Sprockets - Does new bike have the wrong ones?

I can wait for either, just didn't want you forgetting! :) I'm busy reading hugo short story winners from the last few decades... (amazing stuff btw).
 
DanMach said:
I'm busy reading hugo short story winners from the last few decades... (amazing stuff btw).
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At first I thought you were reading victors of the Victor Hugo Award - I suspect M. Hugo would not have like our tax structures either. I guess it's generational.
I just hope my new-found curiosity :umm: about Mr. Gernsback doesn't slow down my sprocket switch attempt tomorrow morning.
 
I have a dirt bike which I know is off topic on this forum,but pertinent in that both have gear ratios. On it[a '75 Dt400],It came out with a 14/40 gearing,then I bought a new chain set[chain and both sprockets],but instead of 14/40,I got 14/44,which was much lower in ratio. 14/40 is a 2.86/1 ratio,14/44 is 3.14/1,quite a difference,particularly when you consider that it's primarily a dirt bike that has lights for the street. After changing the chain,sprockets,it has explosive power and will raise the front wheel up at will in any gear. At one time,this would be my dream,to be able to wheelie at will with a twist of the throttle,but not now,at 60yrs.I bought a 16t primary gear[2.75/1] which should give a slightly tamer performance,though very fast.These machines have a top speed of 87mph with stock gearing with a standing 1/4 mile of 14 seconds flat.That's pretty much top speed in 1/4 mile. My bike with different carb,bored,ported slightly is much faster than that,so I'll tame it and make it more street worthy.One can always change primary sprockets easily,and only readjust the chain slack,and be on the road or woods quickly. lha
 
DanMach said:
I can wait for either, just didn't want you forgetting! :) I'm busy reading hugo short story winners from the last few decades... (amazing stuff btw).
Click to expand...

You say that your bike lacks the sidepanels.I've got both from my '82 xs400rj seca.I wonder if they are alike enough to fit.I have no use for them,as the tank that came with the bike was totalled[rusted through].I'd be glad to give them to you if they'll fit,as I have lots of stuff in the way.Send me a Pm,and I'll trace them out on paper,send it to you,and if they'll fit,you're welcome to them. lha
 
:poke:

SUCCESS!

After fuelling up on a Tim's breakfast sandwich with ham on toasted English muffin, I
1. headed for the Gorge with my 16T and ran a couple of hills several different ways;
2. met a group of vintage retirees who were at the Forks (a nice bonus);
3. met my old friend who is buying the sr250 at home to load the bike;
4. went to the DMV and did all the paper work;
5. got the money for the 250;
6. had a nice dinner together;
7. returned home and swapped in the 17T front sprocket; then
8. darkness descended.
 
We want ride review!! Hows the power with the new gearing? Whats your freeway speed/rpm? Hows it feel? (I know I can calculate gearing online but the tach and speedo are both a bit off on these bikes.)
 
DanMach said:
We want ride review!!
Click to expand...
I wondered how long it would take you to ask. It was a busy day and I got almost everything done. Everything but the comparative test of the bike with the 17T since darkness descended as we got it back together. I will do it tomorrow morning, I promise.
I have several comparatives though. I rode up a steep twisting hill twice, once in 3rd and once in 4th (entering the steep part just after a hard left). RPMs at the start point were 3500 and 3000 respectively. In 3rd it accelerated smartly up the steep part. In 4th it barely held its own at the start and gained just a bit.

2nd hill was a straight very steep stretch. I did this one 3 ways. 1st run was from a start on the gentle slope just below. Accelerated up through all five gears and was going 105 kph and gaining at the crest. 2nd run was in 4th gear doing 90 kph at the beginning of the steep part - at which point I gunned it. It accelerated to 95 kph at the crest. 3rd run was same as the 2nd, except in 5th instead of 4th. Gunned it at the same point and it couldn't hold its own and slowed to 85 at the crest.
Can't wait to duplicate these runs tomorrow with the 17T.

The actual swap of the sprockets was as easy as pie - couldn't quite believe it after all my obsessing.:bike:
 
jayel said:
how did you make out with the chain adjustment difference (posistion of rear axle) between the 16 and 17
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Hi Jayel. Almost exactly as you predicted. After loosening the axle bolt, we loosened each of the 2 lock-nuts about a quarter turn and used them as markers. Pushed the wheel forward all the way, did the swap then pulled the wheel back until the chain was right and each lock-nut was the same distance from the frame. I could see 2 1/5 ridges of thread on both sides - about 3/16ths.
 
By the way, I've been messaging svbrian who slotted a 6-speed Seca transmission into his Maxim with stock gearing, and he said it's quite comfortable for highway riding...

Just to throw that option into the mix. Seems this is the official DOHC 5-speed thread now...
 
