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RD350 Project Mustakrakish

Started by bostontrackrat, May 22, 2020, 12:26:31 AM

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bostontrackrat

Well, this weekend I got the top end bolted together and I bolted up the reed cages and manifolds and performed the very first leakdown test!  :clap:


With.... less than spectacular results.   With the help of Windex, I found several leaks around the manifolds and reeds.  I fumbled around and played with these for what felt like hours before finally getting a proper seal.  :bang:  Finally, I was able to get a good seal at this point and the bubbles from the Windex stopped.  But I was still loosing air.   I found one on the right side of the crank by the little gear.  I freaked out thinking that the main seal was bad and I'd have to take the whole mess back apart and split the cases.   So I did the right thing and I stopped working, I went upstairs and took a long shower and cooked dinner.  Giving myself time to cool down and think of it rationally almost always helps.  I remembered there's that little rubber O-ring with the block on it that goes behind the crankshaft gear on that side.   I then realized this was the likely culprit as the bubbles were coming out of the end of those threads that hold the gear on.   I pulled that gear out, gave it a nice cleaning and resembled it with some fresh oil and viola! no more leak.    This left just one final leak that I found.  The copper head gasket.


I went ahead and pulled that head back off and exactly where I found the leak, I also found a slight residue on the head surface that I was having some difficulty removing before and I had thought I'd cleaned it up "good enough"..... sigh.     Well I got to work very carefully with a razor blade and a scotch brite pad and cleaned it up until it was new.   I had one extra copper gasket laying around and I threw that in for good measure and reassembled.   This time the leakdown test was MUCH better.   I only lost 1.1psi over a 5 minute period compared to before when I would loose all pressure over about 30 seconds.


Fortunately the basement was really quiet, and I was able to hear the last leak.   It's still coming from the right side head that I just re-installed.   It's much less of a leak than before, and windex doesnt actually show any bubbles coming from there.  But you can juuuuust barely hear a faint high-pitched squeal coming from that area.  It sounds like a 16kHz sine wave.   I'm starting to feel like I'm not impressed with these flat copper gaskets that come in the Vesrah kits.  There's no crush portion in them.  I'm going to give these a try.  https://www.economycycle.com/shop/yamaha-rd250350400r5ds6ds7-parts/engine-related/gasketsseals-engine/yamaha-rd350-r5-head-gasket-all-years-reproduction-replaces-oem-278-11181-01/

Quote from: dgorms on August 15, 2020, 11:05:28 PM
Boston, every time I have used something to "get me by" it F'n blew up right before I got back to it! Just speaking from 40 plus years of "DUH"............................................D

You know.... I hate it, but you're right.   Never let it be said that I dont listen to people with more experience than me.   I just ordered up those copper head gaskets and new Wiseco pins and clips from Economy Cycle.   It'll only set me back a few days and it's much better than destroying my cylinders after only a week.   One of my buddies in USCRA just had the pin clips fail on his CB350 last week and the pin carved a whole canyon in his side walls! 

Quote from: Economy Cycle on August 17, 2020, 12:50:19 AM
Looks good, that's one of the older riveted drums with the square triggers that can cause the engine to start in the wrong direction, and those rivets were known to loosen up over time. They changed the drums several years ago to a one piece cnc drum with ramped triggers.
John
EC

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

Thanks John! I had no idea.  I'll put that on my shopping list for the next time.  Like I mentioned above I just placed an order for the pins, clips, and gaskets around lunch time, and you guys already got them shipped out today! Killer!  Thank you, I really appreciate the fast help!

Quote from: toffee on August 17, 2020, 06:25:08 AM
Great thread!
I too am fitting a VAPE Powerdynamo ignition at the moment, I wasnt aware of the mods which people are doing,
I gonna check them out.

http://www.2strokeworld.net/forum/index.php?topic=855.0   :toot:

Czakky

Those vesrah head gaskets suck. OEM you can heat up and re-use FWIW.

I have used a bit of the black gasket maker RTV stuff with success.

But nothing beats a Chuck Q squish/combustion chamber setup for RD400 gaskets.

Djg8493

I was given the advise on the copper gaskets to use Permatex 80697 copper gasket spray, it has worked great for me on 2 different occasions solving this exact leak-down issue.
1970 R5, 1975 Rd350, 1978 GT80, 1979 KZ400, 1988 Ysr50, 1990 GSXR750, 2006 WR450 SM, 2006 R6

bostontrackrat

Thanks guys, I'll look into both of those!

rodneya

Are you going to install the motor into the frame with the heads on?

