[strokerspeed]

Some of you might have seen a previous post about a fuel screw being stripped out and stuck. Well I got the screw out but have had no good luck since.

The bike doesn't want to settle back to idle. Something is sticking and I can't figure out what. I'm still leaning towards the needle/seat assembly, but I have messed with it so much I don't know what else to do.

As soon as I put it back together the first time and it had this problem (after getting the pilot screw fixed) I thought for sure it was a sticking needle/seat and ordered a rebuild kit for both carbs off ebay.
Today I put new jets, needles and seats, needles and clips, rubbers here and there, threw it back in and here is what I came up with.
When I turned the gas on (I checked flow and its good) the seats/needles held, but after about a minute gas started pouring out the right side carb overflow hose. I tapped on the carb a bit where the needle/seat is and got it to stop. I thought this was weird to start with cause they are brand new, should not be leaking. Then I started it...ran great at idle for about a minute...I blipped the throttle just a tad and boom back to 4/5K rpm.
The only way I have learned to get it to drop from where its getting stuck is to lower the idle a bunch, then all the sudden at a certain point it will drop the rpm (then being way to low since I just adjusted it low) so I turn it back up a tad to the right idle, blip the throttle and 9/10 times it gets stuck up at 4/5K rpm.

Just for a note...before rebuilding the carbs or replacing anything (except for the fuel screw I drilled out), I was able to clean them enough to get the bike to run flawlessly for about 3/4 minutes...then whatever it was started sticking again and back to revving itself out. Thats when I ordered the kit.

Another thing for note...when I was installing the new needles and clips with all the washers and such I noticed the bigger round white plastic washers around the needles where a tad different from the ones in my kit. The ones in my kit did not fit as well, therefor I used the stock ones. The metal washers in my kit where a tad bigger as well, so I used the stock ones. I don't think this has anything to do with my problem, but it goes to show maybe this kit is just too cheap, maybe the needle/seats are not really working properly even though they are new...

I have not done the clear tube method or modified anything inside the carb yet...my goal is to just get it back to running normal for now, then I will make adjustments to fuel level/tangs/and floats. I know the bike can run normal with the current bowl fuel level...thats why I have not done the clear tube method as of yet.

SO...help please
what are all the possibilities this could be?
I'm almost positive its still the needle/seat assemblies, but I want to be sure it can't be anything else before buying the parts at the stealership (2 needle/seat assembalies are $90 at my local dealer...got whole kit for 50 shipped)

Thanks in advance!!

 

[QuadBart]

I tapped on the crab a bit where the needle/seat is and got it to stop.


I have not done the clear tube method or modified anything inside the crab yet...

Thanks in advance!!

Maybe they have a cream for your CRAB problem?






Sorry......couldnt resist. LOL

 

[strokerspeed]

Haha woops, obviously meant "carb". Well it should get a lot of views this way:haha

Edit: I now realize it was my spellcheck that screwed me...changed them all to "crab"...can't edit title, sorry!

 

[THUMPER 01]

Lets assum your needle/ seat assembly is correct. You need to do the "clear tube meathod" to check to see that the float level is correct. Your overflow on the vent will only happen with 1) a stuck open needle/seat. 2) incorrect float adjustment or 3) the needle/ seat is worn.

 

[strokerspeed]

ok I will get a clear tube and do that in the morning. But like I said I got it to stop coming out of the overflow tube. As of right now I can go turn the gas on and no gas will come out the tubes, I can fire it and no gas out the tubes, still hangs up around 4/5K rpm. Maybe this is due to too much fuel in the bowls so I will do the test first thing but I have a feeling its something else.

I'm just cerious as to what else could cause this high rev. I'm positive its not the cable as I can watch that and even disconect it and use my fingers it still does it.

 

[QuadManiac]

Look, regardless of the state of the float valve, it won't cause the idle to oscillate between normal and high RPM... lots of air is needed for that. You have something sticking or a significant, intermittent vacuum leak - first place I'd look is the slides and their diaphragms.

 

[strokerspeed]

Thanks Quadmaniac.
When I put in the new parts I did change the needle and therefor took the diaphrams out. Both diaphrams appeared to be in good shape...no tears and seem to work properly. Next time the carbs are out I will check them once again though.

I want to spray some carb spray around the whole carb while its running to see if it sucks any in, although I hate spraying that crap all over a running bike, I'm going to anyways here shortly. I'm off to get a clear tube even though Im almost positive it has nothing to do with the revving.

What other places could I check for air leaking? Besides of course the obvious connecting boots...those I check and recheck everytime and are secure, not folded, and in good shape.
Next time I pull it out I will take a bunch of pictures, maybe you guys will see something I'm missing.

