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100 Leak Jet II new issues

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OK, so the original post was getting out of hand... and I had another problem today... thought I'd share what happened.

 

Working on the 05 WR250F now.  Did the leak jet, and was ready to take off.

So I got out to my favorite trailhead, prep'd and took off.  It was evident after about about 100 yrds something wasn't right, and I knew there was something nagging me... you know, in the back of my mind trying to come out.

 

Symptoms happening: 

Took throttle great, no bog, but at partial throttle it was running like crap, cutting out.  Sounded like it was flooded, but it would clear out when I opened it up.  But then it would start it all over again.  So I just went back to the truck.

 

Then it hit me, I never checked the float level.  Quick check, I turned the petcock off and proceeded to ride around the parking lot.  Once the level dropped some, it quit acting up.  Unfortunately, I didn't have the correct tools with me, and neither did the guys next to me, so I packed up.  Didn't finish for the day, but I'm getting closer.

 

When I got home, I pulled the carb and checked the level, it was too high.  So it was flooding out as I was going over bumps.  Easy fix, bend the float tang.

 

So I thought while I had it appart, I'd take pics of what I had done before and post, so here goes:

 

On the YZ250F I soldered up and drilled out 100 Leak Jet.  Then reamed it out to 90.  I used a .54 drill and then reamed it and gauged results.  I stopped at 90.

 

Pics show how to check float level, and the jet ream and gauges.

 

Pic of the jets on the ream shows stock 100 Leak Jet and the one I reamed out after soldering it up.  I figured 60 was too much so I went to 90.

 

Pic of carb with clear line show where fuel came to.  It is supposed to be level with the joint line bowl to carb body.

 

Pic of jet gauges is from a V W shop.  I used these to ream and gauge jets for V W carbs I had modified to use on a Honda Goldwing.

carb.jpg

Jets on ream.jpg

Level too high 2.jpg

V W ream gauge.jpg

Edited by ronbuell

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Well, had some time with it today, wasn't able to affect it much.

I changed out the fuel screw to an extended model with a handle I could adjust easily, which helped a lot.
The pilot jet is a 40, and my drill bits don't range down that low, so guess I'll have to order a couple. 

Fuel screw is 3 turns out now.

 

I was running a 175 main, which felt lean and bogged.  So I committed a major no-no and went back up to 180 and raised the jet needle back up to 4 clip position from top.  Bog is not as bad and it idles better.

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Ron, drilling your own jets are not going to provide comparable results to OEM jets. OEM jets are precision reamed and chamfered. The size is based on flow rate and not diameter. For example, a 90 leak jet flows 10% less than a 100 and is not necessarily a 10% different diameter.

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William,

Thanks and understood.  While I have no way to measure % delta in flow rate, I do have the ability to gauge stock leak jets and changes I make, and results speak for the success I've had on the 1 bike I did.  That was a YZ250F.  I was hoping for similar results on this WR.

Edited by ronbuell

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Ron, drilling your own jets are not going to provide comparable results to OEM jets. OEM jets are precision reamed and chamfered. The size is based on flow rate and not diameter. For example, a 90 leak jet flows 10% less than a 100 and is not necessarily a 10% different diameter.

This is not correct. Mikuni jets are numbered by flow. Keihin jets are numbered by physical diameter.

However, I do agree drilling jets is not really something you should. Maybe when restoring old farm tractors, but not so much on high tuned motorcycle engine.

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"However, I do agree drilling jets is not really something you should. Maybe when restoring old farmicon1.png tractors, but not so much on high tuned motorcycle engine."

 

WOW Does it show that much?  LOL  Just call me gramps, the back 40 is just about ready to plant, after the race.

Actually, its very difficult to drill a jet that small, or to find a drill bit that small.
 

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Just for the record, finished up this fiasco today.  Had a couple of issues going on.

I was able to determine that the pilot jet was not correct. 

It was stamped 40, actually measured 38, which explained why I could not get the fuel screw into play.

 

A #77 numbered drill measures out to .46mm which is about a 45 pilot jet, so I resized the jet and reinstalled it.  Then I went back to my modified leak jet #60.  This bike now responds similarly to my 03 YZ250F, no bog, ripps all the way up, the fuel screw is now in play and I can adjust idle with it.  It still backfires some, but that is acceptable in my book.

 

To the nay sayers, results speak volumes to me, where the rubber meets the dirt.

  Disclaimer: Your results may differ from mine!

 

To those interested, here's what you use:

1/64 = 40 pilot = .0156"

#77 drill = 46 pilot = .018"

#76 drill = 51 pilot = .020"

 

BTW, these drills are very very small, and it is very easy to break them, or lose them. 

If you go this route, work slowly and be very careful because they are about the same size as a sowing needle or shot needle.

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Just finished up final installment on this one.

Rode the bike several times in the last few weeks and it was still not responding correctly.  Complaint was it seemed to load up or hesitate at partial throttle between 1/8 and 1/4.  I could open the throttle and it would get past the problem and clean out, so I reasoned it was fat somewhere.

 

Adjusting the fuel screw did nothing to help.  So I decided to change needle height.  That was it, 1 clip position too rich, so dropping the needle 1 clip cleaned out the mid-range totally!

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To those interested, here's what you use:

1/64 = 40 pilot = .0156"

#77 drill = 46 pilot = .018"

#76 drill = 51 pilot = .020"

 

 

I get it, but I hope your not using a hand drill or drill press and expect accurate results. 

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