Help With 85r Slow Jet Broken?

[Onetrackmind]

I know I have started way to many "Help Me" threads lately...sorry., but I'm addicted to this machine and I want to get it running good ASAP.

Tonight I started to rebuild the carb and got as far as removing the slow jet when I realized that the head of it was broken off and the jet is stuck. i definitely want to get this out and replace it but I think I have only one option. Should I use a screw extractor to try and pull it out (don't have one) or just leave it be and rebuild the rest of the carb?

Thanks

[onformula1]

Get it out.
Soak it over night in PB Blaster before using a extractor. Clean it with carb. cleaner spray before using the extractor to remove all oils.

[jb2wheels]

I like to try reverse twist (left hand) drill bits when digging out old screws.

I normally break the extractors and then I'm screwed.

[Onetrackmind]

Update:
I went and bought a micro set of extractors at Sears and turned it super-slow. It worked and I didn't screw the carb up! Woo-hoo!

Thanks for the advice.

[Onetrackmind]

So I got the bike back together yesterday and ran it long enough to warm it up to set the idle. Shut it off and intentionally left the fuel on overnight to check the float. This morning I found nice big puddle of gas under it. The leak was coming from the carburetor overflow tube.

When I had the carb apart, it did already have an aftermarket plastic float that wasn't leaky...but I did not check the level. Is there a way to check the float level without a float guage?

Thanks.

[Dirtcrasher]

No, there is some junk in your (I forget the Fn name, lol) pointy rubber piece slid on float. The rubber can dry out and a complete rebuilt kit 15$ and a good cleaning with carb cleaner will do it. Fuel valve, float valve, I forget; IDK the names anymore I just know how to fix them :D


I've even had rebuilt carbs do this and a smack em with the handle of a screwdriver when they hang up.....

[Onetrackmind]

Thanks
Is that valve you are talking about called a needle valve? I put a rebuild kit in it and it came with a new one. I also cleaned all of the passages with carb cleaner and blew it all out with compressed air. I guess I will take it apart again and make sure that valve is fully seating.

[Onetrackmind]

Ok, I cleaned out the valve seat and put the carb back together and hung the tank last night. Left the petcock on and went to bed. This morning I went to the garage and found more fuel under the bike (in a plastic wash pan this time :p). It wasn't near as much as the first time, but it's still overflowing.

What I'm thinking is that the float tab that pushes the needle valve into its seat isn't quite doing its job. Can it slightly bend that tab to make it push the needle valve a fraction more into the seat?

Thanks.

[Dirtcrasher]

Aren't they plastic?? May want to replace them.

Maybe they sat in old gas for awhile??

Do it once, do it right and be done with it.....

[Onetrackmind]

Thanks for the heads up. I took the carb and float up to my dealer today to see if they had any ideas. He said the float looked great (actually the whole carb did) and his only suggestion was to "slightly" adjust the float to get the valve to fully seat.

I did that, sat the tank on, hooked it all up, and ran it for about 15 mins...it ran great. While it was warm I went ahead and checked the compression. It was 165. I know the manual says 170-200, but I really don't want to do a top-end right now...is 165 going to hurt anything?

It's been about 6 hrs and not one drop out of the overflow, so maybe that issue is fixed. We will see in the morning I guess.

One other issue that has been troubling me is the lower end power on this thing. I have never owned a 2 stroke bike, but I have had several 3 wheelers (biggest being a 200x) and my current ride is an '08 TRX 400EX. I understand powerband, but I keep thinking that this R should pull my arms off in 1st and 2nd with a thumb-full of throttle. It wakes up in 3rd and pulls really good after that, but low gears it's not that hot. It revs really well, just nothing getting to the wheels (almost like the clutch is slipping).

Could the fact that the carb has been flooding it out have this effect or is it low compression...or something else that I don't want to hear?

Thanks for all the help.

