Those of you with HMF pipes

[2old2race]

The HMF rep told me to just change the main jet from a 145 to 155 and I should be good to go. You would think the HMF rep would know his stuff. ?????
I have also read some other posts that are a bit more involved with drilling out the plug to adjust the air mixture and changes to the pilot jet.
Has anyone just gone with the main jet change as recommended by HMF?
I also got a K&N filter which I am installing at the same time...along with a 13 tooth front sprocket.

Thanks!
Eric

[Outlaw6;=-]

Did the rep ask u what alt u are at ? I tried the 155 and was not even close. I had a 155 just from adding the k&n air filter so i knew for sure that adding the pipe it for sure was not going to be a 155 jet. I took the advise from other people on this site and started out large and worked my way down. It is always better to run rich then run lean. If u don't want to drill out the air fuel mixture screw just go up 1 size on ur pilot jet then.

[2old2race]

Nope, no questions asked.
I am at 600 feet elevation.
I guess I will need to buy a jet kit then by the way it sounds.

It sounds to me as if changing the jets are a bit of a pain and that the K&N filter makes the jetting even more sensitive.

I am not a lazy rider, but I like to get things setup and let them be. lol

The K&n directions says that chanign to their filter should not impact any carb settings. ?????

[katch26]

no 155 (round abouts) would be right with the stock box in tact

[katch26]

is the k&N round or flat, like the stock replacement. The K&N flat one wont make enough of a difference with the lid on to effect jetting, if its the round type that you run with the lid OFF then start out around 165 but it could be 1-2 either way. Generally speaking youll be somewhere in the 162-175 range leaning more towards 162-167.5.

edit: I thought this was for a predator so disregard the flat k&n question but the other info is still the same regarding running the lid or not

[Outlaw6;=-]

I am also at around 600 ft and i went to a 165 and turned the fuel mixture screw out 1/2 a turn. Even after i changed the jet which i stayed with mukini jets my buddy who is the mechanic at the polaris dealership came over and checked it for me and said it was perfect. For winter I have to change the jet to a 170.

[2old2race]

Thanks guys!
I run with the lid on.
The Outlaw lid is kinda neat because it still has the opening in it.
I would hate to run without the lid being as how sometimes i run in coal pits.

Outlaw 6, I am going to try your approach. It makes me a bit mad because HMF charged me $10 for the 155 jet and told me it was all I would need. :rolleyes:
One last stupid question outlaw 6- was that an additional 1/2 turn? Or, is that 1/2 turn out from being turned in the entire way?

Thanks !

[2old2race]

I installed my K&H, HMF, and 165 main jet toady. I went with a half turn out from full seat.
One thing I noticed immediately...this mix adds somes balls. It is LOUD! Compared to my bike its not too bad. But for a quad, it sounds awesome!
I also notice that the throttle is a lot more responsive. I did not actually get to ride because it poured today!

Can't wait to see how it rides. I am just praying I lost no low end torque. :chinese:

[barbakos]

I can't really tell but to me it sounds like you turned the mixture screw all the way in then only a half turn back out? You are supposed to turn it an additional half turn from where it was originally. You should be around 2.5 turns out.

For what it's worth, I have an HMF sport, modded airbox lid, original filter and I ride 5000-8000 feet. I have a dynojet kit with a 165 main and am just a little over 2.5 turns out on the mixture screw. The thing runs like a gut-shot comanche compared to stock! Enjoy

[2old2race]

Originally posted by barbakos
I can't really tell but to me it sounds like you turned the mixture screw all the way in then only a half turn back out? You are supposed to turn it an additional half turn from where it was originally. You should be around 2.5 turns out.

For what it's worth, I have an HMF sport, modded airbox lid, original filter and I ride 5000-8000 feet. I have a dynojet kit with a 165 main and am just a little over 2.5 turns out on the mixture screw. The thing runs like a gut-shot comanche compared to stock! Enjoy
Well, I was wondering about that.
Yes, I seated the screw and came out 1/2 turn. So, I guess it would then be what running too lean? That is what it appears Outlaw6 said who seems to ride around the same elevation as me.
It seems fine.
But, I don't know.
I am limited in my knowledge on carb tuning. But, you are at 5-8000 feet. I ride 6-1000. So, I am sure ours need to be set up differently somehow. ????

[barbakos]

How far did you have to turn it in to seat it? It should be back out that far or farther.

[2old2race]

It actually turned in 3 full turns.
So, with the jet change it should be at least 3 back out?
Factory is 2.5 turns out and the plug was not removed.

So, I am ASSUMING I should probably turn the screw out 3 full turns from seated?

Why did it run so well then at only 1/2 turn out????? lol

I am praying I can get a screwdriver up into that hole. It is a pain having to remove the carb.

Thanks alot!

[barbakos]

You could just twist the carb. Not as big of a pain. I think when I did my jetting, I had the carb out like five times. On the screw, I would probably try somewhere between 2.5 and 3 turns out. 3 is about max, anything more and you should probably just change the pilot instead of having it out that far. You should be good with about 2.75 though.

[2old2race]

Yes, the twisting does work well. I was just a bit concerned about kinking my throttle cable. it was starting to get a bit of a bend in it.
So, I guess I'll go with 2.75 then.

Thanks alot! Maybe this slight adjustment will add a bit more power even! :devil: