No One Knows whats wrong with my Polaris 90

[Sjorge450R]

I have a race predator 90 with the Hetricks power up kit. The thing is, when I ride it at my house the quad rocks, but when I went to my race this weekend it had NO power. I believe we currently have the stock jet size in right now. Does anyone know whats wrong...please help me out quick because I have another race this weekend. and we currently use a #8 spark plug (because of the head)
Thanks
Steve

[Pappy]

are you at sea level at home, but race at a much higher elevation?

[Sjorge450R]

im at about 40ft above and i cant remeber how high it is where I race, but its below 3000ft. I think like around 1500-2000. Should I just carry a extra carb with the next jet size in it?

[Pappy]

that would be my first geuss. the minis seem to react differently with less elevation changes as do the adult quads.


are you still allowing the oil injection to work like stock or have you removed it and blocked it off so you can pre mix the gas on your own?

[Sjorge450R]

thats what i was wondering, when i got my dynojet jet kit for my 300ex it has everything set up for under 3000ft. Is there anything else that could be going wrong? also the only electric in the quad is from the stator and such. Why is it only my quad doing this and no ones elses???
Steve

[Sjorge450R]

i forgot to answer your question about the oil, and yes i do mix gas. Removing that oil injection was the first thing that we did. It causes too many problems. I currently have a 82.5 main jet... please help me out pappy.
Thanks,
Steve

[Pappy]

i wish i could tell you from here, i can only offer suggestions as i am the farthest thing from a mechanic you will ever see..lol


i would do the basics, re check everything. ive seen problems that seemed to pop upp just after traveling and they run the range of dirt in the carb from transporting the quad on its grab bar, to bad gas from out of town.

is it just losing power on top end or all over?

does it smoke worse at the races?

im sure if we ask enough questions and you try enough of the suggestions sooner or later the problem could be isolated. we found a nagging issue yesterday and it ended up being the rear brakes causing a bog issue, but it wasnt just noticable at the house.

[Sjorge450R]

yeah see like i said it only happens at two tracks that we go to and works amazing here outside of Philadelphia. We are going to up my main jet to a 85 and then take a spare carb with a 87.5 with incase that doesnt work. (we will also take spare jets.)

To explain the problem more, When we lifted the rear up and gave it gas it sounded horrible. It was breaking out at full throtle and had no power down low. and no it wasnt smoking. Could changing the plug to a hotter plug work, or would that be to risky with over heating the head?

Like you said you arent a mechanic but you seem like the only person on hear that knows anything. So now we narrowed it down to jetting because it works fine here. Now i just need to find a tread that posted how to figure out what my elevation is.

[Sjorge450R]

i just found out how high my elevation of my next race is and it is 1128 feet. Just thought i would let you know.

[Pappy]

if it was happening at home also i would say jetting could be it , but since it seems to only happen at 2 tracks, get thier elevations. or better yet, see if you can get some test time at those tracks or in the same area.


my 450R ran perfect at home, but 2 hours up the road it would barely pull out of its own way. a pipe change made all the difference with no jetting change whatsoever. i hate intermitten issues..lol

The plug may help, but to many people think a colder or hotter plug is a cureall. it can be in some cases, but to often it doesnt help one way or the other.

are you still running a stock cdi?

what about how hard the quad is run before the problem raises its head. does it do it from teh minute it hits th track or after it gets good and hot? alot of kids ride alot harder at the track then they ever do at home there by causing different things to show only at the track.


***edit***

im sure someone who builds these little engines could tell you if they feel the 1000ft change would cause the problem. i dont see why it couldnt.

[Sjorge450R]

being a hard rider, yes I am. weighing 130 and close to 6' ft its funny to watch me race a 90. (much rather be racing my 300ex,but I still am a threat to the younger kids in my class.) The thing is the problem happens as soon as we get unloaded at the track and start the quad up. From the second I started the quad it had no power. The elevation i gave in the post before this, was for the track i am going to this weekend. The track I was just at is at 1015 above. I am completly conviced that the jetting is the only thing to blame. Only because it runs like a champ here.

[Sjorge450R]

O and I have a unlimited CDI box on the quad. I am going to call Hetricks tomorow because my quad is powered by them but i built it.

[Pappy]

id have to agree, but until you try it or find something that happens to point out differently, the only thing now is to see if your changes will work. i hope they do, you sound like an intelligent kid, and that is a rare trait these days:p

please keep me updated, the only way i learn alot of stuff is by follow up posts.

good luck to you on the track and off:)

[Sjorge450R]

yeah thanks alot Pappy and I will let you know what going on with my quad after this weekend.

