Topic: 530 to520 chain conversion

[antinora]

Hi:

Recently I've purchased a 520 setup from Sprocket Specialists.  The 17t front sprocket which was sent to me does not have the 2 threaded mounting screw holes.

Specialists told me they've been selling them that way for year and to just "mount it with the clip we've provided".

I am leery since once mounted there is about 1/2-3/4" of side-to-sdie free play.

Any thoughts would be greatly appreciated.

Thanks,

John A

[Philly550K1]

can you post a pic? i can't picture this clip.  and which bike?

[antinora]

i can't seem to locate the jpegs on this PC, which I took last weekend...so i'll take off cover this weekend and post pics early next week...thanks for the reply....

the clip sit in the a groove on the drive shaft....this clip have two hole in it which two screws pass through.

after passing through, these screws, screw into the 17t sprocket pulling it toward the clip and thus fixing it onto the shaft....

[antinora]

sorry...it is a 1975 CB550 K

[antinora]

located the pixs

[Terry in Australia]

G'Day Mate, I think Philly wants to see a pic of the Sprocket Specialists supplied clip? Me too. Cheers, Terry.

[cb650]

Same as the 650 and I wouldnt put it on. Could ride to one side and wipe out somtin portant.
What is the reason for the 520?



                         Terry

[Matt at PSB]

I'm baffled by the sudden flavor of the month trend to convert any streetbike from 530 to any other chain size. 530 is abundant, low cost & strong: In those areas it is superior to other chain sizes.

Yes I understand the weight savings & reduced friction arguments. To me this is pure penny wise & dollar foolish thinking. You can't beat a good 530 for strength, cost, & service life. Never the less this 520 conversion is all the vogue right now. If you have a streetbike & not a racebike I find this conversion to be the height of folly.

Sure I sell this stuff because people want it. I sell Harley parts too for the same reason. I stopped asking why, except to myself, years ago.

Matt at PSB

[oldbiker]

If I understand you correctly, the supplied clip is the same as the original clip? They told you to fit it and not worry about the lack of screw holes. DON'T DO IT.  The whole idea of this clip is that when the screws are in place, the sprocket/clip assembly cannot come off the shaft because the machined splines are mis-aligned. Without the screws the two parts can work round and when the splines are aligned the pair could come off the shaft. The cover could be destroyed, the chain could fly free and lock the back wheel and if this happened at 70 0r 80 mph I'll let you guess at the result.
The best solution is to assemble the sprocket and clip on the shaft, adjust their relative position to get this locking effect and mark the position of the holes in the clip onto the sprocket. Drill and tap the neccessary holes in the sprocket and assemble in the normal way.

[Terry in Australia]

Quite right, Mr Baker. I agree with Matt too, it is a fashion, and the benefits certainly don't outweight the trade off of increased chain and sprocket wear and shorter component life. Still, if you've purchased quality components, your sohc-4's modest power output will not make the conversion a danger, there are guys racing modern sports bikes with two or three times the power of our bikes quite safely with 520 chains.

What would be more dangerous would be running an "el-cheapo" chain from China or Malaysia, these 20 buck items are about as good as the original OEM items that were susceptable to breakage in extreme circumstances, particularly if poorly maintained. Not good. Cheers, Terry.

[cb750_chris]

Hello. 

I would take the advice of those telling you to modify that new sproket.  If this chain is indeed modern and strong it should be fine.  If it is an el-cheapo you will surely be repeating history with the case damage you inflict on your engine.  I've talked to several guys who owned new 69-70 750's and they all have chain horror stories.  My first of two engines also has the scars to prove it. 

[antinora]

sorry for the misunderstanding...I'll take a pic of the supplied clip & post it on Saturday.

I am just trying to lighten the bike and I've changed the rear sprocket to give me slower off the line acceleration but smooth highway speed.

I am a local back-and-forth to work rider....

