MCX Turbo Nytro pulled home tonight

[Nytroman]

Sled was idling a bit rough while loading it after a ride on Sunday. Started it up tonight, and was still idling a bit rough. Drove about 1/2km at half throttle to ensure was good and warm, and when I opened it up, it started to loose power, and seemed like it was only running on 1 cylinder. Pulled it back to the shop, pulled plugs, looked good, no codes showing, checked fuel pump, seems to have lots of pressure, thinking maybe the fuel regulator stuck open, pulled the return hose and has alot of flow going back to tank? Don't have a compression tester to fit into the deep plug holes. Not sure where to go next for troubleshooting. Hope some one may have some advice.

 

[BigFish BC]

was it making boost?first check all the plugs in the nose of the sled make sure none have water in them will make the sled do crazy things.check & make sure you are getting spark on all cylinders.how much boost are you running & what type of gas.if it wasnt making allot of noise ie knocking then it probably not a motor issue when these motors go they usually make a bunch of noise.

 

[Boondock]

WOW Good luck!!!

Check wires, battery and all that stuff under the hood!!

So many wires and stuff under my hood!! One wire gets messed up and I am searching. Good thing the wires haven't had any problems in mine!!

 

[DLUX]

Boost/ Vac lines

sounds kinda like what my sled was doing a few weeks back up in the hills, after taking apart everything and looking all over i realized that my boost gauge line had broke off, reconnected it and all was fine....maybe not the same problem, but worth a look, i had no idea that that 1/8 line could cause such a huge prob

 

[Nytroman]

It was making boost, and the pop off valve was working, although I never broke 8-10# since I took it out of the shop tonight. I only run 12# with premium, and usually run a few litres of C112 for extra protection. It made no unusual noise in the engine that I noticed, and wasn't over half throttle.
It started acting up on Sunday when I drove into the parking lot after riding down the trail from the hills. I was following some slower sleds, so there was alot of mist, but sat in the shop for the past 3 days. I will check the spark and conections on the front relays, shouldn't a code come up if it was electrical??

 

[Rioplay]

Same thing happened to my machine when the line to the boost gauge froze up. Coughed and sputtered, so I put it in my garage and thawed the machine out and when I fired it up it backfired and purred like a kitten again.
I was thinking about installing a valve in the line to blow out the water when it accumulates because the line is always full of water.

 

[PwdrNut]

Be sure that the line to the MCX EFI box is connected at all points. If this hose is off or has a leak, it will idle rough and not give the extra fuel when under boost.

 

[alrevedup]

Be sure that the line to the MCX EFI box is connected at all points. If this hose is off or has a leak, it will idle rough and not give the extra fuel when under boost.

Is that why you put a ziptie on mine? Is the boost gauge fed by a vacuum hose or is it electronic?

 

[Nytroman]

Checked for spark this morning , all three aok, put the palm of my hand over the plug holes, pto side and center ok, no compression on the mag side. Nice!!!!!

 

[alrevedup]

Checked for spark this morning , all three aok, put the palm of my hand over the plug holes, pto side and center ok, no compression on the mag side. Nice!!!!!

I am sorry to hear that! Was your Air/Fuel mix lean before the problem?

 

[SNOW JW]

That sucks who did the install??? Let us know what the problem is.

 

[McLovin]

No way doesnt sound right.......keep us updated.

 

[Nytroman]

Valve dropped after almost 750km on the exhaust side, don't look like it touched the piston though. tops of the pistons look excellent and consistant color, plug coloring looks bang on also, no signs of anything wrong on the cam shaft, retaining clip or something? Tear out the engine tomorrow I guess, rather be working on an old Piece of #$^%. Down fall of Turbo=warranty

 

[Mountaintech]

Was the head off for the install? My guess is that it was. I'd be pointing the finger at the installer. Seen it happen more than once before. Hats off to the engine for holding on for 750kms. Yamaha engineering!!

 

[Hot Dickens Cider]

Was the head off for the install? My guess is that it was. I'd be pointing the finger at the installer. Seen it happen more than once before. Hats off to the engine for holding on for 750kms. Yamaha engineering!!

valves dont need removed to add the head shim or change cam timing for the shim....something else sound like it was faulty here. good luck with the fix, sounds like you'll be back on it before long.

 

[Mountaintech]

valves dont need removed to add the head shim or change cam timing for the shim....something else sound like it was faulty here. good luck with the fix, sounds like you'll be back on it before long.

I didn't say anything about taking valves out! The mistake has been made more than once when taking head off. Cams are out and valvetrain parts get out of place if you're not careful. Ask anyone familiar with these type of engines......which you obviously are not.

 

[ottsum]

I thought this was a good site but there sure is alot of bashin goin on. lighten up man, It's not a contest!

 

[Mountaintech]

I thought this was a good site but there sure is alot of bashin goin on. lighten up man, It's not a contest!

It is a good site, and welcome. Just a little frustrating at times when erroneous things get posted.

 

[Hot Dickens Cider]

I didn't say anything about taking valves out! The mistake has been made more than once when taking head off. Cams are out and valvetrain parts get out of place if you're not careful. Ask anyone familiar with these type of engines......which you obviously are not.

hehehehe, thats some funny chit about not knowing these motors, obviously a valve keeper has come out somehow...

 

[Nytroman]

I did the install due to the wait for having it done (proud of it), had a buddy that has made a living moding 4 strokes since he was in high school help with the head shim. Dropped it off at my dealer today who I have been dealing with since 1983, they are going to get me back on the snow asap at their cost, even though they didn't do the install. Also have their demo Nytro booked for me for my next rides or till mine is ready. Now talk about Yamaha and some of it's dealers. Eat your heart out BRP owners, proud to be a Yamaha owner again

X bombardier rider