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Offline SilverCycle

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #20 on: June 12, 2019, 09:02:48 AM »
Thanks yes. Great update. I did study the Otto cycle at degree level, but it was a long time ago, and anyway, specific industries - in this case I guess motorcycle tuning - evolve their own jargon for elements the acedemics have different names for. New version much clearer.

For anyone following, I guess in AFR you mean "fuel" rather than "water", unless water is used as a reference to standardise for different fuel densities?

Online Oyabun

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #21 on: June 12, 2019, 09:10:00 AM »
Thank you for the proof reading, typo corrected.
I've only studied internal combustion engines to a college level, my masters are in Business and applied mathematics.
Fuel densities are standardised through their mass equivalence - so fuels burned in Otto (and also in Miller or other exotic petrol burning engines running mass available pump gas) have an average 14.7-14.8 stoich AFR, while other fuels have different mass air fuel ratios. e.g. pure ethanol 6.4, natural gas 15.5, diesel 14.5.
Academic community like the use of Lambda as far as I understand - but fueling variations are so small represented in Lambda that AFR is a much easier to comprehend value with it's two digit higher changes (hat's what is commonly used in the car amd motorcycle tuning community. E.g. a moderately rich petrol AFR of 13.2:0 what is considered as the rule of thumb to tune to for performance has a lambda value of 0.9 compared to AFR and 14.7 and lambda 1 respectively.
« Last Edit: June 12, 2019, 09:29:17 AM by Oyabun »

Offline Bern_Grt

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #22 on: June 12, 2019, 12:19:57 PM »
Just goes to show that this bike really appeals to a lot of different users !
My X is mostly used for work commuting which for me is a mix of suburban roads, some back "country" roads and occasionally a shortish bit of dual carriageway.  I don't do long distances, if/when I go out for a day's ride with no particular destination in mind, I tend to stick to back roads such as these...

As for "technically" challenging sections, opportunities, even for just "green laning" are quite limited in my area. The most "challenging" roads look like these...

... Not all that technical really !
Anyway... I had changed from 15/41 to 16/41 after only a few hundred miles from new as 1st gear was just too short for me and, it's a quick and easy "fix". A couple of weeks ago, and after over 10000 miles on 16/41, I decided to change my original chain which had developed some very stiff links (it wasn't that well looked after !). Checked out Ebay prices and having found some reasonably priced stuff, I decided to change not only the chain but also the front & rear sprockets to end up with 15/39. What can I say...
It's great ! It was fairly time consuming for me as I had never split & riveted a chain before and the tool I have is probably not the easiest to use but well worth it for me. 1st gear is not as tall as with 16/41 but still much more usable than I recall the 15/41 combo being. As for the other gears, I have regained a fair bit of "responsiveness" I hadn't realised I had lost ! All in all, I am now really happy with my current configuration and it's a keeper for me :)
Bern.

Offline Jonathan

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #23 on: June 12, 2019, 04:13:42 PM »
*Originally Posted by Oyabun [+]
Sorry, editing time window is over.
It's gonna be off topic here, this is really an answer to a question about switchable maps.

To summarize in plain language.
We have ECU (Engine Control Unit) reflash (kind of reprogramming the operation parameters, not the entire operation) solution for the oem pre-19 ecus - but the maps are not switchable.
Currently on the fly switchable maps available with external hardware Dynojet Power Commander V.).
AFR means Air Fuel Ratio - where AFR 14.7 (14.7 weight unit of air is mixed with 1 weight unit of fuel) also called stoich, or Lambda 1 is the mixture of lowest emissions. This is where the engines are normally set ro operate. Smaller numbers mean richer, larger ones leaner mixture.
One of my maps is developed for performance with richer mixture, more aggressive ignition timing and no fuel cutoff at deceleration. The other one is an economy - cruise setup with leaner mixtures and conservative ignition timing.
Hope it helps.

So what's the limiting factor of switchable maps on the fly? Probably most beneficial for those who are doing more serious off roading, or anticipate crap fuel quality on a big adventure, but a plug and play option for the X would be a good seller, albeit niche.

Offline Lysdexic

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #24 on: June 17, 2019, 03:28:39 PM »
I agree 100% with the OP. I made that gear change on my 2013 at 12,000 km. It now has 44,000 km and it is a pleasure to ride, long distance at high speeds (cruise at 130KPH no problem) and slow twisties are equally easy with no feathering of the clutch required. And we have roads here that have massive switchbacks that take you all the way down to the bottom of 1st.
It's horses for courses, I love the X for it's ease of handling and dependability on roads far removed from assistance as well as navigating dirt tracks and tiny village streets. If I wanted a trials bike I'd buy one. May as well denigrate a Cadillac for not winning the Pikes Peak Hill Climb.
Best mod I made, period.

Offline Jonathan

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #25 on: June 18, 2019, 03:58:46 PM »
15/39 here and I prefer it to stock but I do notice a couple of 'holes' where it's lugging and I need to change down. I'll try a 16 on the front in due course...should take off a bit quicker. Compared to my old V twin Transalp 600, the X needs to wrung out a bit more...

Offline manray

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #26 on: June 26, 2019, 06:40:52 AM »
*Originally Posted by Jonathan [+]
15/39 here and I prefer it to stock but I do notice a couple of 'holes' where it's lugging and I need to change down. I'll try a 16 on the front in due course...should take off a bit quicker. Compared to my old V twin Transalp 600, the X needs to wrung out a bit more...

Just picked up a 39 Tooth rear.  Does your 15/39 setup still use 112 link chain?  Thanks.

Offline Jonathan

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #27 on: June 26, 2019, 05:31:14 PM »
I'm going to say yes, but I'll double check my receipts....I bought an endless chain rather than a split or rivet link and it was a good few months back...I'll post back in a bit

Offline Jonathan

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #28 on: June 26, 2019, 05:35:14 PM »
*Originally Posted by manray [+]
Just picked up a 39 Tooth rear.  Does your 15/39 setup still use 112 link chain?  Thanks.

No...110
DID Gold and Black X-Ring Endless Chain G&B 520VX2 110 Links
( 401417793216 ) from Brooksbarn

I went with an endless as I was regreasing the swingarm bearings and shaft so it was all apart at the time.....next one will be a rivet link :016:

Offline manray

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #29 on: June 26, 2019, 06:10:26 PM »
*Originally Posted by Jonathan [+]
No...110
DID Gold and Black X-Ring Endless Chain G&B 520VX2 110 Links
( 401417793216 ) from Brooksbarn

I went with an endless as I was regreasing the swingarm bearings and shaft so it was all apart at the time.....next one will be a rivet link :016:

Thanks for quick reply.  I installed a new OEM chain a few hundred kms ago and was hoping I wouldn't have to cut and re-rivet for a perfect fit.
« Last Edit: June 26, 2019, 06:12:51 PM by manray »

 


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