MZB iggy started backwards

[Nkreig]

Yesterday I went for a little spirited ride.  I recently installed some PWK's on my 75 RD.  Its pretty much dialed in on the jetting (thanks Mark for the starting point).  I took it up the road after a warm up and opened it up a bit.  I rev'd it out in 4th and when I shifted into 5th and backed off the throttle I noticed on my EGT gauge there were no numbers displaying and the bike was bogging.  I pulled into a lot and discovered the right cylinder was not running.  I shut the bike off and turned the back on and got my gauge back but it was still not firing on the right side.  After a few revs it came to life.  When I left the lot to go back home it sputtered on the right side for about 20 seconds then appeared to be fine.  I got back home and shut the bike off and restarted it again to see if i could replicate the issue.  When I kicked it over it started backwards.  I have never had this issue in the 6 years ive had this iggy on the bike. I did read on economy cycle that there is a revised rotor because of this issue.  Has anyone else experienced this before?  I feel like I have two issues going on, rich on the main causing the right side to foul and older style rotor on the MZB causing the reverse starting issue.  Let me just add, when starting the bike it will fire with just half a kick.  The idle was set very low and I only kicked it easy when it started in reverse.  Let me know what you guys think.

[Striker1423]

My old dyna iggy did this routinely to me. Ditched it for the Vape. But, the MZB is the Vape. So... weird. Check your rotor to sensor gap, make sure it didn't slip too.

[Economy Cycle John]

The older style drum had 2 issues. One was the square trigger and the other was the rivets would loosen up over time. So several years ago, Vape changed the drum to a one piece with no rivets and a ramped trigger (trailing edge) to prevent reverse starting. With those old drums no half kicks or lazy kicks to help prevent backwards starting.

This is the new rotor, you can see the ramped trigger at the 4-5 o'clock position and no rivets on the front.


https://www.economycycle.com/shop/yamaha-rd250350400r5ds6ds7-parts/electrical-ignitions-lighting/ignition/mzb-rotor-updated-design/

[m in sc]

yup. could have been worse...

this was in 09 or so. same thing.

[Nkreig]

yup. could have been worse...

this was in 09 or so. same thing.

That was my flashback Mark! lol.  My 74 did the same thing with the crane cams hybrid iggy that you helped me build when the old site was up.  Had to replace the whole bottom end on that one.

The older style drum had 2 issues. One was the square trigger and the other was the rivets would loosen up over time. So several years ago, Vape changed the drum to a one piece with no rivets and a ramped trigger (trailing edge) to prevent reverse starting. With those old drums no half kicks or lazy kicks to help prevent backwards starting.

This is the new rotor, you can see the ramped trigger at the 4-5 o'clock position and no rivets on the front.


https://www.economycycle.com/shop/yamaha-rd250350400r5ds6ds7-parts/electrical-ignitions-lighting/ignition/mzb-rotor-updated-design/

John, I see you have those rotors on the site.  Guess I better put in a new order.  BTW, I picked up the adjustable preload fork caps from you and they are money!  So nice to have the sag dialed in with the simplicity of a screwdriver instead of cutting spacers over and over again.

[m in sc]

That was my flashback Mark! lol.  My 74 did the same thing with the crane cams hybrid iggy that you helped me build when the old site was up.  Had to replace the whole bottom end on that one.

ah shit, sorry about that. must have been one of the earlier ones w out the big pie cuts. sorry about that. 

[Nkreig]

That was my flashback Mark! lol.  My 74 did the same thing with the crane cams hybrid iggy that you helped me build when the old site was up.  Had to replace the whole bottom end on that one.

ah shit, sorry about that. must have been one of the earlier ones w out the big pie cuts. sorry about that. 

no worries lol!  that bike has a HPI ignition and runs amazing now.  The old crane cams deal worked great for what it was actually.  Ran for years like with no issues. 

So, i had a chance to pull the cover off today and check things out.  Turns out, the bolt was backing out for the rotor and i suspect the rotor slipped timing a hair when i was revving it out.  When i tightened the bolt it snapped off in the crank end.  Fortunately and unfortunately i never put locktite on the bolt and was able to drill it, then back it out with an impact driver.  I was sweating that for a bit but it backed out easily.  I found a 1/4 thick flange washer but need a new bolt.  It was an 8.8 hardened bolt in there that snapped!  Does anyone remember the torque setting for that bolt???  I plan to pick up a 10 hardness if i can locate one.

