Where to find info about performance mods for 80cc Honda?

[AustinS]

I'm trying to find out info about making a custom exhaust (no one makes them for the CH80) and also about rejetting the carb and putting a new airbox in..

I'm guessing I'm goign to have to be the pioneer for the CH80 because I can't find any information on upgrading it.

Mine hits 42 on flats and I feel like it should be going much faster.

So what effect will rejetting, exhaust, and airbox modification have?

I assume if I free up the amount of air coming into the carb by giving it a more free flowing airbox this will cause the engine to run lean. I would assume this can be adjusted using the air/fuel mixture ratio screw so what would be the point and letting more air in?

Second up, what would rejetting do? Does this just allow more fuel into the air/fuel mixture?

Lastly, what would putting a more free flowing exhaust do to the bike? What order should I go in to do these mods?

Are there any tutorials on building an exhaust pipe? I assume depending on the CC size of the engine and the amount of backpressure required will effect how the pipe is built. How do I find out about this type of stuff? Is backpressure even a concern on these small engines?

[Wheelman-111]

Greetings:

AustinS Axes about Eighties:

I'm guessing I'm goign to have to be the pioneer for the CH80 because I can't find any information on upgrading it.

There just isn't much out there...

Mine hits 42 on flats and I feel like it should be going much faster.

The first step might be to get it running correctly as a stocker. I've read they're normally good for 50, so perhaps it has issues that fancy pipes won't correct?

So what effect will rejetting, exhaust, and airbox modification have?

The engine will be able to process more fuel mixture at a higher rate of speed = more power.

I assume if I free up the amount of air coming into the carb by giving it a more free flowing airbox this will cause the engine to run lean.

That's true.

I would assume this can be adjusted using the air/fuel mixture ratio screw

Not so much - the screw is only for adjustment of low-speed mixture.

so what would be the point and letting more air in?

I don't know what you mean by that... More air mixed with the correct amount of fuel = the capacity to burn greater quantities of petrochemical energy per second = More power.

Second up, what would rejetting do? Does this just allow more fuel into the air/fuel mixture?

The HIGH speed mixture adjustment is accomplished by removing small brass fittings and replacing them with ones that have larger fuel-metering holes - quite precisely machined - to correspond with the increased volume of air the derestricted engine can now process. See above.

Lastly, what would putting a more free flowing exhaust do to the bike?

See above.

What order should I go in to do these mods?

Small changes, one at a time and tune to each. Taking off an airbox is easy. Determine the correct jet for that alone first.

Are there any tutorials on building an exhaust pipe?

See Advanced Technical section and be prepared to read a while.

I assume depending on the CC size of the engine and the amount of backpressure required will effect how the pipe is built. How do I find out about this type of stuff? Is backpressure even a concern on these small engines?

It's a lot more complicated than "Backpressure"... You will learn to expunge the word from your Tuner vocabulary.

Good luck, Hope this helps, have fun!

[Kenny_McCormic]

Wheelamn, do remember we are talking about a 4 stroke.

Mine hits 42 on flats and I feel like it should be going much faster.

So what effect will rejetting, exhaust, and airbox modification have? Quite a bit with any luck.

I assume if I free up the amount of air coming into the carb by giving it a more free flowing airbox this will cause the engine to run lean. I would assume this can be adjusted using the air/fuel mixture ratio screw so what would be the point and letting more air in?NO! on a slide carburetor the screw is for idle fine tuning ONLY(there is only 1 exception to this, anybody know what bike it is?)

Second up, what would rejetting do? Does this just allow more fuel into the air/fuel mixture? Adjusts fuel/air mix

Lastly, what would putting a more free flowing exhaust do to the bike? What order should I go in to do these mods? On a 4 stroke you want the freest flow possible, a lot of power can be gained from a stright pipe on a 4 stroke.

Are there any tutorials on building an exhaust pipe? I assume depending on the CC size of the engine and the amount of backpressure required will effect how the pipe is built. How do I find out about this type of stuff? Is backpressure even a concern on these small engines?

You do not want any form of "back pressure" on a 4 stroke engine for performance, 2 strokes need it because of how they work, 4 strokes just need to get rid of it.

I think you should be going a bit faster too, check for carbon buildup(a seafoam treatment never hurt anyone). The driver pulley in the transmission could probably use a rebuild.

Gut the muffler and get a dual layer UNI air filter and put it directly on the carb. Get some main jets and get tuning. Run a 4 stroke too lean and they like to burn valves. A CHT gauge is nice.

[AustinS]

thanks for all the answers! Phew that helps a TON.

You guys are great.