From his note to me:

The main shaft and countershaft (and gears of course) dropped right in. The shift drum and its hardware is also needed and probbly the shift forks (sorry I can't remember but I probably used the seca ones). The maxim shift shaft assembly was used (looks the same but was in better condition). I also used the seca neutral switch cover but I think the maxim part is the same. No surprises and works like a charm. I cruise at 100 km/h with 5000 rpm in 6th gear. Need to downshift twice to get anywhere fast on the highway. However dropping a tooth on the front sprocket might be an idea as 6th seems a bit tall for my liking and there would be less clutch slipping requried from standing starts (especially annoying when the engine is cold). I haven't really ridden with the 5spd so I can't say if its worth it. I did the swap because I already had the parts and the engine was being disassembled anyway. Hope this helps.

I'll be trying this out next winter. If I get around to it, I'll post a how to.
 
Lou Ranger said:
Can't wait to duplicate these runs ... with the 17T.
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I rode up the steep twisting hill twice again today, once in 3rd and once in 4th. RPMs at the start point were 3500 and 3000 again.
Virtually no discernible difference from yesterday with the 16. In 3rd it accelerated smartly up the steep part. In 4th it held its own at the start and gained a bit.

Did the same 3 runs on 2nd hill with the straight very steep stretch.
1st run was from stopped on the gentle slope just below. Accelerated up through all five gears and was going 102 kph (vs-105 yesterday) and gaining at the crest. I can't say for sure that I shifted at exactly the same points as I did yesterday. I am still freaked by the 10,000 rpm red-line and my ear simply can't believe I can rev it that high without an explosion.
2nd run, again in 4th gear doing 90 kph at the beginning of the steep part - where I gunned it. It accelerated to 93 (vs- 95 kph) at the crest.
3rd run, again in 5th gear doing 90 at the beginning of the steep part. Gunned it at the same point and it couldn't hold its own and slowed to 80 kph (vs- 85) at the crest.

Cruising along at 80 kph (50 mph), the rpms are now 4,650 (vs- 5000). At 98 (60) it now runs at 5,500. I am delighted with this result and only wish it was a bigger difference.
I could not make it behave any differently from a dead stop (something I worried about) so I am very pleased. Maybe it is idling better today because it is hotter and much more humid - don't know - but I noticed no difference.

It achieve my #1 goal and I do not believe I will notice any overall performance loss. Occasionally I will now downshift to 4th instead of just leaving it in 5th, but conversely, some other times I will just leave it in 4th going through town instead of up-shifting to 5th. So, all kinds of riding considered, I will end up shifting gears the same number of times.

Not everyone is bothered by the high frequency note while cruising, but if you are, I would highly recommend the switch. B-W, try it before sinking a lot of money into a Seca parts bike. It only cost me $23 and doing the switch was so fast and easy it would be no hassle to go back if you change your mind.
If I were you Petei, I would definitely try the 17T. If you test it in the mountains and don't like it, I would still take both size sprockets on my trip home (& a few wrenches) with me and run the 16 until the downside of the Rockies and then 17T all the way from there.
Same goes for you Dan. When you go up to Flagstaff, switch to the 16 and run the 17 down below.

For what it's worth guys .......:woowoo:
 
Thanks man!! That sounds perfect for me! Gonna order it once I finish my next shipment design lol. This bike is going to be 80% new parts before 2012 is over.
 
bentwrench said:
I checked my front sprocket, and it looks just like the 17t - there's a raised centre section.
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It's not that I'm a worrier B-W, but when we took the retainer clip off, I expected to see that raised centre section, but it was the flat side of the sprocket.
The raised centre was on the back side. So we put the new 17T on that way too (naturally), but then I wondered if the PO had done it right, or had he simply put the 16T on so the "16" stamp would show.
The reason I wondered? The JT sprocket has the size stamp on the opposite side. Can I assume the side that's stamped is irrelevant and the raised centre faces in/flat side faces out?
Thanks, :er:
 
I would say center in... just because the lock plate would lie flat (bolt up) against the sprocket that way, but check chain alignment to be sure.... trust but verify
 
bentwrench said:
When in doubt, check the manual. The parts manual shows a flat side out, so I suppose the PO on my bike set mine up wrong. Thanks for the tip!
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Bienvenue, but most of the wisdom I am able to impart comes purely by accident. All it proves is that I had a better PO than you did.
Why didn't I think of the manual? Sure enough, the transmission diagram shows a flat side. But can we be sure that the manual doesn't show a sprocket with no raised centre on either side? Can't see one when I peek through that hole on the drawing .....
I do know mine works beautifully now, and the chain 'appears' to be lined up perfectly. Did you ride yours very far with it in the other way?
 

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