[vwbobby]

Man it would be cool if he could do one of the old school TTR engine guards for the TW, I know some people adapted some, but something with some tubing to protect the side cases a little. Don't know if it's even feasible with all the stuff he's working on...

View attachment 233988

I know he's super busy with tons of parts, but figured if you don't ask, you'll never know.

I would buy a set. Sent him a pic a few months ago of the ones TCI used to sell, so he's aware of it.

 

[vwbobby]

That looks interesting. I'm wondering why stainless though. Isn't high carbon steel stronger?

Probably is stronger, Brad's looks lighter too, (more holes).

He has lots of experience building motors, part of his Bio: Brad Covington is a professional ATV Racing National Champion where he was not only a race ATV builder but also a professional engine builder. He also has years of successful experience in other forms of motorsports such as dirt track open wheel modifieds. For the past 16 years Brad has been designing and developing parts and components for a commercial lawn mower manufacturer. He has 6 U.S. Patents and counting. Using his manufacturing ideas and connections Brad has been able to design and develop products for the ever growing powersports vehicle market.

He tested the cam sprocket on one of his older bikes and was impressed with the outcome.

Ordered mine this morning and it's still not here yet.

 

[TWBigBlake]

I would buy a set. Sent him a pic a few months ago of the ones TCI used to sell, so he's aware of it.

View attachment 233989

Thats the one I was thinking of, I just couldn't remember off the top of my head this morning. Thanks VW!

 

[Ski Pro 3]

Advanced cam sprocket on the way. Excited about trying it out.

Prototype

View attachment 233987

valve timing advance does the following;
1. Improves low end power and throttle response
2. Intake valve opening event happens sooner
3. Decreases intake valve clearance
4. Moving 4 degrees causes peak torque about 200 rpm sooner.
Bear in mind that the TW200 stock cam may be designed with "ground-in" advance, where the centerline of the cam and the centerline of the crank are not aligned. Same with using a TTR225 cam or an XT225 cam in the motor.
As far as I can tell, the cam gears between the TTR, XT and TW motors are all of the same valve timing. No one is advanced or retarded in relation to the others.

If you want to experiment, you can cut a new keyway at any tooth on your current cam gear and set it for 4 degrees advanced compared to the existing keyway. I'm kind of surprised that's not what Bradly does: has a keyway for stock valve timing and another for 4 degrees advanced. One at 176 degrees from the other.

I'm currently running a TTR225 cam in my motor and I don't know the cam profile compared to a stock TW200 cam. I can tell you that the duration is less on the TTR but that it opens more. This results in a longer duration for compression to build. And that allows for a higher compression in a lower compression ratio combustion chamber. A low compression chamber with longer closed duration equals higher compression. I get 155 psi engine compression. 4 degrees advanced adds another 4 degrees of compression to build, likely improving torque but only if the intake valve doesn't hit the piston. I'm already seeing evidence of valve contact with my piston. It's likely caused by weak valve springs and at higher rpms allowing the valve to float and make contact, but I don't know that for sure.

I guess what I'm saying is to be careful adding 4 degrees of valve timing if you have other mods going on in your motor. I'd also recommend pulling the head and measuring the valve springs for spec with this mod. Especially on older engines. And by older, I don't mean higher mileage, I mean manufacturing date. The valve springs under tension will weaken with age.

 

[Ski Pro 3]

Here's a stock cam gear with a red mark showing the timing key is aligned with the TDC of the crank/piston:

And here is Bradly's cam gear showing there's 4 degrees of advance by moving the key counterclockwise by about half a tooth.

You can cut the same keyway in relation to any tooth and place it at TDC of the piston/crank and get your 4 degrees of advanced valve timing.

Another observation:
The stock gear is coated with a sound dampening coating and 3 large holes. The Bradley is not coated and instead has 6 smaller holes. I have no idea what this is going to sound like, but I think there's a reason the stock is damped, and the holes are the size they are.

For what it's worth, stainless steel is weaker than plain steel. The area is bathed in oil. I see no advantage to a SS cam gear. Why do you think motorcycle chains are not made of stainless steel? It's not strong enough.

And one last thing:
I think it's important to change the gear and the chain as a set. Cam chains stretch and they break in to the gear they were installed with. I'm surprised Bradly doesn't sell a chain with the gear.

I would enjoy hearing Bradley's take on my concerns.