I've taken the carb apart and cleaned it but haven't done anything else. The stupid thing is missing the dipstick so I haven't even been able to check the oil level. I'm just going to drain it all and replace it with new oil.

The oil check bolt doesn't have the dipstick attached ot the back of it. I ordered one from a 87 model but it seems to be different compared to the 86 model that I have. Mine requires some sort of floppy dipstick that is attached to the back of the bolt, while the one I ordered has a stiff plastic stick on the back of the bolt.

Oh well. I've never taken the drive train cover off to see what kind of shape the belt is in, so I will do that first thing when I start working on it. (Vacationing in Destin, FL right now)

[jesse1234]

I almost bought a ch80, and it didn't go over 42, and was in great shape

[Atis]

I have a 95 Elite 80. I weigh about 160 and on level ground with no wind 45-47 is about max. It's entirely stock. I'm told it sat in the shed about 5 years before I got it. It took three attempts to get the carburator properly clean. I replaced the plug and air filter and a missing cooling shroud. Now I just ride it and don't really plan on any mods since I've yet to hear about anything that will made a "cost effective" difference. But I'd love to hear about your results if you make any changes. Good luck.

[noiseguy]

Ah, the CH80. There's a repair manual on that bike here now. I think you're on your own for parts.

First of all is gearing, if even available, b/c you'll only get so much speed for the power.

A 4 stroke. So I'm thinking raising compression, less restrictive exhaust (there is tuning involved but nothing nearly as complicated as with 2-strokes), remove cam and have welded / reground to increase opening time (I doubt there's an aftermarket cam for these, this will need to be done in conjunction with the decked head), play with the intake and carb maybe. Float in some larger valves?

[Kenny_McCormic]

Honda has been making the same bike for the last 20 some odd years. I find it difficult to believe that there are no aftermarket parts for the thing.

[noiseguy]

Honda has been making the same bike for the last 20 some odd years. I find it difficult to believe that there are no aftermarket parts for the thing.

Well then, prove us wrong.

[AustinS]

I found an aftermarket exhaust on ebay made by a company called battlescooter. the posting mentioned rejet and air box mods, so I emailed them and they said they sell a jet kit for CH80. Website is http://battlescooter.com

[DJPhatman]

I found an aftermarket exhaust on E-bay made by a company called battlescooter. the posting mentioned re-jet and air box mods, so I emailed them and they said they sell a jet kit for CH80. Website is http://battlescooter.com

I have a '88 CH80, with a battlescooter exhaust. It is very very loud, with only marginal gains in acceleration. I weigh ~300lbs, and mine will just hit 45, with a tail wind. There are very little speed parts for the CH80. To go faster, put a bigger engine on it. Up/down jetting a 4 poke doesn't effect speed as much as fuel mileage and emissions.

[Wheelman-111]

Greetings:

Thanks, KMcC! I confess I was operating under the incorrect assumption that we were discussing a 2-Stroke 80, which was the Aero, not the Elite.

That said, 2-Stroke or Four, the faster an engine can move mixture in and exhaust out, the more power it can make. Hence de-restricting the air filter and muffler still apply. I've spent several years fine-tuning a mostly-stock Sportster. With its oddball 315/405 firing order, all kinds of pressure waves are flying around both sides of the combustion chamber. Big, thick books have been written about getting the most from these agricultural beasts, or at least striking the best compromise.

Back to AustinS's issues, I still believe he will see some gains from an open filter and freer-flowing exhaust, though perhaps not as dramatic as similarly-modded 2-strokes. My advice still goes, except I have no idea how the jets on the (Keihin?) 4-stroke carbs are adjusted.

Maybe we should develop a 3-Stroke?

[AustinS]

thanks wheelman.

I think I'm just going to work on getting the basics working really well and then start with a airbox modification and exhaust. Then I want to learn about rev limiters and rollers. How can I tell if the rev limiter is kicking in?

I do have a question about basics that is driving me nuts.

Either I'm retarded and don't know where the dipstick is, or this bike had it replaced with just a standard bolt. I've looked at service manual and owners manual and I'm almost positive I'm looking in the right place. According to the manual a "floppy" dip stick should be attached to the back of this bolt. Well mine has nothing attached. So I got a dipstick from a 1987 and it doesn't have a floppy dipstick, it just a stiff plastic dip stick.

Anyone have a clue where I could get one of these? I'm thinking about trying to just drain all the oil and put back the amount specified but I really want to be able to check my level.

here is the one I got off ebay

http://www.iowasalebarn.com/components/ ... e74e8c.jpg

[DJPhatman]

That's the one! It is located under the engine, and under the exhaust pipe. It's not a bolt, but a twist on and off tube and stopper. You may have to look from ground level, but it is on the right side (while sitting on the bike).