flyday58 Posted September 23, 2012 Share Posted September 23, 2012 Any chance of a short video, upload to photobucket or similar, then copy and paste the link here? Link to comment Share on other sites More sharing options...
Moderator Cynic Posted September 23, 2012 Moderator Share Posted September 23, 2012 When you put the throttle cable into the carb slide (or valve?) do you have the locking plate that fits in place to trap the clip and the cable in place with the carb spring. It is basically a posh washer but it has a tang that points down and fits into the grove in the throttle slide where the cable fits preventing it from coming out no matter what. Also without it the needle can lift and make things go right strange. just a thought.... Link to comment Share on other sites More sharing options...
DT175 1978 Posted September 24, 2012 Author Share Posted September 24, 2012 Thanks for all of the good ideas. I actually thought of one more basic thing I’ve skipped over, and that I had better get squared away. (you guys might have assumed I already did) I hadn’t even looked at the spark plug yet. I know, I’m sorry for posting online before checking that – I’m such a “n00b” with this stuff. I was thinking fuel because the carb was spewing fuel and I kind of skipped over thinking about spark at all. The spark plug when I pulled it was pretty ugly. I think it may be black enough to be fouled. Also, while the bike does run, but runs poorly – I worry some of my earlier details may be misleading as it really does not run poorly in as much of a predictable manner as I had previously described. It’s kind of unpredictable in exactly how it struggles. I’m thinking more and more it’s fuel starving or not sparking. My plan, as it stands, is to: Get a new, properly gapped spark plug installed Get a new, properly oiled air filter installed Get the fuel petcock and filters cleaned out and reinstalled. Then I’ll see where I’m at after all of that and report back / ask questions. If I’m still having trouble I’ll look into taking a video, but that’s not easy for me to do (I need my kid’s help LOL) Thanks for all of the help so far, you guys seem very helpful. I’ll let you know how I do. -Matt B. Link to comment Share on other sites More sharing options...
flyday58 Posted September 24, 2012 Share Posted September 24, 2012 Keep us advised. Also, while my icon is NOT who I am, I resemble that dude cos I'm, well, old. More than a few of the chaps here have seen at least 4 decades, 5 in my case. My kids didn't have to help me with vids and pics only because the help on this forum is stellar. Get back to us, we are one with The Force! Link to comment Share on other sites More sharing options...
Moderator Cynic Posted September 24, 2012 Moderator Share Posted September 24, 2012 The lil ol DT holds a soft spot in the forum, hell the squires meet could almost have been the DT appreciation society. We have everything from sweet restored rides like Blackhats and Airhead to my working classic. The best bit, nobody askes how to de restrict em, also you rarely get a 'how fast??' question either. We all know, don't care and just enjoy. She will run properly again, bear with it and us and you will be an expert in no time. Link to comment Share on other sites More sharing options...
DT175 1978 Posted September 27, 2012 Author Share Posted September 27, 2012 So, I did a couple of things to the bike over the last couple of days. I got the petcock done. I drained the fuel from the tank and removed the fuel petcock, got every last drip of fuel out of the tank, wiped out the neck of tha tank and cleaned up the threads a bit, then disasembled the pet cock. The screen was clear, and I'm not surprised as fuel did not seem to be obstructed, but the seal between the tank and petcock was shot. I came up with something that worked to replace the seal, cleaned all parts of the petcock, and reasembled. It looks a lot better, and it doesn't leak at all anymore like it did before, but fuel comes out at the very same rate and this did not improve how the bike runs. (Oh well, it was still not wasted time). I got a brand new spark plug to replace my old ugly one, check the gap - it's cortrect, and installed. Still not "the fix" for the problem I'm having. My very next move is to get a new air cleaner installed. I wasted time looking for one locally and now I just have to order it online and wait for it. After that, I'm running low on ideas... starting to wonder if it's electrical? Maybe I should check the coil? I did actaully think that it may have run a little bit better after the things I did, but then again, maybe not... I want to get the air cleaner on before I really give it a good test. I'm also wondering if I should tear into that repo carb I bought and take a look, as I've seen a couple of posts about improperly installed O rings strait from that factory. Link to comment Share on other sites More sharing options...
