Carb shim mod.
 

I performed the carb shim mod tonight on my bike its basically stock with baffelectomy shimmed it out to .060 and put back together. First thing i noticed after syncing carbs and taking it our for a spin was i cant keep the friggin front on the ground(sweet)and im 6'7" 270 lbs even tucked into the tank it takes almost nothing to get the front end 36 " of the ground.
I was way happy with the mod. but it appears i lost some midrange power
under hard acceleration has any one else done this mod with same
results?



and btw pair is removed.

Mine seemed to run better with the mod but I believe I only went .026 on the brass washers I bought. You might be running a bit rich with .060 but if you're happy with it leave it be.

+1 .060 is quite a bit. .020 to .040 is about all it should take and it sounds like you are comming on to the mains a little to soon.

Well i think you may be right i was just going by this post from the Admin from about a year ago i found

ill try out .040 if i can keep the low end torque and get a bit of mid without to much work(money) that will be perfect. raining today so
looks like a perfect time to tear it down again.

It's just every bike is a little different and you have to tune to what your bike wants. One may run great with .060 where the next one might want .020. if you have the time, just keep playing with it till you're happy as it sounds like you are very close right now. :thumbsup:

Along with the tps mod, this is the best bang for the buck. $1 at radio shack if you don't all ready have some.

Way back in either '98 or '99 Dan Kyle did a back to back dyno test on this mod and found that the bike he was testing made more power with the shimmed needles than either the Dynojet or Factory Pro jet kits.
As always YMMV. :cool:

Hmm, Sioux Falls, SD is 1400 ft above sea level. This mod is intended for sea level. Try pulling out one washer.

You're getting slow there Greg - beat ya to it again Attachment 1230

We're that high up? (to make a difference?)

Ok im a Tool i went to pull a shim and realized i didnt put my velocity stacks on (duh). Slapped them on and it went nuts pulls hard though
2.8k to 8k no problem. Now i can pull the front up in second gear
with no clutch even. but just to be sure i pulled it down to .040
and lost alot of bottom end torque so put it back to .060
runs great now i can pull a wheelie for about 1.5 blocks now no problem smooth power. i guess for anyone reading this with a stock bike
and baffleectomy and your looking for some power shim your needles.

Now i just wish i could buy a can of High Compression Pistons and just pour em in :). that will be this winter Thanks for all the help guys.

I've done that before but usually I find the stacks right after I button up the air box- I've never got to the point of running it without them. Glad to hear you got it sorted out

Sure, but

a) You didn't look up the elevation for Sioux Falls, and
b) I just had to run and help out my roommate with an overheating car.


Oh, and c) :nana:

:mrgreen:

Just can't pass up the chance to give the Navy a hard time.....:D

Would someone mind giving me some dimensions on this shim/washer that you guys use to do this please? I understand the varying thickness, but a maximum O.D. and minimum I.D. would be appreciated. I haven't gotten into my carbs yet and i'd like to find something to have ready, rather than have to search for.

PATIA!

What type of difference would this mod have compared to swapping the stock slow jet 45's for 48's? What about the extra work involved?

I've done a bunch of work on my bikes, like putting in gold valves and checking valve clearances, but I've never torn carbs apart. Like slim, I'm trying to get an idea of what I'd be getting into.

The ones I've got measure .312" OD, .127" ID, and .030" thick.
They are a #4 washer from the Home Depot. Any #4 washer should do, you might be able to find thinner/thicker variations though. (Smaller than 1/8" (I think) they call the bolts/nuts/washers by #: ie #8, #4.)

Not sure on the main jets difference, but I think the washers affect the A/F through more of the throttle range.

As for difficulty, if you are mechanically inclined at all, it's not hard. Take your fuel tank off, air box out, loosen the carbs and pop the black covers off. Careful of the 11" spring (stock). Use one of the cover screws to pull the plunger out of the slide assembly, and don't lose the small stock washer on the needle. Put your washer(s) in and reassemble. The spring can be tricky, but if you hold your tongue just right you'll get it in no time ;)

The first time I pulled the covers, I took the carbs all the way off. Since then I pulled out one washer and did the rear carb without taking the carbs off, and I just pulled the carbs out of the boots to get at the front one.

Perfect! Thanks!

By raising the needles you allow the trasition to the main jets happen sooner


The trick to installing the spring is to compress the spring on the shaft of a screw driver and then you can put the compressed spring into the cover. Then hold the slide up with your finger through the throat of the carb and pop the spring into the slide and install the cover.

I slowly compressed the spring into the cover, then put a spacer (an old reflector lol) in to hold the slide up while I held the spring in with one finger until it started onto the slide shaft piece.