175 Bogging Down - Why

[KJDonovan]

Greetings,

Last weekend, after a couple of years of restoration work I started my 72 Jack Piner for the first time.  Idling it runs fine, revving it in neutral runs fine.  When I take off though, it bogs down when I give it throttle, eventually loading up and stalling.  Sometimes this happens in 1st, sometimes I make it to 2nd or 3rd. But it always seems to be happening.  The engine is completely rebuilt (crank, all bearings, piston rings ect), brand new 30MM type 84 Bing carb.  My initial thoughts were that this was somehow related to the clutch, as I noticed that the clearance at the actuator was only 1-1/4" in lieu of the 1-5/8" to 1-3/4" speced (my thought process here was that it was possible the clutch was not completely disengaging).  So I changed out the clutch springs, push rods and the little pin that is in the barrel of the clutch actuator.  After putting everything back together the clearance at the clutch actuator now measures 1-3/4" and the clutch snaps out like it should.  But I still have the same problem.  I can leave it idling forever or rev it up in neutral.  But when I take off I go a short distance it bogs down and pukes out.  If anyone has any ideas or advice on that to check next I would really appreciate hearing them.

Thanks in advance,

KD


Kevin J. Donovan
Foster, Rhode Island
72 Jack Piner (My Ride)
72 Six Day (Wifes Ride)

[thrownchain]

I would take it's flooding out. If your timing is spot on, it's time to check the carb for proper jetting. Air filter clean, exhaust pipe clear?? Check the easy stuff first.

[KJDonovan]

Thrownchain,
I have checked the carb appears good, the air filter is new and not overly oiled.  I rebuilt the pipe, but I will try running it without the baffle and see if that makes a difference.

Thanks,

KD

Kevin J. Donovan
Foster, Rhode Island
72 Jack Piner (My Ride)
72 Six Day (Wifes Ride)

[firstturn]

KD,
  Just have start with take off the filter and try it. If that doesn't help try it without the pipe.  You see where I am going...just eleminate one thing at a time.  Without being there in person I initially would think the bike needed a bore job because it is fine without a load, but since it is a fresh bore that should be thrown out. Just for grins I would check compression unless it obvious the compression is high just by how hard it is is to kickstart.
  Next I would be contimplating anything that has drag on the engine once you put it gear.  Got to go, but I have about 10 hours of windshield time today to think about it.  Hopefully by then we will find out it has a weak spark or only needs a new spark plug or plug cap[].  Oh, be sure to check all the grounds especially if you powdercoated the frame.  Good luck.

Ron Carbaugh

[tomale]

Did you say the Carb was brand new or was it rebuilt.... On a Bing carb the needle jet and the jet needle wear pretty fast, was all the jets replaced? Are you sure that the jets are stock sizes.. If these are not in good shape it could be the problem and when it comes to jets, you can not tell if they are bad, the only way to know for sure is to replace them. you said it idles nice so I do not suspect the pilot jet and the main does not really wear that much and besides  it would not effect what you are experiencing so that is why I suggested the needle assmebly. If you have any questions about proper jets for the bing, give Bing International a call, they have been very helpfull in the past for me.
Does it start easy or does it take more than several kicks to get it started, What I quess I am getting at is that if the timing is spot on and it starts easy then it is probably not the ignition, thought I have seen coils that seem to work fine but in reality have an internal short and it does not show up until you put them on a load. I had that happen to one of my bikes earlier this year at first I thought it was a ground problem but after cleaning everything it changed nothing, I knew the carb was fine because I had cleaned it and up til then had run good I exchanged the coil and wham! The problem disappeared. I put it back on and there it was again.... Good luck!!

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
75' GS400 (project bike)
72'sixday (project bike)

[thrownchain]

Didn't think of that, could be electrical. Check plug, coil, cap and condenser if there is one.[ not really up on 175 ignitions ]

[hrbay]

Using fresh fuel? I tried some old premix in my 200 and 175 this season and had trouble similar to what you are having until I got fresh hi test in them. Stuff would'nt run in my weed eater either.

GC

[AndyL]

KD,
One other thing to try......
I had a Hodaka that did the same thing.  Rev'd out on the stand just fine, heat cycled it several times over two days and it never fouled a plug or stumbled.  As soon as I jumped on it and tried to ride it up a steep hill to the driveway it would always bog and die.