DT175 1978 Posted September 27, 2012 Author Share Posted September 27, 2012 The carb off ebay, is it a new aftermarket or OEM? OLDBIKEREHAB and myself bought non-OEM and both of us found damaged o-rings on the idle air screw: Didn't think I would have to disassemble a 'new' carb. With problems I kept having I decided to go back with the Mikuni carb and I'm glad I did. Did you install the carb, find that something was wrong, and then take it apart to find this? What I'm wodnering is, if you tried it and noticed something was wrong, what condition did this cause? (how did the bike run with this problem?) My carb off of eBay is aftermarket, and is cheap, I wonder if I should take it apart to look for such issues? If I do that, can I re-use the same gaskets as it's still basically new? I don't have to order a rebuild kit to get new gaskets just to take it apart, do I? Link to comment Share on other sites More sharing options...
flyday58 Posted September 27, 2012 Share Posted September 27, 2012 It's worth dissaembling to know what you got, no guessing. Gasket should be reuseable no prob. All the parts in the aftermarket I bought were de-identified, so no way to adjust jetting and such. So I ended up finding a Mikuni on ebay and rebuilding it. IMO carbs and like parts on these bikes are like some parts for American vehicles: there's just some things Ford, GM, and Dodge know how to do right.Went thru 3 NAPA lifetime warranty alternators on my F250 before someone on the Ford forums suggested going with OEM. Been happy since I did. Went thru the same thing with igntion coils on another truck. And I am really glad I bought the OEM Mikuni as I can fiddle with the jetting to get it right for today's ethanol-based varnish they laughingly call gasoline. That said, I repeat that Oldbikerehab is satisfied with his aftermarket unit. Link to comment Share on other sites More sharing options...
oldbikerehab Posted September 28, 2012 Share Posted September 28, 2012 A few things I've found with my 30 something dollar Chinese carb: Besides the o-rings being shot and requiring me to get new ones, the throttle adjust screw and pilot air screw don't tune the carb properly when set according to the DT 175E specs for Mikuni, as listed in my Clymer manual. I had to back the pilot air screw almost all the way out and tighten the throttle adjust screw in almost all the way to get my bike to idle at 1300 revs. Also, mine was sold on ebay as being for the dt175, the manufacturer's website lists it as being for a 125cc. Add in some unmarked mystery jets and needle and you've got a cheap carb that can be made to work. I have my needle raised to the max so it's kind of a fire hose setup. I get a pretty boggy throttle response from idle to 1/4 throttle, but 1/4 to WOT is a MF to hold on to. Not that I necessarily think your carb is solely to blame for your problems, but you'll want to get it set right. If you've got a bit of patience and some hair to pull out along with some basic mech skills, you'll get that old mare kickin' ass again. Oh, and you need beer to make this whole thing work. Link to comment Share on other sites More sharing options...
DT175 1978 Posted October 4, 2012 Author Share Posted October 4, 2012 Thanks for the input, oldbikerehab. It's taken me longer than I'd hoped to get the correct air cleaner, but I should have that in a few days. Once I have the new air cleaner on, if that doesn't help things out then I'm going to take apart the reproduction carberator and check for assembly problems, if all looks well, I'll try to adjust the carb for better performance. I am a little worried about it being the right carb - eBay listed it as being for a '78 DT175, but when I go to the manufacturer's web site (zoom zoom parts) they don't list a carb for a DT 175 at all, only for DT125's... I called the number on their website, and they answered and talked to me about it - they say that the one I ordered is right and that it's only on eBAy, and just not up on their website yet.. the 125 and 175 carbs on eBAy do have different part numbers, but I don't know - Zoom Zoom told me that if what I recieved looks like what's in the picture, then it's the right carb... but of course the 125 and 175 carbs look the same from the outside (probably just different main jets?) At any rate, I am not confident in this reproduction carb.... I think I want to rebuild the original carb. We'll see how that goes - the floats were pretty messed up inside - one bent all the way up, the other bent all the way down - like it was done on purpose to wedge the float valve needle open or something. I'm hoping that the floats and float bowl gasket out of the reproduction might fit in the original, of so, I'll just use those parts to rebuild the Mikuni. I'm not going to do anything untill I get the new air cleaner on though. Once I get all that done, I'll post up about it - but I'll probably start a new thread to be more specific to exactly what is going on. I'll make sure to involve a cold beer with all adjustments to reduce stress. Thanks. Link to comment Share on other sites More sharing options...
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