97 Yamaha Mountain Max 700 question

Bunn

Active VIP Member
Joined
Nov 22, 2007
Messages
319
Reaction score
258
Location
Calgary
My brother owns a 97 Yamaha Mountain Max 700 triple that has been a great sled but has developed a strange issue as of late that is intermittent.The sled has just over 2000km. The issue we are having is one cylinder(pto side) is over oiling,yes that is correct,only one cylinder is over oiling.The other two cylinders are oiling properly and spark plug color is good.It has triple pipes and oil is spraying out of the pipe tip and out the seam all over the engine bay.It seems to only happen when working the engine hard and at higher rpm.I am a Ski-doo guy and know them inside and out.I am a little confused on how this engine injects oil.The oil supply line runs to the oil pump then a small line runs up to the fuel pump.Is this where the mixture happens?Does anyone know exactly how this injection system operates so I can better understand.Also,has anyone come across this before? The spark plug for the cylinder is covered in oil,I know it's oil and not fuel because it does not evaporate.Any help is greatly appreciated.
 

retiredpop

Active VIP Member
Joined
Mar 18, 2007
Messages
1,691
Reaction score
5,014
Location
Calgary
Oil is injected into the fuel pump as you mentioned. Therefore one cylinder can not receive more oil than the others unless it is getting more fuel as well but the gas/oil ratio is the same for all three. More than likely you have incomplete combustion in that cylinder which is causing the problem. That mixture you see coming out of the pipe is a combination of unburned gas and oil. Causes could be a faulty plug wire or plug cap for that cylinder, faulty ignition coil, low compression, carb problem for that cylinder etc. I would lean more towards the electrical side being a problem. Replace the plug wire and cap on spec even if they appear okay. I have had high speed misses caused by a plug cap. Next would be to replace the coil as it could be intermittent at high revs but appear okay at idle condition when you check for good spark.
 
Last edited:

Bunn

Active VIP Member
Joined
Nov 22, 2007
Messages
319
Reaction score
258
Location
Calgary
I had replaced the coil and plug boot with no change.I found the problem thanks to another S/M member.the choke(enricher) cable was out of adjustment.The rod adjustment was incorrect.Thanks for the info.
 
Top Bottom