[thcowboy]

I wouldnt think 5 psi would make a difference

[yaegerb]

165 is low and MAY NOT hurt anything, depending on what's going on. Did you kick it over with the thumb throttle at Wide open? The way I test now (as advised by Harry Klemm) is to put the 250r in a higher gear, thumb throttle wide open, push the bike and let it roll over six or seven times....way more accurate than kick starting. As for your "low gear" problem, it almost sounds like you are too rich on pilot or needle circuit. A properly tuned motor will "hit" quickly in first and second gear if you want to. What does your plug look like? Should look like a brown paper bag.

[Onetrackmind]

Yes, kicked it with WOT about 15 times and 165 is all I got after about 12-15 mins of idle and feathering of the throttle. I'm ok with being a little low as long as I'm not hurting anything. I will try to do the test as you described if it's not too wet in the morning...we are expecting snow tonight. Compared to kicking it, how does this method differ in the reading? High, low...depends? I've never heard of it...just curious.

The plug I have in it is about two months old and really can't be used for much of a diagnosis now. (It was wet and very dark when I pulled it out for the comp test.) I put it in before I even started messing with the carb (fresh kit) or anything else for that matter, so I will put a fresh one in tomorrow. In addition to the slow jet being broken (fixed that), the airscrew it had in it before the rebuild wasn't even the right one. It was a solid 1/2" shorter than the one from Shindy...I'm pretty sure that didn't help my mixture any.

BTW, I know the book calls for .028-.031 gap...what do you recommend for stock jetting? I am at 500'. This one was on the high side...maybe even .032, so I put it at about .029 (coin style gapper-not very accurate).

[yaegerb]

.29 is fine for stock. How many turns out is your air screw?

[Onetrackmind]

The book calls for 2 turn out, but I put in Boyeson Power Reeds a few weeks ago (the old ones were shot) and they say the Power Reeds will make it run a bit rich. I have mine at about 2 3/4 turns right now and will adjust tomorrow for highest idle. Does that sound about right?

I'm hoping that a lot of these issues were being caused by the combination of broken slow jet, overflowing bowl and the tiny air screw... If I don't have gas on the floor tomorrow, I will put the bike back together and go ride it for confirmation.

Btw, I think I edited/added to my last post while you were posting.

[Onetrackmind]

One more thing...sorry. Does the position of my throttle slider look normal for a closed throttle? It opens all the way (maybe more) when at full throttle.

[yaegerb]

Air screw needs to between 1-2 turns and come off idle (throttle blip) crisply. I like mine between 1.5 - 2. If you are at 2-3/4 turn it down to 2 turns and see if your throttle blips are crisp. 2-3/4 sounds like way to much to me. That's a lot of air to compensate for your pilot jet.

Pertaining to your question about compression testing, don't take my word for it. Click the link below and read from the man himself. Scroll to the bottom of the page. When he says "surprised" by the difference between kicking and pushing....I was more than surprised, more like " mind blown"....pushing is the only way I test now.

http://www.klemmvintage.com/squish&comp.htm

[El Camexican]

Try this. Works for me. Sorry if there's some crap in this, I wrote it for someone else. You can just skip to step 1 and 2

The jetting that comes with a new 38 Keihin is very close for most 250/300 two strokes being used under 5,000ft of elevation, You can just bolt it on as is, or if you picked up a used one, open it up and install something close to a 48 PILOT JET and a 175 MAIN JET before you put it on your engine. Set the NEEDLE CLIP in the middle groove and set the AIR SCREW at 1-1/2 turns out from closed. These jets and settings will start and run your engine. You can leave these jets in to do your heat cycles and break-in before you start jetting which will require your engine to be at full operating temperature and ready to be leaned on. Meanwhile you should be able to putt around with no fear of damaging anything with these jets in it, just don’t haul off and top end the thing, or go hill climbing until you get it broken in and jetted properly. Once the engine has been run a few times and you know it has no mechanical issues you can start jetting it.

