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Discussion Starter · #1 ·
my 87 1100c is a bit too lean since i went to the k&n and gutted the baffles. it was pretty lean before the mods. the plugs for the two years i've owned it are always just clean as a whistle, which i see as a marker for being too lean. i rebuilt the carbs about a year ago and put new float gaskets and j&m industries diaphragms and standard size jets. however i also ordered the next size up. on my recent trip to cal i found my top end power was quite puny as i came into the lower elevations. i don't want to "over richen" the carbs so i am thinking that rather than going a size up on jets AND adding a washer to the nail, i would go at it one step at a time and do either the washer OR the larger jets but not both at the same time. soooo,.... my question... should i do the jet first or the needle? i'm leaning towards lifting the needle with a washer first. i think it might a less radical adjustment than raising the jet size??? all advice is most welcome :neutral: :mrgreen:
 

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I'm sure someone will come along that will have MUCH more knowledge, but until then, I'll keep your thread at the top. :D

Best answer, it depends! How does the engine run at WOT? THAT is where the jets play a key role. If it's fine at WOT, then raise the needle one slot. If it leans out at WOT, then install the larger jet.

It's my understanding that you should tune for WOT first, as that also will affect the needles. Once that's good, move to step 2 (the needle height).

A great website for going through tuning is here CV Carb Tuning Procedures

or this guide:
http://forum.highlifter.com/Basic-CV-Carburetor-Tuning-Guide-m1872049.aspx

Hope they help.
 

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I was running a bone stock VT1100 (2000 ACE Tourer) no mods to exhaust, stock air filter. Plugs looked lean to me. Throttle response was a bit hesitant, and a bit uneven at times cruising at 1/4 throttle. From everything I've heard, the stock settings are all to the lean side.

So after putting in K&N air filter, cutting the baffles out of my stock exhaust (and went with new plugs just for good measure) I put in +1 sizes on all jets. For my bike that was 180/185 main jets, and 45 on pilot jets. I didn't touch the needles.

Bike now runs awesome. Much nicer throttle response all the way around, more even power, etc.

If you do start with raising the needles, let us know how it works. I think it's wise to make one change at a time (but pulling the carbs multiple times is a royal pain).
 

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Discussion Starter · #4 ·
I'm sure someone will come along that will have MUCH more knowledge, but until then, I'll keep your thread at the top. :D

Best answer, it depends! How does the engine run at WOT? THAT is where the jets play a key role. If it's fine at WOT, then raise the needle one slot. If it leans out at WOT, then install the larger jet.

It's my understanding that you should tune for WOT first, as that also will affect the needles. Once that's good, move to step 2 (the needle height).

A great website for going through tuning is here CV Carb Tuning Procedures

or this guide:
Basic CV Carburetor Tuning Guide

Hope they help.
thanks c5, i would have done it backwards. my WOT performance poor, like gutted. the rest is ok. i was going to add washer(s) first, then if needed larger jets. i have the jets i need. so thanks for your help, i'll pay it forward.:cool:
 

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Discussion Starter · #5 ·
I was running a bone stock VT1100 (2000 ACE Tourer) no mods to exhaust, stock air filter. Plugs looked lean to me. Throttle response was a bit hesitant, and a bit uneven at times cruising at 1/4 throttle. From everything I've heard, the stock settings are all to the lean side.

So after putting in K&N air filter, cutting the baffles out of my stock exhaust (and went with new plugs just for good measure) I put in +1 sizes on all jets. For my bike that was 180/185 main jets, and 45 on pilot jets. I didn't touch the needles.

Bike now runs awesome. Much nicer throttle response all the way around, more even power, etc.

If you do start with raising the needles, let us know how it works. I think it's wise to make one change at a time (but pulling the carbs multiple times is a royal pain).

thanks tom, looks like you and c5 are on the same page... and now, so am i.
cheers friend
 

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General rules:
Start/Idle speed = low speed jet
Mid range = needle shims
W.O.T. = main jet.
Float height affects everything - make sure it is accurate and the same on both carbs.
Mixture/air screw mostly affects idle.
 

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Discussion Starter · #7 ·
General rules:
Start/Idle speed = low speed jet
Mid range = needle shims
W.O.T. = main jet.
Float height affects everything - make sure it is accurate and the same on both carbs.
Mixture/air screw mostly affects idle.
great rules to memorize GOM, thanks. ;)
 

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Remember to make all your observations on a warm bike, at least a 5 mile ride. The best way to set the main is in 2nd gear mid throttle get on it and it should pull hard all the way to the rev-limiter. If it falls off before then go up one more size and try again. The needle is all mids, shim to get rid of surging or stumbles but only after main is done.
 

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I have had my carbs out maybe 15 times.... I love to get things just right and have tried lots of needle heights and jet sizes... some of those times are from trying to many things at once.... one thing at a time is better!

WOT is jets.... but needle height will affect it as well as I have found out

I have the Dyno adjustable needles and shims to tweak, clips have 1mm movement and shims .4mm

I had 160 Dyno jets (178K) and with the needle up would get great WOT but needle down one wouldn't so needle does affect WOT but with std idle jets a had a bit of a dead spot down low so upped the idle jet one size (45)

I have tried 185 K and 200 Keihin as well

200 with the needle down low Ran great down low but top end lacked and fuel usage was OK

185 with the needle down one from center gave me enough down low and great power higher, I am still testing this latest setting but cruising 60mph and under on easy road gets the best MPG I have had while still hitting over 100mph in 3rd (4speed) and powering all the way through were as the other settings the power would drop of rapidly up the top end.

