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15 tooth front sprocket, Anyone make this change and not like it?

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Hi, as the title reads, I am considereing the 428 conversion and am trying to decide on if I should try the 15 tooth front. Any input positive or negative appreciated.

Thank you

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hahaha.

Nitrobandit,

It might help your question if you tell us what you are running. I'm running 16/60 428 chain conversion. I believe BBR runs a 15/55 428 chain conversion. I don't even recall what the stock 520 chain set up is.

What are you running now? Answer that and I'm sure you'll get some answers.

I want to change mine to a 14 front/54 or 53 back but I still have a lot of life in my chain so I'll just run it for a while. It works fine, but I want to play with some gearing to see what happens.

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A 428 chain has smaller links therefore the sprockets will have more teeth but will be the same diameter as the 520 equivalent.

I am running a 15T 428 on my chinese pitbike and it looks pretty close (without actually measuring) to a 13T 520.

Cheers, #319

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04CRF150F#319,

hahaha This is getting funny. O.K., I'll run with it.

So you're running a 15 front sprocket. What do you have in the rear?

Nitrobandit,

You can run anything that will fit in the front sprocket. Same goes for the rear. I can run a 13 in the front and get more bottom end then a 16 up front? How? Well, it just depends what I'm running on the rear sprocket.

Here's a tip for you though. If you only add a tooth to the front, it would be the same as adding 3 to the rear. Hope that helps.

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You shouldn't be so quick to laugh. :ride:

If you only add a tooth to the front, it would be the same as adding 3 to the rear.
Adding to the front is equivalent to subtracting from the rear, proportionally. And vice versa. :thumbsup:

Your comment about 13 vs 16 bears careful reading. With a fixed rear, you'll always get more low-end with a smaller front sprocket. What's your point?

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I ran a 14/47 and did not like it. It is close to a 15/50 in final drive ratio. I switched back to 13/47 and I like that quite a bit more.

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You shouldn't be so quick to laugh. :ride:

Adding to the front is equivalent to subtracting from the rear, proportionally. And vice versa. :cry:

Your comment about 13 vs 16 bears careful reading. With a fixed rear, you'll always get more low-end with a smaller front sprocket. What's your point?

Did I say that backwards? :ride::thumbsup: What an idiot I am. hahaha.

Well, your example was what I meant.

My point was he asked about putting a 15T up front. Doing so is only half the equation. You're example, however, mentioned a fixed rear. That was my point. The rear sprocket is the other half of the equation. That's all.

If he's running a 16/60, for example, and went to a 15, he's get a lot of lowend. That's not all though. His 1st and 2nd gear would become totally useless unless he was getting into snail races.

If he's running a 55 in the rear, however, I bet it would round pretty good.

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...I am considereing the 428 conversion...

Don't do it. Many of us have previously commented on this. It doesn't work out for the $$$..stay with good 520 gearing, etc and be happy. Invest some time in the search function "428 conversion, 428, etc" and make a truely informed decision about the 428 swap.

You will find hours of reading to keep you busy

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I just installed a 14 tooth CS sprocket yesterday and dropped to a 49 tooth rear sprocket for a 3.5 gear ratio vs. the stock 13T Front, and 50T rear with 3.85 ratio. Just moving to a 15 front and keeping the 50T rear gives a ratio of 3.33 which means more top speed, less acceleration. Doing a 14T front and 47T rear is equivelent to the 15/50 or = 13/44. I'm wondering if installing a revbox will help acceleration after moving to the new gearing (14/49) essentially making the bike accelarate faster and have more top speed? I also skipped the 428 conversion because it wears out the chain and sprockets faster, plus there is a reason why they use 520 chain because the power of the bike requires a stronger chain you would think.

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Hi Thank you all for the replies, I guess what got me thinking about this was coming accross this article... http://www.off-road.com/dirtbike/projects/crf230f/4/

Toneconsultant, I'm all bone stock in the gearing right now. and as that article reads I do find first kinda low and almost unusable.

mcdrz, I will definately do some searching and hopefully I can make some sort of rational desicion... Hopefully...

Thank you all for the replies.

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Could be so easy.

Just search the forum.

I did te conversion (and am still alive, it works).

Without a 428-conversion, what is - in my eyes - just bullsh... as you weaken your powertrain.

http://www.thumpertalk.com/forum/showthread.php?t=379516

If you guys over there don´t get hands on that 15-tooth Kymco-sprocket for 520 chains, just let me know. We´ll find a way to send it overseas and I´m going to be rich, jeehaw!

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I can tell you the difference as soon as i get my chain on, I have to get some lengths cut and then I'll give it a spin. I have a trailtech computer and it will give me a good indication if it adds anymore topspeed. I went with the 14 tooth and a 49 tooth rear sprocket. If you want to know if it is worthwhile mod I will tell you within a few days if not today.

