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Removed and posted in turning wrenches

Another weekend, more time on bike.  I managed to find some NOS cable pieces and put together a factory cable, all sent to my house while I was on the West Coast last week.  Routed cable, reinstalled gas tank and fired first kick with an idle of 1500 rpm's.  No issues turning left to right throttle slides adjusted and I got my first test ride in before the rain started.  Think I am going to get a set of Indian cylinders (that were discussed in another thread)  and do my first port job later this summer after plenty of reading and searches.  Thanks all for the help

Hi All,
I searched the forum for some definitive answers to my question and nothing detailed, so here goes.  A few years back I posted an article when I had my last RD (73 350), then sold it and am back in the game after selling my stash of spare parts.  I was running NOS NGK B8HS plugs in my bike without issue, everything that I see now seems to be a resistor type plug from NGK and sources online.  I have a stock ignition (soon to be upgraded to a Dyna S) with stock coils.  When rebuilding, I checked resistance of coils and within spec, and I believe the NGK caps that are on these coils add 5K resistance.  My question is what is the appreciable change from my old b8HS plugs (I actually have 2 left) to running a plug that is a resistor type? I ask as I like to have 2 new plugs in my tool kit so I don't get stranded with a fouled plug (happened in high school on my mint 70 purple and white R5, good thing is that I broke down in front of one of the prettiest girls in schools house and she let me keep it there for a few days till I got it sorted)  Regardless, if anyone could shed some light on this or pros/cons would be much appreciated.  Thanks

I happened to get an hour and pull the carb cables out all together, drop the slides in the bores.  First kick fired up and idled at 1500 rpm.  I bought an new throttle cable when rebuilding and then swapped the ends from the splitter to the carb.  Upon firing it up the rpms increased again.  I noticed the throttle was very loose and the new throttle grip had the handle bar insert where the cable attaches torn loose.  I think this is all throttle cable related, as the adjusters were zeroed out.  Will put on original cable on next week and reach out to supplier whom I purchased the new stuff to resolve.  Bottom line is that it works without the cable.  Thanks all

I drilled out the passage and tapped this for the screw in jet, believe this is 2.0 mm.  I reads somewhere about machining the portion of idle jet that sticks up into the carb, did nothing with this other than just pressing in.  I do have a new throttle cable on bike that I bought from John, the carb ends have 2 different lengths that can be interchanged. I think I can remove the cable in its entirety and put back together and see if the issue exists or idle drops, and if it goes away, will swap cable ends..  Will jump on it again next weekend, thanks for advice.

Another weekend, more time to work on bike. Bike is stock bore 75 350 with DG pipes.  I ended up ordering a K&N with a new Y boot from John @ Economy along with some more main jets and a new throttle tube.  I put everything together and have the carb currently (set up with Dave F mod)5DP7 jet needle, 169P0 primary needle jet, 27.5 pilot, with 200 mains and the needle clip in center position, air screw 1 turn out from seated.  Upon startup the bike raised in RPM's to 4K and idled at this value. I turned the air screw on each carb out to 1.5 turns from seated and the RPM raised a little more, as expected.  I then turned these back in to .5 turn from seated and the RPM dropped a little, but still around 4K RPM.  A little info prior to starting bike: I had the carb slides bottomed out and I checked these with a boroscope thru Y boot prior to startup and have these set to 1/2 turn from where they started to move upwards using adjustment screw.   I could also see both slides raise to the top and fully seat by using the throttle.  Was thinking could be cable hanging up, I took the adjustment out of cables regardless with no change.  The carb slides have the cutout facing the rear and the bike was leak down tested prior with no issues.  I was then thinking, OK this has to be an air leak.  I sprayed the reed block, carb (i.e. all connections downstream of the air filter to the cylinder, spark plug holes and exhaust flanges with starting fluid looking for a change in RPM, nothing.  So I can only surmise that the bike is getting too much fuel? Thinking of dropping main to 170 or 180 (I have pairs of jets from 170 thru 220).  If an air leak, starting fluid would have found path, any thoughts?

I am looking into a new Y boot and a K&N,but have a few questions.  Will the K&N filter fit on the factory Y boot, or is the "kit" specific by having a slightly different Y boot?  I ask as this is the only RD that I have owned where this boot is soft and pliable, others hard as a rock and needed the wintergreen oil treatment.  Additionally, I am thinking of putting a different set of manifolds on with a crossover tube, I looked at an old invoice I had from Chuck Q, he sold banshee intakes, is this direct bolt on and is anything needed for the reed cages? I have read where individuals have cut and modified these banshee intakes, trying to get solid info as searches vary in content.  Just trying to put together everything at once to get the bike running and have some seat time.   

