HOW TO: Gear Ratios Explained - POWER REPUBLIC

This week we're explaining gear ratios, how to use them and when to adjust them.
Subscribe here: / powerrepublic
For more information head to our website:
www.powerrepublic.com.au
Or check out our social media at:
/ powerrepublic
/ powerrepublic
#POWERREPUBLIC

[@tonymac144]

excellent for us aspiring mechanics/dad engineers

[@PowerRepublic]

thanks tone,

[@CatlowRacing]

im an aspriring mechanic and these videos have been incredible and a complete life saver and you have so much commitment! will defo be watching every vid you have and be sharing 👍👍

[@PowerRepublic]

Best of luck!

[@markbridge7571]

This kart dad is appreciating your videos. Simply explained for the newbie! your videos are now my spare time killer. Thank you!

[@PowerRepublic]

Hey Mark, you are very welcome and thanks for the good vibes. All the content here is free to a good home, specially for the new guys 😊. thanks heaps for tuning in

[@Adventure-Story]

Thank you Sir ! you are awesome.!

[@PowerRepublic]

Thanks for watching and sharing the vids Bro 😎

[@davidjeal2626]

just got my first kart and found the channel looking for tyre changing. Great info, well explained and good tips on tools too. Noq exploring all the other topics. Cheers.

[@PowerRepublic]

Glad it helped!

[@garrettfrankenberg1746]

Extremely helpful thank you

[@PowerRepublic]

Hi Garrett, you are very welcome

[@motorsportministries7843]

Will you guys ever do videos on the lo206 briggs and stratton with the growth of drivers in that class? I know 4 cycle is simple but a mini series on that could help a lot, especially because in north america and australia beginners start out on 4 cycle? Cheers

[@PowerRepublic]

its a great beginners class. stay tuned....

[@nicoletriplett9389]

@@PowerRepublic I have a lo206 Briggs and Stratton we run a 1/6 mile dirt track what gear ratio would be best for my son is beginner boxstock…

[@DEKarting]

Love the channel, has helped me so much since i started karting 18 months ago, thanks for supporting and helping us all. You should tag “what different types of chains should I use” in your description for this one, I watched it aages ago and have been looking all morning trying to find it again for your bit on o ring vs no o ring etc I’ve been running o ring all year (tag 125 restricted) but thinking of going back to non o ring 🤔

[@PowerRepublic]

Happy to help! yeah our search could definitely do with some updating

[@Eastendhunter9]

Great video

[@PowerRepublic]

Thank heaps!

[@WillWalker]

Amazing content Amazing channel Love it!

[@PowerRepublic]

Will Walker 英國留學生活 thanks mate, please feel free to share any vids with your Karting friends or people who would appreciate them.

[@WillWalker]

Power Republic definitely

[@Theoliviasqaud]

You’re the best brotha!!

[@PowerRepublic]

Thank mate, appreciate the good vibes

[@petersjuri]

Ah video about Shifter Karts in general would be greatly appreciated!! Maintenance and stuff I need to know in order to have my shifter race ready 🙏🏼

[@PowerRepublic]

Hey Juri, what sort of shifter kart have you got?

[@petersjuri]

@@PowerRepublic My chassis is an Otk (Kosmic Mercury R 2019) and I have a 2020 Vortex engine

[@jasontietnan5447]

Just bought a 2020 Kz tonikart with a tm K9 engine,a gearing video on the shifter karts would be greatly appreciated,such fun to drive but also quite challenging

[@grahamedleston4994]

Hey DJ, awesome videos! I have learnt soooo much from them only getting our first kart a few months ago! Its a 2014 Mad Croc with Rotax Senior Max ......and every day is a school day at the moment.... They've helped From servicing it, removing and refitting tyres to servicing the carb and resetting up the mixture (its now running x10 better)- amazing job, keep them coming!! Next subject is gear ratios for us... We are currently running it at our local track here in South Wales, UK (Llandow) but are heading off to Whilton Mill in a few weeks. The recommended gear ratio for WM is 12/80 on the Rotax Max (currently it has 11/76 on it with a 104 chain) - if I was to change to the 12/80, how do I work out what chain I'll need? or will the 104 do the business for me with the engine adjustment? Its roughly in the middle of its adjustment at the moment - Any advice is much appreciated as about to order the 80 sprocket, Diolch Graham

