Jet carbs for aftermarket exhaust?
 

Hello. Just got my Hawk about 2 weeks ago. Haven't even been able to ride it yet. It's been at the dealer since I bought it. Turns out it needed some stuff for inspection and I wanted it looked over to see if I needed a valve adjustment, carb cleaning, etc. The dealer is now tellng me I have to get a jet kit installed due to the devil high mount dual exhaust. They said the low end response in first and second is terrible. Is this usually the case with these bikes? Does the exhaust require the jetting? It's getting pretty pricey to get the bike out of the shop. Any thoughts? Thanks guys. Can't wait to ride this thing. Killing me to have it in the shop this long.

My bike was completely stock when I got it. I put a set of free flowing mufflers on it and took it to the shop for a dyno run to check the air/fuel mixture. The result was that my bike was running WAY lean. Off the charts lean at some RPMs. It came to a decent mixture at around 7000 RPMs. I had to jet mine. I haven't got it back on the dyno to see the results yet. The quote from the guy that dynoed my bike was "Jet that bike before you burn a hole in your pistons!"
Sounds to my like your bike is in a similar state as mine was.

Yes you do need to get the carbs dialed in.

There are two schools of thought on what you should do. The first and most popular is to install a jet kit. In doing so you increase the main jet size and use a different needle. While you can and do get good results with this method, it's not really what this bike needs IMHO.

The reason I believe this is that like bikephreak, on the dyno the bike showed lean until around 7k or so. What that tells me is that when the bike is on all the way on the main jet, things are pretty good. So instead of increasing the main jet size (which I believe makes the bike run to rich on the top end) I up the pilot jet to a #48 (which also gives you just a little bit more up top so you get a real nice mixture at 7k and above) and then shim the needles up between .040-.060" to enrich the mid range. Also instead of spending over $100 for a jet kit, this will set you back under $20.

It is the set up I use except I do have a set of HRC needles in mine but the stock needles are actually very good and the last time I had it on a dyno the bike had 70k miles on it with just a set of slip ons was putting out 109hp and 70 ft\lbs.

Of course YMMV but whatever you do, tell them to set the TPS to 490 ohms+\- 10 as the factory sets them to the 800-900 ohm range.

OK, I am going to make myself sound dumb here buuuuuut.......what does YMMV stand for?

YMMV - Your Mileage May Vary :)

I did not jet my bike since putting on my cans a while back. I do run a bit lean in Phoenix, but most of my riding gets me up to Prescott - Flagstaff - Payson where I find the bike runs quite well.

anyone know of a good tutorial to remove the carbs?

Take everything off until you see the pistons, then go back 4 steps.....lol

Actually it is no big issue to remove the carbs.

Remove the air box.

Disconnect the TPS plug

Loosen the clamps on the isolators

Rock the carbs from side to side to loosen them and pull then from the isolators

Remove the rear enrichment cable, be careful of the plastic nut as it is easy to break and should be snug at the tightest.

Remove the coolant line from the rear carb

Remove the throttle cable stay and throttle cables

Remove the coolant line from the front carb

Remove the front enrichment cable.

If you have removed the emissions and pair the carbs are free, if not you have a few vacuum hose to remove.

To re-install just go in reverse. Also a bit of spit in the isolators help the carbs slide back in much easier.

Cool thanks for the quick tut. Just got my hawk and threw some D&D's on it right before i put it away last year. Also sorry for jacking the thread but i know people will appreciate the general knowledge!:evillaugh:

Ok. I am going to jet the carbs as suggested. I got the bike back the other day and the throttle response doesn't seem bad. Although I haven't done anything but roll on the throttle from about 4000 rpm and higher. I've avoided WOT because of the jetting issue. They said the problem lies below that range. I want to get the bike in optimal condition. The issue I'm facing is I can't afford to do the work until May. Will damage result by riding it until then. Dealer says no, but I wanted to see what some of you guys thought.

vtr 1000f superhawk dyno jet kit?
 

have a 98 superhawk with d & d pipes..just bought the bike...im not sure if its jetted yet or what..bought it how it is....if i jet it if it isnt jetted do you think i can tell the difference in power?
what does jettin it do even?
thanks alot

you will need to either jet the carbs or shim your needles to avoid having s lean mixture because you are running higher flow exhaust canisters. Trust
me, you need to do one of them. No you won't be able to Tell if you're bike is jetted based on the power. Basically what a jet kit does is supply more fuel, which is essential when the bike is moving more air. I'm no expert but I've lesrned this all first hand with my own hawk. Get it right or it will be s nightmare. Do s search and you will find various threads on the subject.

steve, since your bike is running so well after all the tinkering we did, it would be good if you"d list your latest numbers so that others might have a good starting point.

