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Discussion Starter · #1 ·
Still haven't decided if I'm gonna attempt to jet my quad myself or just take it in somewhere, but I guess either way I need to know the answer.

I have a dynojet jet kit, wondering if the jets it comes with will work with a full Yoshi exhaust and hotcams stage 1 cam.
 

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which stage jet kit?
 

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if it is stage 2 kit it will be fine...
And have a quick look at the jetting instructions shown as a stickie...
It is real easy, I did mine today, took 15-20 mins...
I am no mechanic...
Read the insructions for the jet kit or go to www.dynojet.com and see the pdf file listed against your bike..
It will tell you what jets to run...
 

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Does the stage 2 come with bigger pilots too? like 25s or 27.5s?
 

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Discussion Starter · #5 ·
Its a stage 2 jet kit.

Its me and a buddy workin on this, I decided to let him have a go at the jetting. He said he used the recommendation for full exhaust at our elevation. I guess they were the biggest of the 3 sets for our elevation according to the sheet that came with the kit. Figure that should be a good starting point?

I guess I'll look through the sticky at the top of the forum for other ideas as well.
 

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yea thats what i did. just go to teh dealer and say u need the next size bigger or next couple of sizes bigger.
 

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but he has the dynojet kit...
Just follow the instructions man if ya know your bike...
you will know if it lean by backfiring and cracking... if to rich it will blow smoke or just rev real deep sounding rev with no punch anymore, may take a few times to jet it right but once you do, yeeha, it will be cracking...
I am still sorting my own out, been making mods and each mod leans it or richens out...
good luck man !!
 

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Are you sure it backfires on a lean mixture? I know the pipes will glow on a lean mixture and you can always do a plug check when in doubt. However, first time I heard of this. I thought I was running rich when my bike was backfiring, at least that's what my plug was showing. I have to adjust my air/fuel mixture screw. Its time consuming trying to dial in the bike. However, you really get to know your bike when you do it yourself. :)
 

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Backfiring can occur with any mixture but is most common with a lean one. Backfiring on decelleration (let off the gas and let it slow down) is often associated with a lean mixture.
 

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I was looking at the Mikuni / Dynojet comparison chart and maybe I'm interpreting it wrong, but the chart appears to be incorrect. A stock Rappy comes with 140/145 jet set-up. The DYNOJET kit instructions for a stage 2 set up recommends a 144/146 setup below 3000ft w/ slip-on exhaust. If you compare the DYNOJET sizes against the MIKUNI, according to the chart you will be running a lot leaner than stock. This chart doesn't even show a 144/146 on the DYNOJET side. :confused: Besides, you're going to want a richer fuel mixture with the intake & exhaust. According to this chart you would be doing the opposite if you follow the instructions on the DYNOJET KIT. What am I missing here? Is this chart off, are the instructions in the kit incorrect, or am I interpreting this all wrong? I tried going on the DYNOJET link above, but it didn't let me go any further than the main page. :confused:
 

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dj's numbers are smaller because they are for fuel flow and mukini's numbers ae the diamete of the whole. i may have it backwards. but their lower numbers are larger than mukini. i've never used dj but there are those who have on here and love them and they say they work and are pretty much on.
 

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LODO said:
I was looking at the Mikuni / Dynojet comparison chart and maybe I'm interpreting it wrong, but the chart appears to be incorrect. A stock Rappy comes with 140/145 jet set-up. The DYNOJET kit instructions for a stage 2 set up recommends a 144/146 setup below 3000ft w/ slip-on exhaust. If you compare the DYNOJET sizes against the MIKUNI, according to the chart you will be running a lot leaner than stock. This chart doesn't even show a 144/146 on the DYNOJET side. :confused: Besides, you're going to want a richer fuel mixture with the intake & exhaust. According to this chart you would be doing the opposite if you follow the instructions on the DYNOJET KIT. What am I missing here? Is this chart off, are the instructions in the kit incorrect, or am I interpreting this all wrong? I tried going on the DYNOJET link above, but it didn't let me go any further than the main page. :confused:
You are not mistaken, every DJ vs Mikuni chart that I've ever seen on the net is WRONG.
 

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I was thinking about trying the CT Racing jet kits instead of the Dynojet. I just found out their shop is close to my house and they seem to have good customer service. Does anyone know if their jets are numbered like Mikunis or do they have there own numbering system like Dynojet?
 

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LODO said:
I was thinking about trying the CT Racing jet kits instead of the Dynojet. I just found out their shop is close to my house and they seem to have good customer service. Does anyone know if their jets are numbered like Mikunis or do they have there own numbering system like Dynojet?
CT just uses mikuni mains and their own needles.
 

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Hey Maddog, I've already tried following the instructions for the Dynojet 144/146 and the bike ran better stock. Tried different set-ups with the Mikuni 145/150 and 150/155 and I'm still not happy. Any tips?.....Slip-on exhaust, open lid K&N filter, under 3,000 ft elevation riding. :help:
 

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DJ 146/148 is about equivalent to Mikuni 170/175, if you want to match 144/146 you'd be close with 160/165 mikuni. The latter jetting may still be on the rich side though. What problems are you having that you're not happy with the 150/155? I believe the rule is something like drop one main size for every 1500 feet right?
 

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At 3/4 throttle I'll get a backfire every now and then. The 144/146 setup Dynojet recommends, you don't feel any power. Pipes are glowing and plug DOES show signs of a lean mixture with the Mikuni 145/150 set-up. However, since I only have a slip-on exhaust, I was thinking anything higher with the jetting would be too rich. I've been playing with both set of jets. I haven't found the right combo. What worked okay and it happened by mistake was a 145 Mikuni on the left and 150 Dynojet on the right. It worked good with and without a lid on the airbox. But I know I could find a better combo.
The other problem is that I haven't been able to run the bike on the streets (I live in the LA). My testing takes place with the bike on jack stands going through the gears.
So in your opinion that set-up you recommended is worth a try? The no lid requires a few jumps on the jetting numbers? ................Sorry for delay response........phone rang.
 

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145/150 mikuni is only one size jump from stock, with a no-lid setup you're going to need more than that.

At 3k feet I'd guess you'd want to be more in the 155/160 mikuni range, it takes a larger mikuni number to flow equal to a dynojet. If you're not getting any power with the DJ 144/146 you could be too rich to burn off all the fuel entering the head.

A quick way to spot check a jetting is to lay the lid back on and see if the problem gets better or worse. If it gets worse the jetting is already too rich, if better the jetting is too lean. Since you're reading plugs you may not need that tidbit of info but I thought I'd include it. It's hard to check plugs if you're not under load as the engine can have different burn charachteristics when it's free-revving but it still shouldn't be backfiring.

I'd try a 155/160 or 160/165 mikuni or a 142/144 DJ judging from what you've explained to me. Since you're not getting backfire or a stutter in midrange I'll assume your needles are in good shape.
 
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