TAV2 backing plate to a clutch?

[noseoil]

Has anyone changed a TAV 2 backing plate into a chain-to-chain drive? I'm getting up to 15 hp & thinking I may want to run a chain-driven clutch instead of the belt system it comes with from the factory. Seems like I could just run the jackshaft with a sprocket as a driven part, make a sleeve to run the nut against to take up the slack & just run a better clutch in the front on the motor. There are plenty of choices available for a clutch & I could change ratios easily with two chains. More like the original setup, but I don't have one to use now & I do have the TAV that's already in place.

Feels like I'm getting some slipping now, but I've ordered a new belt. The old one is getting tired, but I've read that the TAV2 just isn't up to the task when you start adding more ponies. It was fine with the level 1 setup, but with the motor I'm running now, it's feeling like it isn't holding up to the motor on a hard pull.

Maybe the 7" driven unit is what I need instead?

 

[gbabins1]

Has anyone changed a TAV 2 backing plate into a chain-to-chain drive? I'm getting up to 15 hp & thinking I may want to run a chain-driven clutch instead of the belt system it comes with from the factory. Seems like I could just run the jackshaft with a sprocket as a driven part, make a sleeve to run the nut against to take up the slack & just run a better clutch in the front on the motor. There are plenty of choices available for a clutch & I could change ratios easily with two chains. More like the original setup, but I don't have one to use now & I do have the TAV that's already in place.

Feels like I'm getting some slipping now, but I've ordered a new belt. The old one is getting tired, but I've read that the TAV2 just isn't up to the task when you start adding more ponies. It was fine with the level 1 setup, but with the motor I'm running now, it's feeling like it isn't holding up to the motor on a hard pull.

Maybe the 7" driven unit is what I need instead?

I have used a TAV backplate as a jackshaft and it worked fine.

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[noseoil]

Gabins, curious what you did to mount the driven sprocket on the shaft. I thought of two different ways to do it:

1 - cut the shaft & tap it for the nut so it's shorter or
2 - make a spacer-bushing to take up the slop that will be there once the driven pulley is removed & set it back in place. I can probably get some DOM tubing to make the bushing so I don't have to butcher the shaft or buy another one online.

Did you do either of these?

 

[Raskin]

I'm interested in this also coz i may want to to run my mb200-2 on the lawn and small dirt road and would like 11 to 1 ratio w 19" tires to give me awsum torque and engine braking on the slope..i do miss the exhaust note :laugh:.i was thinking those two options,cutting shaft seems like more trouble then worth if you ever wanna go back to tc...could use original tc cover if using spacers so really wouldn't show..

 

[delray]

noseoil, a 7inch would only bump it up little bit . compared to what you really need to get it up too.
i believe you installed a black mamba cam. so that cam if set up correct would pull a easy 8000 rpm's.
the engine on a baja bike? correct?
so it would be safe to say you are only pulling 4000 max rpm's right now and the gearing is just holding back the motor.
thats the problem with building a motor like that and trying to make it perform well on stock minibike. it's kind of like building car engine and you installed with a stock tranny and converter and you got a set of 3:08 rear gears. it's just not going to perform at it's peak.
you could try the 7inch and also change the rear sprocket to the largest one that will clear the ground safely and that might get you close to the performance you are looking for or just go with a clutch(that can handle the power) and the biggest gear you can get on you rear jackshaft and also a large rear sprocket on the rim. for example you would have a 10tt on your clutch and a 20-25tt or more on your rear jackshaft and next to it would be a 10tt again and then back to your rear sprocket and that would also be fairly large too.
one big problem you can run into and hopefully it would be controllable. that would be wheel standing the bike from a dead stop/take-off.
one thing you got going is the bike is nose heavy.
need to buy a tach with memory. that will be your life saver when dailing the motor in........:thumbsup:
right now it's just a guessing game...:shrug:
have fun with it. once you get it dialed in your going to have fun with it.....:thumbsup:

 

[Havasu Dave]

...

 

[delray]

yes dave i am well aware of the 5000 rpm for comet units, but thats more of a magical myth. i have been doing alot of testing with the comet units this summer and found with correct parts you can make them work . specially on a bike like noseoil where he is just hot rodding around and just getting on the gas hard once awhile.
for me i like like 340 unit,but for most people thats something they would not want to deal with or it just won't fit or work for there application.
also when i say i like the 340 unit. thats for strictly drag racing.
https://www.oldminibikes.com/forum/tecumseh/131688-tecumseh-ohh-build-6.html

 

[SAS289]

noseoil, a 7inch would only bump it up little bit . compared to what you really need to get it up too.
i believe you installed a black mamba cam. so that cam if set up correct would pull a easy 8000 rpm's.
the engine on a baja bike? correct?
so it would be safe to say you are only pulling 4000 max rpm's right now and the gearing is just holding back the motor.
thats the problem with building a motor like that and trying to make it perform well on stock minibike. it's kind of like building car engine and you installed with a stock tranny and converter and you got a set of 3:08 rear gears. it's just not going to perform at it's peak.
you could try the 7inch and also change the rear sprocket to the largest one that will clear the ground safely and that might get you close to the performance you are looking for or just go with a clutch(that can handle the power) and the biggest gear you can get on you rear jackshaft and also a large rear sprocket on the rim. for example you would have a 10tt on your clutch and a 20-25tt or more on your rear jackshaft and next to it would be a 10tt again and then back to your rear sprocket and that would also be fairly large too.
one big problem you can run into and hopefully it would be controllable. that would be wheel standing the bike from a dead stop/take-off.
one thing you got going is the bike is nose heavy.
need to buy a tach with memory. that will be your life saver when dailing the motor in........:thumbsup:
right now it's just a guessing game...:shrug:
have fun with it. once you get it dialed in your going to have fun with it.....:thumbsup:

I agree with your car engine example. Why would you build a 8k RPM engine for a mini bike that tops out at 4500 or 5K RPM's on the road at top speed? The power the engine was built for is unusable.

