Am I going to blow my motor? Getting a rekluse.

CR Scott

Member
Nov 10, 2005
24
0
Hi everyone, I have a semi delemma on my hands. I've got an 02 CR 250 that for the second time took off like a sewing machine gone mad and I had to kill it by stomping it into first with both breaks applied and dropping the clutch. The kill switch wouldn't do a thing. This happened this AM after cleaning the bike, opening up the line to give some gas, closing the line back down and pulled the choke (just wanted to fire up the bike after washing it and not store it with a full carb). Did I create some kind of vacuum by closing back down the petcock? It happened right when it fired up?? This was not the typical load up scenario that drops after the warm up cycle.
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The redline experience also happened last winter when climbing a snow rutted hill near pinned in 2nd right when I reached the top of the hill. When reaching the fire road I had to turn into the hill and drop the clutch after a number of attempts on the kill switch. Normally the kill switch works fine to shut down the motor at a standard RPM, but this was going off the hook. I can rule out a number of things:
1. Last year this happened with the Mikuni jetted fine (s8,190m,30p,75 needle middle, 3000 ft @ Pillsbury 40 degrees and humid. Stock piston, stock porting. The slide was clean, the cable was routed correctly, No air leaks, etc.
2. This time it was in my driveway after washing but now I have the Keihin airstriker off the 00' CR jetted with 180m,45p, 715 needle middle, 500 ft 60 degrees and humid. The carb is practially new, 2 rides with a new throttle cable, recently ported by Eric G for low to mid with Wiseco piston and new reed gaskets. Also installed a new moose billet throttle tube which checks out smooth.
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I've read through numerous threads after the first experience, checked for air leaks around my v-force reed with carb cleaner, checked the cables, and didn't find anything??
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My real concern is I just ordered a rekluse z-start and was thinking, what if this happens to take off again with an auto clutch???, I've got an oversized Clarke and can't get to the plug ...If this happens again is it gonna blow my motor with an auto clutch? Any way to shut it down?? Any ideas out there would be great. I love my powerband and would hate to have to send another jug out for porting.
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Here are my mods if it helps.. Keihin, v-force 2 on low tension, Gnarly pipe, Q silencer, Eric G porting, Stock plug, 14 oz fww, running 91 w/ spectrol @ 36/1. Eric ported for pump gas at altitude. The bike doesn't tend to ping/knock and I keep the RC cables in spec. What makes no sense is this has happened with 2 different carbs, two different cables, ported and unported. And no worries in between yesterday and last winter?? I read a post somewhere about the engine getting so hot it runs on its own but this is two different scenarios, one hot and one cold.
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Thanks for any advise all. Sorry for the long post, just wanted to give as much info. as possible. I'm just lost at this point.
 

Rcannon

~SPONSOR~
Nov 17, 2001
1,886
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Is there the slightest chance the throttle itself is damaged? I had a KX 125 with a very rough uppet throttle wheel. On occasions it would stick the whole works wide open.

I imagine I had the carb apart 47 times before I realized it was ok.
 

Okiewan

Admin
Dec 31, 1969
29,555
2,237
Texas
OldMaiconut said:
You could still stall it with the brakes as long as the motor is screaming.
With an auto clutch?
 

crashnburn

Member
Apr 24, 2004
108
0
My bike is set up exactly like yours, and i have the auto clutch. You MIGHT be able to stomp the brakes and stall the clutch but I wouldn't count on it, I have only stalled mine twice since the auto clutch (both times high gear to stop). I had a similar problem with the throttle when I ran a G2 throttle tube on my protapers. I took it off went back to stock nylon and have never had a problem. I don't know how long you have been running the billet throttle tube, but something to think about.
 

CR Scott

Member
Nov 10, 2005
24
0
Thanks everyone, some great suggestions. I think I may have covered them, but will pull the throttle apart again and make sure nothing is binding. The throttle tube was just installed and seems to work great. The throttle cable does have a slight bend at the top of the Keihin due to the routing at the side of the 3.2 Clarke tank, but I ran the stock tank with the Mikuni during the first redline? Maybe the cable was held up? Very light angle though and I lubed the cable with some teflon lube? The action just seems really smooth and snaps back everytime?
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I called Rekluse and spoke to Brian. He had a CR and a few times it took off on him because his main was lean? I know the stock 00' Keihin comes with 180m and 48p and typically the stock bikes are jetted rich for sea level, so was figuring at 2000'+ and with my mods the 180 would be fine. I actually ran a 178 last month but wasn't on it hard with no worries (was riding with my 4 year old). Brian upped his main one and he never had the problem again? Maybe I should throw on the 182m, put the stock tank on and run some plug chop tests at altitude prior to putting in the auto clutch? Brian noted by the time I catch the redline effect with the Rekluse, I would have a hard time stuffing it in gear and if I did the bike may flip. Not a good deal..
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Thank you again for all your suggestions. I'll fire back up the post if anything develops or if I learn something that may help others out there. Hopefully you won't see me e-mailing Eric to inquire on a jug anytime soon.
Scott
 

