motoplat ignition

[steve_jay]

I have an '84 Husky.  The original ignition went bad and a motoplat system was purchased.  The bike never ran again. It was given to me several years ago and I just got around to checking it out. There is no spark.  Once when I was trying to troubleshoot it, I had the sparkplug in the cap on the cylinder head. I was rolling the bike, in gear to try to see if there was ANY spark. When I rolled it backwards to turn around, I got a beautiful, continuous spark.  The arrow on my stator, indicates that it is turning the right direction.  DOes the top coil have to be matched with the bottom, for direction?  Any advice would be greatly appreciated.

Steve Jay

[3putt]

Steve, not sure if you ever found an answer to your problem. I found it interesting enough to hang onto it, and recently saw something in a forum post dated 11-23 titled "Is Novemberkasan known".  Please note the comment from Doug Wilford regards the Husky timing for this event.  Could this be similar to what you are experiencing ?  It would be an easy tank to discuss with Doug and see if they are similar or not, and if so, the fix is straightforward.
 Good Luck.  Nelson

wnm

[steve_jay]

3putt...  thanks for the reply.  I've always known that many designs of 2-stroke would run in reverse with timing close to TDC, but that doesn't (unfortunatly) explain why my machine refuses to spark when rotated inthe correct direction.  On some ignition systems, the relative positions of the charge and trigger coils, can be quite relevant.  On Motoplat, however, it is not possible to move one without the other.  Regardless of timing, the CDI box should produce a spark.

Steve Jay

[fzrr750]

Yes, the infamous TDC to run in reverse. Steve, I can say this for you about the spark you are looking for. Check your shaft/key on the stator and make sure it has not worn down (even a little bit). A stator is of course nothing like a set of points but it works sort of like it. Another thing I would do and put on a known good coil and try it again. The bike sounds like it is timed for TDC if it is sparking while  pushing backwards. But you say it is rotating the correct way(way of the arrow).Kick it over again several times and watch the way it turns and make sure it is only going one way. Also push it forwards and watch for spark (even weak spark). Do something else...hold in the clutch handle and kick it over to see if it does spark. Yeah, go ahead and laugh about this but I know of one guy who did this to get his bike started up. I laughed at him when I told him to do it and so did several of my friends. This was his first bike (used) and he bought it with out hearing it run. Well, it fired up after he pulled in the clutch. Some safty feature on his old Kawasaki.  Also, Put it in gear and try it. Some bikes back in the old days (vintage Desert racers on deep dunes)had their bikes set up so they could set it a TDC and kick it over and back out of some real deep sand. Some racers who reaced in the winter time did this too. My older Yamaha golf cart motor runs in reverse when I turn the key in the opposite direction.
 If you do not have one..go out and get a service manual for your bike. Nobody who owns a bike should be without one. This is the best way to learn and understand about this bike you own. Even if you are the worlds best builder buy one and keep it if not for you, then for whoever you sell the bike to later on.
 This week I will be at a friends house in Deltona, Fl who is one of the best builders of two strokes  I know at this point in time. He has built some of my TZ and RV and RG500 motors for my older road racers. I will see him on Wednesday and ask him about your problem. I tried to call him today but his wife said he is helping a friend set up the cycle shop and he will be back Tuesday late. What a way to get some time away from the wife!!!
 Well, can anybody else help us out here? I will get back to you, Steve.   Ed T.

71 Suzuki TM400,72 Suzuki TS400 Desert racer,76 Suzuki RM250,74 Yamaha MX360,79 KTM 250MX, 87 Yamaha FZRR750 X-endurance racer #112.

[Rocket]

If you pull the clutch in on a Penton and give it a kick, be careful because there will no resistance, they don't have primary kick, ability to start in gear.
Rocket

 

[fzrr750]

Hey, Rocket, thanks for the advice on the Penton clutch/primary kick. I have been riding for almost 38 years and as far as I know, I have never owned a bike from the 70's (Japenese) I could not start in gear. I have not owned a Penton since 1975(it's hell getting old) and do not remember if I could start it in gear or not. I had to sit down and talk to some of my old riding buddies and they could not remember either. I have never stalled my KTM in this great Florida sand and muck yet to see if I could do so either. Right now I have the motor apart waiting for my new piston and ring set. But I am curious about it now....

71 Suzuki TM400,72 Suzuki TS400 Desert racer,76 Suzuki RM250,74 Yamaha MX360,79 KTM 250MX, 87 Yamaha FZRR750 X-endurance racer #112.

