200X wiseco 10.25:1 Vs 12:1 piston - opinions

[Leevvii]

ATC200X wiseco 10.25:1 Vs 12:1 piston - what is the benefits of each, any suggestions.

[deathman53]

the 12:1 needs race gas, but bottom end will be much better.

[wonderboy]

My opinion: 12:1 was just a bit too much trouble if you just want to ride. 10.25 seems like a nice increase in power, but without the headaches of 12:1. I was always worried about running high enough octane and worried about sitting at idle too long (no airflow through the head to keep it cool). If maximum power is the only goal, then 12:1. Otherwise, I'd run the 10.25.

[christph]

I was wondering the same thing back when I rebuilt my 83 X. I went with the 10:25 because I didn't want to run race gas. I'm happy with it but left wondering how much more performance I would have got with the 12:1. I'm not sure if you have to run full race or 50/50 with that piston. You might contact Mickey Dunlap at Four Stroke Tech for X advice. He has worked on these engines and offers a 250 big bore kit.

[oldskool83]

10:25.1 more then that buy a 350x

[atc300r]

I was talking to a guy at the races about this .He knows another racer that is running a 12:1 on 91 octane.Says he has no problems.

[RIDE-RED 250r]

12:1 is pushing it for pump fuel, generally speaking. You might be able to buy yourself a little leeway by jetting it rich, but in so doing you are dialing back peak performance so you might as well stick with 10.25:1, run 93 octane, hit the trails and enjoy a significant boost in power over stock.

My brother has a 350x with a 10.25:1 and it's a bear, very torquey. Also a miserable SOB to kick over, even if you know what you are doing, his auto-decomp parts failed years back and he took them out...

[yaegerb]

ATC200X wiseco 10.25:1 Vs 12:1 piston - what is the benefits of each, any suggestions.

Race gas for 12:1 and 91 or higher for the 10.25. 12:1 will run too hot IMO without race gas. Mine ran happily on VP C12. Run lower octane at your own risk.

Your motor/wallet will be very happy with a 10.25 on 91 with a little more aggressive cam than stock plus you can keep the VM 24 Keihin.

Unless you are going ballz out with a dedicated racer it's not worth the extra compression.

[Leevvii]

Thanks everyone. Think i'll stay with the 10.25:1, im not racing, just bush bashing. One more question, what octane do you guys in the US, consider to be race fuel? We have 91, 95 and 98 octane available at pumps. I will also need to run a lead replacement in my '84 200x.

[christph]

I consider full race 110 octane.

[RubberSalt]

Christph is right, we typically consider 110 as race gas. An alternative are alcohol based fuels like e85, which is 105 octane and runs cooler than gas typically. Like all fuels, it does require new jetting. e85 and race gas typically require richer jetting.

e85 is the poormans race fuel. Most machines make more power on e85 than 110. The problem with e85 is consistency. Many pumps mix ethanol and gas as you pump. Consistency lacks. VP makes a race version of it, c85, which like all their race gas, is consistent.

If your in the bush, I'd stick with pump gas. Maybe some of that 95-98 (should run cooler). Your not racing, no point to build a racer.

Compression gives a direct increase in power across the entire rpm range. It's usually pretty linear and makes a big difference. You can expect about a 15% increase in power before you factor in the fuel's capability when going from 10.25 to 12:1.

2 stroke pipes, turbos, super chargers, pro chargers, they all add compression. They blow an air/fuel mix into the cylinder under pressure, upping the compression drastically.

[plevib]

That's very interesting. I've never considered running e85 so I didn't realize it was 105 octane. So to someone who has run it, does it gum up carbs pretty bad? How long can you let it sit in the fuel bowl before it turns things green? I've just always avoided it, but being able to run 12:1 for less money than even 87 (I run 91 %100 gas in my small engines) it might be worth draining the carb when the trike sits. ...

[Mickey Dunlap]

For most of my customers I take a 12:1 and round it off so there are no sharp edges, then I'm at 11.5:1 and I run a pretty big cam, makes it go from 10 rwhp to as much as 18 rwhp with my 30mm carb kit and a new stainless head pipe made to up grade the DG pipe. It's all about getting the cylinder pressure down so you can run pump gas. Mine didn't make any more power with race gas with this set up either. With the 10.25 you can't run a big cam with out killing the bottom end and making it rev slow.

233019

[oscarmayer]

the 12:1 needs race gas, but bottom end will be much better.

Incorrect. It needs proper jetting and 93 unleaded pump minimum. I ran it all day long in my old engine I sold. Years. Never had an issue. Again. Tuning is key.


If your not racing it or needing the extra 1-1.25hp then stay with the 10.25:1. In my opinion, the best is 97 octane. Any higher and your not benefiting. Since it sounds like you r trail riding the 10:25:1 will suit you just fine. I recommend you look at upgrading to a mikuni 28mm carb. Also look at upgrading the exhaust. All these mods together will help a lot.


Sent from my iPhone using Tapatalk

[Leevvii]

The shop that is reboring my barrel suggests i go with the 12:1, he claims to have done this before on these type of engines, uses 98 oct and all OK. He said that too much engine paint on the fins is a big heating problem with the barrels, maybe moreso than the compression, suggests cutting slots in the front mudgaurd to up the airflow if im concerned. Makes sense. He tells me that the head had been ported previously, and was impressed with the porting. Im stuck with the standard carby, and i assume standard jetting, for the moment, will this be OK [not too lean?] with the 12:1 ?

[oscarmayer]

If your running a higher compression piston, your jetting will be different.


Sent from my iPhone using Tapatalk

[350for350]

Anything you do to give it more power will require rejetting. How much bigger depends on what you do to it.

