Coming on nicely

Ref the crank - as it was exported to the US you paid zero UK VAT at 20% saving you roughly £70 and postage was £80, so you actually got that crank cheaper than I could ! - UK internal postage would be a more than £10. (born free and taxed to death)


For someone who in an earlier post made the comment “grew up penniless” that workshop is well appointed - fair play to you !
Just waiting to see what else you have in there, your parts washing facilities are something else


_________________
Nick

Rebuild project NSR250 MC18 R4J


Last edited by Rothmans_SPud on Sun Dec 15, 2024 7:31 pm; edited 1 time in total

Cheers Nick! Yeah, the parts washer is a bit posh, the downside is that access is limited to the times that no one else is around to witness...the pennilessness is thankfully buried deep in the past and so I was able to do a couple of more orders..

First off I couldn't lay my hands on the main shaft and countershaft bearings that are supposed to live in these round spaces in the centre of the picture. I later found them, but knowing that they had endured media blasting I assumed them ruined...even if not...why have the whole refurb process be founded on the only two critical bearings that were not replaced. I was able to paste the part numbers (#32 91022-KV3-003 & #33 91024-KV3-003) into US based parts warehouse Partzilla website to amazingly have a couple of OEM replacements pop up...to be honest - it appears there are actually 2 choices of bearings for the countershaft with the last numbers...003 or 004...I shamelessly ordered the only one available and will research the possible catastrophic difference between the two later as the engine rebuild is paused until the bearings get here.





In the meantime I unpacked the transmission. Cleaned, magnafluxed, racecut, new bearings.

The second thing to be installed. Clutch actuator arm. I have all the bits...they just need a clean...


removed the old loctite with a whiz of a wire brush...


...grabbed the red rubber grease which I use to fill in the space at the back of the oil seal. I like to think it keeps them supple. has to be red rubber grease though- other grease's may attack the rubber. apparently. install can be made easier with a wave of blow torch over the area to heat up the case and then a thin smear of rrg helps the oil seal slide in....


Check with archived photo that the spring on the correct way...


Yes...but never count on the previous owner getting it right...


Bit of Loctite...


and then while I was here and had the rr grease and blow torch out.....decided I shut fit the shifter oil seal...




and then why not the neutral switch...


boom. 3 new things in place....


make that four....clutch cable holder....I'm working on the premise that if I stumble upon a component and I know where it's fastener is, I install it before I forget where I put it.


frickin' chaos in here...

When you fit the transmission, be sure to keep an eye out for the spring that needs hooking into the casing. Many a time it's overlooked and the bearing carrier is cracked as the retaining screws are tightened.

Simple rule; if the bearing carrier doesn't simply fit fully into the housing just by hand, the end of the spring is trapped between it and the case. Don't think you can just tighten the screws and pull it into place. It'll break.
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Andy.
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Regarding your transmission, what did you have done? Did you have some of the dogs undercut? Only modification I ever did to the transmission was I put in hybrid ceramic bearings. I always felt it shifted better than any other bike I've owned. It takes very little effort and just a small tap of the foot to shift up or down. So I'm curious if others have done under cut to improve things even more. I've never hit a false neutral or popped out of gear.

If I were to someday build another motor I might consider cryo treating things then microblue coating. Probably not because it's gonna make me go faster, more because I would be interested to see if I could get just a little less friction.

The stock transmission is in fact, very good, however... the HRC transmission (with undercut gears) is undeniably so much better! 😉
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Andy.
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Hi,

I believe Andy is referring to this. Use a large flat tip screwdriver to flick the spring end up while pushing the transmission carefully into its final position.

Do not forget the pin at the top which is in one of your photos.

Sami

sami1 wrote:
Hi,

I believe Andy is referring to this. Use a large flat tip screwdriver to flick the spring end up while pushing the transmission carefully into its final position.

Do not forget the pin at the top which is in one of your photos.

Sami

That's the one!
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Andy.
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That’s valuable information on transmission install Andy and thanks for the pics Sami1 MUCH appreciated. Lack of insider knowledge has failed me before.