[@SelfMadeism]

Thank you

[@PowerRepublic]

You're welcome

[@cesaroliveirafotografia6401]

Thank you for your videos!! I bought a kart a weak ago and your videos was an amazing help!! Keep going the good job! Thanks! 😃

[@PowerRepublic]

Hello my friend, you are very welcome. Thank you for tuning in. Please feel free to shared the HECK out of our videos ;)

[@cesaroliveirafotografia6401]

By the way, my gear ratio is 13-82, the track that I race is not too big, I should use 11T or 12T front sprocket? I feel that my engine (non evo rotax max) is too slow exiting the corner (I’m a beginner too). Thanks!

[@PowerRepublic]

@@cesaroliveirafotografia6401 gee 13T, must be a massive track. What is the max RPM you are getting?

[@cesaroliveirafotografia6401]

@@PowerRepublic I don’t know yet, I will get my rpm display this week, I hope.

[@PowerRepublic]

​@@cesaroliveirafotografia6401 great idea. roughly how long is the main striaght ?

[@clarke4574]

Great work. Very helpful

[@PowerRepublic]

Thanks heaps Clarke

[@ktm150sx2]

Power Republic also you always leave a comment if people are asking questions thank you very much!

[@ktm150sx2]

Power Republic also you always leave a comment if people are asking questions thank you very much!

[@SammyPProductions]

So what should I do for a 4ss torini super max engine with a clutch gear 16 teeth? Should I aim for a 68 to 70 axle sprocket

[@timcoley6064]

Great vid m8 how about one on cleaning kart and engine after a meeting and one on de-carbon exhaust

[@PowerRepublic]

Hey Tim, how's the racing been up north? I most certainly can do that for you. I'll add it to the list

[@cregkarting9556]

Do you have a video or can you consider in a video touching on the difference between a standard machine sprocket vs. a machined skip-tooth sprocket? Is the advantage of the skip-tooth sprocket primarily less friction on the chain travel? Is it a matter of wear and tear or is there a performance difference? We run the Rok VLR100. Thanks!

[@PowerRepublic]

I haven't used them my self, but they were quite popular a few years ago. I don't see them that much anymore. Maybe the qualifying sprocket has lost its way.

[@IggySport1388]

Derek can you shed some some light on the O-ring chain in terms of initial lubing...do you add lube on top of the factory grease lube? And then how often do you lube these when racing? Noticed you mentioned on the non-o ring chain to lube between every session... is it the same for the O-ring?

[@PowerRepublic]

Hey Chris, you can use an O ring chain with your rotax engine no problems. they last way longer than a tradition non O ring chain. I still lube them every time like I do for either chain. Yes I do personally lube them the first time over the factory grease. then every time I come in off the the track I re lube the chain again. Yes both chains and sprockets need Lub every time. Remembering that the chain is steel and so is the front sprocket, so with steel on steel you need some lube to keep the friction and the heat down between them.

[@nate1593]

Thanks for the info, super helpful. Do you have any videos for newbies to show changing a front and or rear sprocket and then I'm guessing you then need to change chain length and how that is done? Cheers and thanks!

[@PowerRepublic]

Sure do man, basically google ‘how to’ ‘go kart’ and the ‘problem you have’ and one of our vids should pop up.

[@nate1593]

@@PowerRepublic thanks heaps

[@russellcooper2900]

i have loved all your Videos they have helped me out so many times with maintenance etc, Thankyou from the UK. On the Sporocket sizes I was informed that a formular to use regarding chain length was if you add the sproket sizes together and then add 10 links that would give the best chain lentgh, Is this formular correct? Or do you use another formular? So say 76 rear plus 12 front = 88 plus 10 = 98 link chain length.

[@PowerRepublic]

Hey Russ. Nah I haven’t tried that one. We deal in the same karts/engines/track combos so we can guess the length for most people

[@armandorangel8337]

Great video, I currently have a 12T and 84 sprocket with a 110 o-ring chain that I just installed last week. But still nervous about the chain tension. I follow the manual instructions and still not confindent about it. If I switch from 12T to 11T could that make it faster or do I also have to change the rear sprocket? Thanks

[@PowerRepublic]

that will make for faster acceleration if you put the 11T and leave the rear sprocket the same

[@KartFreedomGoKartTrack]

What is your recommendation and what setup you prefer for middle speed track? X30 max speed on track 125 km/h, low speed is about 53-55. Would you like to use 11-76 or 10-69 gear sprockets? Or it does not matter at all? Thank you

[@durhamphoenix6669]

Great video, how do you know what size chain to use?

