yamaha mountain max bog

[bogeyfresh]

hey i'm hoping someone can help here,

2000 mountain max 700, bogs out of the hole then pick up and goes, it just started doing this, carbs are clean and dialed in properly, fuel pump good, new plugs and caps, compression good,

I'm wondering if maybe it's clutch related?

I'm running out of ideas

 

[Stg2Suby]

Could be sacked out or broken primary spring absolutely. Had a ZR700 doing similar years ago, we figured motor issue but turned out the pri spring was shot. What happens is the spring can't counter the flyweight force when the clutch engages so it upshifts way to fast bogging the motor. Good luck with it.

 

[Clode]

Does the sled reach shift RPM ? I would have a look at both clutchs.

 

[bogeyfresh]

ya the sled will hit 8500 rpm i replaced the secondary spring but no luck i took it through some deeper snow and it started to power out a bit then hit like 9000 rpm then on the hard packed went back to normal

 

[Clode]

Check the roller condition in the primary, they shouldn't have play in them. If a roller bushing is worn the clutch binds when the weights don't push evenly.

 

[bogeyfresh]

will that cause a bog too?

 

[Clode]

It can, weights contact the roller uneven, the moveable sheave then binds on the shaft causing all kind of odd things in the rpm, over reving, hanging up on throttle chop causing clutching to be in to "high of gear" causing bog, etc.

 

[bogeyfresh]

ok im at a loss now, new rollers still doing same thing i think worse now, it bogs of the start then gets up and goes, then will under rev over rev bog a bit more

any suggestions?

 

[bogeyfresh]

i also checked under the hood while engine was running it's bogging before the clutch even engages

 

[Stg2Suby]

carb and fuel tank vent lines are clear?

 

[bogeyfresh]

ya they are, i think i fixed the over and under revving though there was snow getting in on the belt through a hole i cover hole up went out for a ride and it didn't do that once except still bogs

 

[bogeyfresh]

ya line are clear i fixed the rpm issue seems some snow was getting in there causing it to slip, but still a bog the only thing different with the sled is I wrapped the pipe with header wrap but i don't see that effecting it to the point of bogging

 

[Clode]

How is the throttle free play adjusted? The switch on the carbs could be causing an issue, just unplug the wires and see if its better...you may have to plug the wires together on the harness side...its been so long since I had mine I cant remember for sure.

 

[bogeyfresh]

i've tried that already with no results

 

[Clode]

If you give it a blip of the choke does that help?

 

[bogeyfresh]

ya a little bit, im aware this could be related to the pilot jets but the sled never used do this, i've also cleaned carbs more than once already

 

[Clode]

Did you remove all the brass from the carbs and varify with a wire that the pilots are not plugged, and clean the passages without the brass in the carb. Did you remove the nozzles and make sure that the needles and nozzles are clean?

 

[bogeyfresh]

carbs are clean

did a compression test 90psi on pto 105 in the other two, top end job I know but would that cause a bog?

it's funny though with that kind of compression sled still goes like stink


what do you think?

 

[Clode]

Compression is low, does the bog get worse when the sled is hot? Usually a bog from low compression is way more noticable when the engine is hot. Compression below 100psi is too low and a top-end is required. How many miles on the old max?

 

[bogeyfresh]

bog is worse when she gets hot, i was already looking for another sled, sad day but i sold her today i'm going to miss it but wanting another nytro to ad to the arsenal