[Leevvii]

Heres what i have, i dont want maximum performance, but a little more zing would be nice. Also, looking to maybe do more to it in the future, hence i thought the 12:1 piston might be the best choice for now, even if it is "underperforming" a bit at present, if you follow me? So, any advice on jetting the KEIHIN to suit the 12:1 wiseco, or am i just wasting time with this. Any advice welcomed, i wont hold you to it! LOL

My plan is :-

66.00mm bore, wiseco 12:1 piston, but 10.25:1 remains an option

Head is ported [non factory, by previous owner],

Standard 200X camshaft.

I will purchase DG pipe in near future [most likely DG RCM - #04-2108 ],

Running 98 oct fuel.

24 mm carb [with unifilter]. I have 2 carby's to choose from..

1 x Standard 200X - KEIHIN PD-62B/AVI
FUEL JET: 125
PILOT (SLOW) JET: 40
JET HOLDER: No markings
AIR SCREW: Standard-No markings
FLOAT VALVE and SEAT: seat marked 20
THROTTLE SLIDE:

OR

1x MIKUNI Carburetor Carb M CA06 [EBay .........wot!??LOL allegedly for a 200X '84, ...but seems massively under-jetted to me??]
FUEL JETS: 95
JET HOLDER: No markings
PILOT (SLOW) JET:- 15

Drive gearing :- 13 - 44 teeth.

[Leevvii]

233139
Seems the jetting in the Keihin is non standard on mine.

[yaegerb]

Use the 1st carb. The 40 pilot and 125 main should be a good starting point.

And get a more agressive cam to better suit the 10.25 or 12:1

[Leevvii]

The 40 pilot and 125 main should be a good starting point.
For the 12:1 piston, .....yes?
Think i will wait for the agro cam, curious, are they available readily?

[yaegerb]

Should be ok for 12:1. Full disclaimer though. I never could get my 218 running right on a stock VM 24. But it was a pretty wild little motor. I had to step up to a 28mm mikuni that had some specific tuning done to the carb and I ran a custom air intake.

Never heard of agro, sorry. I suggest mega cycle or web.

[Leevvii]

Should be ok for 12:1. Full disclaimer though.Thanks for the advice, i'll' send you a postal bomb if it dont work!:naughty::lol::lol: .............joking, of course, i hope that comment does not trigger the NSA terrorist alert criteria, we live in strange time dont we!

agro cam = aggressive camshaft. Are they available readily to buy or is custom machining required on my current cam?

[Leevvii]

I restored the carby by using the boiling water and vinegar method, ......freakin big difference.
BEFORE:- 233151233152233153
AFTER:-
233145233146233147233148233149233150

[yaegerb]

Thanks for the advice, i'll' send you a postal bomb if it dont work!:naughty::lol::lol: .............joking, of course, i hope that comment does not trigger the NSA terrorist alert criteria, we live in strange time dont we!

agro cam = aggressive camshaft. Are they available readily to buy or is custom machining required on my current cam?

Ready to buy, look on webcamshafts website.

[Leevvii]

thanks, that good info, cheers.

[RubberSalt]

If it was me, I'd follow Mickey Dunlops suggestion on the build.

e85 has a shelf life of about 90 days in a nice contained environment. with it containing so much alcohol, it's more prone to absorbing moisture in the air. Depending on were you live, I'd say 2-4 weeks it need's to be drained out.

I love e85, but for just running through the bush, I'd stick to strictly pump gas. It's a proven fuel that is readily available. You also don't want to run e85 with out increasing the jetting. It requires 30% more fuel than premium, and if you don't rejet, you'll over heat pretty bad.

[DohcBikes]

E85 is trash. If you need more octane, buy race fuel.

In order to properly advise jetting and octane requirements, altitude and your regional method of calculating octane (yes there are multiple formulas-RON MON and AKI) will help get you closer. 98 octane RON is plenty to run 12:1, but 98 MON is generally not. I believe your ratings are AKI, which is somewhere in the middle. Keep an eye on cylinder temps through the jetting process, run it as rich as you can without fouling plugs or bogging, and you'll be fine.

[oldskool83]

90 days....had crap go bad in 2 weeks. Buy fuel mix it or put somthing in it a day before you go ride, then ride and drain your carb bowl. Being doing that for years...never have carb issues again.

[Leevvii]

Australia is RON from what i can tell.

[DohcBikes]

Australia is RON from what i can tell.Ok. In that case, 98 pump gas will be plenty enough to run the 12:1 without concerns.

[Leevvii]

From the Wiseco website :-
HONDA ATC 200
TWO HIGH PERFORMANCE PISTONS HAVE BEEN DESIGNED BY WISECO FOR THIS HONDA APPLICATION:
The 4289 Series has been designed for racing applications and requires the use of racing gasoline of 102 octane or better.
Use of low octane pump gas with the 4289 series will cause denotation and severe piston and engine damage. The 4156
series piston at 10.25:1 compression has been designed for fuel having minimum octane rating of 92 {(R=M) / 2 method}.

Is 98 enough!!:wondering

[DohcBikes]

From the Wiseco website :-

Is 98 enough!!:wondering
It needs proper jetting and 93 unleaded pump minimum. I ran it all day long in my old engine I sold. Years. Never had an issue. Again. Tuning is key.
Oscar is correct, with proper preparation and tuning this could be possible with that engine. Speaking from experience running 98 octane, it will be even easier to tune.

[yaegerb]

From the Wiseco website :-

Is 98 enough!!:wondering


Can't speak for Oscar, but I have built quite a few racing 200x's and I already told you, use lower octane at your own risk.