[@PowerRepublic]

Hey Pete, thanks for tuning in. its trial and error. and experience. if you know hat ratio you have, and kart type, your local kart supplier should be able to recommend some sizes that are close .

[@zacfonner5426]

Thanks for all your they are very helpful.. I just got my first KA100. I have been told i need to run a solid gear vs a split gear. I know that the KA produces more torque but can you discuss why you would run a solid gear and not a split gear or visa versa.

[@PowerRepublic]

Hey Zac, are you asking about the rear sprocket? if so I wouldn't use a split one if I didn't have too, like on a KA100. Hope that helps and thanks for tuning in

[@zacfonner5426]

@@PowerRepublic Correct I am talking about the rear sprocket. What are the advantages to running a solid rear sprocket vs. a split rear sprocket.

[@brg88tx]

Good explaination. I'm trying to gain more speed, so I am going to go with a 12t sprocket on my jackshaft instead of the factory 10t. Should lower my gear ratio from 5:1 to 4.17:1. More speed, less torque.

[@PowerRepublic]

hell yeah it is. better to practise low, race higher if necessary

[@brg88tx]

Well, the sprocket didn't fit the jackshaft bolt. 5/8" is not the same as 16mm. Anyone know on any 16mm sprockets besides the 10t and 20t that come standard on the coleman mini bikes?

[@Kawshun911]

Hi, Love the videos. Just wondering should you hit the max RPM 16000 on an x30? and how long is too long to be at 16k? Don't want to cause damage to the engine. Thanks.

[@PowerRepublic]

Hey thanks heaps for tuning in. yeah 16k is best, they have a rev limiter and you cant damage them any more than normal. g

[@christianbuczko1481]

I presume reduce the rear until i hit max at the end of the longest straight to get absolute best??. Increase if im red lining before the end?

[@PowerRepublic]

Other way round if you are talking about the rear sprocket. Bigger rear increases acceleration and smaller rear increases top end speed. And it is relative to your competition.

[@jesperek6402]

Hi, can you make a video for a beginner like me, how to change the sprocket and chain, and show when you adjust the engine, and how much you lube the chain before each pass. I have a standard gold chain on my Tonykart and I think I have to change the chain aftet next pass. And if I have to shorten the chain, how, and what tools do I need? I wanna let my son try different sprockets, but I wanna be shore not to do anything wrong. Cheers / Jesper

[@PowerRepublic]

kzbin.info/www/bejne/f2TGZ3t-hpmsi5Y check that one out Jasper

[@jimnrel]

How do the DID O ring chains survive in dirt kart racing on WOT Rotax.

[@PowerRepublic]

IMO they will be way better than the standard chains in the dirt Jim

[@walktallracing7967]

Hey mate, you say 13 front for rotax in extreme cases. Our current configuration, we change every 5 races in a season, has two straights 182 and 230 m ong. Slowest corner is around 6400 rpm, but only the one. The rest of it is pretty flowing. At 915 m total our lap times are 40 secs or so. Consider that extreme? I'm at 12/78 and considering a 77 to pass italian motors x125 at end of straight, but wondering about the 13.

[@PowerRepublic]

You could try a 13/82or 83 for that little bit extra. It is hard to pass the X30 at the end of the straight and still get the engine to move out of the slowest corners.

[@jordanwhitehead4618]

Say I'm trying to hit a 4.0 ratio. And say running a 56 rear and 14 front, or a 60 rear and a 15 front sprocket both hit a 4.0. Will those different sprockets but same ratio react any different? or will it be the same?

[@PowerRepublic]

Hey Jordan, great question. I have never run that high, but if you're at a massive track and need top end I would go for the biggest front sprocket combination. Maybe there is more top end in it for you, but it would be hard to quantify with out a little back to back testing on your track with both gear ratios and then overlaying the data from your mychron to see.