On the transmission: It was my inability to understand how to shim an H2 transmission to the cases that connected me with Mark Doucette of R&D Motorsports.

Somewhat legendary in drag racing culture, renown for producing indestructible transmissions and with some new found respect for strengthening the transmissions on them Hardley’s on the ill advised Bagger Racing class over here, since 2020, Mark has somehow found the time take care of my H2 and RZ rebuilds by firstly magna-fluxing each component (checking for cracks) to ensure it is sound. He’s ruthless when it comes to diagnosing each part- if it’s not almost perfect it gets thrown out and you have to find another. (He's patient too.) He then gave the dogs a race cut which is almost mandatory in the drag race circuit. A swifter more engaged shift over your competitor can produce that slim margin to victory.

For me though, a simple dedicated street rider, I was just excited to have a specialist work on the H2’s and perform the black magic of the shimming. I have not regretted all the work I put into sending him the whole bottom case assemblies. I know that his attention on the transmission and Fast By Gast’s barrel and headwork (blueprinting only) would help me assemble strong motors that can handle the acceleration addiction that I succumb to every time I’m at the front and the light goes from red to green.

After witnessing the lack of care and attention that my NSR had been exposed to I decided the transmission needed Mark’s stamp of approval before I put it all back together. He magna-fluxed each component, replaced the bearings with OEM units that I provided, (I didn’t know about hybrid ceramics!) and then undercut the dogs. I think it looks beautiful.

I'll get a better pic of the dogs and throw it up here later...


Never having ridden one, I have no idea what to expect from this engine, but I think I’m doing my best to have all it's components perform well together by ensuring each and every part is checked out by me or a specialist. That’s the beauty of a two stroke. There aren't that many parts.

Which brings me to the NSR’s oil pump. The heart of the bike, who's failure, well, means death of a sort. With my LC’s: there’s a renown oil pump guru outside of Liverpool (UK) who has refurbed all my LC oil pumps- but that’s the only brand he likes to work on. I found someone in the US who checks over and heli coils the delicate alloy of H2 oil pumps. I’ve browsed through this forum but the time I dedicated to the search (probably not long enough) didn't help me find out if there’s anything I can do to prepare oil pump for more years of active service.

Apart from an 8mm washer and an o-ring, (ordered) the parts diagram shows the oil pump as assembly #3, one piece…no component breakdown illustrating replaceable oil seals etc….that says it all really. And then of course the service manual is quite clear: "Do to attempt to disassemble the oil pump." (to see how it works:0)





True- to avoid al anxiety- premixing might be the safest way to go but I really like all my projects to function exactly how they did when they rolled out of the factory.

Main shaft and countershaft bearings arrived and went straight into the freezer. Looking forward to this weekend!

The oil pump shaft oil seal can be ordered dimensions 9 x 16 x 4 mm. If you are going to replace it, carefully clean where it sits with a non abrasive material.

The spring side of the seal should face upwards when the oil pump is upside down. Make sure it sits properly in its housing.

If I remember correctly, fitting the engine back onto the chassis with the oil pump on is quite tricky as the oil pump obstructs alignment for the front long engine bolt.

I fitted the oil pump after having fitted the engine onto the chassis.

Don’t forget the washer that sits at the bottom.

Sami

The oil pump shaft seal is the most "common" oil pump "failure" on the NSR. It doesn't fail as such, but can unseat from the housing and slide down the drive shaft. This in turn allows the oil tank to dump all its contents into the transmission casing! Not saying the pump can't/won't fail, but in my 30 years of NSR experience, I've never personally seen one fail mechanically.

