Unofficial Royal Enfield Community Forum

Royal Enfield Motorcycles => Bullet with the UCE engine => Topic started by: Drifter on June 25, 2010, 07:02:58 pm

Title: Sprockets on C5 vs G5.
Post by: Drifter on June 25, 2010, 07:02:58 pm
From looking at the pictures and seeing the bikes the cases are different on the 2 models, based on my dealer and the feedback on here a 19 tooth front sprocket can not be added to the C5, how about the G5 does that case have room for a 19? Are the rear hubs different? 
Title: Re: Sprockets on C5 vs G5.
Post by: ace.cafe on June 25, 2010, 07:38:00 pm
The G5 has a 17 tooth sprocket and 19" wheels.
The C5 has an 18 tooth sprocket and 18" wheels.

It is my understanding that the G5 can take the 18T sprocket, but that's as far as it can go.

I believe  that the hubs themselves are the same. But the wheel diameter is different.
If you used 19" wheels, with tires that aren't "squattier" in profile, this should result in a longer roll-out distance, and make  the effective gearing taller, by maybe the same as what a tooth on the sprocket would give you(if you're lucky). I don't know the exact ratio change, because I don't know the roll-out of whatever tire would be selected.

However, the theory would be that a longer roll-out of the larger wheel and tire would make the gearing taller by some amount.
Title: Re: Sprockets on C5 vs G5.
Post by: Drifter on June 25, 2010, 10:30:01 pm
Ace, you are correct the larger wheel and tire would be equivalent to adding a larger front or smaller rear sprocket. So with the larger wheels and the 18 tooth on a G5 it should make a noticable difference in the RPM at any given road speed and a more relaxed engine.

 Anyone with a G5 changed the sprocket?
Title: Re: Sprockets on C5 vs G5.
Post by: t120rbullet on June 25, 2010, 11:32:32 pm
Anyone with a G5 changed the sprocket?

I changed to a 18 tooth sprocket on my G5.
As you can see in the pic the sprocket comes pretty close to the boss just to the rear of the sprocket. The sprocket in the pic is a 17. An 18 come real close to the boss. I don't know if you could squeeze a 19 in there if one was available. Holding a 19 tooth 4 speed sprocket over the sprocket on the G5 I don't think it would. Maybe with a bit of Dremel action it would.
Also note that the case directly in front of the sprocket is pretty thin. A loose chain on a large sprocket could cause an oil leak or 2.
CJ

Title: Re: Sprockets on C5 vs G5.
Post by: Ragmas on June 27, 2010, 02:52:36 pm
I changed to a 18 tooth sprocket on my G5.
As you can see in the pic the sprocket comes pretty close to the boss just to the rear of the sprocket. The sprocket in the pic is a 17. An 18 come real close to the boss. I don't know if you could squeeze a 19 in there if one was available. Holding a 19 tooth 4 speed sprocket over the sprocket on the G5 I don't think it would. Maybe with a bit of Dremel action it would.
Also note that the case directly in front of the sprocket is pretty thin. A loose chain on a large sprocket could cause an oil leak or 2.
CJ


What kind of performance results did you get with this change?

Sam


Title: Re: Sprockets on C5 vs G5.
Post by: t120rbullet on June 27, 2010, 03:11:55 pm
Didn't really notice any difference. At least the motor didn't notice it. Probably moved the vibration point up a few MPH.
IMHO the G5 should just come with the 18 on it as there were no downsides to the change at all.
CJ
Title: Re: Sprockets on C5 vs G5.
Post by: Drifter on June 27, 2010, 04:51:19 pm
Thanks for the pic! If the sprocket in the pic is a 17 i think you are right a 19 would not fit.
Title: Re: Sprockets on C5 vs G5.
Post by: Drifter on July 01, 2010, 06:36:00 pm
T120, how much clearence was there after you added the 18 tooth with the chain on it?  I wonder if grinding the boss a bit would allow a 19 to fit or cutting a notch and welding a patch over the hole?  Then there is the problem of getting someone to make the complicated splined sprocket i really dont understand the logic of there design...
Title: Re: Sprockets on C5 vs G5.
Post by: t120rbullet on July 01, 2010, 07:44:25 pm
T120, how much clearence was there after you added the 18 tooth with the chain on it?  I wonder if grinding the boss a bit would allow a 19 to fit or cutting a notch and welding a patch over the hole?  Then there is the problem of getting someone to make the complicated splined sprocket i really dont understand the logic of there design...

