Carb Experts!!!!!!

[Flyingw]

I am in the process of rebuilding a few carbs for the SX/ES but one of the carbs is from an 85 TRX250. Its the same basic carb as the SX/ES carbs with one differance, the hole for the primary jet is blocked and not threaded for the jet. This TRX carb is a QA04AC. The jets called out for this are almost the same and everything else is the same. A couple weeks ago, I took a call from one of our guys who rebuilt a QA04A and put an SX carb kit in to it for his SX and it wouldn't run for crap so i thought I would try to do the same thing to see if I had the same result. I haven't assembled it yet but can anybody tell me why on this carb for the TRX would the primary hole blocked off and not used?

The pic showing the threaded hole is the SX carb and the non-threaded hole is the TRX carb.

[Flyingw]

Well I assembled the carb with the SX carb kit and installed it. I had the same exact results as Larry did. It starts up and idles fine but if I hit the throttle, it falls on its face but if I ease through the throttle, it will rev up. The motors on the TRX this came off of is basically the same motor as the SX/ES. I dont get it.

[shortline10]

I just rebuilt one of those trx carbs a couple weeks ago and remember a rubber plug in that hole . Are you sure its blocked off and not sucking fuel threw their ?

[Flyingw]

There was no rubber plug when I tore it apart nor could I blow air through that hole but for chits and grins, I'll stick a rubber plug in and try it again.

[Flyingw]

Hey Shortline, do you have the factory manual for the 85 TRX250? I'm wondering it it calls out for that hole to be plugged. The fiche is hard to tell but item 24 appears to be a plug/cap but cant tell for sure. I'm looking for a picture out of the book that shows that hole blocked. I have an 09A carb that's rebuildable but if I cant get the 04A going then I wont waste my time.

[Flyingw]

I found the manual and now I'm really confused. The manual confirms a QA04A carb but it shows it as having a primary jet not a blanked off hole. WTF over!!!!!!

[Flyingw]

The book also doesn't list the QA09A carb for the 87 TRX 250.

[atc007]

AS far as I know,,they come w a black rubber plug. I've never switched them back and forth that I remember. You said it is a 85 carb off the tRX,they DEF changed them 86 and 87,but you know that. Every one I remember tearing apart had a plug. I have a customers 85 here at the moment ,w the engine out,,so I could peak in it Real quick for ya if you need me to check anything out . I think all you need is a plug.

[Flyingw]

would you mind doing that. I'm curious to know whether its jetted or plugged.

[atc007]

Yep,you need a plug,,it's flooding itself. And yes,,of course,,all 4 screws were stripped! Nothing a pair of vise grips didn't fix quick.

http://i1116.photobucket.com/albums/k566/atc0087/DSC00396.jpg

http://i1116.photobucket.com/albums/k566/atc0087/DSC00398.jpg

http://i1116.photobucket.com/albums/k566/atc0087/DSC00397.jpg

[Flyingw]

Thanks very much. I will install the plug and reinstall it. Yikes, that carb's a mess. This weekend I had 9 carbs to rebuild 01, 02, 04, and 09. Of the 9, I have sucessfully rebuilt 4 of them with 2 more to do today and this includes the 04A. A couple of them were worse than that one but the bead blaster works wonders on the corroded bodies. I just finished putting my latest SX build up on the stool. I'm pulling the carb with one other to rebuild to throw in to the pool. I already have one set aside for this build. Thanks very much for checking on this.

[atc007]

LOL,,my friend,,in OUR climate,,,,THIS carb looks as new!! I am NOT kidding. No crud in the bowl,,nothing. I will make it look like yours if he ever pops for an engine. But I see much worse from abusive/neglectful customers. But then again,,They don't bring them here because they run great! They bring them after they won't move any longer. I pushed PM for years,,some took to it ,most didn't.

[Flyingw]

I hear ya on the PM. People fail to realize the costs of not taking care of their machines.

[shortline10]

Nice pic's Bill :lol: Hope it works out for ya Jim .

[Flyingw]

I have 1 plug luckly so I'll let you know how I make out later. Right now I'm working on an 01 and an 02.

[Flyingw]

Interesting result. With the airbox off, if I hit the throttle fast it falls on its face and dies BUT if I put my hand over the carb intake and partially restrict airflow, it works as its supposed to. I have two other carbs to install and test but before I put it back together, I will put the 04A back on with the airbox and see what I get but I'm thinking this carb is designed to have restriced airflow whereas the SX/ES carbs can run without the airbox.

