175 Bogging Down - Why

[TGTech]

Kevin,

   Ron's suggestion about the continuity is valid, but you can't depend on a reading from a meter to tell you if you have a ground that is sufficient. Meters are usually only operating on 3 volts, where the Motoplat ignitions' grounds are carrying around 190 volts. If the meter tells you that you have some continuity, that won't necessarily carry the ground for the ignition system.

   It is alwasy my suggestion that you scrape at least one engine mount    on the frame and engine, free of paint, so you are absolutely sure that you have a sufficient ground.

Dane

[KJDonovan]

Dane / Ron,

The frame is powder-coated. And now that I think about it, I am not all that confident that I have a good ground between the frame and the engine.  I say this because my tail light only works intermittently; in fact the only time it worked was for a few minutes on Sunday while I was dinking around with the throttle cable.  I'll start here tonight by running a test lead from the ground under the tank directly to the jug.

Thanks guys,  I'll let you know how I make out.

KD


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

[OUCWBOY]

KD,
Also make sure your coil has a good ground as well.

Donny Smith

[slvrbrdfxr]

KD,
Ron and Dane make a very good point about the grounding issue as a place to start searching. Having had the opportunity to help Larry troubleshoot his bike a little bit last summer, your problem sounds very similar to what his bike was doing. I even got a chance to push his bike across my fairly level front yard a couple times. Just wish we would have gotten the trouble solved before he had to push it up that darn hill so many times. One other thing I can of think since you said compression seems low. Did you get the deck height setting correct when installing the new piston ?? If you have too much deck height then compression would be low even with a new piston/ rings. Good luck and keep us updated on the progress.
Dave McCullough

[Randy Kirkbride]

Kevin,
Here's my 2 cents worth.
My first Penton was a brand new 1972 Jackpiner.  Mine did exactly as yours is doing.  It had the old black wire coil & motoplat.  The dealer exchanged the motoplat and installed a red wire coil and that solved the problem.  My question is... did you have the motoplat & coil tested when you did the restoration?

[KJDonovan]

Guys,

Problem is not solved yet but I think I may be on the right track, here is where I stand.

After work last night I started checking out grounds.  First I removed one of the engine mount bolts and ground the paint off the frame where the nut backs up against the frame.  Next I removed the coil and where it bolts to the frame I removed some more paint where the nuts back up to the frame.  Put things back together and started it up. The bike ran as it did in my earlier tests, but now it is not dying out completely, but I still cannot tach it up under a load.  Additionally, the headlamp and tail lamp light are both now working, but both are really dim.  This has me even more confused because this past weekend when the taillight worked for a few minutes it was extremely bright while the bike was idling. At this point I am now leaning towards this being an electrical problem, which is definitely not my specialty.  I am guessing that I hosed up the wiring or the coil is bad.  Part of the problem here is that I am using an aftermarket light switch which is nothing like one of the original dipper switches (which I was never able to locate).  This switch contains a kill button, and lights off/hi-beam/lo-beam switch. Unlike the dipper switch though it only has one connection for incoming power. Below is a picture of the wiring diagram I made up using this switch and my existing motoplat.

[img][/c:\72wir.jpg]
(Hopefully the diagram displays below, I never posted a picture here)  If anyone sees any glaring problems with diagram please let me know.  

Also in response to Dave's question, regarding the deck height of the piston, I did check this before I put the head on and it was at 7MM.  Randy asked if I had the motoplat tested during my restore and the answer is no.  It was something that I was hoping was good, because the basket case I started with was retired due to a broken crank.

I will not get another chance to work on the bike until Friday.  My plan is then to disconnect anything connected to lights and swap out the coil I have with a spare and give it another try.  But as always if anyone has any ideas, I sure would appreciate hearing them.

Thanks Again,

KD


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

[firstturn]

Kevin,
  Sounds like you are making progress.  I agree with disconnecting the lights first since the switch  is not original.  The next step I suggest isn't a popular one, but itis necessary if you expect to ride this bike and not have future problems.  I would take all the engine mounting bolts out and sand the inside of the engine mounting brackets to bare metal and put a electrical conducting grease (NAPA) and then bolt it back up.  Next I would do the same to the coil mounting bracket.  Then try the bike.  If it still does light to the moon change the coil.  

  If the bike is working next check out all the grounds for the lights.  We will wait for a report back so that the real experts on this site can get involved.

Ron Carbaugh

[cubfan1968]

Kevin this is really coming from left field but is enough gas flowing to the carb? If the gas was just tinkling out it would get enough to idle ok but as soon as you started to ride it wouldn't keep up. Just a thought. Good luck.

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

[linglewn]

Kevin,
I don't mean to over simplify your problem, but I looked back through the posts, and I don't find anywhere that you have tried a new spark plug. Just because the plug fires at idle doesn't necessarily mean that it will fire under load. A crack in the ceramic insulator can cause it to misfire under load which generates higher combustion pressure (similar to a weak Motoplat spark). Certainly keep looking for ground problems, but a plug change is so easy it is worth trying. Good luck.

Nelson Lingle

[KJDonovan]

Nelson,

I failed to post it here, but a new plug is one of the first things I tried.

Thanks,

KD

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

[tomale]

KJ, I agree with firsturn, sanding off the paint on the outside of the motormount is a good start but really you should sand off the inside of the mount, the reason is that it provides alot better, more direct path for ground. With the outside of the motor mount, the path includes the bolt and washer, and it relys on the hole in the engine to creat the path to ground. I had never thought of using dyalectic grease before, but that makes sense to me... I will add that to my assmebly procedures.

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

[firstturn]

Thom,
  I thought I said sand the inside of the engine mount?  I don't normally sand the outside of the engine mounts because I have just spent $$$ to powder coat it and don't want it to look trashed.[8D]

Ron Carbaugh

[tomale]

Ron, you did say inside and with good reason:D

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

[thrownchain]

How about running your ignition lead direct to the coil? Bypass the after market switch all together. This also takes the lights out of the mix. Possibility that the lights might have a short that's drawing power from the ignition? Is there a way to check ignition output to the coil??

[t20sl]

Kevin:  Instead of removing engine etc...try what all of my Pentons and Hondas had done before I ever rode them.  Run a wire from stator plate to coil bracket.  Make sure coil bracket does have a clean ground between it and a clean no paint frame mount hole.  I also used to run a ground wire from there to the kill switch.  You are not relying on frame bolts that corrode or steering bearings at this point.  In your case to see if that is the problem you don't need to do the kill switchground now.  The japanese always run ground wires to lights etc so there is always a good path for the electricity. If this doesn't work I agree with Ron and get another coil to try.  Maybe you can borrow one. Ted