I have a 98 VTR with Jardine high mount slip ons, K&n air filter, removed pair system (with blockoff plates), and ape cct's...by the way this site was great for making that job real easy!
The problem I am having is riding steady at 45 or so in 3rd gear...the bike begins to stumble and backfire. Playing with the throttle eliminates this problem.
Also, on the highway..I am having trouble getting the bike over 100-110mph.
The bike will do the same thing...losses power and backfires..when it gets down to about 50-55, it will accellerate once again.
I also can not hold a steady highway speed even at 70! same issues there.
If I play with the throttle and dont hold a steady speed, it seems to run fine.
I had a Dynojet kit installed at my local dealer a couple years ago, and I have been having these problems since.
By the way, I will never go there again....I had them clean the carbs at the same time, and they changed virtually new iridium plugs with standard plugs after I told them not to switch them.
When I changed the standard plugs back to the iridium a day later, I was able to remove them by hand...unbelievable!
Anyway, I think they set it up too rich...the plugs foul black in color.
They used 190/195 for mains and set the clip on the 5th notch. The mixture screw is 2 1/2 turns out.
From what I have read on this site, it seems like most people either are using 180/185 or 185/190 mains, setting the clip on the 4th or 5th notch and setting the mixture screw around 2 1/4 turns.
Any help would be greatly appreciated.
Thanks in advance,
Mike

 

My two cents;

Your main jets are too large.

I've got V&H street baffle slip-ons, OEM air filter, Dynojet needle fifth from the top, DJ mains 175f/180 rear. My bike runs perfect.

2.5 turns out on the pilots is fine, Ca. bikes 2.75 is better. Needle on fifth is fine. You might get away with a 180/f and 185/r with the K&N, or go with 180r and 175f. If that doesn't do it, I'd lose the K&N, get an OEM filter with the 175f and 180r and then I'm 99% sure you'll be fine.

 

+1 Your plugs have got to be black as coal

 

Another two cents;

The guy who jetted your bike doesn't know his *** from his elbow.

In his defense, if you follow the Dynojet instructions- +1 on the mains for an aftermarket filter and another +2 for a "free flowing" exhaust, your bike is likely to end up pig rich.

I don't think the rather quiet Jardines qualify as "free flow" and the K&N doesn't flow much or any more air than the OEM Honda air filter.

190/195 mains are way too rich for your set up.

 

I just did my jetting (factory pro ti) and currently am running 180f 185r needle on the #2 ring from the top 1.5 turns out on the mixture screws with the #150 pilot jets.
Seems fine I will report my findings when I get her back on the dyno (maybe Friday)

 

I agree with you completely, and that was and will be the last they will see of me.
I guess thats what I get for trying to save some time and headache by having it done "professionally". HA
I should have some time tomorrow to play around with it, so should I drop 1 size for each...making it 185f/190r, or should I just drop down 2 sizes 180f/185r?
Thanks

 

By the way, when I spoke with someone from Dynojet the other day, they told me to move the needles to the 4th position, and the mains should be OK at 190/195?
They say the clip position is the only thing that has to do with partial throttle response?

 

from your description though it doesn't sound like you have top end either though.

 

I think 185/190 will still be too rich. I'd go 180/185 only 'cause of the K&N. Other wise I'd go 175/180, which might be better anyhow.

 

My third set of two cents;

If the Dynojet guy said that 190/195 will work with a stock motor and street baffle Jardine slip-ons, he doesn't know his *** from his elbow either.

 

Thanks for the input RK1,
I will try 180/185 setup tomorrow, and leave the mixture screw as is and the needle on the 5th from the top and see how it goes.

 

I'd bet dollars to donuts that works. If it doesn't, drop down to 175/180. Let us know how it turns out.

 

It pays to remember that on a CV carb that the main jets will have an effect on the entire rev range. That is why you should always set you main jet sizes before working on needle position and pilot jets.

So your midrange problem can be caused by the main jets, which sound too big to me too.

 

Well, It seemed like it was better than before until I got onto the highway and experienced the same problems when trying to get to about 100....bike would backfire and lose power.
While driving to the highway (around 40-45), it began to experience the same symptoms as before, but not as bad.
Although I did notice a little flat spot around 3000 rpm that I dont think I had before.
The main jets are now at 180/185, mixture screw is at 2 1/2 (I decided to check since the dealer did such a bang up job before...and it was out 3 turns!), and the needles on the 5th from the top.(I think...I didnt check, but thats what it says they did a few years ago...knowing them, its the 2nd)
So what to do now? I guess thats where I wait for your replies and see what all of you think I should do.
Thanks again in advance,
Mike

 

Unfortunately the best solution is to keep going. I have done so many jetting changes on my bike, I reckon I could do it in my sleep now.

As RK suggests, I would try the next size down as well and see what difference that makes. Another thing to try will be the needle clip position, as the 4th slot may be better. One change at a time for testing.

Do you have extra holes drilled in your carby slides? I know DJ recommend this, but it did not work in my bike, giving me a flat spot at about 3000rpm. I tried lots of jetting options (you name it I tried it) and filling those extra holes was the only solution. My bike is very unusual in its set up and yours is not, but is it worth remembering if you run out of options.

 

I'm starting to think that your slides are sticking, I mean playing with the throttle will not do much except moving the slides, but the carbs have been taken apart so many times, someone would have noticed.
When you say backfire, do you mean exhaust or intake backfire ??
If it's exhaust we could be searching the wrong spot.
Anyway find a multimeter and check the bike's voltage at idle and 4000 just to rule out a few possibilities, some SH have too high voltage and are frying stuff like coils.
You may run out of fuel at higher speed too, the fuel demand increase as speed increase the bowls may drain completely dry, try a run with the fuel cap slightly opened, check the vac line from the petcock for crack and gas inside.

 

For the record, clip position is not the only thing that affects partial throttle, all these circuits overlap. I'm running 195/190 and my bike runs great, had to up the pilots to 52s because is was lean when cruising around town. But thats AZ winter (ha) and the air is dense.

 

I figured I would update this thread today. After a couple of years of a horrible running Hawk and lots frustration to say the least...the bike is running perfectly!!
I tore the carbs apart a few times...replaced my CCT's, changed jetting (which I think was too rich anyway), and learned alot about this bike. Only to find out that the diaphragm in the petcock had about a 1/2" tear in it!
I just find it unbelievable that the dealer wouldn't have been able to figure this problem out. It boggles my mind. So Thanks to all of you for helping in getting my bike back up and running like new.

 

I see that kind of incompetence at local shops all the time.