One thing that keeps comming to mind is how if the idle screw is turned out enough, the rpm realese back down. This happens suddenly, like its as soon as a passage is blocked or opened it catches. When looking in the carbs, thier are two holes going ?-somewhere-? at the bottom of the brass flapper(s). It seems as soon as the first hole is closed (the idle screw is turned out just enough) is when it drops back down the idle. Anyone know what those two holes are and where they go?
Thanks again for all the help!

Edit: I sprayed carb cleaner. 4 times out of 5 it did nothing. Once (I think out of quincidence) it dropped idle as soon as I sprayed. This time after running it for a while and spraying carb cleaner, gas started running out one of the overflows again (the right carb). Can a sticking needle/seat cause the high revving or no?

 

[QuadManiac]

Revisit the slide diaphragms, make sure they aren't pinched from their re-installation and recheck for leaks.

Also look carefully at the throttle cable, the butterflies and the throttle actuator cam - remove the cable from the cam and feel the friction as you turn the cam by hand - look for any evidence of sticking.

Unwanted air can get in thru the slide diaphragms, the shut-off diaphragm (I think), and the intake manifold boots. Spraying cleaner around the carb will tell you about boot leaks, but not necessarily the slides or shut-off. They'll need to be inspected carefully.

You mention the 'idle screw' - what are you describing - the fuel screw (called pilot screw in the manual, one on each carb), which adjust idle air/fuel mixture; OR the idle speed adjustment screw, the knurled thumbscrew on the left carb only which acts as a lower stop for the throttle actuator cam?

By all means, check float bowl level using a clear tube - although I don't think this is causing the idle speed changes, extreme incorrect float levels can cause all kinds of interesting issues, and will make proper carb adjustment impossible.

 

[willykiller]

Another thing to check is the oring that seals the needle's seat into the throttle body, check that it is proper and seals, that it is the correct size and also the bore that this assembly sits in, that body isnt damaged or corroded, any leak past this area will cause your problem for fuel leaking from the over flow.................

 

[strokerspeed]

Thanks for helping me out guys, its greatly appreciated, I hope this thing gets concurred today.
First off, I'm talking about the idle adjustment screw not the pilot (fuel) screws, those are at 2 turns out and I don't think those are giving any problems.
I revisited the slide diaphragms and everything up top. WillyKiller you where right, one of those rubbers was not seated in right and it was kind of cocked one way (can't believe I didn't notice this!) so I put new rubbers on both and checked, checked, and checked again for proper fitment. I thought that must have been it so threw it back in and nope, same problem. Good call though! Both slides and rubbers and everything look flawless, although I guess they are next to be changed since everything else is new.
I'm thinking about just buying used carbs...I'm in these for $120 as of now. Could have bought used for $70 (+3 hour drive each way). BUT I know a used set could have the same problem or worse, so I'm hesitant.

I'm 100% its nothing with the cable. I have been playing with the butterfly by hand for quite some time now and can't feel anything wrong (haven't felt anything weird their since I started this fiasco). Everything feels smooth, everything has been cleaned and cleaned again, and everything looks right

Float bowl results: Left carb was dead even with the seam between the bowl and the housing. Right carb was 4mm higher than that, I know they are off and I plan on making them 3mm above but right now I don't think that can cause my problem so I'm not planning on messing with it until this problem is found/fixed.

 

[strokerspeed]

Here are a few more pictures. These look good to me, the rubbers are "weak" and/or "flimsy feeling", but I assume thats normal. It will fold over on contact type of flimsy...but again I think its normal?

EDIT: one thing I just thought about looking over the carb diagram online.
The rebuild kit came with two little brass "pipes" or jet looking things (no threads). I thought they went in between the carbs somewhere and I had not broken the carbs apart. So I just got done breaking them apart and they don't go in there anywhere...? what are these little brass pieces for?

Edit again: put it all back together and tried it again, still doing it. I don't know what else to do, I've got this thing spic and span looking like new and still I get crapped on! So I haven't taken apart the accelerator yet...could that cause this problem? Whats the best way to get to the accelerator?

UPDATE: maybe I'm getting somewhere. I turned the fuel screws in one turn each, thus making them both 1 full turn out from seated. Then I fired it, still catching at 4/5K, so as usuall I backed down the idle to get it to drop (always works) and this time when it droped I didn't turn it back up to where its suppose to be (1400), instead left it around 900 (guessing). Leaving it there allowed me to blip the throttle, snap it to full throttle, and didn't really hang up. It seemed like it wanted to a couple times, but overall seems to be much better with lower idle. I don't think lowering the idle is the fix, but this could of been why it was working for that short period of time before, therefor making me think maybe its the pilot jets afterall? maybe I need the 25's instead of the stock 22.5's. If I remember right...turning the fuel screw in is richening it right?

I still think above all, it has something to do with the two little holes the brass flappers are closing when the idle adjustment is turned way down, I wish I knew what those holes where related to in the carb.

 

[QuadManiac]

They're the output side of the fuel screws, I believe... when you gently close the screw, you should see the point sticking out that hole - if we're talking about the same ones.