Where can I get a #48 pilot jet?

The best way is to find a dealer that has them in stock already for @ $6.00, if you have to order them from Honda the new price is $16-17.00. They are Keihin series 21 pilots and are used with some offroad models as well.

I found these KEIHIN CARB/CARBURETOR PILOT JET 35 38 40 42 45 48 50 52 55 58 60 62 65 68 70 72 | eBay
I have devil high mount pipes would just the #48 pilots fix the elevated heat caused by running lean?
Also it there a way to take the float bowls off with out taking the carburetors out to change the pilots?

Those are the right ones. Just changing the pilots will not fix all the issues as you would still be lean in the mid-range, well except for the spot where the front carb goes rich. Though that is all explained in my carb set up thread.

For your last question, there is no way that I know of to get the bowls off without removing the carbs.

So I went ahead and purchased the dynojet kit off of ebay.
Honda VTR1000 Super Hawk DynoJet Jet Kit | eBay

On dynojets website the installation instructions http://www.dynojet.com/pdf/1185.pdf say that they come with 3 sets of main jets DJ170 DJ175 / DJ180 DJ185 / DJ190 DJ195
Since they come with no pilot jets should I also get the #48 pilot jets KEIHIN CARB/CARBURETOR PILOT JET 35 38 40 42 45 48 50 52 55 58 60 62 65 68 70 72 | eBay or will the new shimmed needles and main jets be sufficient enough?

Anyone know?

if you install 48 pilots with a DJ kit, your idle will be pig rich even if the mix screws are closed under 1 turn. That has been my experience.

Where is the mixture screw on these carbs?

It's the "D" shaped screw on the bottom of the carb. ;)

Found it today, Thanks.

I took the carbs out today to jet them with the dynojet kit only to find that it was jetted already with factory pro:eek:. I was wondering what the best way to run the factory pro kit with what I have. I have a devil high mount exhaust with stock air filter and box. It is running really hot at idle and when moving right now I'm running #50 slow jet #182 main front #185 main rear. The needle clips are on the 2nd from top and the mixture screws 2.25 turns out. Any help would be great.

Best guess, the mains you have work best with a K&N and are too big for a stock filter. But, I do not think that anyone has run successfully with the needles set on groove #2 and aftermarket exhaust. And since you are hot at cruise, this suggests that you need more fuel. Move the clip to #3 for starters. This should enrich the mixture enough to improve things. You might also need to turn the mix screw on the rear out no more than 1/4. If you find this to be a bit too rich then turn the rear screw back in and also turn the front in a little. If the engine starts from cold without choke, this indicates richness.


If you do this with the large mains then look for overly rich fueling WOT 4-6 K RPM. Like I said, this is a best guess only since I have not installed a FactoryPro kit.

What affect does changing the throttle position sensor resistance have on the bike? Someone mentioned having it set to 49050 with factory being 800 - 900.

search hawks "throttle position sensor" thread.. alot.. and he said 490 +/- 10 ohms.. which means 480-500.. but 500 is what he suggests to turn tps down to... alot of members have had 800-900 no their tps, which is way to high... mine was 600, not so high.. but still a great difference in throttle response / low level rpms... the manual states 490 +/- 10 ... the factory way overtuned it selling these bikes, that is what he meant by factory being 800-900.. not that it was correct ;).

- Shane

My guess on the tps is that when the rack of carbs is being assembled they may set the tps at 500 with idle screw backed off. Then the setting is changed when the manufacturer or dealer sets the idle speed before delivery.

Does anyone know of any "D" Shaped Air/Fuel tools to turn while on the bike?
Any links would be great I am in the market to buy one.

It is set for emissions (hence the shear bolts holding it in) not performance from the factory.