Dynamic

Hey everyone, I just got myself a 98 VTR, but am a bit disappointed by the lack of grunt so have bought a jet kit an K&N filter having heard that they make a big difference to the performance. After cracking open the carbs, it turns out that it already has a dynotjet kit fitted, but the bit hadn't been drilled that the kit tells you to drill.

Drilling done, K&N installed, an it seems a little better top end, but backfires alot in the mid-range. Currently on 180 main jets, an #4 clip position on the needles and the mixture screws two turns out(the European kits come with pairs of same size jets, unlike the american kit).

I'm running a pair of scorpian race cans with the baffles out, an as said above, a K&N airfilter.
Midrange implies needles right? but the kit suggests clip position #4 without mentioning the K&N, so I'm not sure it needs to be any leaner.

Any ideas?

Cheers,
Phill

killer5280

The instruction sheet that comes with the US Dynojet kit says to go up two sizes on the mains and put the needle clip in the 5th notch when using a K&N filter. You're way lean.

RK1

Instructions for Dynojet kit #1185.002, U.S. Models

""When running a good aftermarket exhaust with high flow baffle use DJ180 main jets in the front cylinder and DJ185 main jets in the rear cylinder. NOTE: If you are using a K&N filter then use a main jet that is 2 sizes larger... You will also need to raise the needle to groove #5."

killer5280

Is there an echo in here?

I know that when I dropped a K&N filter in my VTR without changing anything else, it was so lean it would hardly run.

RK1

Hey Hey Hey... I didn't see your link link link.. before I posted the quote.

I'm not sure if instructions indicate going one up for cans and 2 up for K&N means +3 if you've got both or +2 with both, but either way Dynamic is running lean.

Dynamic

Well, since the UK kit was a bit vague, I went off the US instructions, an fitted the 190 jets and put the needle on the #5 grooves to start with an that was really bad backfiring in the midrange, so I changed it to the 180 jets an #4 clip on the needle, an it wasn't as bad, but as you guys are saying, with a filter, that should be running too lean but it doesn't seem to be...

I could just keep going leaner but from what the kit says, I should have to keep it pretty rich.

The only other thing I can think of is if something hasn't gone back together properly, but I've had it apart an back a couple of times an everything seems ok.

It's pretty much on the jetting it was on before now, so the only new bits are the drilling of the slides, an internals, and the K&N filter...

Tweety

Well Euro or US kit it shouldn't have same sized jets in both carbs... that would mean one is either rich or lean when the other is good...

Might be an idea to try 180/185?

Dynamic

Well, there was a spacer under the e-clip for the needle in the rear carb, but not the front, which woud make the rear run that bit richer... unless the front one bounced out when I wasn't looking, but it may explain why European kits have pairs of same sized jets rather than stepped sizes like in the American kit?

RK1

Dynamic;

I believe you should have the same/same spacers on both needles. If one is missing that could be at least part of your problem.

I still think #180 mains are too lean for those cans and a K&N. Dynojet's equivalent of stock jetting is 175f/180r on U.S. bikes.

What about the pilot screws? I'd make sure they are 2.5 turns out, maybe a little more. Are you balancing the carbs each time you put them back on? My bike won't run right if I haven't.

I can't imagine you need to go leaner. Were it my bike, I'd do the pilot screws, make sure I have the same spacers on both needles and needles in the 5th groove. I'd maybe install the #185s and sync carbs before a test ride.

Tweety

Since you say you got pairs...what pairs? what sizes do you have to choose from?

Definetly should be the same spacers on both needles... I can't see ANY reason for getting pairs? sounds very odd to me...

RK1

Tweety;

VTRs shipped by Honda to the U.S., Australia etc., places where it can get hotter than hell in the summer, were shipped from Japan with a richer main jet in the rear carb.

VTRs shipped to cooler places like the U.K., had the same mains in each carb.

Similarly, U.S. Dynojet kits come with six different size jets, U.K. Dynojet kits come with three matching pairs of different size main jets.

My best guess? The VTR runs fine with matching main jets in moderate temps. But the cooling system on the VTR is a bit marginal. Honda compensated for this by placing a +1 jet in the rear carb of bikes shipped to countries where it might be 110F or 115f degrees in the summer. It doesn't ever get nearly that hot in the U.K. so that compensation wasn't needed. I can't think of any other possible reason for the difference.

Dynamic

170's, 180's an 190's...

I think I'll go back an try the 190's again with the clip on the #5 position, mixture screws out another half a turn an see how it goes...
I'm getting a set of vacuum gauges off a mate in the morning, so will make sure the carbs are properly balanced then an let you know.

Cheers for the tips.
Phill

Tweety

Well... I dunno if you know the climate here in Sweden? But if anything it's colder than the UK... And it dosn't get to those temps...
And all bikes I know of here have been shipped with assymetric jets... So to me it sounds odd...

killer5280

I suggest making only one change at a time, either mains or needle clips. I know I have chased my tail more than once by changing both at the same time.
No one has suggested it, but I think that with the K&N filter the pilot jet probably needs to go up a size. FWIW, I took the K&N out of mine and made a cleanable filter using a stock filter with the paper element replaced by green filter foam. Works great. The consensus is that the only benefit of the K&N is cleanability; it doesn't add power.

skokievtr

I did the same with my NT650 and VTR, playing around with different foam; whose did U use?

