Im currently in the process of rebuilding my NSR250. My bike is a MC18 R5K however im fitting a MC28 engine from a donor bike.

My issue is while doing the waterpump I found the clutch basket inner and outer move together and do not rotate separately. The clutch plates are completely removed there is nothing left inside. If i remove the main nut both baskets rotate as expected however when its torqued up they do not move separately. Does anyone have any info whats causing this issue?

If I can add a little more info to this thread as I'm helping (or is it hindering!) my son in this process.

The Engine in question is from a MC28 R3S and we have no history on it.

However, I was wondering if this was a common problem with the Dry Clutch set up (wear wise)? as I notice that DMR-JAPAN (see Part E5-21028 Figure 1) do a complete Collar replacement set and wonder if there are a wear issues with the collars wearing and not throwing the Inner Clutch Basket away from the Outer Clutch Basket, or am I missing something very simple? (!!Was always told to look for the simple things first!!)

Additionally, I noticed that the Outer Clutch Basket on the MC28 R3S Engine may be from an earlier date (Part No 22101-KV3-780) as the one fitted (see Figure 2) has no Castellations [well Castellations of a sought], although, I was led to believe these parts are Interchangeable!!!

I have now managed to get a new Outer Clutch Basket, although it was advertised as Part No. 22101-KV3-780, I believe it to be the later Part No. 22101-KV3-980 (see Figure 3), as it has the castellations.

Apologies, for butting in on this thread, but we are at an impasse as to moving this forward.

Many thanks

PS: Can I take the opportunity in thanking everyone in the help received so far, as although it’s been a struggle to get this far (Bike has been in boxes all over the place in the past 25+ years) as without all the help from the Forum and the Forums Knowledge Base it would have been an impossibility.
Here’s hoping to another NSR250 to return to the roads sometime soon.

Is there anything in this post that helps

http://www.nsr250.net/forums/viewtopic.php?t=9881&highlight=mystery+clutch
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Why do things simply when you can complicate them

RobH wrote:Is there anything in this post that helps

http://www.nsr250.net/forums/viewtopic.php?t=9881&highlight=mystery+clutch

Thank you that seems to be similar or same issue i have. Will go through it and check and see if i can find some specs of the parts if they are different.

After managing to get hold of a better MC28 Dry Clutch assembly I am now able to shed some light on the problem of the Inner Clutch seemingly locking itself to the Outer Clutch Basket when the Centre Nut (20) is tightened up.

The Dry Clutch when tightened, clamps Collars(17) & (3) [Said Collars Ilustrated in Fig 1.] firmly together on the Gearbox Mainshaft and if either or most likely both Collars wear at the ends then, as in our case, Collar(3) isn’t pushed away from the machined surface of Clutch Drive Gear(5) [where it sits behind Oil Seal(27)] by Collar(17).



The Collar(17) measurement 'A' (see Fig. 2) taken from my Son’s Dry Clutch was 45.06mm as compared to 45.17mm from the one I obtained [!!who would think just over 0.11mm would make a difference!!! I didn’t take Collar(3) out to measure it, however I suspect that had some wear on it too].



This can possibly be better explained using Fig. 3.

Using the Newer Clutch Drive Gear(5) and its Collars(17) & (3), when the Clutch Drive Gear(5) is pressed down onto a flat surface then it pushes Collar(3) back against its machined housing in Clutch Drive Gear(5) which in turn pushed Collar(17) up showing that there to be a 0.20mm Gap [Note: I am not sure what this Gap should be as can’t find anywhere that mentions it].



Therefore, when Tightening up the newer Clutch Drive Gear(5) and Collars(17),(3) up, that 0.20mm must provide enough free play between Collar(3) and the Clutch Drive Gear(5) machined housing enabling it to spin freely.

On my Son’s Dry Clutch when doing the same, there was a slight Gap between the 2 Collars(17)&(3) inside the Clutch Drive Gear(5) [they had obviusly worn down] and therefore when pressing the Clutch Drive Gear(5) down onto a flat surface it didn’t push Collar(17) up at all and obviously there wouldn’t be any end play!

Consequently, when this it was all bolted onto the my Son’s Gearbox Mainshaft, there was no free play, therefore Collar(3) was pushed firmly against its housing inside the Clutch Drive Gear(5) and the result was, it clamped it all together.

I hope I haven’t made too much of a hash in this explanation, only your feedback will tell me if I am totally up the Creek without a Paddle (and not for the first time either).

I have also ordered some new Collars from DMR-JAPAN [you can't get these Collars anymore from Honda] and when they arrive, I will put some more accurate dimensions down which can be used as some sort of Reference only. Obviously, all new parts would be required to make more of accurate measurements.

ADMIN: Edited to put images inline to make post commentary easier to follow. Fig.3 caption edited to correct item number and add OEM part number missing from the original.

Great piece of investigation. All good information for anyone else in the future
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Why do things simply when you can complicate them

Well it looks like problem solved (fingers crossed wait for it to be fully tightened up!)

New Dry Clutch Spacers/Collars arrived today from Webike Japan (Parts 3, 16 & 17 as shown in Fig 1) from third party supplier DMR-JAPAN...



...and were fitted to the Primary Clutch Gear as shown in Fig 2 so measurements could be taken.

Net result was there was 0.15mm free play between the spacer and Clutch Primary Gear which can be seen in Fig 2.



I then fitted the Clutch Primary Gear onto the Gearbox Fig 3 and using a basic homemade Spacer, tightened it all up on the Gearbox Mainshaft and result, the Gearbox Mainshaft spun independently of the Gearbox Mainshaft (I know it should have, given the free play, but belts and braces!).