Steve

[newnick]

I'm no expert, but I can share a few idea's with you. If a mini is more sensitive to elevation changes and really needs to be rejetted for that small of a increase you need to go smaller with the jet not larger.Air gets thinner as you go up. The next thing I'm thinking is, did you possibly over oil your air filter??? Then finally, you said when you lift it up it's breaking out real bad. I think your problem is a loose wire. Over the last couple of months my sons quad has been doing the same thing intermitantly. I've been thinking it was the gas or jetting also. I've spent days playing with the jetting and different types of gas and sometimes it runs good sometimes not. Saturday we go to the track and my son makes several laps and he say's his quad is running great. I'm thinking thats good, I finally got it figured out. We rode back towards the trailer to take a break and I hear the breaking up stuff again. So I asked my boy why he's telling me it's running good when it's not. He said it just started to do it. So I go all through the carb again, put in a smaller main, still breakin up. I decided it's got to be the wiring. It took me all of 5 seconds to find the problem, one of the coil leads was just resting on top of the terminal. It would run good sometimes bad at others. Now it runs great. I would feel real stupid about this but I've been doing so much jetting and plug chopping, I feel I've gotten real good at reading plugs and I hope I can tell the difference between carb trouble and electical trouble. Sorry about the long winded story.

[Sjorge450R]

are you 100% sure that you go down in jetting when rising in altitude?

And like I said... it cant be electrical because it works perfect here and at another track and because there isnt many wire in my quad. Just not a these two other tracks.

[newnick]

No, not 100%, I said I'm no expert. But I'm sure the air gets thinner as you go up, thats why I say you need a smaller jet if it is jetting. Less air requires less gas. If I'm mistaken someone will come and say so.

[newnick]

Our quad doesn't have many wires either.It takes less time to check it if you only have a few wires, can't hurt.

[Pappy]

yes, thinner air usually requires less fuel. atleast thats what they told me when i was raisng heck about my R pulling like turd.

[Sjorge450R]

yeah like i said im just going to call the people who get paid to know this stuff. (Rich Hetrick) Once I call them i should be able to figure everything out. Thanks for all your help, Pappy and NewNick
Steve

[Pappy]

rich is awesome, i chat with him as often as possible. he should be able to get technical with ya..lol


i never did understand that tho, i would think leaning out the air (higher elevation) would require more fuel. i have enough to remeber without worrying over that stuff:p

[Sjorge450R]

yeah thats what i thought. You go up in altitude you go up in jets... anyway im just going to ask Rich tomorow when i get home from school. (first day tomorow.....:ermm: ) Again thanks for all the help.
Steve

[newnick]

I'm sure Rich can be of more help also. Just think for a minute though, lets say your quad is running perfectly. Lets also say that it is setup at 10 parts of air and 1 part of gas. If you go to a altitude that is only allowing you to get say 8 parts of air through your carb instead of 10, your now running 8 to 1, it won't be running perfect anymore. It works the same way with tempreture, very hot conditions requires less gas because the air is lighter, colder denser air requires more gas. When you find out what it takes to get your quad running right let us know, we're all here to share experiense.

[newnick]

Let me clarify that last post. Your still going to have the same amount of air going through the carb but less of it will be oxygen when you go to a higher altitude or the temp goes up.

[Arctic Cat Dad]

On the air thing. Michael's quad was jetted at over 3400'. That's what our house is at. When went to the South Carolina National a few months ago,I did a plug check like I do when we get to the track. Good thing I did because the plug was white as a ghost. I had to go from a 116 jet to a 122. Hope this helps. I to think it's a jet problem. But call Hetricks I call them all the time and they have never told me wrong!

[Sjorge450R]

i called them an newnick you were right. You go up in altitude you go down in jets. Well the real test is going to be this weekend. This time im not signing up until i get the quad running right.lol:macho

[newnick]

I'd still check the wiring if your quad is cutting out or breakin up.

[Sjorge450R]

its not that because it works at home and on my homemade jump fine for over an hour of running.

[newnick]

Must be really sensitive to the change in altitude.

[Sjorge450R]

a little update. I went up to Back Mountain for the PA Series and i have to say. My 90 worked...lol. The thing is i have either too big of a pilot or too small. I had no bottom end, but when the thing started on the main jet I was flying.... :D so all i did was use the front brakes and kept the throttle in... i guess this is one of those times it is better to be bigger on a small quad so that you can throw it around.... just thought that i would let you guys know. Oh and i have a 85 jet in there now and it ran real rich. But hey, at least i finished this time 4/12.
Steve

[newnick]

Glad to hear it ran better for you.

[QuadJunkies]

So can I ask this....
When you start out in the lower RPMS is it sluggish ,then one you get going, it runs fine??? If so, you may have a bad choke!! We thought we had jetting issues for a looonnngggg time , then Rich Hetrick suggested we check the choke(we still run the E start and a kicker for back up) we ended up having to rejet cause the whole time we thought it was fat and could never get the jetting right.

[Sjorge450R]

i dont have a choke... i put and auto choke on the hole so nothing would go into it but didnt plug it in because i have no where to plug it in... yeah thats what it does, runs sluggesh then flys.