srx 700 missing around 7k rpm - Snowmobile Forum: Your #1 Snowmobile Forum

ryanbgb22 · 01-24-2009, 05:02 PM

This morning I took the sled out, and noticed that it was missing pretty bad abouve 7000rpm. I brought it home, changed the plugs, and took apart the exhaust valves. Everything seemed to be free moving and the buildup on the valves wasn't too bad. I put the valves back on and went back out. It ran great for about 20 minutes, then it started to miss every once in a while around 7500 rpm. After about 5 more minutes of riding it started missing very bad.

What would cause it to be fine then start missing? I just started using yamalube 2s oil. Also, today was the first time that I started using my electric shield.

Chevyho · 01-24-2009, 11:33 PM

Possibly fouling plugs? I would warm it up, drive until it starts missing again then switch the plugs again right away and see if it goes away for a bit. Might as well rule out plug fouling before you start really tearing into it. Possible that the diff oil is fouling the plugs for some reason...?? Also did you unhook your shield when it was missing, maybe your coil cant handle the extra load?

ryanbgb22 · 01-24-2009, 11:38 PM

Quote:

Originally Posted by Chevyho

Possibly fouling plugs? I would warm it up, drive until it starts missing again then switch the plugs again right away and see if it goes away for a bit. Might as well rule out plug fouling before you start really tearing into it. Possible that the diff oil is fouling the plugs for some reason...?? Also did you unhook your shield when it was missing, maybe your coil cant handle the extra load?

You said exactly what I was just planning on doing tomorrow. Yea, I tried it with the shield unplugged. Is is likely that the stator is bad? It really seems like some kind of spark / ignition issue...but it came out of nowhere.

Chevyho · 01-25-2009, 12:06 AM

If it didnt make a differance with the shield unplugged I doubt it is the stator, however weirder things have happened. Did you have your brights on, hand or thumb warmers on? all these things put more load on the coil... Although I do find it odd it just started once you changed the oil.. What did the plugs look like when you pulled them out? In my limited experience a high rpm miss was 9 times out of 10 a bad plug. Another thing gap the plugs..

ryanbgb22 · 01-25-2009, 02:38 PM

OK, just went out to the garage and pulled the plugs. The mag looks pretty clean. See pic, mag - center - pto.

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.

Here is a pic of another cylinder for comparison reasons.

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?

srxer · 01-25-2009, 03:27 PM

You should only be using BR9ECS plugs in that sled. I have the same one. Try changing plugs, they are 12 bucks instead of 5, but thats what you need in my opinion.

Chevyho · 01-25-2009, 03:36 PM

Well I am not sure if that exhaust problem could cause the high rpm miss but better get it fixed, if it is leaking it will lean out the cylinder. I dont have any experience with the BR9ECS plug, but I do believe it has a larger gap. I would recommend the BR9EYA if you are infact fouling plugs.. the BR9EYA has a v-groove that will help prevent fouling. Did you try running it then switching plugs as soon as it starts missing?

ryanbgb22 · 01-25-2009, 03:36 PM

I was running br9ecs earlier that day when I first encountered the problem. i went to the dealer to get plugs, and they gave me those. THOse plugs have about 25min of total use, about 20 of which was before it started missfiring again. Do you think it could be the exhaust doughnut missing causing my problem?

ryanbgb22 · 01-25-2009, 03:38 PM

Quote:

Originally Posted by Chevyho

Well I am not sure if that exhaust problem could cause the high rpm miss but better get it fixed, if it is leaking it will lean out the cylinder. I dont have any experience with the BR9ECS plug, but I do believe it has a larger gap. I would recommend the BR9EYA if you are infact fouling plugs.. the BR9EYA has a v-groove that will help prevent fouling. Did you try running it then switching plugs as soon as it starts missing?

I havent tried this yet, have too much homework to get done for class tomorrow afternoon. However, I had the same set of old br9ecs in there all year, (about 300 miles) and never had a fouling / misfire problem before yesterday.

Chevyho · 01-25-2009, 03:46 PM

I would stick with the plugs that were working good for you then. Is this sled injected or carb? Sorry dont know much bout yammys. From the pics of the plugs they look lean, but I assume those are the plugs you just threw in and they havent had time to color yet. Did you adjust the oil pump, jetting, pilot mixture, or needle setting lately? If it is carb.

Chevyho · 01-25-2009, 03:46 PM

I would stick with the plugs that were working good for you then. Is this sled injected or carb? Sorry dont know much bout yammys. From the pics of the plugs they look lean, but I assume those are the plugs you just threw in and they havent had time to color yet. Did you adjust the oil pump, jetting, pilot mixture, or needle setting lately? If it is carb.

ryanbgb22 · 01-25-2009, 03:51 PM

Quote:

Originally Posted by Chevyho

I would stick with the plugs that were working good for you then. Is this sled injected or carb? Sorry dont know much bout yammys. From the pics of the plugs they look lean, but I assume those are the plugs you just threw in and they havent had time to color yet. Did you adjust the oil pump, jetting, pilot mixture, or needle setting lately? If it is carb.

It is carb'd. I havent touched any setting on the sled since I got it. Thanks for your help though...I think I'll prob go buy 2 sets of br9ecs plugs tomorrow, and wait for the problem, when it starts switch plugs like you suggested...but until then, any further input is much appreciated.

Chevyho · 01-25-2009, 03:53 PM

oops sorry for the double post, I meant to say the mag side plug where the loose exhaust is looks leaner, so before you run the sled much more you should take care of that then go on with what you are planning... good luck.

Snakeman · 01-25-2009, 08:20 PM

I agree with srxer.Get those BR9ES'S out of there and take them back to the dealer and ask for the right plugs.Whoever gave them to you shouldn't be on the parts counter.

ryanbgb22 · 01-26-2009, 12:56 AM

Quote:

Originally Posted by Snakeman

I agree with srxer.Get those BR9ES'S out of there and take them back to the dealer and ask for the right plugs.Whoever gave them to you shouldn't be on the parts counter.

My goal for tomorrow is to fix the exhaust and go out and give it another try with new plugs. Does anyone know if I can get br9ecs at an automotive store?

ryanbgb22 · 01-26-2009, 08:32 PM

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.

Chevyho · 01-27-2009, 04:03 AM

hmmm... well that pretty much rules out plugs, possibly stator? Correct me if I am wrong but can a stator not start acting funny once the engine gets hot? Does the motor seem to be running real warm?

ryanbgb22 · 01-27-2009, 05:27 PM

Could it be from the colder temps? I've never heald it at WOT for as often or as long as I did the other day. Perhaps its running lean enough to make a miss when being held at very high rpm.

**RJ Gleason** · 01-28-2009, 03:34 AM

The plug on the right is a bit lean, the middle one is the best looking one.

Chevyho · 01-28-2009, 03:42 AM

well if it is leaning out at wot, find a flat area and hold it wide open for about 30 seconds hit the kill switch while you are still giving it and then pull the plugs as soon as you come to a stop.. this will tell you if your main jets are too lean. Might as well eliminate the simple stuff first.