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Discussion Starter · #1 ·
Hi All,

My vt1100 has jet kit and hardkrome 2 1/2 inch staights with baffles. Bike was running like a raped ape. I decided to add a K&N filter and now the damn thing stumbles on wide open throttle, But still idles smoothly, revs great in neutral. I did not save the stock filter before I test rode it. Should I buy a stock filter or is there something else wrong.

Needle is on fourth clip.

Any input is appreciated
 

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Does it run good at a constant freeway speed (55-70mph)?

If so, your main jets need to go up a size.
 

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Discussion Starter · #4 ·
My stock jets were 165.

The jet kit came with 150, 155, and 160.

I remember calling Dynojet for tech support because my factory jet was larger than any in the kit. So the tech guy said the jets are smaller because the needle is more tappered. So i used the 160 and put the needle on the fourth clip as per the instructions. And the bike ran great.


The bike does not stumble if you accelerate normally, only when you wack the throttle. And runs smoothly at highway speed
 

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Couple of items - maybe litnin will comment on the validity too:

Could a low float level be the cause? A little to low with the added volume of air?

Fuel filter not keeping up with demand?

Install the stock 165 and see if that will fix the problem?

Shove a rag into the K&N and restrict the flow somewhat.

Just tossing some ideas out there for consideration.
 

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Does wind direction affect the stumble? No joke. My 83 750 will run perfect ..or not...depending which way the wind blows. One way down the street it will stumble. I make a U turn and it will run perfectly. I am stumped.
 

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Steve157 said:
Does wind direction affect the stumble? No joke. My 83 750 will run perfect ..or not...depending which way the wind blows. One way down the street it will stumble. I make a U turn and it will run perfectly. I am stumped.
No mystery, it's a Japanese bike, they always run better heading toward the 'Rising Sun' (East). :wink:
 

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Discussion Starter · #8 ·
Just installed the 165's and checked the float height, put it back together and took her around the block, but it is still stumbling on full throttle. I will pick up a new OEM Air Filter. If that corrects the problem, then i will list the K&N on the parts board


Like i said in previous post, i rode the bike for almost 100 miles and it was running perfect. The only thing i did was add the K&N air filter
 

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Steve157,
Oh my god...I never heard anyone else that had the same problem as I did. FINALLY!!!
I had that same problem before I re-jetted my bike. I even took it back to the dealer and they said it must be an issolated incedent. The dam thing would run smooth as glass when the wind was blowing from the left side of the bike, but if I headed into a wind from the right, the bike felt like it was surging. I was getting to think I was losing my mind for a minute. I'm assuming it's from the way the air enters the air cleaner under the seat. I even tried to re-route the air by using duct tape on the bottom of the seat and it seemed to make a difference. since I installed Dial-a-Jets and re-jetted the carbs (different exhaust) the problem seemed to go away.
I was always wondering if anyone else had the same problem and now I feel a bit of relief.
 

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I have two carbs, one I rejetted, but the stumbling started before I rejetted and I didnt rejet to stop the stumbling. I dont know what or why it does it. It still does. I put the stock aircleaner back in, I have a K&N, it stumbles. I did change the gas tank and thought it was a venting problem so I rode with the cap open...it stumbles. Mine is consistent when the wind direction is at about 1 o'clock. EVERYTHING on my bike is as new. I cannot explain why it started doing it or what to do to stop it. I changed the frame and the engine so I had everything off and put back on. Today I stuffed some plastic bags in front of the air inlet as a type of dam and it helped somewhat. I am baffled because EVERYTHING is as it should be and in good condition. I can go one way down the road and it runs perfectly...a U turn down the same street and it stumbles...depending on the direction of the wind. It is irritating. I thing I did something to piss off Feng & Shui. Maybe they dont like my LED taillights...who knows??
 

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Yup, exactly. Mine would start to stumble at wind direction coming at me at 1:00 postition too. Making an air dam in front of the air inlet seems to be the only way to prevent the wind from interfering with the engine. What the.....
Maybe someday, someone will give us the answer. >PD<
 

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But the damnedest thing is that the bike didnt stumble at all before I changed the frame and everything was cleaned and reconditioned as new before I reassembled it! That is why I never dammed it prior to today. Oh, I DAMNED IT PLENTY before today!! I still do!
 