I took some measurements (see Figs 4a, 4b & 4c) of the old and new Spacers/Collars to give some basic measure of the wear, although I should point out that I was using a cheap Digital Vernier Gauge, the differences are very small between the old and new parts, but this small amount of free play must be significant.





Any wear on the Spacer (16)...



...which spaces out the Needle Roller Bearings inside the Clutch Drive Gear, is probably insignificant, as I don’t think there will be any lateral loading on these Bearings, as you can see in Figure 5...



...the Collar (17) sticks out just slightly proud of the 2 Needle Bearings and their Spacer (its even more pronounced on the Original Honda version)!

Several things baffled me though (not difficult I know):

• The Spacer (16) and its associated Needle Roller Bearings aren’t shown on the MC18 R6K Dry Clutch Diagram, although they use the same Bearings on both the Wet and Dry Clutches! Perhaps that's the reason why, but there is still no spacer shown!
  
  
• Why hasn’t Honda published any free play tolerance, as there must be an issue if a third party supplier goes to the trouble of making replacements!
  
  
• Leading on from that, if there are known issues, wouldn’t it have been better to provide some shims and free play tolerances as all the Collars/Spacers (except spacer (16)) are tightened up and rotating in the same direction (I understand when in neutral they can be stationary whilst the Clutch Primary gear rotates, but this shouldn’t cause an issue I would have thought)!
  
  
• Lastly, those of you would have noticed that the overall length of the New Collar/Spacer is shorter than the Old one. This is not a mistake as it’s the length of B which is critical (I hope!).

I hope you find this post interesting, but as always, any comments please. You can probably see from any of my previous posts I am a fairly newbie to the land of NSR250s and still learning and hopefully continue to learn all the time, as there is so much good stuff on this site.

Old New
A 45.08mm 44.91mm
B 40.14mm 40.8mm
X 17.91mm 18.0mm
Y 10.91mm 10.95mm

PS Couldn't attach all Diagrams on this post so will insert the other 2 Diagrams on the following Post

ADMIN: Edited to place the images inline to make the commentary easier to follow.

The 2 Diagrams that should have been on the previous Post.
Phil

Apologies, forgot to add that although the Dry Clutch in question was from an MC28 Engine, the reason I was looking at the MC18 R6K Dry Clutch was that the outer Clutch Basket fitted looked more like it was from an earlier Bike aka MC21/18.

The Clutch Basket had no castellations and looked like Figure 3 below.

Phil

Great follow-up, Phil, and extremely appreciated.

I hope you don't mind; I took the liberty to edit your posts to embed the images inline to make it easier for future readers to follow.
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Andy.
NSR-WORLD.COM

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Many thanks Alan that's made it much clearer.

I am going to see an ex engineer who has much more accurate measuring equipment than me, if you think it worthwhile I can get some more accurate measurements fed back?

Phil

philup_7@hotmail.com wrote:I am going to see an ex engineer who has much more accurate measuring equipment than me, if you think it worthwhile I can get some more accurate measurements fed back?

Definitely. You can never have too much information!
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Andy.
NSR-WORLD.COM

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The following measurements listed below are an update to the previous measurement shown. These are a lot more accurate and were kindly done by my friend and ex engineer Terry with professional Vernier Calipers.

However, before going any further I have to own up to a previous mistake on Diagram 4a. The previous Diagram 4a shows measurement ‘B’ going to the first shoulder on the Collar (17), this is incorrect as it should be to the second shoulder. The new Diagram 4d illustrates my mistake.
Diagram 4a has been updated to reflect this change and a new Diagram 4b lists additional measurements not listed before.

The important difference in measurements here is ‘B’ on Spacer/Collar (17), as if this wears then there will be no free play in the Clutch Primary Gear.

Accurate Vernier Caliper Measurements in mm
- - - - - OLD- - - - - NEW
A - - - 45.07 - - - - 45.08
B - - - 40.08 - - - - 40.92
C - - - 22.03 - - - - 22.03
D - - - 27.98 - - - - 27.99
U - - - 27.98 - - - - 27.99
V - - - 22.04 - - - - 22.03
W - - - -nm - - - - -15.07
X - - - 17.94 - - - - 17.97
Y - - - 10.92 - - - - 10.978
Z - - - - nm - - - - - -2.97
nm - Not Measured

Hi all

Well the good news is that we managed to get the NSR250 started, running (althought a few niggles still to sort) and the Dry Clutch seems to be working fine after the replacement Spacers, even more wonderfully no water leakage from the Water Pump.

I thought it worthwhile to further document my findings in the attached file of Page 9-13 (mainly because I am becoming very very forgetful in my old age, as I have reached that point where I have to write everything down LOL).

The text in RED on Page 9-13 (although it looks like a Page from the Honda Manual) does not reflect any of HONDA or NSR-World's official views it is purely for my personal use as an addendum to the official Service Manual, but I thought that it might be useful to share with others on the forum.

For access and further reference to NSR-World's NSR250 MC28 on line Service Manual please cut and paste the following link. However, before doing so make sure you are registered with NSR-World and logged in as it won't work!

http://www.nsr250.net/forums/members/nsr250r_manual_mc28/index.php#p=1

All the very from one very happy monkey and hopefully another Honda NSR250 back on the road soon.

Phil

Great update to the thread, Phil. Thank yuo.

Also great to know the NSR's up and running again!
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Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

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