Need post needle shim carb help

[irishjohn]

Ok, shimmed the needles on my wife's 09, 2 washers. She has a Hotbodies Growler slipon. Shimming the needles really helped. Much smoother in the power delivery, faster.

However, it has developed some strange issues I need help diagnosing. Starting the engine cold is difficult. Full choke it starts but really struggles, almost seems to be running on one cylinder, though it really is running on both. RPM hovers around 1000, can't get it to go higher until it is really warmed up. I have tried adjusting the idle to raise that rpms and that helps. But as the engine warms up, I get an idle which keeps creeping up higher and higher.

Once the engine is up to operating temp, it runs fine. Starting from a dead stop is good as long as the idle rpm is at least 2500-3000 rpm.

Should I go to a larger size pilot jet or add another washer?

I will say that shimming with 2 washers really improved the performance. Prior to that, 100mph was the top end, it now will easily run 110mph.

[kkim]

how does it start w/o using the choke? can it?

[bob138]

You might need to pull the caps over the air mixture screws and tune those in. Otherwise seeing as you have a slipon you'll probably have to grab some new jets to tune it in.

Did you do anything to the intake side? Snorkel removal? Pods?

Even warmed up it won't idle well so you set it high or it idles high when warm because you tuned the idle high to get it to start?

Bob

[irishjohn]

Bob you nailed it. No mods to the intake. It will start with the choke, usually take 2 tries, first time runs for a couple seconds then dies. Restart, it will run, but only at about 1000-1200 rpm. Takes about 5 minutes before it will be warm enough to partially close the choke and use the throttle.

[kkim]

what size washers did you use?

[bob138]

Found this elsewhere : "You may also want to richen the pilot mixture by adjusting the pilot screws or going up one size pilot jet as the pilot circuit may be a shade lean from the factory."

Had the bike sat for a while? Could there be clogged pilot jets?

Do you still have the stock can? If so, swap that on and see if the problem goes away.

Much easier to isolate the cause before trying to solve the problem

Bob

[irishjohn]

3mm washers, Pilot jets may be the issue. I'll switch to the next larger size and see what impact that has.

[dubojr1]

Wait... I think you may be moving a little too quickly here.

Very first question...

Prior to the shimming....how did the bike run. Was idle an issue then? Has it always started with choke on but died the first time and ran on the second? We would want to find out if something may have went wrong during the shimmimg process before we start making additional carb. part replacements. I also think few of us had to change the pilots to the next size. I would have to revisit the jetting database to confirm but I don't recall many having to do that.

Your thoughts?

[bob138]

Originally Posted by dubojr1

Wait... I think you may be moving a little too quickly here.

Very first question...

Prior to the shimming....how did the bike run. Was idle an issue then? Has it always started with choke on but died the first time and ran on the second? We would want to find out if something may have went wrong during the shimmimg process before we start making additional carb. part replacements. I also think few of us had to change the pilots to the next size. I would have to revisit the jetting database to confirm but I don't recall many having to do that.

Your thoughts?

I agree. It should be pretty quick to bolt the stock can on, start it up, reset the idle and see if the problem goes away. That way we can confirm it's the can, I know that rejetting for the new can is the most probable answer but personally I prefer to prove to myself that it's the right answer before I pull carbs and remove gas and floatbowls for potentially no benefit.

Also, if it is the can causing a lean low end you may be better off adjusting the air mix screws first. I'm pretty sure the air mix screws overlap with the pilot jets in tuning enough that you can save the time and money compared to getting new jets.

Last, did you pull the carbs or did you just pop the caps and shim the needles?

Bob

[dubojr1]

Thanks Bob. If the problem was current before shimming then we may need to change our thought process. I know my 2008 250, the mixture screws were set out a different count of turns from the factory and the bike was hard starting and took forever to warm so I would like to make sure this concern was not present previous to the shimming. I also would like to confirm there is no damage to the rubber diaphragms on the needle slids. A small tear can happen occasionaly if they slip out during re-assembly.

kkim is our carb guru and he will be of great help to solve this. His questioning usually starts slow but he has good intent. More times that not it is something small or something missed and he usually determines this quickly. kkim are we are on the right track now?

[spooph]

Sounds to me it's slightly lean all around, and I don't think shimming is going to fix it.... The Growler is a massively open can.

Here's some general guidelines:
- 4 washers = 1 idle jet size larger
- 3.5 turns out on air/fuel mixture screw = 1 idle jet size larger
- idle jet governs idle only.
- air/fuel mixture screw governs off-idle (up to 1/4 turn of the throttle)
- needle position governs 1/4 to 3/4 turn throttle
- main jet governs 1/2 to full turn throttle.

I would start with the air/fuel mixture screw, and backing it out 1/2 turn maybe 1 full turn. If you're at the max of the above stated guidelines, it's time to enlarge the idle jet. I drill my jets with a set of very small drill bits - I think they're like 80-60AWG. Typically, 2 drill bits = 1 jet size, so you can tune using "half jet sizes". Hope this helps.

[irishjohn]

The problem began only after the needles were shimmed. No idle or starting problems prior to shimming with the stock or the Growler can in place. Switched back to the stock can this morning and the problem seems to be less noticiable. The performance is not as good as it is with the Growler in place. I am running 2 washers at the moment. What does everyone think about going to 3?

[HKr1]

Originally Posted by spooph

Here's some general guidelines:
- 4 washers = 1 idle jet size larger
- 3.5 turns out on air/fuel mixture screw = 1 idle jet size larger
- idle jet governs idle only.
- air/fuel mixture screw governs off-idle (up to 1/4 turn of the throttle)
- needle position governs 1/4 to 3/4 turn throttle
- main jet governs 1/2 to full turn throttle.

Thats some crappy guide lines, I think you really need to check your faxs on how a carb operates

[dubojr1]

Steve it sounds to me that something may have went wrong during your shimming. Double check all connections of vacuum lines and such first. You may also want to pull the needle slides again to make sure the rubber on them did not get pinched during re-assembly.

[spooph]

Originally Posted by HKr1

Thats some crappy guide lines, I think you really need to check your faxs on how a carb operates

Please straighten me out - possibly PM so as not to hi-jack the thread?

[kkim]

um, I would have recommended you add/remove a shim or put the bike back to stock to see what difference either made to try and troubleshoot your problem.

there are many ways to ultimately find the problem... there are no right or wrong ways. my advice usually is based on past problems others have had and/or to put things back to the original condition to see if installation introduced an additional problem due to some sort of work error.

yes, I usually start with very simple questions to avoid making assumptions that may lead down the wrong path and may end up confusing troubleshooting efforts.

what I have learned from the board is that when one member tries to help another in a thread, it usually is a good idea to let that one person help the OP instead of multiple members trying to help, unless they end up down a dead end or ask others for their thoughts. it keeps the troubleshooting down to a minimum and lessens the confusion.

[slow_2k10]

it is def a botched shim process..

if i were you..

i would go through the process again to make sure each of these things are in correct place or in there period..

SPRING( make sure the spring is in there and that it has the white cap at the needel side end)

DIAPHRAGM( make sure it is not torn and that its sitting in its grooves correctly

NEEDLE( make sure that the right needle is in the right place both carbs use a different needle they have part numbers)

[irishjohn]

Update on the post shimming issue. Changed to 3 washers/shims and resynced the carbs. N damage to the diaphragms, springs ok, no change to the pilots. No more problems! Starts easily, idles smoothly, runs great!! Thanks for everyone's input.

[bob138]

Awesome! Great to hear

Bob