Before you start jetting make sure that you have proper play in your throttle cable and check it at both ends of the steering radius to be sure it has slack through the movement of the bars. Make sure you have fresh fuel in it with the oil ratio you plan to use in the future. Make sure the plug is gapped correctly, install a clean air filter that is not over soaked with oil. Make sure the stinger has good packing in it and that the pipe has no leaks. Have a paper and pencil ready to note your changes and a good supply of jets on hand. I’d start with at least all sizes of PILOT JET from 40 to 55 and all sizes of MAIN JETS from 168 to 180. Don’t worry about slides and needles for now. During these adjustments your engine could get very hot from being in one place. Setting up an electric pedestal fan in front of the engine will help a lot, but if you think you are over-heating it stop and let it cool down. Also, don’t bother doing this on an extremely hot, cold or rainy day unless that is when you plan to ride the most. Oh, and I hope it goes without saying that you need to do this in a well-ventilated area.

- Step 1: Fire the engine and take it for a spin to get it up to up to operating temp, make sure your idle speed is not too low, but don’t crank the idle screw in so much as to make it scream either. Just a tad higher than you normally would like it.
- Step 2: With the trans in neutral and the engine at idle open the throttle to about ½ way open as fast as you can from an idle and release the throttle. Repeat until you have a good feel for what it is doing. If it falls flat dead on its face for a moment, or seems to want to stall before it revs up you are lean, if it stumbles and burbles before it revs up you are rich. Adjust the AIR SCREW accordingly, turn it in to make it richer, or out to make it leaner, 1/4 turn at a time till you are close and then 1/8 at a time. Do this until the engine comes up nice and clean from your idle. As you are making these adjustments your idle speed may change and you should adjust it as needed it to keep it about the same RPM as you started with as a very high idle will mask problems and a very low idle (or cold engine) will always die out even if the jetting is correct.
- Step 3: Once you have gotten it to rev up as clean as possible shut the engine off and turn the AIR SCREW in to see how many turns from closed it ran best at then return it to that position. I think the rule of thumb is that if you are not less than ½ a turn from closed, or more than 2-1/2 turns from closed when it revs up nice and crisp you have the correct PILOT JET (or slow jet), but if you can’t get the engine to run well in that range you need to change the PILOT JET according to what the AIR SCREW is telling you. Let’s say it ran best with the AIR SCREW 3 turns out then you should put a smaller PILOT JET in. If it ran best at only ½ turn out you should put a larger PILOT JET in. NEVER GO UP OR DOWN MORE THAN ONE SIZE AT A TIME ON ANY JET OR CLIP SETTING, or you will end up getting lost and frustrated.
NOTE: When you change PILOT JETS you must repeat steps 1 thru 3 until you get your engine revving up cleanly with the AIR SCREW set within the parameters specified. The reason for keeping the AIR SCREW in this range is because in theory you will be adjusting it anytime the air temperature, or your riding altitude changes (“air density” is the correct term if you want to get technical). Some guys adjust their AIR SCREWS any time they go for a ride and multiple times if they are going up or down a steep mountain. The idea is that if you start your ride with it set in the nominal range you won’t have to worry about changing a PILOT JET on the trail as the AIR SCREW will have enough adjustment left in it for most circumstances.
- Step 4: Once the AIR SCREW and PILOT JET are set to your liking go for a ride and with the throttle at just under ¼ open in second gear whack it open for a split second. On a two stroke you want to do this before the engine comes on the pipe. It works even better if there is a slight uphill grade you can use when you are testing. You are looking for that same dry dead drop in power (lean) or that rich stumbling burble that you eliminated while setting up your AIR SCREW and PILOT JET, only now the adjustment is made with the NEEDLE & CLIP. Repeat the test a few times to be sure you have established a trend before you start making adjustments. Two strokes can accumulate fuel in the cases and it is always possible that your first test seemed rich because you had a pot full of fuel to clean out before the engine would react “normally” to the throttle input. In other words if it reacts one way on 2 out of 10 tests and reacts the same during the other 8 don’t worry about the ones that were slightly different, follow the trend of the majority of the tests.
- Step 5: To eliminate a lean condition you need to “lower” the CLIP which “raises” the NEEDLE and lets more fuel in relation to your throttle position. “Raising” the CLIP has the opposite effect in that it drops the NEEDLE lower into the inlet tube and creates a leaner condition in relation to throttle position. Adjust the needle accordingly.
NOTE: If during these adjustments you find yourself using either extreme of the available grooves in the NEEDLE you may have to either make a change to the PILOT JET (again), or THE MAIN JET. If your optimal air screw setting ended up being between 1 turn and 1-3/4 turns out then the issue can likely be rectified when you set up the MAIN JET, but if you were close to either extreme of the AIR SCREW settings when you settled on your PILOT jet then I would got back to the PILOT JET and change it to get the AIR SCREW closer to 1-1/2 turns out. Yes it’s a PITA, but it’s worth it.
- Step 6: Remove the 172 or 175 MAIN JET and replace it with the 180 you bought. Pack up your tools, MAIN JETS and a plug wrench and go find a nice long (SAFE) straight away.
- Step 7: Take it for say a 4th gear wide open blast. If it seems to struggle to rev up, break up, or burble you are rich and that is where you want to be at this point. Now replace the 180 MAIN JET with a 178 and repeat your top end run. It should be better, but if it still seems to be laboring to wind out stop and put in the 175 MAIN JET. Repeat until it seems to be running strong and you have a big smile on your face, but once it is good, you either stop or try one size smaller if you wantl, but that is it, check it once and then return to the larger jet that it ran well with. You don't want to be too lean and it will run very well when it is lean, just not for too long. If you get all the way down to your 168 MAIN JET and it still seems rich I would question your interpretation. You can try a 165, but I think you are getting into the danger zone with that jet. Now pull the plug and see what it looks like. It should be that light tan brown your find in pictures on the Internet. If it seems too dark put a new plug in and do a plug chop test (you’ll find the how to about that on the Internet) but I never bother as I do most of my riding well under full throttle, so I prefer to be a little rich and safe than lean up top.
NOTE: Once you have the MAIN JET set you may want to repeat all these tests again from the beginning. It is possible that your NEEDLE CLIP position may be better suited in a different grove if your MAIN JET ended up being a few sizes off of where it was when you made the original adjustments. Regardless of what you may read about what portion of your throttle position is effected by which jet there is always an overlap between the circuits during the transition.