[@SelfMadeism]

I have a question? What is the chain length to buy for a iame ka100?

[@PowerRepublic]

depends on the track and chassis you're using. 102-106 normally

[@federicosansone4213]

Hi! I love the channel! I am planning to buy a Kosmic kart with a Rotax Max Evo just for hobby. I was wondering what should be the best o-ring chain size for me in order to preserve the engine (I don’t care about lap times). Thanks!

[@PowerRepublic]

probably a 108 or 110 link DID O ring Chain

[@federicosansone4213]

thanks! @@PowerRepublic

[@ktm150sx2]

I am wondering if a belt drive would be any good for a go kart?

[@PowerRepublic]

I have seen them before but if you would want to have the perfect gear ratio diameter before you got them made up, my guess is it wouldn't be cost effective v's performance increase. definitely cleaner without chain lube. maybe for an electric kart?

[@ktm150sx2]

What engine do you have in the go kart you showed the example of chain tension on? Would a Honda gx160 or gx200 be any good?

[@PowerRepublic]

Vortex Mini Rok, most kart engines fit on karts with some re engineering. depends if you want to race or just play around. when you are racing you have to have \the same as everyone else

[@ktm150sx2]

Power Republic okay thank you I’m only just playing around not doing any serious racing!

[@davidjeal2626]

what about chain length relative to sprockets? do you recommend the total teeth +10 approach?

[@PowerRepublic]

nah I haven't tried that one. is that an approximation or something ?

[@kartbroertjes]

How about the length of the chain. I heard longer = better (no pun intended). Is that true or does it depend on the type of tracks or engine?

[@PowerRepublic]

I have tried both 11/80 with 108 chain or 12/85 with 112 chain. Didn't change my world. We did put some new tyres on and that mak=de a big difference. Basicall on short tight tracks I use the little front sprocket combination and on the longer faster tracks I use the bigger front sprocket combo with the longer chain. Hope that helps

[@andreasjacobsen1637]

I was out karting the other day I had just changed the chain and the back sprocket. I lubricated it the day before I went to the track but because I'm new to all this I forgot to lubricate It through out the day. I drove about 2 hours and now my sprockets are all beaten up and my chain is way too loose. There is also metal Shavings is that clearly because of my stupid mistake or could there be something else??

[@PowerRepublic]

Andreas Jacobsen yeah not good. Need to lube chain every session. The metal is the sprocket that has been chewed up. If it were me, start again with brand new chain and Front & Rear Sprocket.

[@christianbuczko1481]

I just recieved an alfano pro ro run on my prd fireball 125 engine. Is there any chance of you having a vid already like that, or could you do one at some point??

[@PowerRepublic]

I don’t have one the Alfano. I haven’t used one for a few years as I always found the Mychron an easier interface, so I am not that well versed in the Alfano product.

[@christianbuczko1481]

@@PowerRepublic no problem, ive been in contact with alfano and can ask at PFI international where i have a contact at karttune. I think i can get it going on a basic level myself, with the rest sorted out down there at min costs. Thanks for responding though.

[@rcmichael6524]

When buying a new chain do you usually need to get rid of some links or do they usually fit right out of the box?

[@Eastendhunter9]

On My son's kart setup (cadet) we use 114L n we end up removing 2-3 links. You do want adjustability.

[@PowerRepublic]

The chain length is important. If you get a new one and it is too long or too short, you won't be able to adjust the engine on the chassis enough to get the chain tension right. Best thing is too take the chain with you to your local kart shop and they can measure and match it for your new one. Other wise, lay the chain on a flat surface and push the chain together to make a long straight line. Then count the links of the chain down one half of the chain in 2's i.e 2, 4 ,6, 8 ,10 ,12 ........ then when you get to the end, for example, you might have 52 links, now double that and you have 104 link chain. This is because the number of links of a chain is measured on both sides of the chain. Hope this helps.

[@codywiggins9659]

I have a 14 tooth front and 72 rear sprocket and i hit gas and cant go no where without a push ill just sit in one spot burning clutch what do i need to do

[@PowerRepublic]

can you change your gear ratio? otherwise maybe you need to clean out the clutch drum and shoes?

[@harryhurstracing]

Can you do a video on cadet gx160 engine clutch and sprocket sizes pls

[@PowerRepublic]

I don't have that much experience with the GX series engines. Where do you race yours Harry?