He needs to gear for the extra RPM's.

 

[Raskin]

Sounds like you need a big tooth rear sprocket if you're running engine capable of 8k as delray said..running high gearing just hard on the tc...

 

[2SlickNick]

Tim, I have done this to my race bike. I have a 10 to the clutch, to a 17 to jack shaft in, And swap between 8,9,10,12 jackshaft out. To 50t on my Baja warrior. So far so good the set up has been working great.

 

[2SlickNick]

Also you'll have to do a little spacing with the clutch and the sprockets, but works fine and I do not have a chain tensioner for the jack shaft

 

[delray]

2SlickNick

I have done this to my race bike. I have a 10 to the clutch, to a 17 to jack shaft in, And swap between 8,9,10,12 jackshaft out. To 50t on my Baja warrior.

could you tell us little more. for example what kind of rpm's does the engine pull? are you running a tach?
also when you say swap between a 8,9,10,12 could you narrow it down so it's not a guessing game for him to buy all them gears.
personally i would never go that small on my teeth(8,9) with the engine setup he has that would curl up those teeth in a sort amount of time.

 

[gbabins1]

I just took the tav backplate (one of the steel ones) and slid my sprockets on, put the clutch on the engine and dialed in my gear ratio for my type of riding... actual did this on one of our old bikes and it worked like a charm. I didn't use spacer but rather locking collars and didn't have any issues. Only used it for a short while but it was fine. Put the nut on the end just in case any of them got loose... I wouldn't lose any of my goods. Also use lock tight.

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[gbabins1]

I also didn't want to mangle the tc plate and hardware in case I wanted to go back to the TAV in the future. [emoji106]

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[noseoil]

Thanks for the replies. I built the motor & wanted to run it just to see how it would work, so "use what you have" was the old Baja Warrior I've been riding. I'm going to put a bike together to use this motor, but it's just in the planning stages still. I run a tach, but it crapped-out this week so there's a new one on order. Should be here in a few days. Still waiting on jets for tuning.

Nick, are you going to the Saturday ride & car show at Westgate this weekend? If you are, could you bring the bike so I can take a look at it? Would like to see the setup, or a picture would do as well for how you're running.

 

[delray]

noeoil, if you decide to go with a clutch setup? couple other things to think about when finding a clutch. you definitely want to makesure it is rated for 15-20hp and has adjustable stall speed setup. i would think you would need at less 3000 stall built into it. for example if you are riding the bike and go to slowdown and turn it and at that point you want to get back on the bike hard. it might lag on you because your rpm's are at 2300 or little more and your clutch is lock up at that point. your engine will struggle little and you need it to rev higher(3000stall) into the power band. that will allow to push the bike better.
assuming you don't have the ability to make a sprocket out of a blank? i did find a company that sell's different rear sprockets for your bike. something you will need forsure.:thumbsup:
4 Hole Mini Bike Sprocket - GoPowerSports.com

 

[noseoil]

Delray, right now with the TAV I'm running 3100 rpm clutch springs, since I didn't want to lug the motor down to 2200 with the standard springs. Have a few more belts ordered, but they aren't here yet. Also have a better belt (racing kevlar) but don't want to use it for tuning & figuring things out yet. Too much $ to not have things working correctly so not putting it on yet.

Am looking into a better clutch setup as well, since it needs to be up at about 3K to even think about pulling from a stop. Need to look at gearing to see where I end up. Have the calcs for top speed, but it's for the new bike, not this one. Still pleased with the build motor in spite of the little problems. It seems to be running well enough. The tach will help me figure out where things are with it, guessing isn't really an option for what I need to do...

 

[2SlickNick]

2SlickNick
could you tell us little more. for example what kind of rpm's does the engine pull? are you running a tach?
also when you say swap between a 8,9,10,12 could you narrow it down so it's not a guessing game for him to buy all them gears.
personally i would never go that small on my teeth(8,9) with the engine setup he has that would curl up those teeth in a sort amount of time.

With JS I pull between 7300-7500 rpms ( yes with tach). I swap out the sprockets depending on my needs ( small tracks I use 8t, larger I use 9t and 10t, the 12t has horrible take off, but tops out around 55mph. I dont really use that one)...

Plus I use a 17T JS sprocket in with gives me more top end ( not like the stock 20t) So when I use the 17T with 9t it is very close to the 10t and 20t setup.

I used the stock JS too and top out around 45mph at 7500 rpms.

another reason I use the 17T is because it doesnt require and chain tensioner like the stock set up... No slack and not too too tight...

 

[delray]

ok nick, base on what your telling us he would want to maybe gear is bike down even more? reason i say that, his motor could spin little higher if wanted too and if he is using it more for off-road use . he want it pull good on the trails.

noseoil, think a clutch setup might just work better for you now. if you where to go with a tav you would almost need a jackshaft setup to gear the bike down enough so pull some good rpm's and that bike really doesn't have the room or the correct setup with having a bolt on tav and then have a jackshaft setup behind all that. you would also have to fab the 7inch driven to fit correct and that just might turn into alot of work. making fit right so it doesn't hit the frame and you would have to make a cover for the tav...etc...

 

[2SlickNick]

I would not recommend a jack shaft for the trails. Hey torque converter is so much smoother and better in the durability and dependability department – especially for off-road use.