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honda mtx125r what is the right two stroke mixture. thanks

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geraghty125
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PostPosted: 20:34 - 04 May 2015    Post subject: honda mtx125r what is the right two stroke mixture. thanks Reply with quote

Hi i have brought a honda mtx125r 1998 and the guy i brought it off dose not no the mix apparently the bottle you put the 2stroke in dose not work so i am tank mixing i have read about but none of it makes sense i am currently mixing 5lt petrol with 150 ml of 2stroke.
Hope to hear some advice thanks in advance.
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gbrand42
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PostPosted: 21:35 - 04 May 2015    Post subject: Re: honda mtx125r what is the right two stroke mixture. than Reply with quote

geraghty125 wrote:
Hi i have brought a honda mtx125r 1998 and the guy i brought it off dose not no the mix apparently the bottle you put the 2stroke in dose not work so i am tank mixing i have read about but none of it makes sense i am currently mixing 5lt petrol with 150 ml of 2stroke.
Hope to hear some advice thanks in advance.


I would think 50:1 would be nearer, so 100ml in 5 litres of petrol
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stevo as b4
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PostPosted: 22:52 - 04 May 2015    Post subject: Reply with quote

It's all down to personal preference, and it depends on how you have got it jetted too. Some re-jet for pre-mix and other's don't etc.

I know injector pumps tend to vary from about 40-100:1, but the logic is that if the bike is going to be used on the road and held either at constant speeds or at high road speeds for long periods, that a richer oil/fuel mix is required, compared to say an off road bike that's not held wide open for long periods or under constant loads.

My KMX is running +2 sizes on the main jet currently, and I mix at 36:1 for road use.
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geraghty125
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PostPosted: 01:45 - 05 May 2015    Post subject: Reply with quote

Thanks so far helpful would be nice if you could dumb it Down abit for me lol
Oh yeah its for road use.
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Fladdem
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PostPosted: 09:55 - 05 May 2015    Post subject: Reply with quote

I was going to run my h100/mt5 on pre-mix because I don't think the pump could be adjusted enough for twice the CC and then the tuning on top of that, I was going to start at 35:1 and then try to work it out from there. I'm sure I've read a guide on here somewhere, telling you how to figure out whether you need more or less oil, but I can't seem to find it now.

Jetting will be a hell of a lot of fun on that bike.... NOT! I think the carb is off an 80's CR80, because its bigger than the original H100. Laughing

EDIT: The Haynes manual for my MT5 says to run a pre-mix ratio of 25:1 in the tank when bleeding the oil pump, but seeing as that's at tick-over, I think it needs more oil, due to less petrol to help lubricate and cool the internals. Just thought I'd confuse matters more with that.
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Current:1991 Honda MT50 (Soon to be a H100/MTX/MT5 hybrid), 1976 Honda Cub C70, 2005 Honda Varadero 125, 1993 Yamaha TTR250 Open Enduro , 2010 Road Legal Stomp YX140, 1994 Honda CRM 250 MK III, 1999 Cagiva Mito 125, 1992 Honda CB400 Super Four, Stomp T4 230, 1984 Honda H100s, 2009 Sym XS125K
Past:2003 Aprilia RS125, 1982 Kawasaki GPZ550(FREE BIKE!)
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geraghty125
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PostPosted: 14:28 - 05 May 2015    Post subject: Reply with quote

Yeah i am currently watching a Haynes manual in my ebay. the bike its self seems to ve running good as far as i can tell i aint no mechanic thoe i am going to take it for a full service and port and polish hopefully in a few days am pretty sure it would help the engine out.
Also is anyone else two stroke thirsty am talking 9lts 9lts/full tank to reserve in 4days i only commute to work and back witch Is a 4 mile ride.
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geraghty125
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PostPosted: 17:35 - 05 May 2015    Post subject: Reply with quote

A little update i put 100ml 2stroke in with 5lt premium but i started chucking out white smoke then it faded abit after about 5mins off riding my bike cut out i didn't stall it any one else had this problem. Thanks
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Fladdem
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PostPosted: 20:36 - 05 May 2015    Post subject: Reply with quote

geraghty125 wrote:
Yeah i am currently watching a Haynes manual in my ebay. the bike its self seems to ve running good as far as i can tell i aint no mechanic thoe i am going to take it for a full service and port and polish hopefully in a few days am pretty sure it would help the engine out.
Also is anyone else two stroke thirsty am talking 9lts 9lts/full tank to reserve in 4days i only commute to work and back witch Is a 4 mile ride.


