Neal Gargantua

Hi

Friday 16th May 2025

1973 RD350 in current configuration.  the motor is from 74 rebuilt by me in 2021 during covid shutdown.  The pipes are from spec 2.  carbs have been replaced with sudco flats which are replicas.  The CDI is from HPI set to 1.8btdc.  The engine internals are all original with the transmission inspected for chips/cracks on the gears.  Tank has been repainted and it's from a 75 250.  Side panels sourced thru craigslist like 10 years ago.  The shocks are hagons and front forks are stock but rebuild last year with new seals. the lights are all LED and runs off the AC generator on the HPI.  I had to float the ground which increases peak-peak volts but still pulses at low RPMs.  

Hope to see you all there!

Reproduction randomness and other

Wednesday 14th May 2025

So I finally decided to purchase another brake caliper.  There were alot of options for the 1970's RD350 but I settled on the OEM since they have been proven reliable for years.  Heck they used these on the TZ race bikes so if King Kenny can use them so can I.  Having scoured the net for NOS and some were as high as a 1000 and thats not yens folks.  Those ads always end with "dont low ball me as I know what I got!"  Yeah ok.  One thousand is too steep so decided to go with OEM reproduction.  These are all over ebay and I decided to try my luck on one of these.  

Upon receiving everything looked in order.  The finish and the casting looked good.  I immediately pondered who made these?  Was it some 10 year old kid in China?  And what was he paid to create such fine work.  And then it dawned on me that it was a casting so obviously it was a form mass production.  Anyway, these were manufactured as good as any of the original factory parts right? So I thought!

When removing the original caliper one must remove the brake line and and the carrier bolt off the fork.  You then rotate the caliper 90 degrees and off the fork.  The idea was for the production race teams easy and quick removal in the pits.  Yamaha engineers were very clever.

Everything went well until I mounted the new one on.  It didn't go on like it should as one must reverse the process.  There was alot of interferrence which made it impossible to mount the caliper.  The solution was to remove the front wheel, mount the caliper and then carefully remount the wheel.  Carefully meaning one must slip the rotor between the brake pads.  It can be done in about 30 mins as opposed to 10.  There is about a 20 min delta t in this case.  

So what went wrong in the manufacturing?  Obviously there is a difference and why?  who knows right?  There is no data on this problem as if all information has been erased even though there are like 1000 reviews.  Maybe I can be the whistleblower and watch the cards fall.  Naw I will say nothing!

  

Hello Corny

Wednesday 7th May 2025

My 50 year old mikuni carbs VM28s were on their last rebuild.  The slide bores wore out and the bowls were warped.  It was time to get replacements...but where?  Penis Kirk sells replacements but they would not sell to me since I lived in ca-lee-four-ney-a...the land of fruits and nuts.  No they didn't actually say that but I shit you not, I heard that from an ex-coworker.  It had more to do with california emission laws and such was the real reason. Nonsense.  So where do you go to get what you want with a "I don't care" attitude and "just give me the money foo".  Well either amazon or ebay of course.  I used the amazon search engine and I was perplexed with all these different carb possibilties.  I reached out to one of the sellers and he or she replied back with 2 words  " Hello Corny".  So weird.  Was it a secret code or encyption of some sort?  I asked my engineering co-workers and they were also perplexed.  I went to ebay instead as I exhausted my attempts in getting answers to questions which I thought was basic.  

On ebay, I found these 30mm flat slide carbs which were described as Keihin PWK distibuted by Sudco. I ordered them and they arrived in a box that was clearly not carbs.  It had alot more mass to them.  Maybe something of more value?  I opened the box and I was greeted with 3" aluminum flex pipe.  Hello corny indeed.  I emailed the seller to my surprise I got a response.  I waited at least a month and finally got the carbs.   I jetted them and tuned them to the best of my ability.  Amazingly, the RD fired right up and ran a little lean at idle.  I had to fatten up the pilot jet to the next size up.  The mains needed to go 2 sizes up and the needle clip was set in the center.  Right away, there was no dead spots or bogs from idle.  Just smooth running and more midrange torque.  The best part is that I got both carbs for only 60 bucks.  This is pre tarrifs prices so get them while they are cheap!

