ENTER THE FIELD BUT THERE IS A FENCE AND I'M STUCK

Consequences:

Offense number 1: 135$
Offense number 2: 290$

That was an hard day... and just to let you know, my only option was to escape, otherwise they would have given me the tickets anyway:scary:

[TRX-RMXJapan]

(1) Check your intake boot for leaks!
(2) Check for cylinder leaks since head has been shaved.
(3) Are the reeds in good condition?
(4) How does your plug look?
(5) If your carb is pissing fuel the float is not set correctly.

Many people say this:
air screw - idle to 1/16 throttle
pilot - 1/16 to 1/4 throttle
needle - 1/4 to 3/4 throttle
main - 3/4 to WOT
BUT the range of the jets actually overlap.

Air screw - off idle to about 1/4 throttle
The air screw meters air to the pilot jet

pilot - 1/8 to 1/2 throttle

needle - 1/8 to 3/4 throttle
an actual needle change will affect 1/8 to 3/4 throttle
clip changes afffect 1/4 to 3/4 throttle

main - 1/2 to full throttle

If your ignition system was working properly before the rebuild it should be ok.

No comment on your tickets.

[PYF]

Originally Posted by TRX-RMXJapan

(1) Check your intake boot for leaks!
(2) Check for cylinder leaks since head has been shaved.
(3) Are the reeds in good condition?
(4) How does your plug look?
(5) If your carb is pissing fuel the float is not set correctly.

Many people say this:
air screw - idle to 1/16 throttle
pilot - 1/16 to 1/4 throttle
needle - 1/4 to 3/4 throttle
main - 3/4 to WOT
BUT the range of the jets actually overlap.

Air screw - off idle to about 1/4 throttle
The air screw meters air to the pilot jet

pilot - 1/8 to 1/2 throttle

needle - 1/8 to 3/4 throttle
an actual needle change will affect 1/8 to 3/4 throttle
clip changes afffect 1/4 to 3/4 throttle

main - 1/2 to full throttle

If your ignition system was working properly before the rebuild it should be ok.

No comment on your tickets.

1- I will, looks like to be in semi-bad shape
2- I will!
3- Brand new
4- Always too rich
5- It was pissing when I rebuild it and won't start, unsticked the floats and started right up

BY the way, not sure the electrical system was running good before the rebuild, it was actually cutting !


Thanks

[ThirtyTwo]

If the plug is black and wet when you pull it start jetting leaner on the main until you get it to a paper-bag brown color. It sounds like a jetting issue to me

when jetting dont just let the bike idle and then check the plug color, you have to ride around going 1/2 to full throttle a lot and then shut it down before it idles much. I cant remember the procedure for doing a "plug chop" but do a search on that.

[PYF]

Originally Posted by ThirtyTwo

If the plug is black and wet when you pull it start jetting leaner on the main until you get it to a paper-bag brown color. It sounds like a jetting issue to me

when jetting dont just let the bike idle and then check the plug color, you have to ride around going 1/2 to full throttle a lot and then shut it down before it idles much. I cant remember the procedure for doing a "plug chop" but do a search on that.

Yeah I've plug chopped it a lot but it's always too rich. I'm afraid to go under the 162 I had before the rebuild since I'm now ported/polished with a new pistons/rings and a fresh bore. Don't know if I should go under 162. Can the extremely high oil mixture hinders the plug reading ?

I should maybe try 155-158 but I'm really afraid of frying the top end since that's really close to a stock jet

The worse is that I can't plug chop anymore since I need to go in the industrial park which is about 750m from home but I must use the streets. I don't want to get another ticket

Seems here quads are illegal. They take quads more seriously than drug dealing

Thanks

[flotek]

your main is way to rich... try a 162 or 165 ...just my opinion ,may need ot experiment with various needles ,lil 34pj stock carb is too smal l on thsoe bikes form the factory ,yo uneed a bigger 38mm airstryker IMO

[ThirtyTwo]

Originally Posted by PYF

Yeah I've plug chopped it a lot but it's always too rich. I'm afraid to go under the 162 I had before the rebuild since I'm now ported/polished with a new pistons/rings and a fresh bore. Don't know if I should go under 162. Can the extremely high oil mixture hinders the plug reading ?

I should maybe try 155-158 but I'm really afraid of frying the top end since that's really close to a stock jet

The worse is that I can't plug chop anymore since I need to go in the industrial park which is about 750m from home but I must use the streets. I don't want to get another ticket

Seems here quads are illegal. They take quads more seriously than drug dealing

Thanks

I think if you tow the quad behind a car it is not illegal, or something like that. So you might be able to get a friend to drive the car and you steer the quad. Check with your local police on the subject

[PYF]

Originally Posted by eviltwin

your main is way to rich... try a 162 or 165 ...just my opinion ,may need ot experiment with various needles ,lil 34pj stock carb is too smal l on thsoe bikes form the factory ,yo uneed a bigger 38mm airstryker IMO

Thanks...I will change for a 38mm later, but for now, I don't think the 34 is 100% the culprit. I will experiment with those mains later this week. I need to change the shifter seal before since the honda dealer made a mistake and gave me the wrong one and it's losing a lot of oil...

And by the way EViltwin, i followed your advice of using a 60 pilot...Stock is 45, I had a 50 and I'm now running 58...IS it possible I'm fouling plugs because it's too high ? The bike just won't idle if I don't touch the gas a LITTLE.

And could you think float level could be a problem too ? Or is it electrical if it cuts...

Thanks again,

Pierre-Yves

EDIT:
Something else, I made the bike idle today just to hears it and the plug was really but really oil fouled. Before I rebuilt my engine, if I would let it idle, it would turn black but not wet...Just another remark

[flotek]

usually its the main that fouls out the plug ,every bike is diffenrt so its hard to say without being there though . id say dont be afraid to drop that main dow n jsu watch the plug and youl lbe fine

[PYF]

Originally Posted by eviltwin

usually its the main that fouls out the plug ,every bike is diffenrt so its hard to say without being there though . id say dont be afraid to drop that main dow n jsu watch the plug and youl lbe fine

Yes I'm gonna try some new setups tonight and won't be afraid to drop the MJ (Not too low though)

Bought 2 fresh plugs...we'll see

I let you know how it goes.