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1st gear pulls longer and the engine isn't overreving as much. 1st and 2nd are better, not perfect but noticeably improved. Shifting seems more natural when I rode on the street, i felt more like i was riding a bike more suited for dual sporting. Still plenty of power on the low end, I noticed less acceleration but not anything i'll miss, starting out I just give it a little more gas and you can stay in first and second longer before you have to shift, pretty much all the gears are more spaced out and you can go faster in each gear before having to shift. When you open throttle it seems a little more drag on the engine for a split second but once its moving into the higher RPMs it seems to stay moving quite nicely and less drag on the engine. I am happy with the gearing and the acceleration of the bike. In the day light tomorrow gonna test topspeed. The trailtech speedo doesn't light up in the dark, why the hell not I ask??!! How do i tell how fast i'm going in the dark with my trailtech??

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Well I maxed out the bike at 71 MPH according to my trailtech. Overall the Topspeed of a 14T Front and 49T Rear with a Renthal R3 O-ring chain, it is estimated at + 5 MPH vs the stock gearing.give or take a mile or two. I remember stock I could get about 67MPH on that speedo. TO put it all in perspective I have an 18 100/100 Dunlop offroad tire, a worn down stock front Pirelli 21'' tire, bigger main jet and pilot jet/ removed airbox snorkel, FMF powercore 4 slip on exhaust muffler. I can say I liked this mod.

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Hi Thank you all for the replies, I guess what got me thinking about this was coming accross this article... http://www.off-road.com/dirtbike/projects/crf230f/4/

Toneconsultant, I'm all bone stock in the gearing right now. and as that article reads I do find first kinda low and almost unusable.

mcdrz, I will definately do some searching and hopefully I can make some sort of rational desicion... Hopefully...

Thank you all for the replies.

Nitrobandit,

Cool deal. As you already saw, I already scuffed the post. hahaha. I wasn't trying to hound you on it. Just trying to make sure whatever answer you got from people, that it made sense.

As for what McDrz said, He doesn't know $hit!!! Just kidding.

:thumbsup: hahaha. McDrz's advice is good advice.

I did the 428 chain and I might have to agree with him. Don't expect power.

I changed to the 428 because I didn't want that steel rear sprocket. Obviously, you know steel is heavier than aluminum. The O-ring stock chain also does have a lot of drag. Those two things cannot be argued. I didn't want to wait for the stock chain to wear out. That would take 40 or 50 year! That's why I changed to the 428.

I was buying a rear and chain anyway so I did it. If $$$ is tight, I'd suggest an aluminum rear sprocket and run it. The stock chain is still a good chain. That way you'll get rid of some weight.

Of course, you weren't even talkin about the rear, but just the front. Looks like I'm trying to clean out your wallet. hahaha Oh well, hope thisinfo helps.

P.S. "Unsprung weight?" I guess technically that's true, but i don't recall getting the bogus 3-4 hp that Motocross Action magazine boasted about. The stickers on my fender gave my bike way more power than the conversion. :ride::cry::ride::ride:

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Toneconsultant, Thanks gain, fortrying to spend all my pennies for me LOL!!

Ya I was hoping someone would say ...ya ! you really can feel the bike accelerate quicker with the lighter chain and sprockets, Oh well... I may messwith the gearing a bit none the less... I do a lot of work on drag cars and we see such huge gains in acceleration when rotating weight is shaved, I figured (hoped) that the 428 would be noticable. Perhaps I will just tweak on the engine in search of a little more power,

I'm toying with the idea doing a little port work and valve job, ( I port automotive heads for a living) Perhaps also kicking up the compression with a Weisco. I don't think I will change cams as from what I have been reading is that most of the cams push the running duration up and all that is doing is moving the power band upwards. With the stock cam and the high comp. piston the trapped (dynamic) cylinder pressure will be way higher. and should offer lots of bottom end-mid snot. Oops i'm starting to ramble... back to work...

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Nitrobandit,

If you can port yourself, that would be helpful. I know one port job is different from the next, so I can't speak for all, but my head was ported. It raised the powerband. I thought that was pretty cool. I basically started going faster because I could ride my gears a bit higher.

Then I got a 170cc kit and cam. I wish I could do them one at a time, but since the engine was apart, I said, "Do them both!!!" Therefore, I can't say which made the difference, but there was a big difference. The problem, however, is I was told my porting wouldn't do much until I got the cam and piston.

Result? So is the cam and piston a good mod, but if you get it ported, it's super? Man, it sucks when you can't tell which mod does exactly what it does.

Anyway, I did all three and my engine runs really well. No complains. It's pretty far from a stock engine feel. Hope that insight helps.

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