RZ/RD 350 & Misc. 2-Stroke Tech BBS

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PostPosted: Sat Apr 30, 2016 11:46 am 
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Just going thru the owner's manual where it states:

"0-500 km (0-300mi). Avoid operation above 4,000 r/min. Allow for cooling off period of 5-10 minutes after every hour of operation. Vary speeds of the motorcycle from time to time. Do not operate at once, set throttle position." Aiming to do a proper break in, not quite sure what the last sentence means - a warning to not gun it (I suspect) until after a 1000kms. That makes sense. Also, do you torque down the head after the 3 break-in periods (500-1000kms, 1000 & beyond)? No mention of that but seems prudent.

Spoke to a gent who tunes 2 stokes 4 the last 35 yrs and just gave this advise regarding the 1st 500k's:

1) 10 min warm up - cool down for one hour. Watch the coolent needle as it will move one min after the first start up. Also do the hand test against the rad to feel for a warm up cause the needle does not always work. Gently drive around the block, return to your driveway and shut her down. Do not let it idle too long - bad for break ins and could lead to an engine seizure later.

2) Next ride it for a 1/2 hour. No red lining it until 250kms. Take it thur all six gears between 5000-7000 rpm. Select a gear to lighten the load below 7000 rpm. Stop for coffee 4 a 1/2 for a complete cool down.

3) Next do an open ride for 1 hour. Do full throttle bursts, at 2nd and 3rd gear, then double shift to 5th gear to lower rpm's and just loaf along during the ride. After 500kms, red line a couple times, slow down, then the break in is complete to seat the rings proper. He advised don't freak when the coolant gauge spikes hot because the hot coolant needs time to mx with the cold coolant in the rad after the thermostat opens during engine heating.

This advise appears counter intuitive to the manual - but he started as a Yamaha mechanic. I know this question should probably be in the engine section but interested in LC owners experience about best practices. The manual also states "Some data iin this manual may become outdated due to improvements made to this model in the future..." Interested to know if the advise given fits the manuals forward thinking. Looking fwd to getting started (proper)! Thx.


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PostPosted: Sat Apr 30, 2016 12:54 pm 
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Location: Houston texas
there are many ideas about effective break in .
all i would say is the LC did not have a thermostat .
so that part does not apply.
cheers mark

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PostPosted: Sat Apr 30, 2016 1:33 pm 
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He was probably referring to the thermosenser which reminds me I should give that a test Mark - thx. I understand there would be a myriad of opinions, on break in process, but I welcome them. There is a lot of wisdom on this form and hope to obtain a consensus on the best route to optimize the power band longevity w/o grenade-ing in the 1st 500kms and beyond.


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PostPosted: Mon May 02, 2016 9:09 am 
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And best to run dino oil for break-in, not synth correct?


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PostPosted: Mon May 02, 2016 9:14 am 
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heehee, these are like 'what oil' discussions... soon we will get someone saying run it like you sole it :)

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PostPosted: Mon May 02, 2016 11:56 am 
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I was suggested mineral oil then flip over to syth. Hmm.,, skip that. Just curious about what kind of stress diet the engine should be placed under to get the best longevity. Follow the manual or updated formula (if there is one) that a form member discovered "ya, that's the ticket".


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PostPosted: Mon May 02, 2016 12:36 pm 
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There is no answer to this question, just a pile of opposing views. I am surprised there has never been a test of the method, would certainly be time consuming.

1) Follow the boring stock break-in procedure
2) Ride it like you normally would from the get-go

Your looking to set the rings so your Dino oil first might be better as its apparently less slippery.


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PostPosted: Mon May 02, 2016 6:03 pm 
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Same as Lc Cnd for me, after speaking with a few old racers, I was advised to use mineral oil for a tank of juice just to bed the rings in then swap over to fully synthetic.
Re the run in I run a few heat cycles checking the head bolts after each cycle.
And not over 7000 for the first few runs.
I was advised also that for a new crank, do a few up hill runs in a high gear at the beginning of the break in period.
If unsure go by the book.

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PostPosted: Tue May 03, 2016 12:40 am 
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LC Cnd wrote:
I was suggested mineral oil then flip over to syth. Hmm.,, skip that. Just curious about what kind of stress diet the engine should be placed under to get the best longevity. Follow the manual or updated formula (if there is one) that a form member discovered "ya, that's the ticket".


Cleverest/safest would be to follow the OEM instructions.
Yama had won more than a Few Races with 2 strokes in thepreceeding decade of 350 development.
They knew their engines.
ALL you risk doing that is wasting some of your time.

You want it to live long? Never exceed 9500 rpms ideally 9000 if you can manage it.
Loadings/wear increase Expotentialy ! with rpms ..no joke that.
Problem inherent is the aged oem Tach can (has) be as much as 1500rpm High OR Low at high revs.. Lovely
The above is just for bore & crank issues.
Mixture / seizing is another 'problem' entirely.

