hesitation at high RPM?

[fishx65]

Feels like I'm hitting sand every 10 feet. It's doing this in every gear when the RPMS get really high. Runs perfect if I'm not on her hard. I'm thinking that it's a fuel supply problem. Any ideas?

 

[silver bullet]

Feels like I'm hitting sand every 10 feet. It's doing this in every gear when the RPMS get really high. Runs perfect if I'm not on her hard. I'm thinking that it's a fuel supply problem. Any ideas?

i was just having same problem. i had a 150 main jet in carb so i put in a 145 main jet and put 6 1in holes in my airbox lid and now im good. try removing your lid and take it for a ride see if that helps.

 

[driftking]

it really depends what youre altitude is. im at like 7000 feet and my bike was doing the same thing and i had to put a 137 jet in it. DO NOT DRILL HOLES IN YOURE AIRBOX LID.

 

[tyler]

it really depends what youre altitude is. im at like 7000 feet and my bike was doing the same thing and i had to put a 137 jet in it. DO NOT DRILL HOLES IN YOURE AIRBOX LID.

why not drill holes in the lid???

And dont put a 137 thats to low for you UNLESS you at a high altitude.

 

[driftking]

cuz some dumb ass drilled holes in mine before i bought it and even though the seat covers it alot of dirt and stuff gets in there all the time and i have to clean the filter every ride cuz gobs of dirt are stuck to it because of the oil.. its horrible

 

[fishx65]

One thing I forgot to mention, I only have about 300 miles on the new topend. I'm pretty sure I had to bore 40 over. Could 40 over require rejetting?

 

[tyler]

cuz some dumb ass drilled holes in mine before i bought it and even though the seat covers it alot of dirt and stuff gets in there all the time and i have to clean the filter every ride cuz gobs of dirt are stuck to it because of the oil.. its horrible

But if you need more air there is not way around it you have to have more air. Get a different filter or something. And he or some other people might not be riding in the same conditions as you cuz i know i was running NO lid and never had a problem with the air filter getting that dirty and the closest piece of paved road is like 3 miles away and i was hardly ever where there wasn't dirt.

Where do you ride most the time? What kind of surfaces straight mud? or what?

 

[tyler]

One thing I forgot to mention, I only have about 300 miles on the new topend. I'm pretty sure I had to bore 40 over. Could 40 over require rejetting?

Having it bored 40 over is going to need a bigger jet to run properly idk if you HAVE to have it but it would run alot better with a bigger jet than stock or whatever you was running with the stock bore.

 

[baddawg]

it really depends what youre altitude is. im at like 7000 feet and my bike was doing the same thing and i had to put a 137 jet in it. DO NOT DRILL HOLES IN YOURE AIRBOX LID.

I guess we all should change our airbox lids back to stock ?

 

[tyler]

I guess we all should change our airbox lids back to stock ?

No dont if its running good then your fine.

 

[baddawg]

I was being sarcastic.....

 

[tyler]

Well back to fish have you got anything figured out?

 

[fishx65]

Tried it with the airbox lid off and it did not make a difference. The spark plug looks pretty normal. Maybe a stupid question, but is it possible to have a high RPM hesitation because of a dry chain? My chain was prertty dry with some sticking links so I waxed the heck out of it tonight and will take her for a ride in the morning.

Can someone explain what the pilot air screw controls and how it effects the engine? My 1987 should be at 1 1/4 turns out but I'm wondering if it should be set a little different because of the 40 over bore.

 

[driftking]

i think that only effects the idle?

 

[bomber315]

your bored size will not affect jetting... plain and simple... first off the .40 over is so very little of a difference in cc to begin with, second all the bigger bore means is that more of the properly mixed air/fuel will be brought in...

im suprised the airbox lid removed didnt do anything for you... i would still try to go down to a 145 main or a 147.5