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 ****ter 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:

[250R-Dee]

(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.

[maggiesboy]

do you have an adjustable pickup mount. (the bearing holder for the counterbalancer)? If that is off, it will run like poo.

Just a thought...

[novaracr70]

you said you shaved the head? maybe you are getting spark blow out ? try tightining plug gap and c if that helps

[PYF]

Originally posted by maggiesboy
do you have an adjustable pickup mount. (the bearing holder for the counterbalancer)? If that is off, it will run like poo.

Just a thought...

No everything were adjusted correctly AFAIK. The dots on the crankshaft primary gear and counterbalancer gear were liner accordingly(If that's what you're talking about)



Originally posted by novaracr

you said you shaved the head? maybe you are getting spark blow out ? try tightining plug gap and c if that helps

I should try it

[PYF]

Originally posted by TRX250RJapan
(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


. I'm not sure electrical system was working properly before the rebuild...


Thanks again to everybody contributing to this thread :)

[PYF]

Just a though...

When the police where chasing me and the quad started bogging, I probably fouled a plug meaning I'm still a lot too rich.

What bogs me is that I was running a 162 before the rebuild and I don't want to run it with that now since I have a new pistons/rings (More compression), bigger bore, Shaved head (again with more compression) and porting...

Question like that, before the rebuild, my reeds were really worn. Was it making the quad running leaner or richer..thanks :)

I probably shouldn't have needed a 162 with the setup I had before hand (People normally run the pipe/filter/open airbox setup with a 155-158)...I maybe had some motor conditions making the jetting innacurate.


Again, just a though :scary:

[fireburns99]

Have you done plug chops? If the plug is coming out a really rich color, than you're probably fouling plugs. Which would cause it to run ****ty throughout the whole rpm range. Your running the stock carb right? I would try going to around a 168 or so, and see how that feels? Just watch the plug, it should be a nice dark tan color.

Also with the head shaved and the higher compression, i found that the you need to gap the plug smaller, or it will miss at WOT.

[PYF]

Originally posted by fireburns99
Have you done plug chops? If the plug is coming out a really rich color, than you're probably fouling plugs. Which would cause it to run ****ty throughout the whole rpm range. Your running the stock carb right? I would try going to around a 168 or so, and see how that feels? Just watch the plug, it should be a nice dark tan color.

Also with the head shaved and the higher compression, i found that the you need to gap the plug smaller, or it will miss at WOT.

Yeah it's too rich for sure but I'm afraid to go too low since as I said, I was running 162 with the unported/shaved motor.

And you will probably find it really funny, but I've never gapped a plug before...Online is the first place I ever heard of that...Don't even know how:ermm:

Thanks

[fireburns99]

With the jetting, just keep going down a jet size until you get a tan color on the plug. If the plug is tan you will be fine. If you kepp running it rich you will just keep fouling plugs.

And to gap the spark plug, just go to auto zone or any auto parts store, and get a feeler guage. It will have a bunch of pieces of metal that all have different thicknesses. Just find the one that says .020-.018, and bend the spark plug tip down until the feeler guage marked .020 just barely fits between that.

[Scott-300ex]

Originally posted by TRX250RJapan
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.

Exactly Wut I was going to say.

58 pilot thats real rich I think

175 I think thats too lean

I would run like a 50 190 set up, thats wut I would think.

Is your plug white-lean or black-rich?


If you think I'm crazy on wut I said to jet it at, then go back to stock and try it, make sure you got everything hooked up right too.

[machwon]

My .02 cents.

155 main, 42 pilot, fresh plug, gapped at .020" should do it.

[250r4life]

i would come down on the main jet

[PYF]

Thanks a lot for all the setups ideas guys !

I was running a 50 pilot jet before but someone advised me to run 58 and now the bike just won't idle. I think I'm gonna try 165/50 first!

It probably didn't work the first time since the plug was probably fouled when I tried lol. At least I'm not frying my top end :p

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

[250R-Dee]

Go buy some new plugs. It is normal to foul a couple plugs when tuning a new setup. I would rather foul a plug than kill a jug!!:chinese:

[PYF]

Originally posted by TRX250RJapan
Go buy some new plugs. It is normal to foul a couple plugs when tuning a new setup. I would rather foul a plug than kill a jug!!:chinese:

I'm going to try it tonight after job!

I think I overrated the problem...Probably just fouled a plug the first setup I tried and the next jet I used just weren't able to run since the plug was no good anymore. Hope it will works :devil: ...It's almost impossible my brand new setup run like crap:huh

I'll let you know what happens with a fresh plug, a 160 MJ and 50 PJ

[Iliketogofast]

There is an air leak. It just happened to me - feel around the where the top and bottom head gaskets are all the way around. You probably blew the bottom one or forgot to but one on (!) even. But the symptoms you described match mine perfectly, and mine was an air leak around the cylinder.

I also think you're jetted too fat. I'm running 145 with the lid off, 140 with it on and I have an almost identical setup.

[PYF]

Originally posted by Iliketogofast
There is an air leak. It just happened to me - feel around the where the top and bottom head gaskets are all the way around. You probably blew the bottom one or forgot to but one on (!) even. But the symptoms you described match mine perfectly, and mine was an air leak around the cylinder.

I also think you're jetted too fat. I'm running 145 with the lid off, 140 with it on and I have an almost identical setup.

I'll try a new setup or two tonight. If it doesn't works, I'll looks to retorque the bolts...I torqued them correctly when I rebuild it this weekend though:ermm:

Thanks a lot though, that could be a cause!

Pierre-Yves

[PYF]

Small update for future informational purpose:


I solved my problem. The machine is now fast :devil:...It was only foulings plugs so when I was trying with a good jet, the machine would still not performs since the plug was fouled...

SETUP 1 I TRIED

162 Main jet
50 PIlot Jet
3th position Needle


OK this setup ran good but was still hesitating on top end, at least the quad was performing AS GOOD as before the rebuild and porting (Not really fun but at least it's working)


SETUP 2

155 Main Jet
50 Pilot Jet
3th Position Needle

Wow Now the bike is getting really faster. I know see a difference. Revving a lot faster and a lot funner to ride :D...My rear tires have about 75%+ Treads left and I crashed when I lost the rear end because of excessive wheel spin :huh ...I think I'll need new tires otherwise it's going to be dangerous lol

Sadly, when I crashed, I totally shot my right outer front wheel bearings lol :ermm:

The quad still bogs a little on top end with a 155 but I rather not go too lean right now and not do too many plugs chops since I'm still on broke-in...I did a small plug chop and looks like I could still jet leaner but it's gonna stay at that for now...


THANKS EVERYBODY FOR YOUR HELP,

Pierre-Yves

[250R-Dee]

Good to hear you worked the bugs out!! Happy roosting bro'!

[Scott-300ex]

You might want to try going up a main jet to to make it richer, then when it runs like crap find the middle, so between 150 and 165 or wutever you had at first. Just a thought, cuz it might make it run even better.

Glad you got it runnin good.

And is there a torque spec to torque the spark plug?

And does anybody know the jetting for an 89 250r stock? Main and Pilot?

Thanks

And have fun with her Pierre-Yves, However you pronounce that.