I want a counter shaft sprocket with another tooth, 1st gear is too low.

 

My 400x has a 14 tooth, with interesting cover over it keeping the rear brake line and wiring out of the way. A 15 tooth will fit in there but do not think a 16 tooth will.

 

Does anyone know if the speed 400 has the same rear sprocket or is it different from the 400X??

 

My Scrambler has a 43 tooth rear.

 

I have used Sprocket Specialists in the USA for many decades. Good company,

 

I just installed the JTF1908.15RB sprocket from SO CAL Powersports $18.98 to the door. It fits perfectly, I still do not think a 16 tooth will fit under that wiring guard, but heck who knows somebody will figure out something if they can find a 16 tooth sprocket that is. Pouring rain test drive coming soon.

 

After 2 hour rain gear testing, boots and gloves failed terribly but gear change has relaxed the engine quite a bit. Well worth the under $20 price.

 

Anybody know what the torque spec is on this sprocket? It’s not in the owners manual.

 

did you need a puller to remove the sprocket? Did you have to split the chain? Could not get the original torque value had to use the rattle gun to remove the nut

 

Howdy all, going to jump in on the back of this one...

I have a speed 400 and am interested in getting a few more MPHs out of it, especially in 1st gear.

@Bent Sprocket, you don't think a 16 tooth countershaft will fit eh? You think its just that little shroud and the wiring on the outside of it that are the issue? I haven't pulled the sprocket cover off of mine yet, but i feel like it wouldn't be that hard to rework that to allow for the extra clearance.

Anyways, i've found a few places that make custom sprockets such a sprocket specialists and rebel gears. If we can come up with the appropriate sprocket specs for a bigger front sprocket i'm definitely going give this a try.

I'll obviously reach out to a few places and see what they need as far as specific specifications but as this seems to be a somewhat common subject with these bikes I figured i'd loop the internet forum community in for potential information sharing.

 

Howdy all, going to jump in on the back of this one...

I have a speed 400 and am interested in getting a few more MPHs out of it, especially in 1st gear.

@Bent Sprocket, you don't think a 16 tooth countershaft will fit eh? You think its just that little shroud and the wiring on the outside of it that are the issue? I haven't pulled the sprocket cover off of mine yet, but i feel like it wouldn't be that hard to rework that to allow for the extra clearance.

Anyways, i've found a few places that make custom sprockets such a sprocket specialists and rebel gears. If we can come up with the appropriate sprocket specs for a bigger front sprocket i'm definitely going give this a try.

I'll obviously reach out to a few places and see what they need as far as specific specifications but as this seems to be a somewhat common subject with these bikes I figured i'd loop the internet forum community in for potential information sharing.

I would focus on the rear sprocket, drop a couple of teeth you’ll be right where you want to be more than likely. When I see one around 40 tooth I’ll try it.

 

thanks

 

Thank you for the reply My sprocket should arrive Wednesday. I will try to arrive at the original torque spect. and post

 

Here's a link to a 15 tooth front sprocket. I have not tried it yet, but another forum (Triumph Rat) said it fits fine.

Amazon.com

 

With the throttle fix and the 15 tooth sprocket bike is now so much better, I am now happy.

 

Has anyone tried fitting a 41 tooth rear sprocket on a Speed 400 or Scrambler? That may be the only option for higher gearing on the Speed 400 as the Speed 400 already has the larger 15 tooth counter sprocket that some have upgraded their Scrambler to. It's easy to take the scrambler to a 15 tooth from a 14 tooth stock counter sprocket as the 15 tooth is available and we know it will fit. A 16 tooth looks like it may not fit at all with the internal guard that exists on both bikes. Has anyone tried to fit a 16 tooth counter sprocket?

Ref notes for some head scratchin' and Old Speckled Hen swiggin':

Scrambler stock gearing- 43 tooth rear sprocket, 14 tooth counter sprocket, 140/80 17" tire. (25.82" diameter)

Speed 400 stock gearing- 43 tooth rear sprocket, 15 tooth counter sprocket, 150/60 17" tire. ((24.09" diameter)

Moto Nonno

 

Has anyone tried fitting a 41 tooth rear sprocket on a Speed 400 or Scrambler? That may be the only option for higher gearing on the Speed 400 as the Speed 400 already has the larger 15 tooth counter sprocket that some have upgraded their Scrambler to. It's easy to take the scrambler to a 15 tooth from a 14 tooth stock counter sprocket as the 15 tooth is available and we know it will fit. A 16 tooth looks like it may not fit at all with the internal guard that exists on both bikes. Has anyone tried to fit a 16 tooth counter sprocket?