What are your mods (exhaust and airbox/intake), and what jets (mains,pilots) are you using?

 

[strokerspeed]

Thanks, but no not those holes. I know there is one hole in each one that the fuel screw sticks through, BUT there is also two more right next to each other (per carb) at the bottom of the brass flapper (further into the carb than the fuel screw hole), those are the ones I'm curious about.

No mods what so ever, still even has the stock baffle in the muffler, stock handlebars even!
As of right now, I can go start it, warm it up blipping the throttle, and it not hang up at all (this with the idle turned lower than I believe it suppose to be). So as soon as I know all my neighbors are out of bed, I'm taking it out and we will see how she runs overall with the low idle.
Could having the idle too high really have caused it to hang up at 4/5K rpm? I feel I have only put a band aid on the problem and its still a problem...

Update: I uploaded a video on you tube so you guys could see what its doing. You will notice, with the idle down low it returns back down to low idle, but when the idle is raised a bit, it will hang up high in rpm.
After taking this video I took it out for a ride. Hiccups around mid to 3/4 throttle, backfired once (while under throttle!?), and then started to want to hang back up at high rpm, so I adjusted the idle even lower (almost dying) and then it no longer hung at high rpm but still had the cut out/hiccup. What is the deal here!? Could it be the accelerator pump? Think its still the rubber diaphrams or slides? I'm so lost on this

heres the video:

 

[QuadManiac]

Okay, have you tried richening up the fuel screws a half turn or so, to see if idle stays more stable without getting 'lumpy'... way too rich will make it idle like a Harley.

 

[existanzrx7]

EDIT: one thing I just thought about looking over the carb diagram online.
The rebuild kit came with two little brass "pipes" or jet looking things (no threads). I thought they went in between the carbs somewhere and I had not broken the carbs apart. So I just got done breaking them apart and they don't go in there anywhere...? what are these little brass pieces for?

I just rebuilt mine and my kit also came with those little brass seats are called main nozzles and I did figure out where they go. Check out your pics. They only come out one way but you have to remove the main jets and the main jet holder and they are located right under the holders. The way to get them out is threw the top of the carbs and they come out towards the float bowls. I didn’t replace mine because I dont know how good these are the stocks look to be maybe stainless steel not brass plus mine didn’t look damaged in any way. If Willy or QuadManiac can chime in and tell us if these ever go bad or if it’s a good idea to replace these that be awesome.

 

[strokerspeed]

Thats great info! Maybe they have gunk in them (like the whole carb did when I started this project) and therefor hanging up the needle? maybe, maybe not, I will try it.
QuadManiac- Am I right when I say turning the mixture screws IN is richening it? Or other way around?
Still wondering if accelorator pump could cause this problem? Just for note: all jets are stock sizes and I'm at 427 ft elevation (still debating on trying 25 pilots instead of 22.5? Thoughts?)
Thanks again!

 

[existanzrx7]

Thats great info! Maybe they have gunk in them (like the whole carb did when I started this project) and therefor hanging up the needle? maybe, maybe not, I will try it.
QuadManiac- Am I right when I say turning the mixture screws IN is richening it? Or other way around?
Still wondering if accelorator pump could cause this problem?
Thanks again!

I did clean mine. Mine wore pretty dirty. I know I am not QuadManiac but I can anwer that one for you. Richening is when you turn the screws out if you turn them in they will make it lean. Intalling 25 pilots will not harm anything if anything it will take less turns on the fuel screws to get it to idle right. Plus as soon as you start modding your Rappy you will need them any way.

 

[willykiller]

I did clean mine. Mine wore pretty dirty. I know I am not QuadManiac but I can anwer that one for you. Richening is when you turn the screws out if you turn them in they will make it lean. Intalling 25 pilots will not harm anything if anything it will take less turns on the fuel screws to get it to idle right. Plus as soon as you start modding your Rappy you will need them any way.

Absolutely right and as for those little brass pieces, I know what you are talking aobut but have no idea why they would be included in an overhaul kit, overhaul kits are generally made to replace worn and or parts that get damaged from the overhaul process.............

 

[strokerspeed]

ok thanks guys, I'm pulling it back out today. Still no answer on weather or not the accelorator pump could cause this problem? Also still curious as to what those two little holes are... I still think its dropping from its high rpm as soon as the flapper closes those holes, I can't figure out where they go or what they control

 

[QuadManiac]

Turning the fuel screws counter clockwise (as in removing or loosening the screw) richens, clockwise (as in tightening the screw) leans.

If you want to find where a particlar hole comes from / goes to, use spray carb cleaner with the tube attached, place the tube against a hole in question and spray - look to see where the spray comes out (it always will, somewhere). Conversely, if you can't reach a particular hole, use the tube to spray into every other hole, jet, passage, etc., until you see it coming out of the hole in question. Added bonus - this cleans the carb quite well!

The Rappy carbs do not have an accelerator pump.