I just happen to have that side of the motor apart right now but it's at the shop and I won't be there until Sat.
I'll take a pic of with the 18 tooth sprocket on it and post it for you. I do lube my chain quite a bit so it's not as pretty as the other pic.
CJ
Title: Re: Sprockets on C5 vs G5.
Post by: Leonard on July 01, 2010, 08:43:28 pm
I just happen to have that side of the motor apart right
CJ

Hey CJ, I haven't been around much lately, what's going on with your G-5?
Title: Re: Sprockets on C5 vs G5.
Post by: t120rbullet on July 04, 2010, 12:31:54 am
Pic with 18 tooth sprocket on G5
Title: Re: Sprockets on C5 vs G5.
Post by: r80rt on July 04, 2010, 12:51:22 am
When I first got my C5 I thought I wanted a taller front sprocket, but after 1500-2000 miles the engine was so much stronger and smoother, that I decided the 18 was just about right and forgot about it.
Title: Re: Sprockets on C5 vs G5.
Post by: 2bikebill on July 04, 2010, 09:25:32 am
"" after 1500-2000 miles the engine was so much stronger and smoother""

This has been the general consensus among G5/C5 owners who have posted on the matter here. The difference in the engine after 1200/1500 miles from new is significant.
Title: Re: Sprockets on C5 vs G5.
Post by: Drifter on July 04, 2010, 01:10:55 pm
CJ, thanks for the new pics!, from looking at that close up i think a 19 will fit!  People with New KLR 650s fit a sprocket that is so close a little grinding is needed to clear and they work fine so i think it will work here also!!

My Triumph has a 19 front and its closer to the case than your pic of the RE with the 18. So now we have to locate a 19 tooth sprocket for the UCE engine.....  Im stoked for the challange now.

Does anyone have a 18 in hand to measure the diameter, the difference should be slightly more than 5% so from looking  at CJs pic we should be able to get and optical idea of how close it will be with a 19..
Title: Re: Sprockets on C5 vs G5.
Post by: shappers on July 05, 2010, 10:02:06 am
Hi t120rbullet, thanks for pointing that out I wasn't aware of that.

Back to plan A then

Cheers, Roger.
Title: Re: Sprockets on C5 vs G5.
Post by: Drifter on July 05, 2010, 02:20:41 pm
Shappers, your numbers indicate that there is apx. .25 inch clearance that is more than enough to run the 19 tooth sprocket.  Now all we have to do is find one or get one made.  Some time this week i will check a couple of places and see what it would cost.

At least we are making some progress, slow but progress........
Title: Re: Sprockets on C5 vs G5.
Post by: shappers on July 06, 2010, 12:13:20 am
Hi Drifter, its closer to an eigth than a quarter but stiil possible providing theres enough room in the corners. I guess getting a sprocket blank shouldn'te too difficult its machining the the centre.  I wouldn't fancy trying to file that out.

Cheers, Shappers.
Title: Re: Sprockets on C5 vs G5.
Post by: ace.cafe on July 06, 2010, 12:20:51 am
How about cutting the middle out of an AVL 19T sprocket, and turning down the outside of the UCE sprocket to fit inside, and then welding the outer toothed part of the 19T to the inner center part of the UCE sprocket?
Title: Re: Sprockets on C5 vs G5.
Post by: r80rt on July 06, 2010, 12:30:36 am
That would work.
Title: Re: Sprockets on C5 vs G5.
Post by: Ice on July 06, 2010, 12:44:56 am

Heres a link to a couple of examples from McMaster Carr,,scroll down half a page.
http://www.mcmaster.com/#sprockets/=7u1p1b (http://www.mcmaster.com/#sprockets/=7u1p1b)

 The multi spline design of the UCE sprockets is much stronger than the few coarse splines design of the earlier sprockets