Edelbrock xr650l carb report


14 replies to this topic
  • budinsac

Posted April 25, 2005 - 08:06 AM

#1

4-24-05
I have had my Edelbrock carburetor for about 3 weeks now and the best way I can describe my experience would be “The Good, The Bad and The Ugly”. I waited for this carb for 6 months while it’s availability was delayed. It is a brand new carburetor model (kit part 3117) and while some of the negative may be due to it being a new product, the design is not different from Edelbrock’s other carburetors.

The Good:
Telling the story backwards, the carb is on, set up and works awesome. Even with the stock carburetor modified, (full Dyno-jet kit, “standard mods”….. nearly every reasonable combination) I still wasn’t satisfied that the bike ran as well as it could. There was a flat throttle response off idle, then it would come alive suddenly. Cruising at low throttle opening resulted in surging (a rich condition). Cracking the throttle open quickly at low rpm resulted in a hesitation or bog. Doing the same at higher rpms was better, but you had to wait for the vacuum slide to catch up and deliver the desired acceleration. With the Edelbrock, you get none of the above. Throttle response is very smooth and progressive from idle to wide open. (It requires more grip rotation to get from idle to full throttle) There is no choke or enricher on this carb, and you don’t need one. It seems that the rpm “sweet spot” where the bike makes good power is extended both higher and lower. With the accelerator pump, I’m able to wheelie by cracking the throttle open from a rolling idle, something the stock carb would never do. I’m running the smaller needle 15E, since I have the stock exhaust. It seems just about right, or a tad on the rich side. Installation was beautiful. There are no clearance issues, it clamps to the stock boots without modification or struggle. The throttle cables fit as they should (cable adjustment is at the twist grip end only). As I was installing it, I was thinking that I would never have to take the carb off this bike again… I was wrong.

The Bad:
After installation, I started the tuning process. I was able to make the bike run well, great actually. However, no matter how far I turned the accelerator pump adjustment in, I couldn’t get rid of hesitation when the throttle was snapped open. I assumed the accelerator pump was not working. This was verified by removing the pump linkage and depressing the plunger while the bike was idling… Nothing… After gaining permission from the supplier I purchased the carb from, I pulled my brand new carb off the bike and disassembled it. I found 2 problems related to the accelerator pump. The first was that the inlet check ball for the pump circuit was not seating. It is a small steel ball in the pump bore. I pulled it out and there was no debris. I used a check ball seating method taught to me 20 years ago by a 70 year old mechanic to fix it. Gently tap the ball into the seat with a drift and small hammer, shaping the seat to the contour of the check ball. The second problem was that the cup on the accelerator pump had a hole in the side of it. It was a u shaped hole that if you made it round, it would probably be .050” in diameter, an obvious manufacturing defect. Edelbrock sent me a new plunger assembly, and I got it in just a few days. With the pump fixed, I was back to tuning again which leads us into…

The Ugly:
Ok, so the bike runs great, accelerator pump works, I’m flying down the freeway and suddenly, the bike starts acting like it’s running out of gas. No way, I know I have at least half a tank. So, I back off on the throttle and I’m back in business. Back on the throttle again and she’s sputtering. Over to the slow lane and cruise to work. I assumed I overestimated the amount of gas in the tank, so I top of my Acerbis 5+ gallon tank and it takes 3 gallons. (It usually takes 4.8 gallons when it hits reserve) Everything is good for another few days, then It starts doing it again, and I’m loosing confidence that I can accelerate out of traffic. I’m entertaining thoughts of putting the stock carb back on. Thinking I might have assembled the float bowl incorrectly when I had it apart before, I removed the carb again and took the float bowl off. Everything looked fine, so I thought I would see what the fuel flow into the carb was like. When I held the bowl very low(24” from the top of the fuel level, it filled up very quickly, however when I held it higher, (6” from the top of the fuel level, it barely trickled in. There was not enough fuel pressure to move the needle away from the seat more than just a little. There is my problem!!! Edelbrock is using a horizontal float needle (unlike any other motorcycle carb I‘ve seen), so while gravity pulls the float down, it doesn’t do anything with the needle. It relies on fuel pressure to open. On a gravity feed system there isn’t much pressure at all !!!! I wonder what would happen on a long uphill climb where gravity would actually push the needle back toward the seat??? Now what, do I just live with this and keep the tank full all the time, or do I go back to the stock carb… or ??? The only way I could think of to salvage this installation, was to install an electric fuel pump. Nobody does that, but why not. So I tried it. I picked up a small electric fuel pump at the local auto parts store and found a place next to the top of the rear shock under the seat that it fits into. It weighs about 2 ½ lbs and draws less than 3 amps. Viola, it works perfect. The carb loves it, the float bowl is full all the time, and the tuning is perfectly consistent. All the way up to 95mph so far with the gas just above reserve and no issues.