With that said, the seal is not available from Honda, but I do believe it's a common size on some snowmobiles and jetskis/waverunners, so should be readily available from good reliable sources. Needless to say, use a high quality seal, not some cheap Chinese no-name seal. (Even though most seals are made in China now! 🤣🤣)

I always advise everyone to check the 2T oil tank level before every ride, and to top the tank back up to full after every ride, no matter how short. This way, if the seal moves (it's never been known to move during use, only when the bike is static, i.e. overnight, after a ride) you will notice an empty oil tank before you even attempt to start the motor! 😉

As Sami says, clean the seal housing very carefully. Brake cleaner and a lint free cloth is ideal, and ensure the housing is completely dry before pressing in the new seal. If you're under any doubt about the fit of the seal in the housing, you can use a little smear of RTV sealant on the outside of the seal to help it "bond" into the housing, but it shouldn't be necessary with a high quality seal.
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As always, great information. Very grateful to have some expert eyes on this.

At first I didn't understand which oil seal we are talking about. I just saw this o-ring , not the standard shape one wold expect of an oil seal and def no spring.


and then looking more closely...there it is...embedded in the pump itself and no indication on any of the docs (service manual, parts list etc) what size it's supposed to be because after what I've read from you lot, only a fool wouldn't replace this potentially 35 year old seal, but it would also be a foolish to replace it with something that wasn't within the exact specs, no room for bodgery here. Thank you sami1 for the 9 x 16 x 4 mm dimensions and this has been ordered.


not perfect but looking better on the outside

Getting ahead of myself I decided to dry-fit the powervalves into one of the cylinders to see if I could remember how it's done and I've run into an issue that might be staring me right in the face...

All the pieces...in order as the parts manual but that round (not oval) washer has to be between the two brackets...



RC valves in position...best to insert from the front here...


Special clip attached.


Then with the collar first the shaft slides into the cylinder and valves noting that the widest gap between the teeth is at the top....




The 'old' o-ring installed just for dry fitting...[img][/img]


First plate bolted in..then the oval washer fits over the shaft...


..then (what I call) the adjuster plate...and I think you can tell here even with a (round)washer in place...the nut will not snug up to the plate and this plate will be loose....and I don't remember it being like that.


It looks like it needs another oval washer...not only the one in between the plates...but one on top of the adjuster plate..


..which is lucky because CMSNL have them...but it's not how it was dismantled...or how it's depicted in the parts catalogue...my first instinct is operator error...I think I must be doing something wrong....whatever I'm going to tidy up and start on the motor...


Like the true rivet counter I am, i finally sourced all the correct OEM washer and nuts to get it all back up to spec and that remedied it all...


Before....with hardware store washers...


After with the real Honda OEM parts..they are definitely thicker...


Then a bit of Loctite and a tourquing of 1.0kg and that chapter is closed, although I still have to learn how to time the valves. One step at a time..



Last edited by Hudtm60 on Sat Jan 18, 2025 3:43 am; edited 6 times in total

Hudtm60 wrote:...but it's not how it was dismantled

Given the bikes age and average of most of the owners back in the day that ^ doesn’t surprise me one bit !

Sadly I can’t help you - but never the less enjoying the updates and journey
_________________
Nick

Rebuild project NSR250 MC18 R4J

Couple of new dowels in the bottom case..

Here....


and here...

Mainshaft and counter shaft bearings dug out of the freezer and matched up with the correct bearing driver size...


They will go in here...


...like this..


..giving them some lifeblood oil...in this case I'm using Motul 10w 30 because I can't get Rock Oil over here...


This in next..


relatively easy...


...torqued....just the recommended generic for an M6 bolt....1.1kg-m or 7ft-lbs


countershaft seal...


...seated.


then these bits went in....shifter arm, spring and the thrust washer goes against the casing...used a bit of Loctite Blue. You can't tighten this one up too much or it will fail to move as freely as it should.



...next was the drum shifter. I located the assembly and was fiddling around with it when ping, doing, plink, plink roll...the contents ejected themselves across the garage...rain stopped play so to speak. I've found everythng apart from the bushing washer. I don't think it's likely I'll ever see it again so I ordered another one from CMSNL. Expensive hobby this...
No idea how all this goes back together...if anyone has any pictures or can shortcut me to a good thread on here please let me know- in the meantime I'll search too.


now they tell me..



Last edited by Hudtm60 on Mon Dec 23, 2024 4:59 pm; edited 1 time in total