mxneagle

Member
Jan 7, 2001
320
0
You had better get that problem fixed, heres a little story to motivate you. Circa 1993 ish I was racing at Budds Creek and on the last lap of my first moto I started having problems with the bike bogging on jump landings. To me it felt a lot like the plug was fouling so I attempted to nurse it to the finish. As I approached the famous Henry mountain I closed in on another rider and decided I could make the pass. As I jumped out off of the top (maybe only jumping about 1/4 of the way down) the bike, a CR500, began screaming wide open. Fortunatly I was already in the air before it happend. The bike looped out and I hung on only pushing away at the last second. I hit the ground in a seated position so hard it felt like someone hit me in the rump with a 10lb sledge. Immediatly I could not feel anything below the waist! Not good. Luckily it was only a stinger and the hospital claims I did not break my tail bone. I got feeling back in about a minute, still I couldn't sit for about 6 months. The only thing I could find was a tiny bit of sand in the bottom of the float bowl. If that story doesn't do it, check out this video posted over on thumper talk: http://media3.guzer.com/videos/dirt_bike_race_crash.wmv
 

OldMaiconut

LIFETIME SPONSOR
Apr 28, 2001
483
0
Sure with an auto clutch. I have a rekluse on my yz. If the motor is screaming than that baby is hooked up, providing you are in gear. The best bet is to find and fix whatever is causing the sticking. Ask BSwift about the funny dance he did on the Mamba a few years back with the same situation... It was entertaining.....
 

CR Scott

Member
Nov 10, 2005
24
0
Mxneagle...absolutely. I'm gonna tear into everything I can think of prior to installing the rekluse. I feel your pain. In 91' I blasted a huge air off a jump at Mt. Bachelor called Barney Rubble snowboarding, fractured my back and broke three ribs all in one 30' - 40' air. Don't want to experience that pain again.. Thanks again everyone for your input.
Scott
 

muddy226

Sponsoring Member
Sep 14, 2003
271
0
If the motor is screaming it must be getting air to burn. Usually this is because the throttle is stuck open, sometimes a problem with the cable, e.g routed wrong or sometimes pulled out of the top of the carb and stuck, or sometime the throttle slide itself can stick through wear so it doesn't slide straight up and down(side to side play). Also, the slide can sometimes freeze (with ice) if conditions are somewhat cold and moisture is entering the venturi. The inrush of cold air can keep the slide frozen, however when you take it all to bits you can't see anything wrong because the ice has melted. I doubt if it has anything to do with jetting, or a crankcase air leak, because if so it would do more of the time. I have had a stuck throttle before, and on one of the occasions it was slide wear. Its bloody frightening, and I can only suggest that you don't ride the bike until you've got the problem sussed. Good luck.
 

longwoodklon

Member
Feb 5, 2006
1
0
I had a similar experience. '02 CR250 that I had to lay down to help a friends kid get her bike started. When I laid mine down, I turned off the gas to keep it from leaking all over. Well, got her on her way and started mine up(forgot to turn on the gas, duh). Rode the trails for a few minutes then hit a straightaway, got on the gas and that's when it started screaming on me. Same as yours, the kill switch did nothing. Pulled the plug, sat there for a while thinking I probably blew up the motor, then remembered I forgot to turn on the gas. Been running fine ever since.
Maybe someone here has an idea? /Mike
 

CR Scott

Member
Nov 10, 2005
24
0
longwoodklon, I thought maybe I created some kind of vacuum to allow a lean condition by shutting down the petcock and firing it up. If this has happened to others like you and I, maybe it was just a fluke thing? I'm still going to tear into everything to rule out all the possibilities. Thanks for your input.
 

CRPilot

~SPONSOR~
Apr 5, 2000
115
0
My guess is that when you were cleaning the bike you pulled the throttle cable where it enters the housing on the grip side.( under the rubber boot) While the throttle appears to be working fine the throttle never returns to a fully closed position. I have seen pictures of some factory bikes where you can see that they safety wired the cable to the throttle housing to prevent the cable from snaggin on somethng and forcing the bike to rev uncontrolled. It can easily slip back into place as well making it very dificult to diagnos. I have had this happen before when washing and once when running through some really brushy trails (tree branch grabbed the cable)

Thats my .02
 

bleeds

Member
Oct 17, 2005
172
0
On my CR, if you shut the gas off it revs sky high in about 30 seconds.. Kill switch wont work either. This is cause by a lean condition by turning off the fuel. It can damage the motor due to lack of lube from the fuel. Do not ever turn your gas off while the engine is running, EVER. My CR wont even start with the gas off. If you have an air leak it will do the same thing. This will happen on any 2 stroke for sure. If you havent had this problem since, and the gas is always off when it does happen, then I would say you caused it with the lean condition. Just my 2 cents...
Bleeds
 

CR Scott

Member
Nov 10, 2005
24
0
The more input you guys give me and the more I talk to others in my area the more this is looking like what Bleed and Longwoodklon have noted, that by turning off the petcock I creating a lean condition which allowed the bike to rev. I really don't want to try and test this with fear of running my cylinder without enough lubrication. CR Pilot noted a great idea to keep the cable from being pulled out with safety wire...all good stuff. And the others that noted to check the cable, slide, throttle assembly, etc. - these areas are all possible suspects. Thanks again.. Feeling a bit better about installing the Rekluse.
 
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