supermarto

I shimmed the needles with two washers, about .050-.060 over stock. I have fully bafflectomied pipes, stock air filter. Buttoned it all up, started right up without choke from cold, idles great for about a minute then drops to about 5-600 rpm and dies completely when I give it throttle... Started up once more, idles great and then dies after a minute almost like it is not getting any gas or no more is in the float bowls. Now the battery is dead from trying to start it, which it won't do unless I charge the battery or jump it. Double checked all vacuum lines and gas lines, all good. Is it possible I:

1) Only need one shim instead of two? or
2) Have to adjust my pilot screws?
3) Need to charge the battery for real, not just jump it?

Carbs were running great before I shimmed. Any help is greatly valued...

cliby

did you hook that little vacuum hose on rear of tank to the down nipple of the vent or the side one? it goes to the side - we have all put it to the bottom nipple many times and the bike does what you describe.

that would be my first thing to check

supermarto

Hmmm... the one with the little clip-type hose clamp that is a royal pain in the **** to squeeze open? I put it on the bottom nipple! I will go check and see if that helps...

Edit:

YEP. Thanks, dude... I knew you guys were way smart!

cliby

it will help. its the vacuum for the fuel tank petcock. The vacuum on the intake of the engine is what starts and maintains the flow of fuel from the tank. it wont get fuel without it. I'm not smart, but I'm pretty sure that same question was one of my first questions on the forerunner of this site runlevelzero - like I said, at one point most of us have hooked it up wrong

Syclone

+1 to that.

Also, I shimmed my needles .060", and found it way too rich. I could smell gas after shutting the bike off. I figured with a K&N and V&H slipons I'd need the extra washer, but I pulled it out, down to .030" last night, and the rich smell is gone without any noticeable power loss. As always, YMMV.

supermarto

So far, I have not logged more than a couple of miles with the shims, I had to go to work immediately after I fixed the vac line just to test. It ran EXCELLENT. I am suiting up, going for an extended ride (yes!) and will smell my exhaust and monitor it all in a few minutes. I still got a few questions, like is this okay for long term or is it meant to be a short term mod until I drop in a jet kit? Does this affect fuel economy at all?

Syclone

My mileage dropped with the two washers to under 30, but that might have been because I was really on it. I haven't checked since dropping to 1 washer.

I haven't decided if I'm going to get a jet kit or not yet, but the there's no reason the shims couldn't be a long-term solution.

cliby

I don't think a jet kit will get you any more than what you've done unless you're doing a bunch of other mods. You could spend A LOT of time with a jet kit and probalby not come out further ahead (IMO).

Syclone

That's exactly what I found with my last bike (Nighthawk). I shimmed the needles until I got the money and ambition to put a jet kit in. I rode it after the jet kit and had no additional gains for the $100 I put into it...

cliby

of course think of how much we learned, priceless, as they say

supermarto

So I tried one shim instead of two. They are around .030 each, in my estimation... I notice no real improvement over stock, and I am going back to two for .060. It really woke the bike up, and it was such an improvement in the whole range especially down low... Seemed to suffer a bit at full bore roll ons in top gear near 100mph (not tested on public roads, of course) but for real world situations, it had really linear power, and none of the backfiring I was getting prior.

Hawkrider

Gotta love PVLIR!!!

Wondering what that is?

cliby

that is great - didn't know it had an official name!

8541Hawk

That common of a mistake just had to be named...... keeps answering that question from getting too boring....

supermarto

I am such a noob, I know, but I PROMISE I did a search for EVERY COMBINATION of words like "carb shim, needle shim, shim mod, radio shack washer shim mod, shimming, shim my needles," yada yada yada... I SWEAR. I actually do think I read one of the posts that had that little factoid, but I just overlooked it like it was a dollar bill in a stack of twenties...

hymey

Dont fit a jetkit unless you are prepared for disaster!!! Just kidding not that bad just several tank/airbox carb removal to get right.

Id stick with the stock needles. 60 thou is to much over standard(20thou). Take one out each side. But first of all if its good on Fuel and pulls hard leave it. If not drop one washer from each side and see how it goes....

supermarto

well, I just completed a full tank of gas test, and I do not like the results. I got a HUGE shotgun blast backfire once when I was cruising along at around 5,000 rpm and shut the throttle, if I remember it right. I still have not done a carb sync or adjustment of the mixture screws or anything... Also, idle has a distinct "wave-like" pattern. Revs normal then drops, comes back, then drops, sounding like it is going to stall. Not like it is hungry for fuel, more like it is hungry for air. I am on the hunt for a tool to adjust the screws today. Carbs are off right now, may try to dremel the screw head....

supermarto

No help from the helpful this time, eh? No matter... I think I figured out the error.

The shims I used were SLIGHTLY making the needles point crookedly... they would not sit straight in the slides. I am thinking this effed up the atomization, may have even prevented the needle from re-inserting itself properly back into it's little hole once they slid out..

OR

The slides were sticking. When I reassembled everything the last time, I actually dipped the tip of my finger in some fresh 10w-40 and ran it around the lip where the diaphragms sit to hold them in place like adhesive while I got the covers back on (flame on, fellas). I then read about keeping petroleum based oils away from gasoline evironments in the post about using die-electric grease on the carb slides... I swear only used a TEENY AMOUNT but when I cleaned the slides and replaced them they did have a slight brown gunk on them.

Anyway, ran a hundred and twenty miles of gas through her today, and she was running AMAZING. I also did the airbox mod of removing the upper half of the plastic flap on the air filter platform and that screwed in rail it sits in, so that may have helped too.

RCVTR

PVLIR. That's good!

Too much shim, I say.

supermarto

Nah, the two shims together amount to exactly 1/16" or .0625. it runs really really good right now... if it were running rich, I would smell gas as well as be using more of it, no? I swear today I got 95 miles out of a tank and the reserve light still had not started to blink... how much more do you think can be gotten once the reserve comes on, anyway? Ten, fifteen, twenty miles? I would say I would have gotten at least 110 to 120 miles out of it today, something I have never done before (although much of that was hwy.)

Also I trust Mr. Nemish. I made my choice based on posts by him where he says to go .060 or more with bafflectomied pipes... so far he has not steered me wrong! I still need to just make sure the carbs are dialed though, with a mixture screw adj., carb synch, etc...

RCVTR

True, that!

That's where I started way back when.

hymey

There is a website with carb shim dyno graphs and add only 20thou delivered more power than adding 40 like you've done.

But every engine is different and its all about experimenting. I must say I have not tried shimming needles but I found with the stock jetting the bike was quite soft in the mid range so shimming will help. As others preach a lot always sync the carbs after rejet. This is a must . Its easy to pull something to bits but unless u understand u are best of not touching it.

8541Hawk

Maybe non-us bikes are different but the ones here like about .060 worth of shim on average.... or at least that has been the case for the last 10 yrs.

hymey

Sorry. I forgot to mention. It was of a US website that I read the dyno graph.

However 60thou may help throttle response. Which in stock form sucks on the hawk.

Mainly due to the stock air filter/45 pilot combination contributing to this!