As far as slide cuts and needle tapers go yes they can be changed, but it would take a far better tuner than me to determine if one was working better than another. I have played with needles before and bought and tested JD kits, but it seemed to me that no one needle was so different from another that the clip couldn’t be adjusted to make the same change as a needle did. As far as the slides go, at $60+ each I don’t feel like buying an assortment to test with. If you buy a used 38mm KTM carb it comes with a slide that is .5 different than the standard issue Keihin, so I have played with them. I have tried both sizes on my 300 bike and my 250 trike and felt no difference. I realize they make these parts for a reason, I’m just not skilled enough to tell you how to test and pick the right ones. If it makes you feel better I’ll bet that 99% of all two strokes ever sold still have the original slide and needle in them.

[Onetrackmind]

That's an interesting read...I will have to give it a try tomorrow (hopfully). Thanks for sharing.

On the air screw: I was just going by a combination of the shop manual and what Boyeson recommends for the Power Reeds. I will do like you suggested and start w 2 turns and see what it does. The manual calls for 2 turns, then adjust for the highest idle without any stutter or misses. Is that still the preferred technique?

Thanks again for all the help.

[yaegerb]

That's an interesting read...I will have to give it a try tomorrow (hopfully). Thanks for sharing.

On the air screw: I was just going by a combination of the shop manual and what Boyeson recommends for the Power Reeds. I will do like you suggested and start w 2 turns and see what it does. The manual calls for 2 turns, then adjust for the highest idle without any stutter or misses. Is that still the preferred technique?

Thanks again for all the help.

Yep, still preferred. Also take a read on what el camexican posted above (if you haven't already).

For what it's worth, I run a rad valve and power reeds and am at 1-3/4 turns.....but I am also using a 38mm PWK

[Onetrackmind]

El Calmexican
Wow...thanks for that detailed writeup. That is really great info. I have to admit, I have been riding for a long time, but have never really done much of my own wrench work before this bike. This is definitely a learning experience and I appreciate all the help and info that guys like you can and are willing to give. This is an awesome site!