[SCOTT CURTIS]

I had the same exact problem when I had a motoplat rebuilt.  It drove me nuts!!!  I sent it back to the fellow who rebuilt it and he swore up and down the unit was OK.  The unit would fire when the wheel was rotated in reverse but would not fire when the wheel was rotated forward when installed on my Jackpiner.  Sent the unit to PVL for Dane to check.  It turns out the fellow did not replace the diode in the stator when he rebuilt it.  I had a old black wire coil which did not have a diode.  So essentially my "rebuilt" system did not have a diode.  I bought a newer red wire coil which had a diode and the motoplat now works.  I was never so stumped in my 30 years of owning dirt bikes.  In short, the red wire coil solved my problem!  I hope this helps, let me know.  Scott

 

[steve_jay]

Thanx guys, for the tips.  I had to laugh at the advice about the primary kick, though.  I have a '76 RM 370. It does NOT have primary kick. Now I'm kind of curious because fxrr750 (Ed??) has a '76 RM250 listed.  In my book, it is listed as NOT having primary kick either. (No offence, Ed)  As for the diode....  It appears that all of my components are of the newer generation.  That is to say...  I have the coil with the red sparkplug lead and my stator is one without the diode.  My understanding is that the diode is inside the red-wire coil now??  Anyway...  maybe the upper coil is at fault.  I don't have a lot of resources around here to compare parts with.  I can't help but think that my stator and flywheel must have some life in them if they can produce a consistant spark in reverse (I used a drill with a rubber wheel chucked in and turned it against the flywheel, with a generous amount of oil in the cylinder for lube.  The spark was excellent and very consistant)

Steve Jay

[fzrr750]

Hey, Steve. I am back from riding. I asked my buddy, Mark about your problem. He said try another coil first(known good one) to see if it will spark going front wards only. The stator if good and no exposed wires or damaged, should give a spark in the forward direction. If not, then there is a bad wire or ground. Mark, as Scott says, If the stator has wires with a diode attached (on some older stators) try checking the diode. Take the stator down to an electrical shop and have them check it out as I did. Then you will know for sure if it is bad.
 My 79 KTM has no diode in the wires that I can see and your 84 should not either as far as I know as it is much newer. I had the stator replaced last summer since it had weak spark and the coil was good. Now there are people who can rebuild these starors I found out early this year.
I did what you mentioned about the primary kick... I went out just now and put all my bikes in second gear and pulled in the clutch handles and I can kick over the bikes. I have resistance on all of the bikes except the KTM as it is torn down awaiting my new piston and ring set(some day it will come in). I bought my 76 RM about 5 years ago and have put in another tranny and crank/kicker twice in the past four years. This is what happens when a friend borrows your stuff!! Unless I put it together with some older stuff it can be kicked over when I pull in the clutch. Go out and try yours for me.
 Hope you get it running. Husky's are great even the newer ones!!

   Many regards.   Ed T.


71 Suzuki TM400,72 Suzuki TS400 Desert racer,76 Suzuki RM250,74 Yamaha MX360,79 KTM 250MX, 87 Yamaha FZRR750 X-endurance racer #112.

[dirtbike]

I'm not sure about the Motoplat but the SEM system I replaced on my last KX250 was a tricky one. I could borrow some functional pieces from a friend who rides Husqvarna and I had similar problems as you have. After consulting the SEM factory it turned out that these units is manufactured in both left and right turning packages. There is nothing on the stator and coil that indicates which. One cannot replace one single piece from a set supposed to turn the other way without experiencing problems. Since maybe the stator and/or the coil on your bike could be replaced with one looking exactly the same but made for a left side mount it will not produce a spark with that flywheel which obviously is OK, unless turned backwards. Like I said, this is true for SEM but I could imagine it to be true for Motoplat too. That other diode suggestion sounds reasonable it this is not the problem.

 

[Bob]

quote:
After consulting the SEM factory it turned out that these units is manufactured in both left and right turning packages.

Yankee twin dirtbikes had two Motoplats ( L & R ). One turned in reverse. Perhaps you have one of the backwards Motoplats.

Jeff DeBell, who frequents this board could tell you more ( he has a Yankee ).

[steve_jay]

fzrr750 (Ed).... Please accept my MOST humble apologies for correcting you (incorrectly).  It seems that the 1976 RM370 is different from all of the rest of the RM family, in that it DOESN'T have primary kick. The 400's in that vintage, share the quirk.  According to the parts breakdown, the 370's and 400's lack a "kickstart idler gear" that the other engines have. The 370 and 400, connect the kickstart to the crank, via  the clutch.  So...  If the clutch is disengaged... so is the kickstart.  Sorry, Ed.

Steve Jay

[fzrr750]

Hey, Steve!! No problem. You had me scratching my head alot. I looked all over for my 76 RM owners manual and repair manual to read what it says about the primary kick. I could not find them. So I must have lost them. So...got to buy some more and they are needed. So if you had not brought that up I would still think I had the manuals. So I thanks you also.
 I do hope you get that beast of yours running!!! I am waiting to find out why you are having this problem. There are a great many good people on this site. Not all of us own Pentons and nobody seems to mind. I do know this...as soon as my wife gets her new car (maybe next year)I want to get another Penton.
Take care,Steve and keep us informed about the Husky, ok?          Ed T.

71 Suzuki TM400,72 Suzuki TS400 Desert racer,76 Suzuki RM250,74 Yamaha MX360,79 KTM 250MX, 87 Yamaha FZRR750 X-endurance racer #112.

[Rocket]

Steve-Jay
I was installing a motoplat on a Penton 100 today and noticed that there is a directional arrow on the stator.  Never noticed it before.  Maybe you should check the one you are having trouble with to see if it correct?
Rocket

 

[SCOTT CURTIS]

Steve_Jay,
   Did you ever get the motoplat working properly?  Scott