XR600 Choke flap issue...

19 replies to this topic
  • bigboredbiker

Posted June 16, 2005 - 02:55 AM


Where have I read about the choke plate breaking off and being sucked into the motor? I've just overhauled the carb on my '98 xr600 and found a bit of it missing. I know it's not in the engine as the rest of the head is also in bits, so I'm guessing that's the reason why the last owner pulled it apart....
Anyway, can anyone tell me what that little sprung flap is supposed to do and please tell me it doesn't need it to run ok.....PLEASE...lol...Why/how does it break off anyway?? Answers will be very welcome and keep up the good work guys :)

  • frankstr

Posted June 16, 2005 - 05:01 AM


It don't need to be there to run.......
It's there I believe incase it backfires with the choke on your carb doesn't blow off.....It probly breaks off due to fatigue.....

  • XR6's_rule

Posted June 16, 2005 - 05:35 AM


The original choke flap on XR6's from '88 on (single carb models) did have a common problem where the plate would break in half due to fatigue, and sometimes the flap would detach itself. Of course, these bits would end up in the engine sometimes causing a catastrophe, depending on your luck. This once happened to me on my old '88 XR600, the piece of choke flap lodged itself between the piston and sparkplug, closing up the sparkplug gap and leaving me stranded, so I learned the hard way!

Luckily, this problem is avoidable by buying/making a replacement choke plate and fitting it, problem solved!

  • captb

Posted June 16, 2005 - 08:59 AM


Xrs only may still sell the billet choke plate, I have one in my 650R it was 25.00.

  • bigboredbiker

Posted June 16, 2005 - 01:28 PM


:) Cheers guys....one less for the wallet then.....

  • Moredesert

Posted June 17, 2005 - 01:18 PM


I lost my engine in Baja 63 miles from no where. What happened was the spring broke on the choke flap and the flap it self was slapping the plate until it broke the botton of the plate off and sucked it in the motor. That cost Honda $2000 to replace the top end. My buddy from Trailboss Tours also lost a couple of bike the same way when he had 600's. I would buy a after market plate from BD before it happens to you. I know of 4 bikes including my 600 that this happened to even if Honda say's it's not a problem.

  • kellismechanic

Posted June 29, 2005 - 08:57 PM


I had the XR's Only Billet Plate on mine, worked great, but now have a Mikuni Flatslide, no plate. :)

  • LVThumper

Posted June 29, 2005 - 10:22 PM


I have a '97 XR 600 and just last October, the choke plate was sucked through the engine, and just destoyed it!! :D

Now here I am, $2,000.00 later, whole new top end, valves, piston, cylinder bore, stage 1 Hot Cam :) , and Mikuni Flat side carb :) . I picked up 5 hp at the rear wheel, and couldn't be happier with my bike! :D

I know that XR's Only has a very nice replacement for the choke plate, so you might want to go that route, or just order a new carb for a couple hundred bucks, jet it, and start grinning!! :D

Good luck!

  • XR6's_rule

Posted June 30, 2005 - 03:40 AM


LVthumper- I've got a 38mm mikuni flat-slide (i think TM series) that I've had on one of my XR6's and it works well- higher rpm, slightly more top-end power, better response. The only thing was, the choke would "overchoke" when the bike was cold, but I learned to just tip the bike over and not use the choke which helped when starting cold. Hot starting and even restarting after a flood was much better.

  • rmhrc630

Posted June 30, 2005 - 12:56 PM


The Flat slide carb you guys refer to on the XR6 - is that a good mo to do?

I thought I had read that fitting a flat slide carn to the XR6 was bad?

On a 628 what sizw would you fit up?

Sounds a like a great mod - what are the pros and cons?

Is it a direct bolt on?

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  • XR6's_rule

Posted June 30, 2005 - 09:20 PM


RMHRC630- Ballards still do the TM series Flat-Slide carb kits for XR's. There are three kits you can get- a 34mm for the XR250/280 etc, the 38mm which is for XR4's and XR6's, and last of all a 41mm for XR6's with big-bore kits (like yours!) and the XR650R.

I have the 38mm kit which I've used on an XR4 and XR6 (both stock engines), here are my pro's and cons.

PROS- Much better throttle response, slightly better top-end power, much easier starting after being flooded, lighter throttle pull (runs a single cable), lighter weight (approx half the weight of stock carb). No "stickyness" of throttle as with the stock carb.

CONS- The choke tends to "overchoke" when cold starting *(being a carb designed for 2-strokes), but as I said in the earlier post, I learned to tip the bike over for say 10 seconds to give it a rich mixture to start it without using the choke and it was fine.

SETTING UP ON THE BIKE- The easiest way to do this conversion is the buy the kit from Ballards (about $420AUS retail), as it comes with the carb fitted with adaptor for the airbox boot, throttle and cable so it is just a bolt-on affair. They also give you a couple of different main jets, in case you need to adjust jetting.

  • rmhrc630

Posted June 30, 2005 - 11:26 PM


So would you definitely recommend this mod for the 628?

  • XR6's_rule

Posted July 04, 2005 - 01:50 AM


It depends if you have the money to burn, want a lighter throttle need even more throttle response and power (!), and wont mind that the cold start routine has a trick to it. If you answer yes to these, get it, but dont forget to give me your thoughts if you do!

  • bork

Posted July 04, 2005 - 05:04 AM


I got a quicksilver edelbrock an dlike it on my xr600r but my bud just sucked in a piece of plate on a 97 600r and wiped out top. 2000 $ later he has billet.
Dont wait! change out plate now and think about set up later.

  • LVThumper

Posted July 04, 2005 - 04:40 PM


Bork -

Trust me, I know how your buddy feels! :) Even if you don't upgrade the carb, at least change the choke plate ASAP! I have since learned that this is not an uncommon problem. All I heard from my friends was how bulletproof the XR 600 was with one little exception, the choke plate. I waited too long and paid the price! :) Just do it!

  • miguelitro

Posted July 05, 2005 - 11:09 AM


not a prob on the newer 650r's???
I had the billet plate in my old 600 and never though about it again but now i'm getting nervous...

  • XR_Dude

Posted July 11, 2005 - 05:36 AM


I too had the choke plate break off and it totally ruined the engine. I took the engine off and sent it to Thumper Racing for overhaul. Since they had it apart, I had them put in a hot cam and bore it to a 660. I added the aftermarket plate also. The problem is, now the bike stalls at low RPM when it is hot. It actually misses and then stalls. I've been on the phone with the mechanic at TR and did everything he said but it still stalls. I adjusted the valves, changed the jetting, the impulse wire, and dropped the needle (one clip) then the bike wouldn't even start so I used my friend's carb off his XR 600. The bike would then start, but it would still stall when the engine got hot. I think it has something to do with the Hot Cam. Anybody got any ideas?

  • XR6's_rule

Posted July 11, 2005 - 08:19 PM


Because you've gone for a big-bore kit and cam, the engine now has the capacity to deal with a larger volume of fuel/air, so now its probably asking for richer jetting. The stock pilot jet is a 62, try a 65 and set the airscrew at about 2.5 to 2 3/4 turns out, and if that doesn't help, go to a 68 and so on. Also I would start off with the needle in the middle (3rd) clip position and you may need to go to the 4th from the top (richer). Testing will tell. Good luck.


  • XR_Dude

Posted July 12, 2005 - 06:47 AM


Thanks, I will try it.

  • Marcia

Posted July 13, 2005 - 01:46 PM


See Precision Concepts for choke plate fix. $29.99

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