A top end rebuild would get it running better than a port and polish jobbie. Although, if you are getting it ported, they may do the top-end as well while they're in there. How many miles has it done? A worn top-end won't help fuel economy.

Two strokes are naturally worse on fuel, the nature of the engine design means that at certain points both exhaust port and intake port are open, allowing minor particles of fuel to be thrown straight out the exhaust without ever being used, helps give her the smell! Laughing The expansion chamber design is meant to help with scavenging, which is essentially making sure all the burnt stuff is gone without taking new stuff with it, the pressure waves from the combustion process is reverberated back into the cylinder, to help push some fuel back in, it also can change the characteristics of power delivery depending on the length, angles of the cones and internal volume. Spannie design is my favourite topic in the world, I need to read into it more.

Anyway, back on topic, my smoker gets about 30MPG if ridden on the pipe all the time, by that I mean with the engine singing, mine is a CRM 250, which I believe evolved from the MTX200, which obviously is related to yours. I don't know how true this is, but I'm sure I've read it somewhere.

I assume 4miles there, 4 back, that's 8 miles. 8X5=40 miles a week, are you taking it down to reserve? If so, I assume like most trailies is a 1.5 litre reserve. Which means you are using approximately 7.5 litres every 40 miles. 40/7.5=5.33 miles per litre. 5.33X4.55= 24.25MPG. This is a touch low for a 125. I would expect a 125 smoker to get between 40-50mpg. Do you do a lot of town riding? A lot of sitting around idling? Maybe hold the revs all the way to the red line before changing up? Not riding conservatively, i.e. instead of doing 30mph in 4th, you may be in 3rd, or even second? Hilly terrain? Poor fuel economy could be all sorts.

geraghty125 wrote:
A little update i put 100ml 2stroke in with 5lt premium but i started chucking out white smoke then it faded abit after about 5mins off riding my bike cut out i didn't stall it any one else had this problem. Thanks


Check your coolant and tranny levels. White smoke suggests burning water, which could be a head gasket or base gasket leaking. It could be transmission oil too, which would suggest the crank seal is gone, which could suggest poor fuel economy, you may be losing petrol through the crank seal into the transmission and vice versa. I'm not a two stroke expert though, just keen.

Can you turn the bike over on the kick start, if so, that's good, it means it's not seized. Try to start it again, see if it still runs ok, I doubt a change in pre-mix ratios will have caused white smoke but I think you went with less oil in the petrol, so in theory you have richened out the air/fuel mixture but leaned out the oil/fuel mixture.

First things first, see if it starts, if it starts, film it, show us. Second thing to do, whether it starts or not, pull the plug, take a picture, show us. The third thing is then to wait for some more advice while your Haynes manual turns up, like you say, you aren't a mechanic, and the fact you were going to take it for a service means you may not have a lot of experience pulling things apart, don't go in too hard and too fast, you will run the risk of ruining an MTX 125, one of my favourite machines in the world.

Best of luck.
____________________
Current:1991 Honda MT50 (Soon to be a H100/MTX/MT5 hybrid), 1976 Honda Cub C70, 2005 Honda Varadero 125, 1993 Yamaha TTR250 Open Enduro , 2010 Road Legal Stomp YX140, 1994 Honda CRM 250 MK III, 1999 Cagiva Mito 125, 1992 Honda CB400 Super Four, Stomp T4 230, 1984 Honda H100s, 2009 Sym XS125K
Past:2003 Aprilia RS125, 1982 Kawasaki GPZ550(FREE BIKE!)
I'm having more fun than a well-oiled midget.
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geraghty125
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PostPosted: 21:17 - 05 May 2015    Post subject: Reply with quote

Wow extremely helpful and not too technical for my brain i do appreciate that and come to think off it. It was raining when i poped the two stroke in then took the 2secound ride to garage. And i have serviced my old 4stroke to the best off my abilities. But i am going to get some professionals to do it this time and i am assuming i am riding with petrol care in mind but am not used to the power off the two stroke. But i will take it in mind everything you have said and i might be able to get a video up touch wood payday i will be getting a go pro (too many crazy cars).
Thanks alot
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