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rejetting to new pipes


Gemeiner

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I bought my 96 banshee about 6 months ago and I've been doing a lot of trail riding. Super steep, Rocky hills and such. I was running Toomey t5s with the Toomey shorties but they were rusty and I heard pc platinums give better lower end power so I decided to switch.

 

I'm at 4000 feet, running pc platinum with 296 silencers (I know! I'll prbly go with 304s later but they were free lol). Open airbox with a uni which I might change later. Not sure what jets are on there but I'm wondering what size range I should be in so I don't have to get a bunch of sets lol.

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After I put em on I rode it because I didn't know you needed to reject. I thought you just swapped out pipes lol. But I could tell something was weird because it seemed kinda slow to accelerate until it hit the powerband. It also seemed to smoke a little more and sounded a little tingy in the exhaust though the sound was already weird to me because of the silencers. And the pipes were turning blueish from the heat right at the engine. So I didn't ride it long. Just up the road and back. Pretty sure it's lean but I haven't gotten to check plugs yet.

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im pretty sure my cylinders are stock but the previous owner believes it was bored slightly over. the head is stock. ill start with trying to adjust the needle and the airflow like you suggested and see what happens. it kind of runs like crap with the choke pulled though which is odd if its lean right? but my new pipes are discolored blue about 8 inches from the head so I know its running hot.

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What do your plugs look like? higher the altitude the richer your a/f mixture will become.  I know you said the pipes were turning blue from heat but overheating is also a sign of rich condition.

 

my first thought would be you could probably clean it up a lot by adjusting the a/f screws. more then likely turning them out to add air.

 

Your jetted pretty fat for a non ported engine even at sea level.

 

Personally I would look at my plugs to decide if its lean or rich and if they are colored evenly.

 

If they look as if it is infact running lean I would do a leakdown test.

 

If the plugs look as if it had been running rich I would drop to 290 2nd clip

 

I have a stock piped banshee at about 800ft ASL with 30/300 3rdclip and its pretty rich...  at 4000ft ASL and much richer then that seems just way too rich. Rule of thumb is every +1500-2000ft you go 1 jet size smaller.

Edited by uman1030
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that's going to be the hottest part of the pipe, some discoloring will happen. I've seen them glowing red when the jetting is off. I don't think your too far off, the discoloring you describe is normal. make small adjustments.

Discoloring is NOT normal. If the bike is tuned properly, the pipes will not discolor. I run show chromed Rockets, and they have never discolored.
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The plugs did look a bit dark and oily but I don't think it looked too bad. Can u post pics here? I replaced the plugs and just idled it for a bit and when I pulled em out they were still clean with a little oil on the ring. But I probably didn't run it long enough to tell. It could be rich though because there is more smoke than before and it seems sluggish not hesitant before the powerband and then it takes off.

I'll have too look up plug and chop.

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so adjusting the air screws seems to make a big difference. its hard for me to tell which way is better though but turning them to the left (opening them up?) seems to make it worse. seems like it bogs more which doesn't make sense to me since that's leaning it out right? so weird sounding with the silencers on it. I don't like em haha.

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got it down now. it totally worked. i had to turn it in like a turn and a half. but that stopped it from running so hot and then a few quarter turn adjustments took away the bogging feeling when accelerating. now its smooth. pretty stoked. pro circuits have some gnarly lower end power. thanks a lot, ive learned a lot about the carbs lol

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