srx 700 missing around 7k rpm

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Ryanbgb22

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srx 700 missing around 7k rpm (updated with pics)

I was riding in about 10*F temps yesterday on very frozen snow. When I first left, it seemed like my sled didnt want to move very well, then I though I smelled the belt burning a little. This got better after some time, but then when I hit the first field, there seemed to be some pretty bad missing at higher rpm's. I took it back home, changed the plugs and looked over the exhaust valves. They were free moving and didnt seem too bad. So, I took it out for a second time. It ran great for about 20 minutes, then stated missing in higher rpms. About 5 minutes later, it was missing almost as bad as the first time I took it out.

The only changed I have recently made were using yamalube 2s oil, and using a heated shield.
 
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OK, just went out to the garage and pulled the plugs. The mag looks pretty clean. See pic, mag - center - pto.
DSC_0099.jpg


I then realize that the exhaust seems kinda loose on the mag. It seems that it has lost the doughnut thing where the pipes connect. cylinder on left, pipe on the right.

DSC_0101.jpg


Here is a pic of another cylinder for comparison reasons.
DSC_0102.jpg


I'd assume that this could be causing my misfire at higher rpm? If so, why would it only be once the sled ran for 20 minutes?
 
Miss

Well those arent BR9ECS plugs which you should be using, but I have used regualr BR9ES with good success so...Before you hop on that sled you should pick up the rear and drop/slam it down once or twice. This breaks the ice and track loose and will save your belt.
Those plugs look spot on, buit number 3 from the left looks a bit lean. I like mine with a little more brown though. Were those new plugs? New plugs are hard to read until some miles get put on them. You probably partially fouled the plugs and they just failed later.
Up north I was running the BR9ES in my 600srx and ditch banging 2 ft of fresh snow ALOT and all of a sudden I got a miss. Stopped and changed plugs and I noticed the ceramic had cracked on one of them.
I ran Yamalube 2-S the whole time, and the sled seen 90mph for miles at a time, no issues.
Dont just choke the sled and idle when cold. Just choke it whenever it wants to stall, give it what it needs until warm.
 
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2strokinit said:
Well those arent BR9ECS plugs which you should be using, but I have used regualr BR9ES with good success so...Before you hop on that sled you should pick up the rear and drop/slam it down once or twice. This breaks the ice and track loose and will save your belt.
Those plugs look spot on, buit number 3 from the left looks a bit lean. I like mine with a little more brown though. Were those new plugs? New plugs are hard to read until some miles get put on them. You probably partially fouled the plugs and they just failed later.
Up north I was running the BR9ES in my 600srx and ditch banging 2 ft of fresh snow ALOT and all of a sudden I got a miss. Stopped and changed plugs and I noticed the ceramic had cracked on one of them.
I ran Yamalube 2-S the whole time, and the sled seen 90mph for miles at a time, no issues.
Dont just choke the sled and idle when cold. Just choke it whenever it wants to stall, give it what it needs until warm.
Click to expand...

Those plugs are the ones that have about 25 minutes on them, earlier that day when I first encountered the problem I had br9ecs in there. I cannot figure out the misfire. It just started out of nowhere. Thats why I am thinking I may have lost that doughnut thing, and the misfire started after that.
 
So??

The misfire has not went away, or its there just at 7000rpm? Could be plug wire/boot arching out at high rpms. I doubt the doughnut would make it misfire unless its completely gone, but then, iffy.
Can you tell its the same cylinder or not by the plugs? Was the sled making 8500-8600 rpm wot, or is it stuck and 7000?
 
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2strokinit said:
The misfire has not went away, or its there just at 7000rpm? Could be plug wire/boot arching out at high rpms. I doubt the doughnut would make it misfire unless its completely gone, but then, iffy.
Can you tell its the same cylinder or not by the plugs? Was the sled making 8500-8600 rpm wot, or is it stuck and 7000?
Click to expand...

The misfire is only around 7k and above. It went away for about 20minutes after changing the plugs and taking out / checking the exhaust valves. The sled struggles past 7k once it starts misfiring.
 
Find it..

You need to narrow done the cyl that is misfiring then go from there.
 
get a new exhaust donut and check the wiring harness for a rub thru. those br9es plugs aren't going to cause a misfire, unless they were fouled of course.
 