My chariot awaits

Tuesday 6th May 2025

One of the problems with 50 year old bikes is that some of the engine components can eventually wear.  The clutch basket take alot of abuse.  The basket is decoupled from the primary gear and is buffered with rubber bushings that eventually wear.  All of the RD clutch baskets develop play where you can move the gear about 5 degrees which can absorb some energy therefore more parasitic loss to the rear wheel.  Another problem is the clutch plates will develop ridges on the basket fingers and the clutch can and will start to drag.  The solution to this is to use a chariot clutch basket.  This is lightened and coated with hard anodize.  The process is to remove the primary gear from the old basket and transfer that to the chariot.  The rubber buffers are also changed to remove the slack or 5 degree of decoupled rotation.  The result is a more snappy throttle response and a clutch that doesnt drag even when it gets hot.  These are all over ebay but there are copies so beware.  A friend uses these on his RD400 track bike and it hasn't failed under that high stress enviroment.  This is a good upgrade to any RD350, RD400 or RZ350.

Its pointless

Tuesday 6th May 2025

Having gone thru my last set of of Daichi points I tried some from an aftermarket source.  The dimensions on the rubbing block was incorrect.  With the dial indicator and my timing light I was able to adjust the points but developed a misfire on my way to see the Adolescents at the Dollhut in the OC.  I was able to limp the bike home on one cylinder.  I decided to ditch the points and install the HPI ignition.  The HPI is an electronic ignition and uses CDI type for spark energy and lighting.  Since it is a CDI you can run without a battery.  I got rid of the old wiring harness which was partially burned.  I re-wired the entire bike for just lights and a kill switch on the handlebars.  The best part about the HPI is that it has an ignition curve so it advances at idle until about 9000 rpm and then it retards the timing to avoid detonation.  It revs much quicker than with the stock heavy flywheel.  There is about a 3-4lbs difference which is a reduction in rotating mass.  This is a very effective upgrade to any vintage bike especially a two stroke of this era.

Pipes and beyond

Monday 5th May 2025

I rode the bike like this for a few years.  The picture shows the 1972 R5 tank that eventually developed a pinhole leak.  The bike was originally purchased in the late 90s from a dude in Palos Verdes.  He bought it in colorado springs and rode it around in college. It only ran on one cylinder when I got it.  The expansion chambers are from a company called motocarrera.  These versions were sold for a few years and they sometimes appear on ebay.  They amazingly woke up the engine after carbs are jetted correctly.  Still have them but are in poor shape.  

RD350 rebuilt in 2021

Monday 5th May 2025

Back in 2021 I had to split the cases to rebuild the 73 RD350 engine to retrofit a new updated crank assembly.  The crank was wasted as the lead weights fell out of the flywheels.  The OEM yamaha RD cylinders were also on the last bore.  The whole engine needed to be rebuilt.  I ordered seal kits, gaskets and most importantly new cylinders.  These are avaliable thru a supplier from ebay.  The photo shows the new crank in place with the crank seal installed.  When I cleaned up the case, I noticed the area where the locating pins on the bearing actually spun in the case.  The new crank bearings have o-rings very similar to the banshee motor.  The bearing pips are not needed as the compressive force from the case halves on the o-ring will prevent any unwanted rotation of the bearing.  The ebay cylinders however needed some work as the casting flash needed to be removed.  I went ahead and grinded and chamfered the ports but left the timing stock.  I will add more photos later of more RD modifications on a relatively stock ported engine.

I'm Riding for Men's Health in The Distinguished Gentleman's Ride

Monday 5th May 2025 On Sunday the 18th of May 2025, I'm riding in The Distinguished Gentleman's Ride with fellow men and women across the globe to raise funds and awareness for prostate cancer and men's mental health on behalf of Movember. Men die on average 6 years earlier than women and for largely preventable reasons. The number of men that are suffering is growing, and we need to do something about that. So, before I press my tweed and polish my boots, I'm asking you to join me in raising funds and awareness for these causes by donating what you can for this meaningful cause and to help the men we love, live happier and healthier lives.