Tri Z 250 running problem (help)

**The R** · 02-12-2003, 10:09 AM

I was able to get the beast to idle in neutral without cutting off, but it still idled very low. I turned the PILOT AIR SCREW out 3 full turns, and I screwed the THROTTLE STOP SCREW all the way in. Without doing this the trike would cut off, but I didn't think I would have to screw the screw all the way in to get to idle. Once I got it to idle I took it for a ride, and when applying full throttle it would stutter, then speed up, then almost cut off until I got out of the throttle. So basically I'm asking what do you think I need to do next to get this trike at least to be reliably rideable? Could the dirt bike exhaust the guy put on it be causing a problem? Also if it has a high compression piston in it ( I don't know what it has) and I've put pump gas and oil at 35:1 in the tank, what type of problems would that cause??

Thanks

**The R** · 02-13-2003, 09:24 AM

Anybody????

**J.D.** · 02-13-2003, 07:44 PM

Here's the specs for a YTZ250N from the book, maybe it'll help.

Carb Type: Mikuni VM32SS
ID Mark: 38W00
Main Jet: 470
Air Jet: 2.5
Jet needle/clip position: 6H3/3
Needle jet: P2
Cutaway: 2.0
Pilot jet: 45
Pilot air screw: 1 turn out
Valve seat size: 3.3
Starter jet: 1.3
Float height 31.3 +/- 1.0MM (1.23 +/- 0.04 in)

And here's what the book says about Idle speed and mixture.

1:the idle speed should be checked and adjusted when it is obviously too high or low. before adjusting idle speed, make sure ignition timing is correct and spark plug is properly gapped.
2:the engine should be at normal operating temperature and in neutral.
3:attach a tachometer to the engine.
4:turn the throttle stop screw to obtain specified idle speed.
5:if the engine misses or runs erratically, turn the pilot air screw in until it seats lightly, then back it out the specified numbers of turns.
6: reset the idle speed with the throttle stop screw.
7: turn the air screw in or out, as required, until the highest engine speed is obtained, then reset the idle speed with the throttle stop screw.

hope this helps.

**The R** · 02-13-2003, 08:18 PM

Thanks for your input, but I've tried that (I have the manual also :-D )already, so I thinkn I'll take the Carb off and clean the hell out of it, and check verything else while I'm at it.

Thanks Again

**J.D.** · 02-13-2003, 08:26 PM

Your welcome. Maybe with the dirtbike exhaust put on there, the jets have to be adjusted?

**The R** · 02-13-2003, 09:07 PM

Originally Posted by SSJ3Goku

Your welcome. Maybe with the dirtbike exhaust put on there, the jets have to be adjusted?

I was thinking the same thing, I mean that can't be good for the beast. So I think I'll order the DG chrome exhaust for it. I'm taking the dirtbike exhaust off tonight and putting the stock one back on until I get the DG.

Thanks Again

The R

**Dynofox** · 02-13-2003, 09:41 PM

What kind of hp difference is there with the dg pipe on a Z? I just bought a tri z and it is coming with a dg pipe, will it compare to an R and tecate now?

**The R** · 02-13-2003, 10:04 PM

I have no idea what the difference is between the stock TRI-Z and one fitted with a DG system. Sorry I couldn't help you.

The R

**mbg75** · 02-16-2003, 03:23 AM

the dg system will wake up the midrange. if you perform the yamaha wrench report mods, along with the dg pipe, the z will scream. it will come onto the pipe a little later and hit hard. easily the best mod you can perform on a tri-z.

**mbg75** · 02-16-2003, 03:34 AM

hey r, as far as getting your tri-z running, try taking the carb off and cleaning it. remove the fuel bowl, spray it with some carb cleaner, make sure the pilot jet and main are clear. also, you might need to buy a rebuild kit for the fuel pump. even with the wrong pip the bike should idle. also check your compression, should be at least 120psi. good luck

**The R** · 02-16-2003, 03:47 AM

Originally Posted by mbg75

hey r, as far as getting your tri-z running, try taking the carb off and cleaning it. remove the fuel bowl, spray it with some carb cleaner, make sure the pilot jet and main are clear. also, you might need to buy a rebuild kit for the fuel pump. even with the wrong pip the bike should idle. also check your compression, should be at least 120psi. good luck

I took the carb off today and cleaned it, then put it back in, BUT I couldn't get the throttle cable to tighten up (IT CAME WITH THIS FUNKY LOOKING TWIST THROTTLE, BUT IT LOOKS AS IF THE GUY TRIED USING THE STOCK CABLE WITH THE TWIST THROTTLE)anyway, after putting the newly cleaned carb back into the beast, I cranked up the beast and OH trailprotrailprotrailprotrailpro!!!!!!!!!! it idle'ed at the top of the rev range (LIKE IT WAS ABOUT TO BLOW UP) so I didn't know what the F@#K to do, and I was about to run out of my garage (THINKING IT WAS GOING TO BLOW) but decided to yank the throttle cable out of the carb and it cut right off (THANK GOD). So it only idle'ed at the top of the range WOT for about 10sec, hopefully not damaging anything. I am ordering a new 38mm Mukini flat side carb to put on it, A real twist throttle with the correct cable, DG header with Silencer, and that's it for this week. After I get it running good enough to ride the beast I do the wrench report on it also.

The R

**mbg75** · 02-16-2003, 03:55 AM

if your interested i can send you the wrench report. email me mbg75@optonline.net

**The R** · 02-16-2003, 04:08 AM

Does anyone know a shop that could perform the wrench report on the Tri-Z?? (head and cylinder)

Thanks

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Tri Z 250 running problem (help)