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Engine Question

4943 Views 17 Replies 9 Participants Last post by  kyforeman05
I put the performance kit from HMF on my 500S (slip-on, 170 main j., 2 1/2 turns out on a/f screw. Last night me and my wife were riding around on my parents place and she said that about 2 or 3 times when I changed gears she saw a small puff of grey smoke come out the exhaust. She said it was just a very small amount and if she wasn't looking right at the exhaust she probably wouldn't have noticed. My question is could this be a little unburnt fuel or could it be too lean? I believe it was only doing it at higher rpm and when I swapped gears. Not worried about it too much just wondering. Thanks everybody!
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Pull the plug. that will give you the best indication of rich/lean.
I did the plug test when I first put the kit on couple weeks ago. I went down my driveway (about 75 yards) in 3rd gear wound up tight then shut it off and took the plug out. It was all black except right around the base of the center electrode(the end of the ceramic at the electrode), it was a tan color. Done this several times with the same results. I was just wondering what the smoke could be, its very little, not much at all. You will see it barely at the end of the exhaust and thats it. By the time you see it it's already gone if you know what I mean.
Could it moisture trapped in the pipe being expelled?
Thats a good possibility. On the way down to my parents house it poured the rain and I didn't have the plug in the exhaust, so maybe the packing got wet.
mine does the same thing it is extra gas that is being dumped in its not a bad thing for it to happen
QUOTE ("Bigvick":1uv85cu6)
Thats a good possibility. On the way down to my parents house it poured the rain and I didn't have the plug in the exhaust, so maybe the packing got wet.

Plug? Are you supposed to plug it when transporting it?
At the underside of your pipe, there is a bolt. You can take this out so water/moisture can drain out
Poof of smoke lol heck i get a blue flame every now and then.
QUOTE ("Rincon 650":arn9b6a6)
At the underside of your pipe, there is a bolt. You can take this out so water/moisture can drain out
Thanks I learn something new on this site everyday!
i'm with sasquatch on this one i get the blue flames
QUOTE ("big_daddy_bigfoot":2m5nucna)
QUOTE ("Bigvick":2m5nucna)
Thats a good possibility. On the way down to my parents house it poured the rain and I didn't have the plug in the exhaust, so maybe the packing got wet.

Plug? Are you supposed to plug it when transporting it?[/quote]


Yeah, I got in a hurry loading it and forgot to plug the exhaust. Didn't realize it untill I got there.

I don't get any blue flames! Matter of fact mine doesn't cough or backfire at all. If you wind it up tight then let off it's just a nice smooth purr until it idles.
I'm about to put the same set up on my 500, (HMF,Dynojet,K&N)......my question is how much power gain did you notice? Was it just a little bit, or a HOLY $&[email protected] thats a lot faster?? I'm going to be adding the quite core insert as well, will that decrease the amount of power I'll be gaining? Thanks guys
QUOTE ("rovmike":2cj2r10b)
I'm about to put the same set up on my 500, (HMF,Dynojet,K&N)......my question is how much power gain did you notice? Was it just a little bit, or a HOLY $&[email protected] thats a lot faster?? I'm going to be adding the quite core insert as well, will that decrease the amount of power I'll be gaining? Thanks guys

Well with mine it was more like a "Dang, That's pretty good!"
You will see a power increase, it was very good improvement on mine.
I feel more low end torque rather than top end and thas what I wanted. Adding the quiet core will take some away but not sure on how much. Maybe someone with the q. core could answer that better.
Yes the q core does restrict the air flow some resulting in less power but not alot, you can remove install in @ 1min so see for yourself. My wife does not like to ride it w/o the core so i leave it out. I agree
Big V the gain is on the bottom end. Pick up the NKG idirium plug its helps,
better than the stock plug.
Good bottom end, and most of all.. The throttle response with a jet kit will amaze you. I had someone ride up on their stock Foreman 500 and ask the same question...I let them ride the wife's Foreman 500 and they came back writing a check for the mods. You WILL notice a " WOW " difference in the 2 mods...( Pipe and Jet Kit )
I got one more short questiong for you kyforeman05, or anyone else.......how much sound difference does the quite core make. I don't want to make everyone behind me wear ear plugs. Thanks for your help guys.
There is a difference in the level seems like what I read somewere @10 db's more w/o the q core, as far as rideing around the neighberhood Its
a good idea to have in but on the trail most of those folk are like minded
and wont mind. I do bring mine along just incase someone does have a issue, if I like'em i'll put it in.
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