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Discussion Starter #1
I've got into this topic slightly in other parts of the site but I'm strictly looking for help with this carb. Right from day one this bike has always popped through the air cleaner but with the airbox in place, it wasn't as loud. I had a dynojet kit installed with a big sucker and V&H ovals. It popped threw the aircleaner still, but was louder. They then installed a 48 slow jet and it didn't pop as much but my mileage went down to 30MPG. I then removed all the dynojet **** myself and installed the stock immulsion tube with the stock 190 main, J&P 46 slowjet, sportster needle and re-adjusted the mixture screw to 2.5 turns out. The bike runs OK but it seems to stumble a little if I'm on the highway doing 65 and I open it up. It stumbles slightly then clears up. I also still have the occasional pop if I blip the throttle too quick off idle or sometimes during deceleration if I blip the throttle to downshift. Any input would be appreciated before I end up scraping this carb and installing a Mikuni42>
 

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It's very possible that the dealer drilled the vacuum port in the slide when they installed the Dynojet kit (it's part of the insts in the kit). When you removed the kit did you replace the slide?? If not, that might explain the stumble.
 

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The Dreaded Carb Fa*t

hedgehog1 said:
I've got into this topic slightly in other parts of the site but I'm strictly looking for help with this carb. Right from day one this bike has always popped through the air cleaner .... I had a dynojet kit installed with a big sucker and V&H ovals. It popped threw the aircleaner still, but was louder. They then installed a 48 slow jet and it didn't pop as much but my mileage went down to 30MPG. I then removed all the dynojet **** myself and installed the stock immulsion tube with the stock 190 main, J&P 46 slowjet, sportster needle and re-adjusted the mixture screw to 2.5 turns out. The bike runs OK but it seems to stumble a little if I'm on the highway doing 65 and I open it up. It stumbles slightly then clears up. I also still have the occasional pop if I blip the throttle too quick off idle or sometimes during deceleration if I blip the throttle to downshift. Any input would be appreciated before I end up scraping this carb and installing a Mikuni42>

Hedghog1:

I probably ought to preface my answer by saying there are at least two ways to look at this. Either you usually ride a steady crusing speed or you extract the maximum potential from your machine by accelerating, braking and downshifting your machine to increase performance. I am the latter sort of rider and approach tuning problems from that viewpoint.

From the factory, a HD carb 'pops' through the air cleaner because the mixture is WAY too lean. They all come that way. When you had the dynojet kit installed, one of the things they did (hopefully!) when they installed the kit was to drill out the vacuum hole in the carburetor slide. This is a very important modification as it makes up for the decreased vacuum signal created by the less-restrictive air cleaner/mufflers and higher air flow through the engine. When you removed the dynojet kit components, I suspect that you did not put in a new slide with the smaller, stock, vacuum port/hole. That's actually good, since you really need the larger vacuum hole in the carb slide to allow a modified HD engine run properly.

It sounds as though you're now on the right track with a #46 pilot jet turned out two and a half turns (I might try as far as 3 1/2 turns), although the #190 Main may turn out to be a little fat (I use a #185 on a carbed '05 FDX). The problem, I believe, lies with your needle. It sounds as though it needs to be 'raised' at least one notch in order to prevent the hesitation upon throttle application.

The other area I'd certainly look at is whether or not there may be an air leak in the exhaust system. If you haven't re-tightened the head pipes at the exhaust port and double checked where the mufflers clamped to the head pipes and replaced the small gaskets where the stock crossover pipe attaches (I think theTouring rigs have one if you didn't remove it to install the V&H's), you should check these areas.

You should also check intake gaskets and alignment on a TC. There is an inexpensive fixture from Harley-Davidson that will allow you to get the alignment right.

Good Luck!


PS:

Popping through the carburetor on downshifting may also be the result of a lean condition created when fuel added during deceleration by the carburetor (this is designed to keep the engine from from popping thru the carb or muffler during deceleration). I think this can significantly lower the fuel level in the float bowl and, coupled with decreased vacuum in a more agressively-tuned engine, the bike can react as if it had a lean carburetor. I also believe the vacuum-controlled "no-flood" fuel petcock contributes to the problem by not receiving enough vacuum to maintain a fully-open fuel valve, further starving the engine and resulting in the dreaded Carb Farts.

A flat-slide carb could work very well on this engine, but the lean problem may not be able to be resolved untill you replace the vacuum petcock with a manual one.
 

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Discussion Starter #4
How can a 190 be too fat when that's the stock jet from the factory. Also, the sportster needle is non-adjustable. Does a dynojet kit come with a needlejet. If so, I don't have the stock one to put in. I also still have the dynojet spring on the slide. If I decide to go for the Mikuni42, should I get the easy kit or the kit with the manifold?
 