I like to put the motor without heads into the frame as it never seems to go in with the heads on and everything gets scratched up and chipped. 400's are way easier with the removable front mount.
Then put the heads on and leak test in the frame

bostontrackrat

Quote from: rodneya on August 19, 2020, 12:27:08 AM
Are you going to install the motor into the frame with the heads on?

I like to put the motor without heads into the frame as it never seems to go in with the heads on and everything gets scratched up and chipped. 400's are way easier with the removable front mount.
Then put the heads on and leak test in the frame

Interesting.   This is my first time trying to put an RD motor into the frame, I had no idea.  I was planning on laying down a blanket and placing the engine on its side on the ground, and then laying the frame down over top of it.

pdxjim

I find it easy enough to put the engine in the frame right side up.

The engine isnt all that heavy and it's easy to wrangle if you use the kickstart lever as a handle.

I put a couple pieces of wood lath 3/8" x 1 1/2" across the bottom frame rails to rest the engine on while I get the motor mounts lined up.
Wasting time on 2T forums since the dawn of the internet. '89 TDR250, '13 300xcw, '19 690smcr, '56 Porsche 356A

bostontrackrat

#67
Wrist pins, clips, and head gaskets should be here in another day or two.  In the mean time I decided to turn my attention to rebuilding the carbs.


The very first thing I want to say is that if you havent bought one of these ultra dorky grandpa magnifying headsets yet, you absolutely should!  I love this thing for working on small bits like jets.


First carb all torn down.  Yes, I have watched every episode of James May: The Reassebler.  Why do you ask?




NOW THEN.  I have a little treat for all of you.  An carb rebuild kit shootout!   :metal:

As luck would have it, I ordered up a set of rebuild kits from CruzinImage.  I've heard mixed reviews on his parts, but some people seem to really rave about them.  For just under 20 bucks for TWO kits, I figured it wasnt a lot of money to lose if they're no good.  Being that he's located in Japan and everything ships out of there, I thought there was a chance he was getting some quality bits direct from the OEM suppliers in Japan (I may have been dreaming, I know).  Well after the order they sat in the post office in Japan for over a month.  I got sick of waiting an bought a set of Keyster kits (a little under 30 bucks PER kit).  Several weeks later the CruzinImage kits showed up anyway.  Oh well, now I have tons of spares.   But, I also have the fortune of being able to compare them back to back, under magnification.

In all photos Keyster is on the left and CruzinImage is on the right

First thing I notice is that both kits include all the same bits and pieces, no kit includes anything more or less.

Starting with the float needles, the Keyster kit appears smoother.  The CruzinImage has a sharper angle of attack at the business end, and comes to a sharper point.  The biggest difference is the smoothness of the spring end.  When depressing the plunger, the CruzinImage needle feels gritty and notchy.  By comparison the Keyster needle is smooth as butter.  It gives the impression that it's less likely to bind or stick, and for that reason I picked the Keyster float needle and installed it.

Magnification!


Here we have the Seats for the needles.  The Keyster looks much smoother overall and has sharper threads.  Tool marks are deeper and more apparent on the CruzinImage part.  It doesnt show up in pictures well, but the Keyster item also has a nicer shine to it.   I kept the Keyster Seat with the Needle I chose, and into the carb it went.


The story continues on the washer for the needle and seat.  They're pretty comparable, but more tooling marks on the CruzinImage washer.


Not much to report on the top cap gaskets.  The Keyster has a nice looking texture to it and it had a softer, more supple feel to it. So I figured that would make it better and conforming to the surface and making a seal.  In this picture you can also see how much cleaner cut the edges are.  Into the carb it goes.


Same for the float bowl gaskets.  Hard to quantify or say why, but the Keyster set had a nicer feel to it.  Felt like a better material. I'm noticing a pattern at this point.


Next up to bat is the Pilot jets.  These looked pretty comparable and if anything, the threads looked a little cleaner on the CruzinImage jet.  I guess Keyster cant win em all.  I wont be using either of these however, as they are the stock 25's and I bought some larger ones already.


Main Jets.  This picture didnt turn out great, but to the eye, the threads and machining were better on the Keyster jet.   Again, these are stock size and I already bought larger jets.


Air screws.  Same story, smoother finish overall on the Keyster.  But the CruzinImage wasnt too bad, I wouldnt have a problem using either.



Ho boy.... here we go....  Needle Jets.  Open this image in a new tab and zoom in and tell me which one you're putting in your bike.  You can feel the roughness on the surface of the CruzinImage needle just by holding it.  The other thing I noticed (didnt get it in this picture) is that where the taper of the needle changes, the Keyster has a nice clean, consistent break from one taper to the next.  The CruzinImage is blended and not as apparent.