My solution is what oldbiker suggested...I am going to drill it and thread it...I just want to know if Sprocket Specialists were wrong when they told me just to use their supplied clip which is just a standard C-clip...

getting back to drilling...their front sprocket is a hardened steel sprocket...any suggestions on drilling (bit type & speed) and tapping? I own a drill press but have solely used it for woodworking...

thanks,

John

[Philly550K1]

i suppose there are other reasons why one would switch from 530 to 520 for its own sake, but my reason, and the only context in which i've read anything on the matter in this forum, is in conjunction with running an o-ring chain on a 500/550.  it is fairly well documented to my satisfaction that a 530 o-ring chain will rub and cause problems due to its greater width.  (there are pics of such damage on this site.)

i guess since i've actively sought the information, it seems like old news to me, but i'd vote it into the FAQ. 

for the miles i ride, the less frequent maintenance alone was worth the extra homework.

back to the current thread, yeah, i think the clip has to attach to the sprocket somehow, and if not via the depicted and discussed holes, then, uh, vegemite?  no, seriously, now you've got two hemispheres curious.  one chilly and one, mmmm, balmy, almost sweltering warm..... 

-jon

[bike54]

try getting some high speed steel drill bits good engenering supply houses normaly stock them or drill bits with a good cobalt % as for tapping, high speed steel tap is the only thing that will touch it keep the metal cool plenty of oil or cutting fluid when drilling or tapping
use the drill press and a vice for drilling as for speed plenty of facts and figures on the web depends on the size remember high speed steel is brittle so get spares and do not try to drill the finished size in one go step drill up to it eg for a 3 eights hole go 1 eights quarter and finaly 3 eights or mark the holes and see if you can find a freindly metal shop who will do the job

bike 54

[Terry in Australia]

back to the current thread, yeah, i think the clip has to attach to the sprocket somehow, and if not via the depicted and discussed holes, then, uh, vegemite?  no, seriously, now you've got two hemispheres curious.  one chilly and one, mmmm, balmy, almost sweltering warm.....  -jon

Hey Jon, get f*cked! Ha ha, just joking mate, yeah I figured there was another clip supplied, just some of the previous posters didn't understand what John was saying about the supplied clip.

More than likely the "hardening" will be "harder" around the sprocket teeth, so where John has to drill and tap, it might just be a thin "skin", just slow your drill speed right down and use a sharp bit with plenty of cutting fluid, and you'll be fine.

Thanks for the weather update Jon, it's really warm here today, pity I have to switch off this computer in a minute and go outside in the rain and cold, ha ha! Cheers, Terry.

[Matt at PSB]

Another thing that is not right about this thread is the engineering diagram shown in the first post. This is a JT brand sprocket intended for use with a 530 chain. The last time I checked Sprocket Specialists did not sell the JT brand of sprockets: Did I mention the part #JTF288 is for a 530 chain?

Lastly JT #JTF288, if that is what you have, is a very good quality fully heat-treated steel sprocket. You will have a tough time drilling it & if you succeed you will compromise the sprockets heat-treating.

So obviously I must be missing something here.

Matt at PSB

[mrbreeze]

When I first started reading this post,the first thing that popped into my head was that you wanted to run an o ring chain and were going to go smaller for the side clearance.Back in 1985,I put an o ring chain on my Kawi 1000 and I can tell you there was a lot less chain adjusting. That bike didn't have a clearance issue though.If you do this, I would second what everyone else said. Put those holes in there and tap them cause thats what holds the sprocket to the shaft.Good luck with the conversion.

[oldbiker]

Just a small point. In the UK it is possible to buy 'Frei' drills which are so hard and strong that they will even drill througha file or case hardened metal. I saw them advertised in the magazine 'Model Engineer'

[jotor]

Another thing that is not right about this thread is the engineering diagram shown in the first post. This is a JT brand sprocket intended for use with a 530 chain.

....and, the drawing shows a sprocket with the clip mounting holes........