Are gearboxes different in quadbike engines?

[lingeringstin...]

This is getting silly. I put what I assumed was a bog standard Honda clone engine (253FMM) from a Quadzilla 250e in my frame and now I can't get the gearing right.

No matter what I do it's way too low geared. What I have now cruises in last gear at about 40 MPH before the engine's revving way too hard, and first gear is so low it's practically useless. I'm using 16" wheels which is the same size as many "cruisers" with the same engines so I don't understand what's going on.

At the moment I have the biggest front sprocket you can possibly fit onto that engine. There is physically no more room for a bigger sprocket and no way to machine out the space.

At the rear I'm using the smallest sprocket they make for my cush drive and it's so bloody small it puts the chain so close to the swingarm it's in danger of rubbing against it at the slightest provocation.

The chain is 428 and my current sprockets are 18 front and 31 rear. Doing some calculations based on the last few sprocket combinations I've tried it looks like I'd need about a 20t front and 25t rear sprocket to get the gearing right and no such sprockets exist. Wouldn't fit on the front anyway. That's almost the same size sprockets both ends! Anyway those sprockets don't exist and that would have the chain fouling the swingarm if there was even the slightest flop in it.

The thought did occur to me to use bevel drives and a shaft but that's a lot of expensive work I'm not going to get into.

I also looked into belt drives. That's a much easier thing to do IN THEORY because the front and rear pully are much easier to get in different sizes and the belts run with less flop than a chain so fouling the swingarm wouldn't be so much a problem but the components are stupidly expensive unless I can find some industrial equivalent that might work but as of yet belt drive is out of the question due to the hideous expense of adapting it to my bike.

I don't think using an 18" rear wheel would make enough of a difference using my current sprocket combination. The extra inch would probably only get me 10-20 MPH at most and no scope for further sprocketing because I'm already at the extremes of what is readily available.

A bit of research shows other bikes with similar or the apparently same engine and similar wheel size to mine using sprockets that would make the gearing far too low on my bike so I'm beginning to wonder if there's a different gearbox in this Quadbike engine than what they put in the same engine intended for bike use.

Naturally, being a Chinese made engine there's little clear information to be found anywhere.

[Polarbear]

I have nothing to base it on but yes, I would expect a quad to have lower gearing than a motorbike.

I am also amazed and impressed at how much time you are wasting on your Chinese POS, well done

I would have long ago consigned it to the fires of hell from where it came and spent my excess money on the BCF traditional hookers and coke.
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Triumph Trophy Launch Edition

[G]

Yes; it could well be geared differently.

What RPM are you hitting at 40mph?

[Evil Hans]

Possibly, but a Quadbike would surely have even smaller wheels, making your box's gearing even lower when installed in a Quad ... it'd pull well but you'd get no speed out of it!

Although I suppose you might get away with a tiny rear sprocket on a Quad rear axle. So yeah. maybe.

(late night last night so apologies if I am talking shite)
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Triumph Sprint ST 1050. And it's Red.

[lingeringstin...]

Belts and braces!

OK after looking at shit online I've decided to go with belt drive. I've discovered if you totally ignore all things belt with the word "motorcycle" in them you can find reasonably priced pulleys and belts in vastly more sizes than chains and sprockets.

A quick bit of research shows that a lot of Sportsters use a one inch belt so a quick look at industrial pulleys and belts of around an inch size shows up zillions of possibilities. I figure I can get a couple of steel pulleys of appropriate size (yet to be determined) and probably weld them to a set of sprockets and be done with it. Industrial belts are far cheaper than motorcycle belts and probably just as good for what I'm needing them for.

[lingeringstin...]

[Polarbear]

[P.]

[G]

Indeed - et tu lingeringstink.

Because cobbled together heaps that have loads invested in them to make them less practical is, alas, trendy these days.

[MarJay]

Lingeringstink was a hipster before it was fashionable.
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[redeem ouzzer]

Have to say the entire process is getting pretty autistic.

Blending an MZ frame (which is meh) with a Chinese copy of the Honda twin commuter engine (also meh) and then choosing cycle parts that make people wonder if the OP is mentally unstable isn't exactly a sound use of one's time and effort. The finished project, as well as looking like someone took a hammer to a steampunk exhibit, will be completely useless as two wheeled transport.

It's a curiosity - if you wanted to build something odd with scrap metal couldn't you of just done some sort of avant garde sculpture and saved the horror of actually trying to operate the said contraption on the public highway?
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Be a REAL MAN!

[stevo as b4]

You've got plenty of spare engines,seeing as your well down this path now. Can you not strip a gearbox maybe and see how the gear ratios compare to the quad bike engine your currently trying to make work.

I don't want to be certain, but the fact your using a quad engine, would to me suggest it likey has very different internal ratio's, and possibly the primary drive ratio is also different to the chinqy clone bike engines.

You could pop off the clutch cover and count teeth, and then see how it compares to one of the bike engines that I presume your other motors are from?

Quads don't use massive sprockets for ground clearance as much as anything, so the reduction gearing must be done inside the motor.

I think you've come too far down the path of trying to get a Chinese twin Honda clone to fit, to turn back and start again with something better, so I would do some investigating personally to see wtf is going on.

I reckon you could get a manual for the genuine Honda 250 twin motors and the info for the gearing. Failing that ask Teflon to count his teeth on his Benley 125's, as im sure it's something he'd get immersed in very easily and come back with every gearbox permutation Honda ever made.

[stinkwheel]

Can I encourage everyone to read lingeringstinks posts in a slightly grumpy Texan accent for the full effect.

And yes, I'd expect a 250cc 4t chinese quad to top out at about 45mph.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Robby]

Quads have very small looking rear sprockets. I assume the gearbox is therefore different.

It should be cheaper and easier to get the right gearbox than to try to make a belt drive system that works.

That said, Harley drive belts last for ages - 150k miles is not uncommon. Harley riders are more likely to fiddle their gearing by messing with the primary than by messing with the final drive pulleys.