 

[bradleytwparts]

Here's a stock cam gear with a red mark showing the timing key is aligned with the TDC of the crank/piston: View attachment 233991 And here is Bradly's cam gear showing there's 4 degrees of advance by moving the key counterclockwise by about half a tooth. View attachment 233992 You can cut the same keyway in relation to any tooth and place it at TDC of the piston/crank and get your 4 degrees of advanced valve timing. Another observation: The stock gear is coated with a sound dampening coating and 3 large holes. The Bradley is not coated and instead has 6 smaller holes. I have no idea what this is going to sound like, but I think there's a reason the stock is damped, and the holes are the size they are. For what it's worth, stainless steel is weaker than plain steel. The area is bathed in oil. I see no advantage to a SS cam gear. Why do you think motorcycle chains are not made of stainless steel? It's not strong enough. And one last thing: I think it's important to change the gear and the chain as a set. Cam chains stretch and they break in to the gear they were installed with. I'm surprised Bradly doesn't sell a chain with the gear. I would enjoy hearing Bradley's take on my concerns.

Ski, absolutely agree on everything. The sprocket is just a tool, and need to be treated as such. We did notice however that if your chain is stretched and causing a cam retard situation then this is an immediate correction. We have lots of miles on these things with no wear showing on the sprockets at all and no piston to valve clearance issues. I agree with you as well about the difference in strength of stainless vs carbon steel. It's the age old argument of which knife is better, stainless or carbon. Lol. We attribute the use of stainless in this application to two things. The laser cutting process causes a heat treatment on the profile, bringing it to the point of melting, which obviously provides a lot of strength and wear resistance, The second is that we want the nicest profile cut possible in this situation and stainless turns out much better than carbon steel as far as a clean cut goes when laser cutting. The factory sprockets are stamped and would require a huge investment in tooling and heat treatment. Laser cutting for low volumes works great for us in this situation. I could just as easily cut them out of steel but the cut just isn't as clean. Yes, they need to be replaced with the chain as a set, but most people won't do it. Ideally they would need to put in a crank to change the lower gear, but definitely nobody will do that. As far as the plastic for sound dampening goes, we can't tell any difference at all. I'm not sure why Yamaha puts it on some of the engines in this family, and some they don't. Unsure on what they were thinking there. I haven't been in Yamahas engine factory but I have been in several and to the best of my knowledge the holes are there for the tool that holds the sprocket during the cam bolt torquing sequence. Also, you are correct on the ground in cam timing. All the engines in this family are all ground on the same lobe centers with varying lift and duration as far as we know. It looks like 108/110 at straight up and obviously with 4 degrees of advance it would be 104/106. All great observations as always!

 

[Ski Pro 3]

Ski, absolutely agree on everything. The sprocket is just a tool, and need to be treated as such. We did notice however that if your chain is stretched and causing a cam retard situation then this is an immediate correction. We have lots of miles on these things with no wear showing on the sprockets at all and no piston to valve clearance issues. I agree with you as well about the difference in strength of stainless vs carbon steel. It's the age old argument of which knife is better, stainless or carbon. Lol. We attribute the use of stainless in this application to two things. The laser cutting process causes a heat treatment on the profile, bringing it to the point of melting, which obviously provides a lot of strength and wear resistance, The second is that we want the nicest profile cut possible in this situation and stainless turns out much better than carbon steel as far as a clean cut goes when laser cutting. The factory sprockets are stamped and would require a huge investment in tooling and heat treatment. Laser cutting for low volumes works great for us in this situation. I could just as easily cut them out of steel but the cut just isn't as clean. Yes, they need to be replaced with the chain as a set, but most people won't do it. Ideally they would need to put in a crank to change the lower gear, but definitely nobody will do that. As far as the plastic for sound dampening goes, we can't tell any difference at all. I'm not sure why Yamaha puts it on some of the engines in this family, and some they don't. Unsure on what they were thinking there. I haven't been in Yamahas engine factory but I have been in several and to the best of my knowledge the holes are there for the tool that holds the sprocket during the cam bolt torquing sequence. Also, you are correct on the ground in cam timing. All the engines in this family are all ground on the same lobe centers with varying lift and duration as far as we know. It looks like 108/110 at straight up and obviously with 4 degrees of advance it would be 104/106. All great observations as always!

Thanks for the details. Much appreciated. Have knowledge of the difference between the stock TW cam and the YFM250? I have a TTR225 motor with a YFM cam, figuring it was designed for low rpm performance. Would that cam benefit from a 4 degree cam advance or would that be too much if the YFM cam has advance already ground in?
Cheers!

 

[bradleytwparts]

Thanks for the details. Much appreciated. Have knowledge of the difference between the stock TW cam and the YFM250? I have a TTR225 motor with a YFM cam, figuring it was designed for low rpm performance. Would that cam benefit from a 4 degree cam advance or would that be too much if the YFM cam has advance already ground in?
Cheers!

I assume you are using the 225 cam and sprocket then. The TTR sprocket should be advanced similar to mine already. I don't think it will provide you with any gains in your situation. I bet yours runs pretty dang good. To the best of my knowledge Yamaha handles all their cam timing on this family of engines with their sprocket. Do you use the CV style carb or the older round slide?