Ok, I fixed the exhaust leak. It runs much quieter and smoother now. I took it out today, and for an hour it ran absolutly perfect. I was in an open field doing wot run after wot run, really beating on it pretty good. After about an hour, it started missing once again when holding it at any steady rpm above 7,000. After it started doing this, I pulled the plugs and replaced them with another set of br9es (place didnt have br9ecs). Started going again, and it was still missing.

Pic of plugs with about an hour of time on them.
DSC_0100-1.jpg
 
Plugs

The 1st plug at the left looks like it could be your issue. It looks pretty good but its blacker/shiner than the last 2. If you look the ground electrodes on the last they are even/ light brown...perfect. But the 1st is blacker, ur problem IMO. CHECK THE PLUG BOOTS/CAPS. Try WD40 the inside of the plug wires/caps re-install ride. It could be a coil is failing, I just changed one on my 2000 SRX, mine was PTO side but yours could be any three.
 
2strokinit said:
The 1st plug at the left looks like it could be your issue. It looks pretty good but its blacker/shiner than the last 2. If you look the ground electrodes on the last they are even/ light brown...perfect. But the 1st is blacker, ur problem IMO. CHECK THE PLUG BOOTS/CAPS. Try WD40 the inside of the plug wires/caps re-install ride. It could be a coil is failing, I just changed one on my 2000 SRX, mine was PTO side but yours could be any three.
Click to expand...

Sounds quite possible. How much did that set you back? And is it possible that it would only be doing it at high rpm after being warmed up and ridden for about an hour?
 
Coil

Yes the coil could be affected by temp or high rpms. The higher the the rpms the more it obviuosly has to work and the more it may arch. I had an entire spare set. If you want pay the shipping cost to you and I can let you try it out...no cost except the shipping. If it works you buy for a fair price used price (( I think 10.00+shipping))...if not send it back to me. But for 10.00 probably better off keeping it.
Before you do that remove the coil that is the problem ((that 1st plug)) and switch it to a differnt cylinder to test it out. No sense buying somethin u dont need.
 
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I'm having the same issues with a 700sxr. one way to check which misfire may be when running and it mis fire to hit the kill switch and then check the plugs. hitting the kill switch immediately kills the spark and should show a wet plug that is not working. this doesn't mean it will be the plug, it only shows that one isn't fireing. I've been told the stator and cdi in a yamaha are very very reliable. I'm puzzled on mine as I have put in 3 new coils and no good results.
 
Check

Well SRX as you know are notorious for wire rubs through under the engine, below the seats and Ive heard a few by the left foot cluster. You can only imagine the host of issues this could cause.
Carbs that start a miss after running well for 1/2 hr doesn't add up either. If you cleaned them Id not go back to that, just make sure they are set to factory specs, if need be lmk I can send a PDF file from factory manual on settings. Check power valves, remove power valve cover and ensure servo is doing its job.
The most important and obvious thing is "single out the problem child, which cylinder is it', life will be that much easier.
 
A guy at the yamaha dealer just told me its likely a problem with my TORS system. He said to disable it and see what happens. How would I go about doing that?
 
TORS will normally bring you to a stop before you can take off again, but a simple bypass will confirm that it is working or not.
 
I've replaced plugs, coils. cleaned carbs, checked TORS, drained fuel tank and installed all fresh fuel, checked fuel filter in tank, cleaned fuel pump and still have the same results, Cuts out at 6000 and higher when warmed up. Buddy said crank seal so pulled clutch and flywheel and seals look good. Stator and pulse ohlms reads proper when cold but how would anyone check it hot? Next item is stator or CDI. Does anyone have any advised before I spend 500.00 bucks?
NOTE: In the tech manual Yamaha changed the stator in the 2001 to an 18 pole with 300 watts. Why isn't there any spec's listed?
 
Hey 2strokinit. I seem to have a simular problem with my ride, but it's not missing at high rpm.As per pictures of the fellows plugs they look simular but my pto plug is wet after cruising slow,also it'll have a popping in the exhaust once in while at slow speed.At cruising it'll have an uneven exhaust tone but when I cranck 'er up she goes to beat the band!It's a 600,I'm leaning on swapping the coils over and see if this moves the wet plug that way I'll narrow it to a coil.then I'll ohm it.Any suggestions?
 
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