Ref notes for some head scratchin' and Old Speckled Hen swiggin':

Scrambler stock gearing- 43 tooth rear sprocket, 14 tooth counter sprocket, 140/80 17" tire. (25.82" diameter)

Speed 400 stock gearing- 43 tooth rear sprocket, 15 tooth counter sprocket, 150/60 17" tire. ((24.09" diameter)

Moto Nonno View attachment 161

Hi moto nonno, I’ve been ranting at triumph uk for weeks about a 16 tooth sprocket. All they come up with is that it upsets the ttc and abs. What a load of rubbish! A 400 40 horse engine spinning up the rear wheel, NAH, and if you can’t handle the braking, there must be a problem with the pilot. I was watching WSS 300 13-8-24 checked out spec, it goes from 250cc to 400cc with speeds up to 120mph. Maybe this is the main problem. RESTRICTION. We’ve got bikes potentially WSS 300. Just saying. If you are going to change rear sprocket do it to 40 or 39. 2.66-1 or 2.60-1 mind the swing arm chain rub? Ronno Sutt.

 

Has anyone found a 41 tooth rear sprocket part number or supplier?

 

Here's the only one I can find that says it's for the Triumph Speed 400. Bad news it's in Australia. But may help with info to find one in USA. I suspect there is one that will work once we figure the mounting dimensions will work/match.

41t Steel Rear Sprocket for 2024 Triumph Speed 400 (rpmmoto.com.au)

Do these dimensions match? More research required. The fun continues.

Moto Nonno

 

Thanks. I split the chain and used a puller to remove the sprocket. All in all pretty straight forward. Took an hour and a half. I just happened to have a chain breaker and the right master link. Had to buy a 27mm socket. I torqued to 90 ft lbs should be sufficient. As it is 90-95 degrees here. Test ride early tomorrow evening. With the throttle fix and sprocket change should be just about perfect. thanks to all for advice.

 

Can you please list the new RPM’s at various speeds?
Thx

 

Is it necessary to split the chain in order to change the sprocket?
Loosening the rear wheel and chain adjusters isn't enough?

 

Chain splitting is not necessary. You can loosen the rear wheel and turn the chain adjusters in about an inch and it gives enough slack to slip the chain off the rear sprocket. Once this is done, the front comes out easily.

 

Thanks for the reply. That's just what I wanted to hear

 

I guess the other part is. I don't think that drawing is correct for the Triumph.

 

Toxigig,

Good info and good research. First I like your dimensions on the sprocket ID, Bolt Circle and hole clearance diameter (66 mm ID, 110 mm BC, & M8 clearance) way more than what 'RPMMoto' had listed. In fact, that link that I found and posted earlier with that 41T sprocket has been taken down... just checked. "Page Not Found". My guess those dims are for a larger Triumph Speed and not the 400. So good info on your measurements. Thanks for the update and correct dimensions.

About the 37 tooth rear sprocket; that sounds like a considerable increase toward higher gearing, (43T to 37T) especially with the bigger dia wheels/tires on the Scrambler. Have you also upgraded the counter sprocket to a Speed 400 15 tooth from the stock Scrambler 14 tooth? Also with the smaller 37 tooth, I wonder about the clearance of the upper chain to the rub block that is on the top of the swing arm. You will have to keep the forum posted on your results. You should have a considerable drop in rpm for 6th gear cruising.

Looking forward to your upgrade experience and results. Are you in BC by any chance... or PEI?... Saskatoon?

Moto Nonno

 

Happy day.
Installed the 37 tooth rear from Rebel Gears. It went pretty easy. Bought a new chain to avoid any master link pin size issues. Just need a 15 tooth for the front, and I'm expecting it will be great.
Also a thank you to Rat400x and Bent Sprocket for the details on the 15T front.

Stock steel sprocket 826 g
New aluminum sprocket 313 g

For anyone wanting a rear made. I can confirm that the following dimensions are good.
ID 66 mm clearance.
Bolt circle 110 mm.
Bolt hole size M8 clearance.
Choose your tooth count (generally in odd number increments).

