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jet questions

Old 03-03-2018, 09:06 PM
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jet questions

Hey all,
ive got a '98 that i just installed Danmoto gp slip on's on, like 2 days ago. Now, i have a Dynojet kit in the mail to arrive this monday. My local shop wants an obscene amount of money to install it, but since i'm an aircraft mechanic by trade, i figured the headache would be worth the pennies saved by doing it myself.

Now i have never worked with carbureted machines in the past, but i understand the general principle and have watched a couple videos of people tearing these things apart. And its my understanding (correct me if i'm wrong), unlike a lot of the 4cyl bikes, a jet is basically required with these bikes after exhaust work since they run so lean.
My questions are:

-Should i worry about getting a dyno run in before and after
-is installing the kit, as is, as-per Dynokit's instructions sufficient? or will i have to play with the pilot jet some more
-what general settings would you recommend for an aftermarket exhaust similar to the one linked above?
-are there any little nuances or tips for removing the carbs on these bikes (except the obvious)
-what is the general opinion of kits (like the one linked above) for these bikes.
-is modding the airbox and replacing the stock filter worthwhile while i have the tank and everything off?


For infos sake im located in south jersey and to the best of my knowledge the bike has been un-bastardized and bone stock before i installed the exhaust.
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Old 03-03-2018, 11:17 PM
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Use the Search function and all your questions will be answered. Welcome to Super Hawk Land.
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Old 03-04-2018, 08:21 AM
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Old 03-04-2018, 03:11 PM
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I actually just took a dynojet kit off my bike because it ran so bad.
I went back to stock jets and needles and springs and it runs so smooth and nice now.
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Old 03-04-2018, 04:23 PM
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I have gutted stock silencers (just a large bore perforated tube down the middle with packing outside that) and stock jetting on mine. Based on the plug appearance, this is just fine, and it runs well too. So before leaping into jetting land, why not check how your bike runs with the stock carbs?

If you do start to change the carbs, good scientific methodology would be to make a single change at a time.
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Old 03-04-2018, 06:19 PM
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Originally Posted by Cadbury64 View Post
I have gutted stock silencers (just a large bore perforated tube down the middle with packing outside that) and stock jetting on mine. Based on the plug appearance, this is just fine, and it runs well too. So before leaping into jetting land, why not check how your bike runs with the stock carbs?

If you do start to change the carbs, good scientific methodology would be to make a single change at a time.
Largely I just assumed it was going to need the jet, since the exhaust is a pretty substantial change over the stock cans. And it was my understanding the end bikes run lean-ish even in a stock setup. Searching through a couple other threads here (before I made my post) had some people saying they were running dangerously lean after installing a slip on.

That being said I rode the bike lightly today and it didn't feel bad, but I don't really trust my judgement in that regard being that I don't think I would really know the difference. The only thing I noticed was some light popping when rolling off the throttle in all rev ranges.
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Old 03-05-2018, 09:54 AM
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Originally Posted by Thomas Gennaro Jeffers View Post
Searching through a couple other threads here (before I made my post) had some people saying they were running dangerously lean after installing a slip on.
Well everyone has different experiences but I have never seen one go "dangerously lean" by just installing a set of slip-ons.
The bike will let you know by popping, banging and surging long before you go lean enough to cause damage.
Also one of the most common jetting "mistakes" on a VTR, IMHO, is going too rich.

So you will have no problems running the bike with slip-ons to see what, if any, jetting changes are needed.
Also as food for thought, I am running a bunch of bits on my engine including one of the better full exhaust systems and am running smaller than stock main jets.......
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Old 03-05-2018, 10:04 AM
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Originally Posted by Cadbury64 View Post
I have gutted stock silencers (just a large bore perforated tube down the middle with packing outside that) and stock jetting on mine. Based on the plug appearance, this is just fine, and it runs well too. So before leaping into jetting land, why not check how your bike runs with the stock carbs?

If you do start to change the carbs, good scientific methodology would be to make a single change at a time.
Good info, thank you. It's popping a little on decel but that's about it, the ride is smooth
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