[Striker1423]

I think it was 12-14 ft-lbs with the hardened bolt. But, might want to check that.

[m in sc]

8.8 = roughly a grade 5. you want a class 10.9  IF you can find one.

[Nkreig]

8.8 = roughly a grade 5. you want a class 10.9  IF you can find one.

Let the search begin.  Any idea what size and thread pitch and length that bolt is?  I know its shorter than the stock one.  Save me some time since the one i have is now a two piece.

[Clem710]

If you have both halves, well, thats how long it was:)

Any hardware store will have a tester for the pitch and dia, you probably will have to clean up your end so it will start tho.  If you find a long one, buy a nut for it too and you can put on the nut,  hacksaw it to length, then run the nut off, repeat and dress with file as necessary.  Can do with a cutoff wheel but since its hardened, maybe better to do it by hand.

Thats not a big bolt but no way that should break at 12-14, even if made of chinesium.  That said, I'd still listen to M's advice. 

The last trailer hitch I put on came with 10.9 M12 fine 1.0? 1.25? and I think car calipers are 10.9 often but will probably be too long and too big. The neighbor and I have a big ass drawer full of old fasteners I could look through if you get the spec and get stuck.  You could also tap your own if you find a long one with partial threads.

[Nkreig]

If you have both halves, well, thats how long it was:)

Any hardware store will have a tester for the pitch and dia, you probably will have to clean up your end so it will start tho.  If you find a long one, buy a nut for it too and you can put on the nut,  hacksaw it to length, then run the nut off, repeat and dress with file as necessary.  Can do with a cutoff wheel but since its hardened, maybe better to do it by hand.

Thats not a big bolt but no way that should break at 12-14, even if made of chinesium.  That said, I'd still listen to M's advice. 

The last trailer hitch I put on came with 10.9 M12 fine 1.0? 1.25? and I think car calipers are 10.9 often but will probably be too long and too big. The neighbor and I have a big ass drawer full of old fasteners I could look through if you get the spec and get stuck.  You could also tap your own if you find a long one with partial threads.

It is no problem to find the right bolt for the job.  I appreciate your suggestions.  Like i mentioned, asking will usually save time and help anyone else in the future if they encounter the same issue.  Ill sort out the measurements and post them here for that very reason. 

[m in sc]

m7.

[Economy Cycle John]

yup. could have been worse...

this was in 09 or so. same thing.

That was my flashback Mark! lol.  My 74 did the same thing with the crane cams hybrid iggy that you helped me build when the old site was up.  Had to replace the whole bottom end on that one.


Yup with the right spring rate and sag, RD's handle very well. Thanks for the feedback.

The older style drum had 2 issues. One was the square trigger and the other was the rivets would loosen up over time. So several years ago, Vape changed the drum to a one piece with no rivets and a ramped trigger (trailing edge) to prevent reverse starting. With those old drums no half kicks or lazy kicks to help prevent backwards starting.

This is the new rotor, you can see the ramped trigger at the 4-5 o'clock position and no rivets on the front.


https://www.economycycle.com/shop/yamaha-rd250350400r5ds6ds7-parts/electrical-ignitions-lighting/ignition/mzb-rotor-updated-design/

John, I see you have those rotors on the site.  Guess I better put in a new order.  BTW, I picked up the adjustable preload fork caps from you and they are money!  So nice to have the sag dialed in with the simplicity of a screwdriver instead of cutting spacers over and over again.

[Economy Cycle John]

We have an upgraded hardware kit for the Vape that works better than the hardware Vape sends in the kit. We include the M7 bolt and thick washer (4-5mm). I torque them to 20 ft/lbs and don't have trouble with them slipping or snapping off bolts.

https://www.economycycle.com/shop/yamaha-rd250350400r5ds6ds7-parts/electrical-ignitions-lighting/ignition/mzb-cdi-electronic-igntion-for-yamaha-rd250350400r5ds6ds7-street-version-hardware-upgrade/