help high rpm bog and no tach

[bc shredder]

Blew up a rod bearing in my sled 2 years ago. at the time it was running good. sled sat for a year and a half. Had the motor rebuilt earlier this year. Installed it with some boyseen rage cages. Now I have a bog at high rpm wide open throttle. the sled revs up and runs good for a couple seconds then bogs down and if I keep it wide open it will die. seems to be less of a problem at low altitude. I jetted down to 380s thinking that the rage cages needed smaller jets as stated by boyseen. Didn't help much. I did a plug read at wot at altitude and the plugs were wet and almost black. Also my tach is not working but I have lights and insterments so I dont think it is the relay. Can someone help. I took it to a shop and they didn,t want to look at it because they did not like my install job of the no2 system. someone suggested the dpm manifold? help please.

 

[Danzick]

sounds like your not getting enough air maybe. if the 380s didnt help, and the plugs have a lot of fuel on them. maybe take the carbs off and clean them up good.

 

[bc shredder]

Already had the float bows off and they were clean. Also I think if it were crap in the carbs I would have the issue always and not just at high altitude. also usually gunky carbs means not enough fuel not too much. Thx for the idea though.

 

[bc shredder]

So far I have checked, Carb float bowls and main jets(found no issues)Also jetted down to 380 for rage cages. DPM selonoid(clicks like it should with a
9v batt, DPM hoses(seem to be in good shape all are tight and clear), Pluged in another tach(did not function either). Visually checked engin plugs and harnesses(all seem to be connected and tight) maby Im missing one hidden somewhere?, choke tension(had some play on the plunger arm when not engaged so seems good),

My next Idea is to remove all the plugs on the mpm and engin, spray them with contact cleaner and silicone lube the re install them, completely remove all no2 wiring and then re check.

 

[bc shredder]

FIXED THE BOG!!!!! Just had to move the location of the air pressure sensor. For the life of me I cant understand how the hell the sled ran like a champ with the pressure sensor in the airbox in stead of in free air for 2 years. All of a sudden when I rebuild the motor bog. reall weird. fixed now though. Still no tach??

 

[demo9asx]

Where did you re-locate the air pressure sensor?