In conclusion, I am very happy with the performance of this carburetor, and I won’t be going back to the stock unit. I am however, disappointed that I had to go thru all this to get here. I can see that the pump issues may just be a fluke, but the float needle issue is an engineering problem that I have heard addressed before. Not everyone will be able or willing to put a fuel pump on their bike to get around this weakness, nor should they have to.

Thanks for listening. It has been a pleasure sharing my experience with all of you.
Bud

  • jlpskydive

Posted April 25, 2005 - 08:14 AM

#2

Great write up. I now will not be buying one until that little problem is fixed. My bike is heavy enough without adding a 2.5lb fuel pump. Thanks for the info.

  • XR Dude

Posted April 25, 2005 - 09:41 AM

#3

Very informative article, thanks for taking the time to write it. I guess I don't have the itch to get one so bad now. For the dollars invested on our end, I agree, they shouldn't have an engineering problem like that one. Thanks again

  • mgs781

Posted April 25, 2005 - 10:22 AM

#4

Sorry but this does not make sense to me. How many carbs has Edelbrock made over the years for dirtbikes and ATVs???? I have never heard of anyone else needing a fuel pump to make thier carb work. All bikes use gravity feed, why does your bike require a pump? The carbs are all basically the same, the XR650R carb is nearly identical to the L carb and all others except for the mounting diameters.

I would bet that the carb is not working correctly, send it back.

  • justicedone

Posted April 25, 2005 - 10:32 AM

#5

Man what a frickin nightmare !!!

Lets see:

Spend $500+

Tear bike down 3 times...

Lose hair and sleep...

Add fuel pump, with its additional future problems


hmmm

I will pass and keep my jetted stocker !

Hope it stays working well for all you have been through, and I would e-mail that report to Vics daughter herself ! (Since shes basically running the show).

  • Motosprtman

Posted April 25, 2005 - 10:49 AM

#6

they cost 500.00???? NO frickin way.

  • qadsan

Posted April 25, 2005 - 12:03 PM

#7

they cost 500.00???? NO frickin way.


I recently priced the 'stock' carb on my sons Yamaha WR426F along with a new brake pedal. The Yamaha part number for the rear brake pedal is Y4XM-27200-00-00 and my cost from an online supplier is $109.99. The Yamaha part number for the 'stock' carb is Y5NG-14101-50-00 and its cost is $978.99.

So far, I've had ~3.25 trouble free years with my Edelbrocks (no sticky float needle issues...yet) and last time I used one of them was this morning while dropping off a few items at the post office on a dual sport 650r.

It could very well be Q/A issue, or a materials issue, or a process issue, supplier issue, etc. The horizontal float needle concept does work, otherwise there would be many more of these complaints. It would be nice to get to the bottom of this once and for all, but it's been fairly intermittent based on the few complaints I've read about in relation to the number of carbs that have been sold. The most likely suspect is stiction which can be addressed (machining, materials, surface treatments / coatings, etc), but intermittent problems can be very difficult to properly diagnose and resolve.