 

[Ski Pro 3]

I assume you are using the 225 cam and sprocket then. The TTR sprocket should be advanced similar to mine already. I don't think it will provide you with any gains in your situation. I bet yours runs pretty dang good. To the best of my knowledge Yamaha handles all their cam timing on this family of engines with their sprocket. Do you use the CV style carb or the older round slide?

Mine is a 229cc cylinder and piston for a YFM250 quad with a TTR225 head and a YFM cam and a TTR225 bottom end.
I am using a TW200 CDI and stator, but a rotor from the TTR225 (which I'm told has a few degrees extra ignition spark duration that is advanced. It would be very easy to replace the TW200 stator and CDI with the TTR parts.
The motor hits very hard right off idle, almost impossible to stall above 500 rpm. It tops out at a hair over 8,000 rpm on flat or uphill/load, but I can get to 9,000rpm going down hill or sitting and in neutral.
It has a stock TW carb with a 34 pilot and the needle lifted with two .010" thick shims.
It has 155psi compression. Easy start, very strong low rpm torque with little power gain above 7,000 rpm but will overrev to 8k without any affect to power.

 

[bradleytwparts]

I have found some good performance gains out of the older 2000 and down round slide carb. The newer CV style carb is crap.

 

[tjet]

I have found some good performance gains out of the older 2000 and down round slide carb. The newer CV style carb is crap.

Good info. Is that an easy swap?

 

[bradleytwparts]

Good info. Is that an easy swap?

Not sure if you are referring to the sprocket or the carb but they both are easy swaps. Takes me 5 minutes to do a cam sprocket now and about 10-15 to do a carb swap.lol

 

[tjet]

Sorry - carb... Thanks!

 

[Ski Pro 3]

Not sure if you are referring to the sprocket or the carb but they both are easy swaps. Takes me 5 minutes to do a cam sprocket now and about 10-15 to do a carb swap.lol

Just be sure you don't drop that cam pin. I played hell fishing mine out of the crank. Eventually a strong magnet through the aluminum crankcase did the trick.

 

[Ski Pro 3]

I have found some good performance gains out of the older 2000 and down round slide carb. The newer CV style carb is crap.

Do you have a carb swap mod in the works?

 

[SEADUB200]

I have found some good performance gains out of the older 2000 and down round slide carb. The newer CV style carb is crap.

-Aaaand, just like that, all the =/< 2000 M.Y. used TW carbs on the interwebs up and went POOOF!

 

[jb882]

Going to a pre 01 carb is not that bad a deal but you do need some parts to do it right. The carb boot to engine and air box to carb boots are different and must be swapped. They are different lengths and the pre 01 carb is smaller on the engine side so the 01+ carb boot will never seal on a pre 01 carb, there is also the resonator tube that the pre 01 does not need. The throttle cables are also different( longer if i remember correctly) and with that the throttle tube is also different too. One may be able to get the throttle cables to work if they were so inclined.

I did this swap on my bike years ago and was able to rob all the parts off an 89 parts bike i had. There is more "performance" to be had for sure, the pre 01 carb and its mechanical slide has significantly better throttle response than the CV carb does so when you twist it the bike responds instantly. Top speed unchanged on mine. I dont think it makes any more power per-se, just significantly better throttle response.

That said i did swap mine back to the CV carb. Why? Since i have two 06's that are for all intents identical i desired to keep it that way for a number of reasons. Biggest is ease of maint and repair when on the road so i swapped it back. As well as a common spare parts inventory at home.

If i had a second pre 01 carb i would probably convert them both.

 

[robtattoo]

Someone posted an earlier thread about upgrading their carb to one of these.....

https://a.co/d/8efnZVi

I think that might be my next mod/upgrade purely for the throttle response.

 

[SEADUB200]

Someone posted an earlier thread about upgrading their carb to one of these.....

https://a.co/d/8efnZVi

I think that might be my next mod/upgrade purely for the throttle response.

👆🏻👨🏼‍🔧🤙🏻

 

[Ski Pro 3]

Someone posted an earlier thread about upgrading their carb to one of these.....

https://a.co/d/8efnZVi

I think that might be my next mod/upgrade purely for the throttle response.

Hell, for 60 bucks AND will arrive tomorrow, I'm giving it a shot.
Now, where can I get a 40 degree angle throttle cable guide?
I would like a turn-key cable, throttle assembly, something like this so I can leave my TW assembly intact:
Amazon.com: Accelerator Twist Throttle Handle Fits for 50cc 90cc 110cc 125cc 140cc Motorcycle 7/8 22mm Twist Throttle Accelerator Handle Grips : Automotive