M7 issues

chevota84 · Apr 6, 2017

So, I'm fiddling with an 06 m7 trying to figure out his problem, it doesn't want to rev past 7000rpm
Mods
Bikeman polaris piston 800
Bikeman modded stock pipe
Bikeman can
Boondocker box
Koso dual egt gauge

What I've done
Checked compression and both cylinders were below spec, one lower than the other so it got pistons, cylinders looked ok. I checked squish and it was at .076, so I took .015 off. No change

Made spacers to hold the powervalves open and plugged a fooler in, no change

Reset boondocker to bmp settings, no change

Plug wires looked a little cracked so I replaced them and put on ngk 5000ohm ends, no change

Threw a new set of boyeson reeds in, no change

Fuel pressure is steady at around 42psi and it does the same thing on the snow or on a track stand. I might try pulling the primary off just to eliminate anything past the crankshaft even though I'm pretty sure it's in the front somewhere.

Could I pull one plug wire off and put a meter in the cap to see if it's dropping voltage at 7k?

Any ideas would be great, thanks

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Betterview · Apr 6, 2017

Sounds like a mouse nest in exhaust, broken stinger in exhaust, or some other exhaust restriction.

chevota84 · Apr 6, 2017

I figured it'd be worse under a load with a restriction, but it's an easy check.

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chevota84 · Apr 6, 2017

No rattles or anything, I don't see any rust or anything else that would lead me to believe something was in there. I'll see if I can come up with a stock can to make sure.

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BBP · Apr 7, 2017

Rule out the clutches, compare L & R exh. & cyl temps with a heat gun, check plugs & piston wash. Might give you a direction to go.

chevota84 · Apr 7, 2017

I'm going to ohm out the stator today and if it checks out I'm going to pull off the primary and see what it does. According to the Koso, they're within 10 degrees of each other. I haven't run it enough with the new pistons to see anything on them yet.

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chevota84 · Apr 7, 2017

The ignition timing sensor is showing 93ohm and spec is 152-228.

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chevota84 · Apr 8, 2017

Well, it looks like a lot of guys get that reading for the timing sensor, so I dunno. I did see some sketchy looking wires and a Scotch lock so I'm going to clean those up.

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BBP · Apr 8, 2017

chevota84 said:
The ignition timing sensor is showing 93ohm and spec is 152-228.

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I ran into that also. Don't remember the year or specs, but the manual was wrong. Ordered a new one & it measured exactly the same as the old one.

flatspeed · Apr 8, 2017

When it hits 7000 RPM does it just stay there and continue to run smoothly, or does it act like a rev limiter?

Have you tried it with no belt on?

chevota84 · Apr 8, 2017

It sounds fat and blubbery, egt's are at around 900 under a load when it does it. If you just whack it it'll go to 74-7500 and come back down to 7, if you come up slow it hangs right at 7. I haven't yet, I was going to pull the primary because I don't trust the clutch to not explode, but its been windy and ugly here so I'm not getting very ambitious.

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chevota84 · Apr 8, 2017

Does anybody know offhand if a pre-ho m8 ecu will run it? I have one laying around that I could try to see if it changes anything.

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chevota84 · Apr 11, 2017

So nah?

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bigjb · Apr 12, 2017

What are the BD #s ?

chevota84 · Apr 12, 2017

I'll have to check when I get home, we set them to what bmp told us. It's fat in the middle with the powervalves open but I can't imagine it wouldn't pull through with not much load. I still need to pull the primary and see if it'll spin up with zero load.

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Rixster · Apr 20, 2017

Check you power valves. Power valve cables and motor.

chevota84 · Apr 20, 2017

Power valves are blocked open with a fooler plugged in right now

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Tmann · Apr 25, 2017

Did you ever get this figured out???? Unfortunately I don't have anything to offer but am in suspense like a good novel. In my opinion "knowledge is power" and if you have some to share we are listening.

boondocker97 · Apr 25, 2017

Not the same sled, but have a M1000 with a cutler 1300 kit on it that is having the same issue. Will run up to 7000 rpm and won't go over no matter if it's on the trail, deep snow, 7000' or 9500'. Power valve servo is cycling and it still won't rev up with the belt pulled off running motor only. I'm leaning towards having a timing issue with it. Port timing or something stupid like the timing key got put in backwards when we assembled it. If we get it figured out I'll report back our findings.

chevota84 · Apr 25, 2017

I haven't got around to trying anything lately. I think we're going out this week so maybe I'll drag it along to see what it does under a load, maybe it's just not building enough pipe temp to pull

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M7 issues

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