I purchased a 75 350 late March (stock bore, someone had put a set of DG pipes on it, stock carb and jetting).  Before tearing into, I put a new battery in it, had spark and then performed a leak down test.  Passed the test (lost 1 psi over 6 minutes), a little tired but will tear into this winter. I put a boroscope in the plug and exhaust hole, little carboned up and some scratches but it sealed and held pressure, again will address this winter  I freshened up the bike with new tires/tubes/rim strips,chain and sprockets, rebuilt caliper, new master and brakes put new rubber and cables on it, rebuilt the carbs and performed the Dave F carb mod (with 200 mains, 5DP7 jet needle, 169P0 primary needle jet, 27.5 pilot, air screw 1 turn out and needle clip in center position).  Upon first trying to get it to run, would backfire thru exhaust.  I reset the factory points to .013" and after swapping the coil wires (found out that the laminated wiring diagram I have has the coil wires reversed),it fired on first kick. Smoked a bit but finally warmed up some and idle settled down to about 1200 rpm, I timed it with a light at 2.00mm. and then started to turn the airscrew out to 1.5 turns each, rpm a little higher when I did this.  The bike is just flat,does not want to rev and I noticed raw gas coming from exhaust when I shut it off.  It has the factory airbox, although a UNI foam filter within that is oiled.  I removed the carbs, and dropped main jet to 190, moved the needle clip up 1 space (2nd from top) and checked the float levels, these were a little high so reset to 15mm.  Put it back together and a little better, but not much.  Definitely not rideable.  I do have a new Dyna S ignition coming today, wanted to get it running with points before I put this on. Looking for some suggestions.  When apart, checked the coils and within spec (original) and put in new plugs before trying to run.  Thinking airbox may be too restrictive, thoughts?  Plans are to bore and mildly port, leave everything else "as is" as this is just a cruiser for weekend runs thru the park and scare the wild animals. 

Just putting bike back together ('75 350) and awaiting final parts from Economy so I can have running by next weekend.  I found that my turn signals are not working, but worked previously before teardown. The stop light on the dash also blinks via the light checker, but this is a bad stop light bulb which is on order.  I have ensured that everything is wired correctly and the laminated color diagram from Evan was a great help.  The flasher gives an 'audible noise" when turned on but does not blink.  I have checked continuity between the wiring connections, all sound and the bulbs are all good.  It appears that the flasher's common wire is via the switch (brown/white) and the brown wire is "hot" as it comes from the regulator.  My gel cell battery is a little low on voltage 11.2, and am thinking that this may be the issue as the bi-metallic switch within flasher is not getting hot enough to snap. I will charge my battery this week and then retry, just wanted to get some opinions for members on best method to troubleshoot the flasher.  I was thinking  maybe hook up switch  to a low current battery charger and check the brown/white wire for voltage or no voltage as referenced against the body or case? (as this is removed and on workbench).  Also, the little ground wire with spade terminal was tight and clean. Thanks, Brian

Much appreciated.  From the many photos I have viewed on the internet, seems that alot are incorrect. 

I understand that the wiring harness routes between the coils (comes down left side thru strap first) and then drops down adjacent to the the voltage regulator before swinging upward to the rear of the battery box for the correct routing.  The clutch cable is in the same loom as the wiring harness, but drops down to the left side of engine just after the coils. I wanted to know the routing of the OEM throttle cable, appears that it is under the right side front gas tank mount then unsure how it routes (where does it transition inward and where does the splitter to the 2 carbs and oil pump go). Few years back, bought one from Economy and was having issues on my 73 350 w/high top carbs where turning the handlebars left and right would pull on the cable and revs would increase.  Just wanted to alleviate issues upfront

Hi All,
I am putting my bike back together ('75 350) and utilizing the cable and wire routing diagram from the manual, wondering of anyone has some detailed pics.  The older I get (and with eyeglass cheaters and blowing up the screen) still difficult to read.  I believe the pics in the manual documentation are R5 related and from research here and on the Aircooled RD forum, seems to be a difference between this and the later RD's.  The pics I took during disassembly are not detailed enough, hoping someone had some so that in future, others could reference too.  Thanks in advance, much appreciated if anyone could share a few.

Thanks, Brian

Thanks for the response.  I had a 1 psi drop over 5 minutes so looks like I am good to go for now.

I have a question regarding a leak down test.  I bought a kit from Vintage smoke few years back and have misplaced the instructions with respect to pressure drop over time.  I searched this site, but did not find anything definitive regarding values.  I have a 75 RD350, wanted to know if anyone could provide pressure, acceptable drop over "X" minutes.

Thanks, Brian

No worries, this never crossed my mind as I just removed, cleansed and bagged and tagged for future use.  I am also interested in determining what is going on, is it a swapped unit or from another supplier/vendor if Yamaha outsourced.  I looked at EBay and have seen some different hubs.  One that has the webbing per Chuck's pics, one that has thicker ribs and no additional "meat" left or right of the tapped hole (where the thread and hardware is not exposed) and this one.  Interesting is the pic of the threaded web having a flat bottom, as if milled and not drilled as the "lead in" would be pointed.  Additionally a standard tap was used when threading as the thread form does not go the whole way to the bottom of the hole, only enough to have clearance for bolt used.  Manufacturing this would require a tool change and a bottom tap, costing time and money put into a part if this was not modified and factory or supplier dependent.  Regardless, I will look at my clutch I have at home and get back to you