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  • frankstr

Posted April 25, 2005 - 01:13 PM

#8

I rode last weekend to my reserve and rode up a couple steep hills to get to the pickup for gas and had no such problem( yet ) I love the E carb so its the greatest mod for my bike........... :naughty:
IMO it probly just a few incidents out there of carb problems.....

  • Old_Man_Time

Posted April 25, 2005 - 01:17 PM

#9

This is the exact problem I had with my Edelbrock on my XR650R. I started a thread on this that had over 2000 views. I was not the only one to have this problem as others privately emailed me confessing the same issue. Mine would actually stick closed letting no fuel through.

In time you will get responses blaming you for not knowing what your doing and so on. Ignore them you are not crazy.

Here is how I ultimately fixed mine after mailing the carb back to Edelbrock with a very temporary fix and the problem came back. They mailed me a new and different design valve which also didn't work.

I finally pulled the shut off valve and polished the inside of the valve housing with 1500 grit paper. I also looked at the shut off valve needle under a magnifying glass and noticed small cuts or imperfections on its bearing surfaces which actually contact the inside of the valve housing so I polished them too. Put it back together and no more trouble for many months now. They are a great carb don't give up on it yet and give this a try first.

  • budinsac

Posted April 25, 2005 - 10:14 PM

#10

Thanks for the support Old Man Time. I probably could have taken several different paths to correct the "sticky needle" issue, but the one I took (fuel pump) was the only one I was positive would work absolutely the first time. It is probably like using a cannon when a BB gun would work. While I am well aware that Edelbrock has MANY carburetors out there with this design, my confidence in it's ability to consistantly keep the fuel bowl full (without assistance) is gone. Reliability is extremely important to me, and I have it back with the fuel pump.
Bud

  • TimBrp

Posted April 26, 2005 - 03:26 AM

#11

That's precisely why I haven't bought one yet budinsac. Yes, many many benefits to this carb but one day stuck in the woods negates any positives from the product. I'll get one, just not now.

  • Supplicate

Posted September 09, 2005 - 07:23 PM

#12

I finally pulled the shut off valve and polished the inside of the valve housing with 1500 grit paper. I also looked at the shut off valve needle under a magnifying glass and noticed small cuts or imperfections on its bearing surfaces which actually contact the inside of the valve housing so I polished them too. Put it back together and no more trouble for many months now. They are a great carb don't give up on it yet and give this a try first.

so polishing the shut off valve that is bolted into the tank solved your problem?

Just making sure I understood that correctly :banghead:

  • zackm58941

Posted September 10, 2005 - 06:00 AM

#13

I am having the same problem with the edelbrock on my 650L. Where did you buy that small fuel pump and how much was it?? I got a 4 gal clarke on the way so I hope I can find a solution soon! Thanks!!!

Zack

  • CAPSIL

Posted September 15, 2005 - 09:45 AM

#14

Ok, so I am reading this pondering wether to install or not. Should I examine mine for the flaws mentioned and than proceed or install and see what happens?
Is there more feedback out there?

  • mgs781

Posted September 15, 2005 - 10:17 AM

#15

Mine works great, I don't know what these guys are talking about. I have put 1000 miles on the bike with this carb and never had a problem. My bike is a 2004 XRL with 10.25:1 piston, hotcams, and a polish/port job.

I really think that the Edelbrock has problems with aftermarket tanks. When large Clarke or IMS tanks get low in fuel there is not enough pressure to keep the bowl full in the Edelbrock. I run the Aloop tank (2 gallon) that sits high in relation to the carb. Other tanks sit much lower, I used to have A 4 gallon Clarke. In short there is not enough gravity to make the carb work with these large tanks when they run out of gas.

I terms of tuning Edelbrock is like fuel injection, you want more or less fuel just turn the knob one way or the other. My bike ran like crap with the built motor and rejetted carb, I could never get it right (yes I had done all the carb mods). The Edelbrock took care of all the carb problems.

I never installed the carb on the motor when it was stock, but I say it is the way to go with engine work.

MGS





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