Finally ended up going down one size on the main jet (Mikuni 34mm) and it got better.  Ended up two sizes down on the main jet, but it finally ran good.

Andy
#14u MOVMX and AHRMA
75 Jackpiner
92 KTM 300
70 Steeltanker

[cubfan1968]

Kevin how long are you letting it warm up before you ride it? Go back and look at some of Larry Seale's old posts I think he had a similar problem. Just don't do like Larry and ride it down a hill keep on the flat. Much easier to push back home.

Rod Whitman
1972 Six Day (Rider)
1972 Six Day (Project)

[Merlin]

...........KJ,if the ignition is good you need to have this jetting:slide #1,slide needle #1 in middle groove,main jet #150-155,needle jet #2.76 or 2.80,pilot jet #35-40 and the new type atomizer #40-404..........the atomizer #40-404 is the one with one small air hole,look down the air bell side in the bottom air passage to see if you have this type,I have soldered shut the 4 large hole type holes and drilled one small .062 hole when the 40-404 was not availible.............

[Paul Danik]

Please don't laugh at my comment, as this has happened.  Are you sure that you have the choke in the proper position.

Paul

[lksseven]

Rod,  I'm still trying to catch my breath from pushing that sucker uphill all last summer [B)] .   It turned out to be a bad coil, but I tried everything in the discovery process (except test drives on flat terrain :-((

Paul,
I was guilty of exactly that (choke on) on my '72 Jackpiner last winter.   Thank God I don't chew gum!!!! LOL  (although I will make the disclaimer that the picture in the '72 manual mislabeled a closed choke as being open).  

I really should have used an alias the first year I was a POG member, so  I could fly beneath the radar of my own goofiness.

KJ,  sounds like an electrical problem to me, that only shows up once the coil heats up and comes under load.   How long is the engine running before it bogs/dies?

Larry Seale
I choose to ride

[Steve Minor]

I had a 77 400 doing pretty much the same thing one time. Turns out I assembled the carb wrong. I mistakenly put the needle clip inside the plastic cup....rather than under the plastic cup....this had the same effect as raising the needle a notch. I thought I'd never figure it out....

Check out the site below for an exploded view.

http://www.bingcarburetor.com/offroad/54x.html

[KJDonovan]

Thanks for all the responses...Based on everyone's feedback I think I am narrowing this down a little...here is where I stand.

1)   The carb is brand new (waited 3 months for this puppy, and Charlie at Bing did the jetting himself, so I am confident it was done correctly.
2)   The choke is in the shut position (plunger down).  I use a thumb lever choke in lieu of the one with the cable so I can see the exact position.
3)   The fuel I am using is fresh 93 Octane (ethanol free) with fresh Spectro concentrate.
4)   I have tried it with the air-cleaner removed, and had the same results.
5)   Last night I pulled the baffle from the pipe and had slightly better results but still completely unsatisfactory.
6)   I let the bike warm up at least 5 minutes before trying it.
7)   The bike will run indefinitely at an idle by itself.

I have a spare coil in my box o parts that I am going to try tonight and I am going to check the compression this weekend after I make up a test kit.  I am hoping it is not an issue with the bore, but at this point that's what my gut is telling me.  When I had the cylinder done last summer it was by a one man outfit recommended by the local KTM shop (Razee's NK RI) and when I put everything together it all seemed snug.  That being said, our 125 puts up more of fight to kick over than this does, but the 125 has a shorter kick starter too (less leverage).  The one thing that I did do, that I wan never really comfortable with was to drill the 2,  .060 lube holes in the front of the piston as repair manual and instructions from Wiseco recommended.  It's been at least 25 years since I rebuilt one these but I never remember doing that in the past.  If anyone has any other ideas I would be happy to hear them.

Thanks!

KD


Kevin J. Donovan
Foster, Rhode Island
72 Jack Piner (My Ride)
72 Six Day (Wifes Ride)

[firstturn]

Kevin,
  Did you powdercoat the frame?  If you did you need to do a ohm resistence check to be sure that your ignition system has the proper ground (condinutity).  I will be back at my shop/home tonight if you need to email me you phone number and I will try to help you.  I hope this helps.

[email protected]

Ron Carbaugh