These are not durable engines,(spare me :smt002 except in a few cases... sadly, like winning the Lotto.. it always happens to someone else.


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PostPosted: Tue May 03, 2016 9:33 am 
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I won't say ride it like you stole it but any idling warm up is not good for break in from much stuff I've read. I've always taken it out and did high rpm off and on pulls, going higher through the gears each cycle. Never had a problem or bad running motor doing this. This guy seems to make sense and has done at least some testing. The biggest problem with 2 strokes seems to be getting the jetting right first time. I try to keep the time running down till the jetting is close.

http://www.mototuneusa.com/break_in_secrets.htm


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PostPosted: Tue May 03, 2016 12:08 pm 
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Bare wrote:
LC Cnd wrote:

These are not durable engines,(spare me :smt002 except in a few cases... sadly, like winning the Lotto.. it always happens to someone else.


This is completely NOT true. These are EXTREMELY durable engines. The RZ can be beat, abused, and rarely worked on and it generally will hold up. Ask just about anyone that owned one back in the day. I expect Rory will say the same for his old LC that he routinely says he beat the heck out of. There was an entire race series using the stock form of these bikes for the exact reason that they were cheap and durable plus good power for the price.


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PostPosted: Tue May 03, 2016 1:53 pm 
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Really!? Been doing this long then?
Simply ain't so my friend, wish it was though.
First started on these in 73 fielding Tz350's.
Good go.. shortish lives. A succinct summary
But as mentioned *some* prove surprisingly durable.
Usually OEM ones though, with reasonable owners.


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PostPosted: Tue May 03, 2016 2:45 pm 
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Bare wrote:
Really!? Been doing this long then?
Simply ain't so my friend, wish it was though.
First started on these in 73 fielding Tz350's.
Good go.. shortish lives. A succinct summary
But as mentioned *some* prove surprisingly durable.
Usually OEM ones though, with reasonable owners.


The question is on the LC, if you got off topic onto the TZ then I missed where. The LC is extremely similar to the RZ. I have no time or experience on the TZ and don't claim to know anything about them. Its all exotic track fun which is of no use to me without a track nearby. The LC/RZ is very durable motor. I believe Rory's descriptions are a great example of how much you can beat on these motors without blowing them up. The RZ cup bikes were often not even given a new set of rings in a season.


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PostPosted: Tue May 03, 2016 3:39 pm 
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There is a good article on engine break-in and other topics that in my opinion make much sense over at Mull Engineering. It is similar to how I broke in new engines and top end rebuilds for the last 45 years with Yamaha & Husqvarna engines. At no time did I ever have an engine problem. Not even a fouled plug on the RZ. The RZ350 used as a street bike has been a very durable engine after enjoying 16350 miles with Belray Si7 only. This was a mix of very hard racing big-bore bikes and some commuting. I am rebuilding this one with 1st over ART piston/rings I hoarded 20 years ago. Synthetic should be good for break-in also. My Corvette's and CTS Caddy all come with Mobil1 from the factory so synthetic should be good for a 2-stroke. IF you read the Mull articles, you will see why running it wide open at break-in is not good at all.

The R5( a precursor to the R6?) was also a very durable engine I had as a high school kid in 1972 between dirt bikes. Zero problems again. But no track riding. The 350 Yamaha's had just won the Daytona 200, 2 years in a row then. But there are some riders/builders that can tear up a wrecking ball in a sand box!!

The biggest problem with someone rebuilding their engine and having a problem afterward is sloppy rebuilding. And anyone can be sloppy. Not everyone can do it right. It is best to read up on how race engine builders assemble engines to understand how attention to detail can make for a great engine.


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PostPosted: Tue May 03, 2016 11:16 pm 
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seahorse wrote:
I was advised also that for a new crank, do a few up hill runs in a high gear at the beginning of the break in period.


This makes no sense at all. A hard run up hill in high gear would put a ton of stress on the crank bearings. Not something you'd want to do to a new crank. However it makes perfect sense if the goal is to seat the rings to the cylinder. I did this on a couple of new 4-strokes and it seemed to work very well.

One thing that the people who advise to go back the book never see, to take into account is that the factory may have alternate agenda when presenting their break-in. The factory likely doesn't give a toss if your engine is properly broken in or if it lasts a long time. They do have a vested interest in avoiding lawsuits from new owners who get surprised by the performance of their new bike. Ask yourself, what changes inside the motor beyond the first 5 minutes that it runs?

As to 2-strokes longevity, holding up a 16,000 mile motor as an example is a it rich to say the least. Most 4-strokes will go 100,000 miles plus if taken care of. I don't see any 2-stroke coming anywhere close to that.

We love these old 80's strokes for what they are but let's not fool ourselves as to what they are.

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