BTW, if you are carefull U can clean the OEM filter with a dash of citris cleaner, grease cutting dish soap n'water + a soft toothbrush (my wife never notices). Do not soak the paper element but work in the suds, rinse, blow dry on warm (not hot) for a bit & air dry. I've done OEMs 2~3 times & checked media condition carefully with a 10X microscope. Seems to work great.

killer5280

I bought a sheet of it from Unifilter's website. By the way, I didn't mention in my previous post, but the custom made foam filter I made breathes like the stock filter, so the jetting is the same; it doesn't require radical rejetting like the K&N. Some day, when I have the time and inclination, I may try to make the K&N work, but for now I'll just stay with what is working pretty well right now.

http://www.unifilter.com/online%20ca...cessories.html

RK1

Tweety;

If VTRs sold in Sweden come with a richer rear main jet, then my "climate" theory for Brit VTRs having matching jets doesn't hold, and I have no idea why Honda shipped VTRs to some countries with matching jets and others with richer rears. Why would they do that?

nuhawk

In all climates the rear runs hotter and needs a slightly richer mix.

Tweety

I have no idea... But I can say for sure that my bike had assymetric jets as stock and two other bikes that I have helped out with the re-jet was the same... And I do not know of anyone reporting anything different... So as far as I know all bikes should be assymetric...

Tweety

That was my understanding aswell...

RK1

"In all climates the rear runs hotter..."

Of course. But why don't U.K. VTRs need a slightly richer mixture? For that matter, why did all carbed VF/VFRs from '83 to '97 come with the same jets for both the front and rear bank cylinders?

nuhawk

Well, if that's the case I can attest to the fact that my 97 VFR is the fastest cat in the barn. My VTR was jetted by a previous owner and this guy or whoever he paid was ON. It has a little cackle off but a whole lotta gotta power on. If I want to get away from some stupid cagers I can open up 300 yards in a flick. I took the big Bird up the country this weekend to spot some trees in for some customers. Nice Sunday ride.

Dynamic

Right, just changed to the #5 clip position, two an a half turns out on the mixture screws, an balanced the carbs. It feels worse, and alot more gutless around the 2-4.5k mark, and after a couple of minutes when it had warmed up, the tickover raised to just under 2k rpm...

The only thing I can think of is if something isn't seated right so it's drawing air, or similar, but it's been apart an back a few times, the diaphrams are sitting nicely, the rubbers between the carbs and head are nicely seated on both sides, what else is there?

<Added>

Ok, from just revving the engine in neutral, it'll rev freely to 3.5k, then if you open the throttle a bit more, it bogs down, then rev it harder an it'll pick up at above 4.5k but won't sit between 3.5k and 4.5k... Suggestions please... I'd really like to get it sorted an go for a blast in the morning.

nuhawk

Sorry mate, but I think your riding for this weekend is spoiled. The tuner needs to work this up again. These are tricky bikes and small changes can make big differences. Good Luck!

RK1

Dynamic;

Not clear to me from your last post if you're still using the #180 mains or went up or if you matched up spacers on each needle.

I've no experience with the K&N but gave up trying to set my bike to the BMC race after about six tries.

Before I did anything else, I'd put in the OEM filter because it is a lot easier than pulling the carbs again and it might run pretty good set up as it is.

Dynamic

Was just testin... what you should have said was make sure you are counting in your needle clip from the right end... Doh...

Really sorry for wastin your time guys, but thanks for all the helpful posts. Worked it out while talking it through with a mate last night, it all suddenly clicked into place. I knew which end they should have gone on, but the ones on the needles in there were at the other end, so just went on auto pilot mode, an put them on the position 2 in from the top...

Sorry again, and I'll accept any ritual humiliation coming my way... runs pretty good now, I just need to fine tune it.

RK1

"All's well that ends well"

Stan Laurel and Oliver Hardy, (And that Shakespeare guy)

hymey

All I can suggest is to buy yourself a decent wideband controller/meter as you may go backwards and pull your hair out!

I have a Innovate wideband fitted to my VTR.

wide open throttle (WOT) should be around 13:1.

185/190 jets in my bike running 95RON premium unleaded on 5th clip I had a air/fuel ratio of 10.8 :1. My seat of the pant impression was way out.

180/185 jets fitted on 5th clip at WOT was 11.4:1. Still to rich.

175/180 I had 12.6:1 WOT.....getting closer. Mind you I took an educated guess and went 6th clip at the same time as I figured the bike would be running leaner down low with the smaller mains. This wasnt the case. I was getting 11:1 ratio mid range(5000rpm) then as revs increased it gradually got leaner to 12.6:1.

So tomorrow I will be dropping back to clip 5 to lean my mid range and top end to hopefully hit that magic 13:1.

The bike idles very smooth at 12.5/13:1 with 48 pilots two turns out. 45s are to lean.

So it seams the hawk likes bigger pilots and richer needles with the K and N fitted. Stock mains are on the money.

I am very surprised how rich the bike ran with dynojets settings. 10.8:1 is rediculous but remember that it is a very safe starting point!

I will let you guys know how I go with it tomorrw. If 175/180 clip 5 is still to rich I will take out the rear 180 jet and run 175 front and rear. Not to keen going 170 on the front cylinder.

Cheers

Joel

ascothawk

hymey,whats the status since your last post?