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Discussion Starter #1
Hi there,

as it is winter here in good old Germany, I am thinking about some maintenance work on my 94 VT1100. I will sync the carbs and plan to get me a dynojet kit or a similar jet kit.

Well, where to start:
--In another thread I've asked about the pilot screw, it needs at least 3,5 to 4,5 turns out to minimize backfiring (yet not perfect), so I was thinking about a bigger pilot screw
--I can't find the thread where I've posted pics of the spark plugs, where one guy said they're almost ok, probably a bit lean
--about a year ago I took the bike to a shop to get the carbs cleaned and adjusted; they said that they kept the 165 needle but put them in another position
--after, overall performance was a bit better
--I have a BMC airfilter, which improved throttle response immediately, I might do a snorkel fix
--it’s a californian VT, the exhaust is more or less standard, compared to German VT1100 it’s much louder. I won’t buy an aftermarket exhaust, there is almost no choice, and V&H are far too expensive.

I think, that the currently used 165 needles are a bit too small. I have searched the forum and I most guys run bigger needles, like 170 or 175. I know that Dyno has different numberings. I have learned that all bits and pieces are relevant for smooth performance (main jets, pilot jet and adjustment, carb sync).


I plan to get the dynojet kit, as they have that improved spring and the needle is tapered, and it seems the kit is kinda idiot proof. Most folks say use the third groove from top, not the fourth. I will also check the float height.
Downside is, that it is kinda expensive (approx. Eur 100,-), and not always the kit includes the spring (which is strange), and there is NO pilot screw. I may buy them seperately.
I dunno if I have the 42 pilot screw (standard?) and I might go for a 45 or even a 48. Some users have reported that this makes a big improvement, overall. On the other hand, I have read that with the tapered needle of the Dynojet kit a different pilot jet is not necessary.

People say that 6sigma is not worth the money, Factory Pro is not available here, an alternative would be carbjetskits.com/ebay, shipping is at around 10 usd from the us and would take some time.

Should I get a stage 1 or stage 2 kit? Jet 2 are a bit hard to get here, and some say that only stage 2 make sense.
I don’t care about fuel consumption, focus is on no-decel-popping and improved performance. Dynojet or something different?

I know that it’s quite some work to get it done. But with such an old Honda, it’s hard to get a shop to work on her. At the shop which did the carbs a year ago, I felt like I’m second class compared to the other clients (with newer, much more expensive bikes).
And here in my village there’s a bike shop but he was not interested in doing the carb sync when I asked him some weeks ago… so I do it by myself. I really love my Honda and want to get her in perfect condition (or sort of).

Many thanks for your help,
Florian
 

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Stage 1 is typically intake and/or exhaust modifications. Stage 2 is typically engine modification ie cam.

Take a look at the Dynojet graph to determine if the jet change will be noticeable. In most cases the difference is at high rpm and I am almost never there on a cruiser. I was able to tune out the popping on decel using Dynojet mains with the stock pilot and adjusting A/F with settings between 4 and 4.5 turns, however it is probably better to replace the pilot jets since optimum pilot screw setting is 3 turns out. I understand each 1/2 turn is one jet size so if you are 4 turns you would go to a 44. Also my front and rear pilot screw settings are different one being hald a turn different from the other so you may want to check.

There are a lot less expensive jets but I don't have experience with them. You could buy a range of sizes between 160 and 170 and see what works but the amount of effort taking those carbs apart was not worth it to me.

I did Dynojet and V&H exhaust when I got the bike in 95 because I found it so underpowered I was not going to buy it. I paid for the V&H and dealer paid for the Dynojet and did the install free. Because I like the look of the V&H Classics I am happy with the setup but if I was looking for performance I would have been disappointed.

G.
 

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Discussion Starter #3
Ok thank you.
Which would be the proper Dynojet set? Has somebody experience with carbjetkits.com?
 