What size jets do you have?
 

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Discussion Starter · #10 ·
this bike... the 87 vt1100c calls for 158's in both carbs. the next size up is 165. i just got done taking the carbs out and changing the jets. got the carbs back on now but still need to hook up the throttle, choke and fuel. that's for tomorrow as the sun is setting. took about 45min so far. i don't know what i dislike assembling most on these 1100's, the air intake is in the running for 1st place. i put some 3n1 oil on the rubber and the carb intakes and that helped a bit. tomorrow i'll run it and see what gives. i have some 45 low speed jets but it doesn't really backfire right now... we will see. as for shimming, well the power curve was pretty flat after about half way up the gears, so may it will need shimming and maybe not, again... we'll see.
 

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Let us know how it goes.

As for working on them, I've determined that it'd be a LOT easier if I had double-jointed elbows! :lol:
 

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Daylight definitely helps .... not as many shadows.

I am getting good at doing it now if you hold thing right and do just the right face impressions they all fall together nicely, doesn't allways work though :lol:


If it doesn't run right plug chop at different revs to check color, helps tell the tail :)

Mine gets the big 2 up test this weekend, about 8 hours riding to do with gear and pillion, I hope the fuel usage is as good with the extra weight (not meaning match the last trip but better than before with gear on) :)
 

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Discussion Starter · #13 ·
still poor top end. i'm going to remove carbs and check the diaphragms. i put j&m industries diaphragms on less than a year ago, they "should" be fine. i'll add a washer. if this dosn't do it i'll put the carbs off my 98 on. they are fit with dynajets and i know they perform. ok, more lare guys.
 

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did you try a plug chop at revs? (Hit the kill and clutch it to a stop) it would be interesting to see what the plugs were like

When I had the 160 Dyno jets I needed to lift the needle 1mm from the setting Dyno recommended to get to the top revs.... (160 was the largest jet I had at the time which equates to a 178 Keihin jet & 165 K is standard in my model)
 

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Discussion Starter · #15 ·
holy mcmolie... sucker runs like a banshee!!! ok, so bothe diaphragms were torn. i'm really disappointed because i just replaced the torn stock ones with j&m industries diaphragms. they are supposed to be better than stock?? fortunately i had my carbs from my 98 spirit to rob as i'm in the midst of overhauling that one's engine. it had dynajets and new honda oem diaphrams so i pulled the rubbers and the slides and the high speed jets and put them in the 87 c's carbs. WOW!! nevr ran so strong. i think its running better than my 98, maybe because of the 98's cams being ground for epa and midrange torque?? whatever it is that old 87 is th bomb now. doing toys for tots with my buddy sunday... total fun!!! cheers guys and that for chiming in for me. happy turkey.
 

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holy mcmolie... sucker runs like a banshee!!! ok, so bothe diaphragms were torn. i'm really disappointed because i just replaced the torn stock ones with j&m industries diaphragms. they are supposed to be better than stock?? fortunately i had my carbs from my 98 spirit to rob as i'm in the midst of overhauling that one's engine. it had dynajets and new honda oem diaphrams so i pulled the rubbers and the slides and the high speed jets and put them in the 87 c's carbs. WOW!! nevr ran so strong. i think its running better than my 98, maybe because of the 98's cams being ground for epa and midrange torque?? whatever it is that old 87 is th bomb now. doing toys for tots with my buddy sunday... total fun!!! cheers guys and that for chiming in for me. happy turkey.


and some say playing with carbs doesn't make much difference ... OK your carbs had split rubbers but I guess the bike didn't go that good when the rubbers weren't torn :p

I know on my bike it went from being able to use lots of throttle to rolling it on gently and being mindful of your speed as you get to fast for a corner deceptively easily ... I just got back from a short two up ride and I think I am all sorted too :D
 

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Discussion Starter · #18 ·
and some say playing with carbs doesn't make much difference ... OK your carbs had split rubbers but I guess the bike didn't go that good when the rubbers weren't torn :p

I know on my bike it went from being able to use lots of throttle to rolling it on gently and being mindful of your speed as you get to fast for a corner deceptively easily ... I just got back from a short two up ride and I think I am all sorted too :D
yes leathel, carb tuning is a very hot item. this bike was in excellent condition when i bought it 2 years ago, stock, a basic cruiser. it wasn't much on performance but it was a good ride. it never broke 90 and mainly was an 80mph bike and that showed through the gears. it was very lean burning. this summer i went to a k&n and took out thee baffles and rode it to sturgis and past up to north dakota, montana, wyoming, down to colorado then home to new mexico. she rode well, did the job. well she quit starting when i got back home and it turned out to be the kill switch, once i remedied that and got her started she just didn't have the punch, not even as much as she had on the sturgis run. i went ahead and rode 3k to cal and back and realized something was not right. this led to the last two days of doing the carbs. using the parts from my other 1100 i put in the dynajets (160) and also the diaphrams. so the grand total of mods from stock = k&n; hole saw mod; dynajet needles and jets. the increase in power is very real and noticeable. i hit 95 in a heartbeat today and shut her down. i could have easily broken 100mph. so yes messing with the carbs is hot!!!
cheers again and happy thanksgiving to all.:mrgreen:
 

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I have some serious reading to do.. this is my 1st carburetor fueled vehicle and I have no idea how it works.. lol, one way to learn I guess!
 
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