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Oh ya, I also replaced the paper in my stock filter with Uni Foam filter foam before re-jetting. I just glued it inside where the paper was (now I can clean and re-oil instead of buying a new onw) I think that made some difference too. I was always wondering if it was maybe my windshield or lowers that were making the engine stumble (maybe?) but I never did remove them and actually check and see if THAT made a difference or not. Looks like an idea for ya if you have them. Just a thought. >PD<
 

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I stated my stumbling problem on OldBikeBarn Honda forum. Great guys, very good technicians, but THIS forum is for Shadows and more specific to my bike. Anyway, I was ridiculed for the wind direction posts until others started to come forward and state that they too had the same problem but were too afraid to say it on a forum. I tried evrything. I put the stock carbs back in, stock air filter, I tried putting duct tape on a portion of the K&N filter. I put the FOAM filter OVER the K&N filter. I tried NO filter. I replaced the gas CAP. I thought it was vapor lock from heat from the fuel tubes because I replaced the fuel lines. I replaced the fuel lines AGAIN with heavy heat resistant tubes. I resealed the snorkel with RTV UltraBlack sealer. I replaced the exhaust gaskets, although I replaced them each time I removed the exhaust pipes. EVERYTHING, every plastic cover that came on the bike from Japan is on it now, nothing is missing, added or different except the exhaust, the filter and rejetted carb. It stumbled prior to the rejet though.
I remember as a teens we had junk cars that needed repair. That is why and how we learned to turn wrenches and fix mechanical things. One friend had trouble starting his car and although we all offered assistance and troubleshooting advice the car would not start. We tried everything. Another friend came along looked inside and said, "empty the ashtray." He actually received some punches for his stupidass advice from the owner of the stalled car. In desperation or guilt that the ashtray was so full, he emptied it onto the ground. That's where we emptied them in those days. The car started.
WHY DO SOME SHADOWS STUMBLE WHEN THE WIND HITS THEM AT 1:00!!! Come out of the woodwork, Shadow owners, do not be afraid. TELL ME WHY!!! I'll even try "emptying the ashtray!"
 

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Steve157 said:
WHY DO SOME SHADOWS STUMBLE WHEN THE WIND HITS THEM AT 1:00!!! Come out of the woodwork, Shadow owners, do not be afraid. TELL ME WHY!!! I'll even try "emptying the ashtray!"
Well, without getting one in a shop and doing some R&D with some specific
equipment, I can't answer your question 100%, BUT...

I'd be willing to be it's simply an air flow problem.

I've seen it before on automobiles.

Turbulence is one of the biggest things that will upset a tune up and upset it quick.
It really gets nasty in a supercharged engine, but that's irrelevant.

Wind hitting the air box just right could very well upset the air flow
in the box enough to cause it to act goofy.
The more turns and ribbing you have the worse it will be.
The best air intake design is equal length, smooth bore, with no
twists, turns, or ribbing.
Anything outside of that can upset it. Outside air simply blowing
across the lid can upset it also. I am surprised to see it on
this many units... Maybe it was a problem that Honda fixed some where down the line. It would be very easy to have an air cleaner that sticks
out in the wind to go in to a negative air pressure state on both sides
of the intake. Outside air rushing past can create negative pressure and
the engine is creating negative intake pressure. If that happens,
atmospheric pressure cannot force its way in to the box.
That's very common on engines with velocity stacks and high mph scenarios.

I don't know that is your problem, but I sure wouldn't rule it out.
 

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Litnin, I thank you for your reply and I agree...an evil wind is blowing from somewhere somehow but why now? It didnt do it before I changed the frame out. Everything has been put back on completely and properly...no cracks, extra holes in the airbox etc, all clamps replaced and rubber boots in as new condition washed and armoralled prior to reassembly. I just dont understand why it stumbles now.

I read somewhere that the 1983 Shadow 750 was the first motorcycle Honda engineers consulted and used feng shui in their design. So here are the saki soaked Japs consulting their gay deities (come on, they HAVE to be... at least on par with interior decorators or fashion designers) and in turn cursing MY motorcycle as a result because the fruity pair do not like the LED taillights I put on it?? Or pehaps it's the tuck and roll pattern of the custom seat recovering that disturbs them so?? It's MINE NOW, bitches! I can do with it as I please! Stop blowing your evil breath on it and causing it to stumble!! THAT would be fabulous!!
 

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Come to think of it, I have noticed that there is a gap between the frame and the bottom of the seat on the right side of the bike, but not the left. That is possibly the problem with air turbulance messing with the intakes. Like I mentioned before, I used duct tape to block the air off on the right, and it did seem to make it run better on windy days. I think your onto something!!
Also, there is an air dam on the bottom of the seat ('96 VT1100) that, when installed, goes around the front of the air inlet on the bike. I'm thinking possibly to prevent a direct air blast into the intake? That is where I used the duct tape and just made it come around more to the right side of the intake hole. >PD<
 

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Discussion Starter · #19 ·
My original post had nothing to do with the wind!!!

My bike ran great with the wind, against the wind, uphill, downhill, on the hiway, on city streets, it just ran great. I added the K&N and it now stumbles at open throttle. If i ride it conservatively then its fine, when i open her up she stumbles
 
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