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My experience with them is they will get you close. I put in all the parameters and ordered the suggested kit. She ran pretty rich at first. Then I dialed her in from there. I ended up with 1 size over stock with the pilot jets (45 from 52), 1 shim under the slide (which I'm going to remove) and stock main jets (178 down from the 180 my kit came with). I'm removing the shim because she's just a little too rich. Not enough to see black smoke but she smells when ya roll on the throttle. Kit called for 2 shims under the slide but, it was too much. Otherwise she runs fantastic.

Sent from my LG-H872 using Tapatalk
 

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If you go to the Dynojet website you can type in the year and model of bike and they will show you what is recommended for what modifications. Jetsrus is much ess expensive but don't offer a kit and is more complicated as they just list a variety of jet/needles etc. Carbjetkits is priced between and you can also order a kit.

Carbjetkits uses shims and the your stock needles but also send a pilot/slow jet. Dynojet claims what you are paying premium for is the research and design of their tapered needles but do not supply a pilot jet.

To me Carbjets are addressing decel popping while Dynojet is looking for performance improvements.

G.
 

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Discussion Starter #8 (Edited)
thank you for your replies. I called a dealer here in Germany, the proper set would be E1152, but as far as he can see without the springs. Jets are from DJ150 (like Keihin 165) to dj155. It's the same as here:
99,- and no springs... I will check an other dealer, if it's always without a spring. Probably I go for carbjets.com.
Called an other one, there no spring in these kits for the Shadow, as stated in the pdf.
Ok, I 've seen shops where the Kit is at about 65,- instead of 100, and always without spring. By drilling that hole the effect is the same like using the spring.
 

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Discussion Starter #10
That thingie wich moves with the diaphragm contains a spring. Today I have learned, that the improved spring of the dynojet kit makes the thingie move quicker. The plug drill in the set to inrease one of the holes in the thingie does the same, one guy told me today. I have no idea if there are sets that contain both spring and plug drill.
The proper set for my 94 VT is the 1152.
 

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Be careful drilling. These CV carbs are very sensitive to unbalancng the vacuum /air flow. Here is from =CARBJETKITS.COM= Drilling Carb Slide?


Drilling Carb Slide?
Should you drill your carburetor slide?

First, there are two pressures applied to the rubber diaphragm, one is the ambient air pressure provided via the half moon crescent on the mouth of the carb and the other is the hole which allows the vacuum in the throat of the carb to be applied above the rubber diaphragm.
If one opens the throttle there will an increase in vacuum above the diaphragm transferred from the throat through the hole which eventually will overcome the tension of the spring and the slide opens which allows more air and fuel to enter.
So, the diameter of the hole will regulate how quickly the slide opens and closes. Notice, we are talking about fractions of second here.
Drilling the slide is not a way of gaining horsepower, but is more fine tuning.
Be very careful when you're dealing with the slides as the diaphram will tear if you're not careful and they are around $100 each!
Apparently, a larger hole has caused poor drivability issues, if you muck up or the larger hole mucks up the drivability, you can't put the material back.
Slide flutter is just one problem with a throttle slide hole that is too large. Another is that the slide can rise too quickly and cause a hesitation.
Just do NOT Drill your slides! There is nothing to Gain!
If you really want to drill holes...just buy you a drill bit (under 1/8th ) for a dollar instead of paying $99 for a Kit that just has a drill bit included.
 

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Here is something I found on a KZ forum about slides.


The hole in the slides is 3mm... they give you a 1/8" drill bit. If you drill the slides, you are supposed to get "more throttle response" but it is essentially a waste of time. Try it and find out for yourself. This practice started with the Harley folk on the CV40s on their big twins... Vulcan owners used to tout the effectiveness. Another "trick" is stretching the return spring and clipping it a bit shorter to also "increase throttle response". That is a waste of time as well but you can try that as well if you are intent on messing around with your carbs.
 

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Discussion Starter #13
Yep, I ve read that one shall not drill. I don't if it's worth it or not, I dn't think that I dare to do it. Thanks for the info that it's not worth it. I have no idea if those tricks are BS. On the other hand, I wonder why Dynojet puts that drill to the set.
 