[El Camexican]

Keep in mind that the manual setting is just a base setting to get your engine started. The idle and air screws on a two stroke are meant to be adjusted daily, if not hourly when changing elevations. I installed easy to reach screws on my trail bike. Comes in very handy in the mountains.

http://slavensracing.com/shop/2-stroke-air-screw-for-keihin-mikuni-by-slavens/

Once you get comfortable with jetting it becomes an addiction. "The quest for perfect jetting" (which is almost as elusive as the Holy Grail):lol: Suspension is the same, just more expensive:)

[Onetrackmind]

Thanks, I will likely have a chance to run it today to see if I succeeded and to get some tuning done. Two more things: can someone tell me if the picture I attched of my throttle valve in post #16 looks right for a closed throttle? Also, what will be the obvious signs of a float bowl that is not getting full enough? I think that I got my overflowing to stop (or did I)? I had just a few drips worth on the floor this morning. (I don't have a float guage, but it appeared level at 16mm). What symptoms should I look for?

Thanks for the link, but more than likely this bike will spend the rest of it's life never changing more than 50' of elevation. And yes, I can definitely how jetting can become addictive. Before this, I had never even held the jet of an ATV carb. Now that I have done it, I want to make it (almost) perfect.

[Onetrackmind]

I've definitely still got an overflow situation and am thinking it has to be a bad (replacement) needle valve. If it were the float that was the problem, I'm thinking that I would have a lot of fuel poring out...correct? This is just a small amount about 5"-6" in diameter. I actually found an OEM replacement needle at the dealership (for $39...ouch) and will try this one out. Is it common to have a bad needle valve in a rebuild kit? It's from Shandy.

It doesn't seem like I can really get too deep into tuning/jetting until I get this overflow condition corrected.

[Onetrackmind]

Got the new valve installed, set the float height to 16mm per the shop manual to where the tang was just touching the little spring loaded plunger on the valve. Put it all back together and put fuel to it and...it's leaking again. :mad:

What I don't understand is how this valve is supposed to hold itself in the seat upside down without anything physically pushing it in. If the float tang is just supposed to touching the plunger, it has about 1mm of travel that is allowing fuel to pass through. And that spring will definitely not hold the weight of the valve, not to mention the weight of the fuel.
What am I missing here?:wondering

[Red Rider]

What I don't understand is how this valve is supposed to hold itself in the seat upside down without anything physically pushing it in. If the float tang is just supposed to touching the plunger, it has about 1mm of travel that is allowing fuel to pass through. And that spring will definitely not hold the weight of the valve, not to mention the weight of the fuel.
What am I missing here?:wonderingAs fuel fills your float bowl, the float floats up and pushes the valve into the seat, thus stopping the flow of fuel into the float bowl. It's possible that there is debris getting into your float bowl causing the valve to not make a good seal against the seat, or the seat surface itself is damaged causing a bad seal.

[Onetrackmind]

The seat looks really good, it could be contamination though. I have poured the bowl fuel into a clear cup twice to look for anything obvious and couldn't see anything.

I will try fresh gas and put in new filter after I pull and clean the carb again. Maybe even a new float as suggested earlier. Maybe I'm measuring my height at the wrong place... I'm measuring from the mating surface to the very lowest point (top of float when carb is inverted). When I do this, the seam in the float is parallel to the mating surface and the tang is just barely touching the plunger on the valve. From what I've read, this is the way it's done. Maybe I'm wrong.

When the bowl is full, are the floats floating level?

[Onetrackmind]

Ok, last question cuz I'm going to quit thinking about this thing for a few days. It's driving me crazy and my wife is definitely not happy about all of the time I have been spending on it.

Worst case scenario is a new carb. What is a good, affordable drop-in replacement carb for this Kehin PE73A? And what can I expect to spend? I really don't want to have to modify/change out the boots, but a new cable wouldn't be bad...it probably could use one anyway.