[Flyingw]

The QA01A carb didn't pass muster. It idles ok but falls on if face completely when I give it gas. I think the pilot circuit has junk in it but considering how bad this thing was, I'm not suprised. I threw it in the trash once and pulled it out. I tossed it the first time because some nimrod stuffed the choke barrel in the hole and backfilled the hole with silcone thus eliminating the choke. I put the torch to it and got the silicone to break loose and was able to get it and the barrel out but the jet stack was pretty corroded so it will come apart and see if I missed something. The other 02A I rebuilt today worked beautifully.

Just for referance

QA01A 85 ATC 250ES
QA02A 85 ATC 250SX
QA03A 86 TRX 350
QA04A 85 TRX 250
QA05A 85 ATC 350X
QA06A -
QA07A 86/87 ATC 250ES
QA08A 86/87 ATC 250SX
QA09A 87 TRX 250
QA10A 86 ATC 350X

[atc007]

Hmmm,the one I took a pic of is def a 85 TRX,and I would be willing to 99% guarantee it's original. It's a 09A right? I scraped as good as I could w my nail,and clicked lol. Carbs are buggers sometimes. I use only Napa acid soak,what we had at School,and what I've always used. There have been carbs I've had to throw away too !

[badass350x]

Does this carb have the replaceable brass sleeve that the slide needle goes through ? If so what kit did you rebuild the carb with?

[Flyingw]

I tossed three carbs this weekend. One was a TRX carb in excellent condition but the top where the throttle cable threads in to was busted off. Another was for teh choke barrel fused in to the hole. The 01A problem child I pieced together with gently used parts so I ordered a few more carb kits. When they come in, I will clean it out again and put new parts in to it and hope for the best.

To answer your question Bad, yes I replace the needle sleeve. They get gummed up and sometimes they will have slight gouges in them. All the kits you find are all basically the same with the same parts. I have been buying kits from RJATV. $17.89 with free shipping.

http://www.ebay.com/itm/Honda-ATC250SX-1985-Carb-Rebuild-Kit-Repair-ATC-250SX-/170864917398?_trksid=p2992.m2065&_trkparms=aid%3D222001%26algo%3DSIC.CURRENT%26ao%3 D1%26asc%3D21%26meid%3D2112097688640788723%26pid%3 D100026%26prg%3D1009%26rk%3D2%26

[atc007]

Ok,,walk over to the garbage can,,pull the nice one w the busted top out! Take the 3 screw top off,scribe onto a new piece of metal,but where the throttle will go down through,leave a nice tab/ear there, drill it ,put cable down through. WALA, fixed that. There is a how to on here somewhere! I searched and searched,, couldn't find it,,and it SOO pisses me off I can't use a simple search !! But,if Monroemike sees this. A link will appear magically from the trikegods! Follow what I'm saying? Very simple fix!

[Flyingw]

Too late, its gone but it was broke pretty badly. More than just the tab was broke off. Oh well..... Some must be sacraficed so others may live.

[badass350x]

The reason I ask is I had the same exact problem with a 350x a few weeks ago, after going through everything about 5 times eveything looked good but still fell flat on its face, when checking those last two parts that I thought would never cause the problem there it was a few parts not to spec, after putting in the original needle an brass sleeve it ran perfect!

[Flyingw]

Gotcha, I verifiy the mark on the needle coorsponds with whats in the book. In any case, I have a few new kits coming so once they come in, I will replace all parts with new and see whst i get. Ive used more than a dozen of those kits so I trust the parts but I do have all the old parts. I never toss the old parts unless they are completely hashed but thanks for the heads up.

[Flyingw]

Well Badass, you were right. I removed the gently used parts in the 01A carb and installed a fresh carb kit and it worked great. I also installed the 04A carb with the airbox and it was ALMOST great. it had a slight dead spot just above idle if I hit the throttle but it did work better. I think now for this one, I'm gonna order a TRX carb kit and install that and see what i get.

[badass350x]

Glad it worked out for you!

Dean

[atc007]

ALWAYS replace them. Just the vibration of idling over the years wears away at both. Suzuki King Quads are Notorious for this ,to the point they foul plugs horribly and will barely run.