[@harryhurstracing]

@@PowerRepublic Tracks all over the UK

[@harryhurstracing]

harryhurstracing,com dad and lad team :)

[@ginoborghese677]

What chain size would you recommend for a 12/82 junior rotax ?

[@PowerRepublic]

108 - 110

[@nacoleon18]

hello! do you have a video on this matter but focusing in KZ?

[@PowerRepublic]

hey Pablo, no I don't have that much on KZ other than the KZ engine building series

[@adamcollingburn430]

It's pretty much the same philosophy - playing with your needle and jetting for the most power in the current temps, then running gearing based on track. I'm did my first race weekend in my kz last week and had great pace, but found I was only in 6th for about 3 seconds down the main straight, so next one I'll run a higher ratio to help me change to 6th faster and achieve a higher top speed at the end of the straight

[@colecurtis390]

I'm just building a go kart how low of a ratio should I go with a 305cc engine I was look at a 14 front 40 back is that ok?

[@colecurtis390]

To clarify I will just be driving around dirt roads and light off road I want to be able to kick up some dirt but I also don't want it to be slow when I'm goin down a dirt road

[@PowerRepublic]

@@colecurtis390 not too sure on that one my friend, we only use the 2 stroke race motors. they are closer to 18/24

[@mariarangelorozco4950]

Hi. I have a rotax fr125. we were on a fast track and notice that using 12/78 will keep the rpm to 14250. can I go 12/80 to go faster out of the curve without damaging the engine?

[@PowerRepublic]

you will need to 12/84 for 'faster' out of the curves. and your RPM might go as high as the 14500 rev limiter. but it won't hurt the engine any more than normal. otherwise if it is a fast track consider going lower anyways and see if your overall lap speed increases. Hope that helps. What track Is it that you are at?

[@mariarangelorozco4950]

@@PowerRepublic Thank you 😊

[@mckenziecapri]

ypu are good....

[@PowerRepublic]

thanks Pat

[@SammyPProductions]

How long do the golds last for if I care for them well

[@PowerRepublic]

depends on the class and how much you lube the chain and stay off the curbs

[@michaelnickle323]

i have an lo206 and im running 19/74 is that good or should i change it

[@PowerRepublic]

depend on the track. what max revs are you getting?

[@michaelnickle323]

@@PowerRepublic 5900

[@ktm150sx2]

Is a 12t on the front and then a 84t on the rear a good option?

[@PowerRepublic]

that all depends on the kart and the track you are racing at. what track do you go to the most?

[@ktm150sx2]

Power Republic i live on a farm so I will ride it in a grass field

[@MrAllenservice]

does gear ratio affect RPM I'm not getting top RPM on iami x30

[@PowerRepublic]

Hey Wayne, sure does, what gear ratio you got? you should hit 16k rpm

[@MrAllenservice]

@@PowerRepublic running 10/94 max rpm 14600 on dirt

[@DexNaquinRacing]

I spend the 45min between races fighting with chain tension. Tighten it up and its too tight, tighten the bolts again its too loose.

[@PowerRepublic]

use your engine stopper bolt as a reference. Screw it up to the back of the engine mount, then loosen the engine mount clamps. Now adjust the engine stopper bolt forward (for tighter chain) or backwards (for looser chain) half a turn and do up your engine mount clamps again. That way you have a good reference point for any finer or coarser adjustments as necessary.

[@DexNaquinRacing]

@@PowerRepublic unfortunately the energy kart I have was a crg made, doesn't have a built in engine stop mount. I do need to make one though

[@PowerRepublic]

probably wouldn't hurt, although not essential

[@ktm150sx2]

My go kart has got 15cm of clearance from the floor to the axle so I think maybe a 84t rear sprocket would hit the ground.

[@PowerRepublic]

we use 84T regularly with out any major issues, what chassis do you have?

[@ktm150sx2]

Power Republic I’m not to sure of the make of chase because it is maybe custom what is the length of a 84t rear sprocket?

[@PowerRepublic]

​@@ktm150sx2 diameter of the sprocket?

[@ktm150sx2]

Power Republic yes please

[@PowerRepublic]

@@ktm150sx2 I'll have to measure one at work and let you know...