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Stop! Someone has you on the wrong track. There is no spring in the Dynojet kit: you don't need one. The drill and screw included in the Dynojet kit are to take the "plugs" that cover the A/F mixture screw off. A/F mixture screws are sealed from the factory but need to be adjusted after rejetting. If A/F screws are visible then someone has already removed the plugs. What Dynojet want you to do is to look for the A/F screw caps/plugs, use their drill to make a small hole, screw in their screw and then pop the plugs off by pulling their screw out. You are not modifying anything.

The Dynojet kit include 3 sizes of main jets so you can match what mods your engine has, 2 tapered needles, 2 e-clips to hold the needles and 2 spacers. I have explained what the drill and screw are for.

G.
 

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Discussion Starter #15
Thanks for your answer and your help. It seems that in some kits are springs, that's what one guy said yesterday. The pilot screws are already accessible since the carbs got serviced a year ago.

I have just ordered the set for eur 55,-, I've found a shop where it's on sale. About Eur 100 or even more is just too expensive. A real alternative would be carbjetkits.com but I didn't want to wait a couple of weeks.
I really want to to this by myself, so I understand how my carbs work and I can see in what condition they are. After the carbs where done by the shop, overall performance was a bit better, starting the engine was a bit better but still can be improved.
I've also played with the pilot screws and, probably by accident, hit the sweetspot: almost no decel popping, and a bit improved overall performance. Then, I thought I can improve it, but I did the opposite.... dammn. Motor is not that smooth anymore.

So I will do the carb jetting, carb sync and will adjust the pilots. Currently they're at approx. 4,5 turns out, that's why I have thought about rejetting in general. The spark plugs are not bad at all, a little bit too light, so I think that the tapered needles and one step bigger jets would make sense.
 

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OK Just to clarify, the Dynojet kit contains 3 main jet sizes but no pilot/slow jets. If your A/F screw is 4.5 turns out you are close to wide open so have no room for fine tuning and probably should replace the pilot/slow jets. And may as well do it when you replace the mains or you will need to take the carbs off twice. Your pilot/slow jet is a Keihin 42 and so you should buy a 45 pilot/slow jet and then turn your A/F screw to 3 turns out from seated and adjust. 90% of the time we are between idle and 1/4 throttle so the slow jet tuning is critical.

G.
 

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Discussion Starter #17
Nope, there are no pilot jets in the set. Dynojet claims, that other pilot jets are not necessary due to the tapered needles. And the tapered needles were, for me, a reason to buy the set (and the availability and the reduced price). To be honest, I have quite some respect for doing that, and my california VT has that evap system, too...
But I am thinking about getting some 45 pilots, they're not expensive. I think they're totally underrated, still most mechanics say don't touch em.
 

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It has to be specifically a Keihin slow jet, the same style that comes out. Don't even try to stick Mikuni jets of any sort in a Keihin carb.

The Slow Jet is for idle and the transition of the opening and closing of the throttle blade.
After that when the carb is seeing vacuum, there is a whole lot more going on and different circuits are involved even though the slow circuit will continue to bleed fuel into the engine.
The correct atomization and dispersal of fuel at 1/4 throttle is a lot more involved than a couple of tiny holes peeing fuel under the throttle plate.
The graphic in the initial post looks like a generic one for the typical slide carburetor, but actually gives a reasonable idea of the situation.
IMHO if you are messing with the pilot jet to richen part throttle running, you are both tuning the bike wrong and wasting fuel.
 

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Discussion Starter #20
I think I will pick the 45 jets as a second step, changing too many parameters at once might make it all too difficult.
In case that the statment of Dynojet about the tapered needle proves to be true, I may be fine with the 42. I think, she's a bit lean overall, but not severe lean.
BTW if you are about to get a K&N air filter, have a look at the BMC brand. They're cheaper but build quality is flawless.
 
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