[El Camexican]

Not to be an ass, but are you sure the fuel line is connected to the right inlet? We've seen a couple guys one here connect to an overflow nipple and not the fuel inlet. Needless to say they leak. Did you clean the seat before you installed the new needle? I spray carb cleaner on a Q-Tip and spin it inside the seat and then blast the seat out with carb cleaner to make sure no lint is left behind. Don't install the needle until the seat is dry, the rubber might swell if it contacts the carb cleaner and don't use brake cleaner on a carb!

FYI You can bench test the carb without bolting it to the engine, just place your fuel tank (or any fuel tank) on the edge of a bench and connect the carb to it to see if it leaks.

The wife is your problem. No one on here has ever figured out how to fix them!

[El Camexican]

can someone tell me if the picture I attched of my throttle valve in post #16 looks right for a closed throttle?
It "looks" ok, but what matters is that the slide stops hard against the idle adjuster screw. Anything other than a crisp smooth snap against the adjuster screw when the throttle is released is dangerous and MUST be fixed before you ride (or even run) the trike.

If you aren't sure it's stopping on the idle screw put your finger on the slide and turn the screw clockwise and you should fell the slide going up. If it's not your throttle cable likely needs adjusting. Don't forget that you need some free play in the cable at any position od the handle bars. aka "lock to lock"

[Dirtcrasher]

You mean Shindy?? And yes, it should pull and pull..... 165 is pretty low. Tear it down and bore it a size or two.

Make sure the crank is good, they spin fastest when they're about to blow up. :lol:

[Onetrackmind]

El Camexican
Thanks again for the info...and yes, the fuel line is hooked to the fuel inlet not the overflow. I will try to clean the seat better and use the bench test method also. I'm out of town for a few days, so I will have a new float by the time I get home as well. About how big is the orifice of the valve seat supposed to be? By looking...it's hard to tell, but mine appears to be slightly smaller than the tip of my valve.

The throttle does snap closed against the idle screw and I can actually see the slide moving with idle adjustments. I just didn't see the correlation between the two before (I'm a newb...sorry). The thumb throttle also had about 1/4" of play lock-to-lock...I think I'm good there.


Dirtcrasher
Yes, I meant Shindy (typo). I'm sure that you are right, and a tear down is in order...I just want to be able to ride this thing a little before I take it completely apart. Thanks for the heads up.

[yaegerb]

Food for thought. With all the time + money you have been spending on this carb which could end up being a fruitless endeavor I offer the following....

http://www.ebay.com/itm/Keihin-PWK-38mm-Airstriker-carb-Honda-CR250-01-07-/231489449555?pt=Motors_ATV_Parts_Accessories&hash=item35e5d8ae53&vxp=mtr

That's the carb I bought for my 85R (great deal really) and seller I bought it from (nice guy). The 38MM is a breeze to tune plus you get the advantage of it being new and fresh....carry on.

[Onetrackmind]

Thanks yaegerb!

PM sent.

[Marty]

The carb you have if it is an 85 atc 250r is a round slide. Carb is good but not as efficient as a well flowing 86 atc 250r flat slide or even a 38mm air Stryker.
Yes your compression is a bit low and I believe in Honda manual is states 180-185lbs but could be wrong but also know 85 atc 250r was the highest compression 250r ever made including all the trx 250R's as well. And I want to say my 85 atc was at 190lbs of compression when I owned it.
I think or believe you are not getting that arm pulling power from your atc 250r because your jetting is so off once you get jetting dialed in your atc will feel like a different bike. But this is just a thought if you have the money consider having it dyno tuned. It will make your life so much better no more guessing what jets work better but you also huge time saver!

[Onetrackmind]

Thanks Marty
I ordered an Aristiker yesterday (thanks for all the help so far yaegerb! :beer) to start fresh on the carb side of things. While I'm waiting for it to come in, I think I will pull the jug and go ahead and do the top end. That's another job that I have never tackled...so standby for another "PLEASE HELP!!!" Thread :p

The rear caliper is still an issue to. I've got fluid seeping from the PB housing...I think I've got a bad O-ring in there. Got it coming too.

If anyone knows of a good machine shop in the DFW area, I may be in the market for a fresh bore.