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Hedgehog, check to make sure your accelerator pump is working. Pull your air cleaner off and twist the throttle while watching to make sure you have a good stream of gas shooting in about the middle of the carb throat. Also Wizwill is right about the main possibley being to rich. I have a 95 inch and I am running a 180 main and 46 slow. I have the air screw turned out about 2 turns. I have had it checked on a dyno and I have near perfect air fuel ratio across the board. I posted a graph on the dyno section. When I was using a 190 and 195 with a 48 slow jet with the sportster needle I was way rich. Every bike is different so unless you get on a dyno you will only be guessing.
 

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Popping through the carburetor on downshifting may also be the result of a lean condition created when fuel is pulled out of the carburetor during deceleration by the relief ports in the carburetor (designed to keep the engine from from popping thru the carb or muffler during deceleration). This lowers the fuel level in the float bowl and, coupled with the decreased vacuum of a more agressively-tuned engine, the bike then reacts as if it had a lean carburetor. The vacuum-controlled "no-flood" fuel petcock also contributes to the problem by not receiving enough vacuum to fully open the fuel valve, further starving the engine and resulting in the dreaded Carb Farts.
Don't quite understand the relief ports or less vacume just because of a free flow air cleaner....what are relief ports in the C/V carb??
 

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Discussion Starter #7
Well, I took the bike up and down the highway trying to tweek the mixture screw, it seems to be at it best at 2.75 turns out. I was going around 60 and I would then roll the throttle wide open. The only problem now it I started to smell gas and when I stopped, I had spots of gas down the right side of the bike. Tell me something, I think I'm going to give up on this CV carb and I want to know whether I should get the Mikuni easy HS42 or the kit with the manifold. At the absolute most, I might eventually put cams and 95" kit.
 

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hedgehog1 said:
Well, I took the bike up and down the highway trying to tweek the mixture screw, it seems to be at it best at 2.75 turns out. I was going around 60 and I would then roll the throttle wide open. The only problem now it I started to smell gas and when I stopped, I had spots of gas down the right side of the bike. Tell me something, I think I'm going to give up on this CV carb and I want to know whether I should get the Mikuni easy HS42 or the kit with the manifold. At the absolute most, I might eventually put cams and 95" kit.
The mixture screw is for IDLE only....when you crack the throttle ever so slightly the mixture screw does NOTHING FOR YOU ENGINE....
You smell gas and see gas dripping from the air filter because your running down the road at full throttle several times tring to set the idle mixture screw, its called fuel stand off and it will happen to the mikuni or any other carb put under the same conditions.
 

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Discussion Starter #9
So will it stop? SHould I put the dynojet stuff back in only whtiht he 180 main like the directions say and leave my 46 slowjet. The bike was running OK with the dynojet, just getting terrible mileage and the off idle pop through the carb.
 

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To improve your gas mileage, insert the clip on the DJ needle one notch higher from last time and go from there (there are 5 height adjustments on the tapered DJ needle, which control behavour of the emulsion tube as it's being fed by the main jet.....I thnk..:D). DJ instructions are a baseline only. Fine tuning is up to you or your tuner. Correctly installed the kit will return 42-46mpg (depending on altitude), great power and throttle responce, and no farts.
It's not rocket science, just time consuming if you decide to dial in on your own (no dyno help).

Once you've found your shortcuts to re&re, start to finish is a matter of 20 minutes.

Good luck.
 

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Some times it helps to start completely over and cover the basics. make sure your choke is adjusted right, make sure the float level is correct and did not not get knocked out of wack (you have to pull the carb off to check the float level), hopefully you did not seat the air adjustment screw to tightly because that will mess things up, make sure that the is a little grease or silicon on the rubber gasket mating your carb to the manifold and make sure the rubber gasket is not torn or folded over causing an air leak. Also if the weather is cold where you are at it makes it really hard to get dialed in because you are going to run leaner. Put your carb back to 45 or 46 slow jet 190 main and sportster needle with the air screw turned out from seated ~2 turns. Your bike has to be fully warmed up to get the air screw right ie 30 or 40 mile ride. Take your time and make sure everything is assmembled properly. Doc was a Godsend to me when I was getting my carb dialed in.
 

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One thing I forgot is when I had a DJ kit put in by a tech who was dynoing my bike he drilled the slide too big ie he did not drill it straight and the hole was oblong and probably about twice as big as it should have been. I don't think no matter what it could have run right that way. I ended up getting a new slide but in the mean time I used some jb weld to plug the hole and redrill it. AS ED Y mentioned if the slide has been drilled and the lighter DJ spring is being used that could cause some stumbling.
 
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