I learned something today.  Sometimes you really do get what you pay for.  I'll be buying good, brand name carb kits from now on. :twocents:

Now I'm curious to look at the K&L kits that are over 40 a piece.

bostontrackrat

One thing I wanted to point out is to make sure the washer is lined up correctly on the seat and ...uh.. seats all the way down flush.  I was a little careless and just tossed the washer on there and started threading the seat into the carb.  I noticed it didnt thread all the way down before it stopped.  Then I found that the washer had caught on the last bit of thread creating a gap between it and the shoulder it's supposed to seal against.  I pulled it back out and lined it up correctly.


Starting to put everything back together.



:help:
Having a little trouble with the slide/spring/carb top situation.  I have 2 sets of carbs.   One was a high top and these are low top.  The high tops are lost somewhere in my buddy's garage.  But the slides had a weight in them that allowed this needle retaining clip to seat nice and flat.   These low tops I'm working on didnt have anything like that, and I cannot get the needle retainer to seat correctly.  Any advice? what am I missing? This doesnt feel correct, so I dont think this is how it's supposed to go together.   Also, is there any comparative advantage between the high and low top carbs?  Is one better?    Thanks!


RDryan

In the last pic there if I recall I believe that tab on the left, facing down is supposed to fit into the slot beneath it. Then it should sit nice and flat and the spring keeps tension on the whole assembly to keep it all where it's supposed to be. Not sure about any differences between low and hi top carbs.

bostontrackrat

Quote from: RDryan on August 19, 2020, 07:52:13 PM
In the last pic there if I recall I believe that tab on the left, facing down is supposed to fit into the slot beneath it. Then it should sit nice and flat and the spring keeps tension on the whole assembly to keep it all where it's supposed to be. Not sure about any differences between low and hi top carbs.

Yeah, it lines up and fits in exactly like that on my High Top carbs, but here, the slot is facing in the wrong direction, so it wont go in.  I can bend the tab the other way, but I was hoping to no have to modify the part.

bostontrackrat

#71
Today I got the other carb cleaned out and rebuilt with the new parts from the Keyster kits!


Then I got to work on the clutch.  The clutch plates are well within spec, so I'm going to use them for now just to ride around for the end of the season, and I'll upgrade it over the winter.


I've found 2 issues.  First is that I forgot to install the bearing retainer right here on the transmission input shaft.  You can see it in another picture.


The second issue is that my parts stack up doesnt match what I'm seeing in the service manual.   The manual says I should have a trust washer between the the two halves of the clutch basket, behind the thrust plate.   I dont have the bearing anywhere, and I also disassembled the clutch from another engine I took apart it it also doesnt have a bearing where the service manual says there should be.   Any chance this is a model year change?   Does anyone else run without this thrust washer?  Or know where to get one?

Part Number 3 in this diagram.


The good news is that I test fitted everything after a good cleaning and it installs nicely and spins freely.  So I'm wondering if the thrust bearing (#3) was an older part that was eliminated as unnecessary.  This engine is a 1975.

bostontrackrat

Been away from the project for a little bit.  Very busy house hunting.  But very excited that the wife and I have found a place and we're moving pretty close to closing the deal down.  New spot will be EXCELLENT for my project addiction.  It has a HUGE 2 car garage and a freestanding shed for storage.   Cant wait!

In the mean time I've been able to get back to work on the RD and I tore the top end back down and installed the new Wiseco wrist pins and clips.  Cleaned up all the gasket surfaces and put it back together with the new gaskets.   I bought the nicer 'crush' style head gaskets from Economy Cycle and they sealed much better than the flat ones that came in the Vesrah kit.





While cleaning and organizing around my basement I found a set of Boysen Power reeds!  I took the stock (and dangerous) metal reeds out of my cages and replaced them with these!  Nice little upgrade.  I made sure to use blue Locktite on the threads when reinstalling.



After a little bit of playing around with the manifolds the engine passed a leak-down test.  I was excited and got right to work putting it in the frame.



At this point I couldnt resist throwing the tank and seat on there just to see it look like an actual motorcycle.   Isnt that a sight for sore eyes!



:metal: :metal: :metal: :metal: :metal:

m in sc

done use either jet needle they are wrong on both kits. i (recently) learned they are copies of the uk 350-b needle which is incorrect as the carbs are actually different. use oem yamaha.

:twocents:

neat comparison.  :clap:


bostontrackrat

Good looking out!  I'll swap the needles back to the stock ones before I put them on.  Thanks!