Initial impressions are good, but no chance for a real ride until next week.

 

I just ordered my 37 tooth rear sprocket on Friday. Should be shipping by Wed. I already swapped-out the 14 tooth to the 15 tooth this past Saturday. That was s decent improvement on its own. Still needs more reduction in MOI, hence the 37 tooth rear being ordered.

 

I tried to upload my gear ration calculator, but .xlsx files are not allowed. So here's a screen shot.

I've been riding the GB400 for around 7 years, and with a recent change to a 120 rear tire from a 110, the increased rolling diameter brought the bike to what I now consider is the ideal gearing for it. Before the tire change, I was considering a single tooth reduction on the rear sprocket. As it happens, a single tooth, and the tire size change yield the same results. Another happy day.

As a frame of reference, I thought the GB was pretty good (34 hp,400 cc single, similar weight). So I looked at speeds in gears (low and high), and RPM on the highway, and settled on the 15 37 combination. I chose 4900 RPM, as that's 100 km/h on the GB, and it's in a pretty happy place. The scrambler has more power, and is plenty strong close to 5000 RPM. I'm expecting a slight range increase.

If anyone wants a calculation posted, Please send me the details, and I'd be happy to adjust the numbers. Or a copy of the spreadsheet, please let me know. Any ideas on sharing the file? I'm happy to email it if anyone wishes.

 

So a cryptic understanding, when I was just a lad we would do a rough 1 tooth front equate 4 tooth rear . so would you be so kind as to post 400x stock with a 14 stock counter and changing rear sprocket to 37 tooth. would be appreciated

 

A final word. The 15T front will come soon, meanwhile the chain is contacting the rubbing block on top of the swing arm just a little bit with my weight on the bike (155 pounds). A heavier rider would have less issues with this. If a 16T front would fit, then the 16-39 would be a better way to go.

 

This is awesome information! I definitely want to change at least the front if not both sprockets now. Thanks!!

 

Toxigig,

Sounds like you have got the right bike for your area. I'm in the south of San Jose CA country near Morgan Hill. But I'm heading out early tomorrow for Chilliwack to visit my brother... not on the Poco Rosso for this trip. I've done that trip in the past on my old Norton Commando Fastback to Victoria up the Pacific Coast Highway and twice at least on my 72 R75/5 BMW to the Canadian Rockies. Got to ride the Canadian Rockies if you haven't. I'm guessing you have. I've got a niece in Saskatoon and a nephew on PEI... Prince Edward Island. Very spread out. No bikers. They just tolerate me. LOL
I will attach a couple of pdf poems inspired by my old Norton for a laugh from this area many, many years ago.

It will be interesting to hear the results of your sprocket swaps. Maybe a Throttle Slop Stopper next for you?

Moto Nonno

 

Before I go about changing sprockets, could sprocket changes void the warranty? Or would that be an ok modification? Would they (dealership/triumph) even know or care?

 

I would think it all depends what is claimed under the warranty. The dealer would have to attribute the claim to the modified sprocket. If it was electrical that would be difficult. I personally not have any hesitation in changing the sprockets.

 

Good question, I had the same concern.
I assume it depends on your dealer.

 

Moto Nonno,

It sounds like you have a strong Canadian connection. There is certainly some good riding in BC. The Kootenays in particular are great. But south of the border, you guys are spoiled for choice.
That's a sweet looking Norton.

If I had a different use case, I'd likely choose the Speed over the Scrambler. The dynamics of the bike on pavement suit me better. But while I'm still doing this amusing, rough and tumble commute, and riding in all weather conditions, the Scrambler makes more sense.

 

Yes, great photo. Sure looks like Canada to me!

You're not riding that bike to U-Vic are you?

Moto Nonno

 

Cool pic, enjoy the Scrambler.

 

This is the best solution I can find so far. It means they need to be bored out, holes on correct pcd drilled, and possibly lightened.

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I'm fortunate in that I am a machinist (albeit p/t now) and am able to finish one to my required specs.

 

Why go through all this trouble, MTXPARTS.COM have it in their catalogue.

 

Good if you have the skills and the equipment to bore to spec. I know of an engineering shop near to me but I would not like to guess how much they would charge.

Would it be an hours work or more?

Ian, at least there is a possible solution available here in the UK