What oil, fuel for new 4 stroke?

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6/23/2022 4:05 AM

Older vet rider, never owned a 4 stroke, but bought a new one yesterday.

Can I run synthetic oil in the transmission? or stick with conventional?

I currently run a leaded high octane fuel in my 2 strokes because of milled heads & porting work and jetted carbs.
What race fuel can I run in a new KX250? Do I have to run unleaded? Can I run Oxygenated without mapping issues?

What about break in? 3 heat cycles?

Thanks and I'll have more questions on this bike in the future

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6/23/2022 4:14 AM

Rotella. w00t

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6/23/2022 4:20 AM

Just looked it up, this isn't what I run in my 2 smokers, but is very reasonably priced. I guess I can run the 4 stroke synthetic? If I read you right

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6/23/2022 4:28 AM

Did the bike come with a manual? It should list the proper oil class in there.

The better the oil, the better it carries particles to your filter. Motorex Crosspower is a Class 4 oil, meaning it is best in class at keeping particles suspended and carrying them to the filter. I buy it by the 4 x 1gallon case.

Beware, starting an oil thread is like just asking to get picked on. Or you just trolled me.

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6/23/2022 4:37 AM

I just wanted perspective. I trust what the manual says to a point. I kind of decided on a couple oils to go with.

I am still definitely unclear on whether I can run a leaded race fuel safely, or oxygenated race fuel and the stock mapping options will work. I've never had a modern 4 stroke mx bike. Perspective from people who have been riding them for over 10-15 years is ok, right?

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6/23/2022 4:46 AM

Just curious, what bike is it? Do you know you are going to be looking for more power out of it?

I would start with premium pump gas (non-oxygenated).

Modern 4-strokes do not use an oxygen sensor, so you can use leaded gas if you want (Lead will destroy an O2 sensor). Just for fun, I've tried about all types of gas in my 4-strokes.... but I'm not looking for more power out of a 450. The only benefit to me is that VP U4.4 smells good.

For a new bike, I run mine for a hour or two on the first oil change. But typically on my KTM 450, I get 6-8 hours on the oil before I noticed the bike doesn't shift as well. I've had a friend do oil analysis for me, and even at 8 hours, the Motorex Cross Power is still within specification. Also, I like to get a baseline on my valve clearance, so I check that at the first oil change and note it in my manual (along with any adjustments).

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6/23/2022 5:09 AM

The first ride on a new bike I do a few 15-20 motos, going faster and upping the RPMs each moto. Usually put about an hour on the bike doing this. Do an oil change, check the oil filter for any big pieces of metal. On a 250f I do the oil every 5-7 hours and the oil filter every other change.

Don't waste the money on race gas unless you have the supporting mods. 93 will work fine.

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6/23/2022 5:35 AM

For my 4 strokes I use Motorex Cross Power 4T 10w-50 and VP T4 fuel. On a new bike I'll change the oil at no more than two hours for at least the first three rides. You will be amazed at how many metal shavings are collected on the drain plug in a new engine.

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6/23/2022 5:42 AM

JASO MA2 rated 10W-40 or 5W-40 for oil according to the manual.

They offer up anywhere from 10W-30 to 10W-50 as acceptable so your selection may vary depending on your riding conditions and ambient temperatures. If you're going to push it super hard, you may want to go up to the 50 for longevity's sake.

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I can do anything, I'm an expert.
MotoTribology.com - Motorcycle Lubrication Education

6/23/2022 5:43 AM

Oh boy

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6/23/2022 6:06 AM

kawasa84 wrote:

Older vet rider, never owned a 4 stroke, but bought a new one yesterday.

Can I run synthetic oil in the transmission? or ...more

Congrats on the new ride!

You can run leaded race fuel no problem. You can cut it with a good pump gas to get some mileage out of it. No need to run it straight. I've never run oxygenated fuel so I have no comment on that.

I've been running Maxima Synblend (10w40) in my 4 strokes for 15 years plus. Price point is great, it's made in the USA and Maxima is very active in moto. I will support companies like that.

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6/23/2022 6:27 AM

All but one are great responses and it answers what I was looking for. The bike is a 2022 KX250.
For context, I'm 56 and have ridden dirt bikes since I was 5. I started racing in 1982 and know my around 2 strokes. I've rebuilt bottom and top ends on them 100's of times through the years.

I've never had a 4 stroke, never had fuel injection and mapping options. Never had electric start. So, hence, my questions on the oil for the trans possibly being different than what I currently run and of course the fuel, not wanting to hurt the motor if I ran a leaded race fuel like I do in my 2 strokes.

With this bike, I currently own 5 mx bikes, so it was only to get perspective from 4 stroke riders since they've been around now for a long time. I appreciate the input

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6/23/2022 6:29 AM

MotoCoUSA wrote:

Oh boy

I probably raced 100's of times before you got your first hair on you're nuts..............so don't worry, the bike's in good hands.

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6/23/2022 6:34 AM

In theory the bike is mapped for 91 octane (check the manual could be 92 or 93) 10% ethanol fuel. Ethanol adds oxygen. You have 3 couplers that are different levels of richness (timing is different too). So you can play around and see what works best on your bike. Fuel injected bikes are more tolerant of ethanol since there is no carb to muck up with the ethanol. I usually mix some 110 leaded with 90 octane ethanol free to up the octane closer to 95. Although right now 110 from a pump is $8/gallon and 90 e free is close to $6 so not much savings there by mixing them now.

My 250f KTM seems to run the same on pump or a mix of 110 leaded / e free 90.

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6/23/2022 6:37 AM
Edited Date/Time: 6/23/2022 6:37 AM

Synthetic maxima. Four strokes run the oil all through the motor and transmission. It’s not referred to as transmission oil like with two smokes.

The bike will run just fine on non ethanol 93 pump gas. A leaded fuel won’t do anything for you and I believe oxygenated fuel would need a remap to utilize it.

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6/23/2022 6:39 AM

The answers I'm getting is why I asked thanks

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6/23/2022 6:43 AM

Synthetic is great after break in but I recommend Amsoil.

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6/23/2022 6:59 AM

I like maxima oil. Premium pump gas is fine

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6/23/2022 7:06 AM

I only do 2 heat cycles… Then go ride. I’m a vet rider so no worries riding too hard. I use Maxima 10w 40 and have for a long time. Never had any issues. I previously just used premium gas but switched to T4. So much crap they put in gas today.
Plus this is just me but after break in ride, I drain coolant and refill with Engine Ice.

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6/23/2022 7:16 AM

=MXM000B-X001-Y003]This is a popular choice. Some people swear by Shell Rotella, but others like to use moto specific oil. Don’t use anything less than premium if you use pump gas.

I have the same bike. I love it. Keep an eye on the chain, mine wore pretty quickly and is almost ready for replacement.

I use the white coupler, I feel way better with that vs the green one.

Vital also has some recommended suspension settings. I used those as a baseline before making a few minor adjustments, and I’m super happy.
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6/23/2022 7:27 AM

731chopper wrote:

Synthetic maxima. Four strokes run the oil all through the motor and transmission. It’s not referred to as transmission oil ...more

Leaded fuel will add additional protection to the valves.

A good explanation from the internets.

'The lead oxide acts as a cushioning agent, and protects the valve and the valve seats. The lead oxide is also a lubricating agent. This reduces wear in the valve guides, as the valves slide inside them.'

I also forgot to add. Try finding a race fuel with an lubricant additive for the fuel pump. This will be important if you are keeping the motorcycle for the long haul.

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6/23/2022 7:52 AM

I’ve always ran Honda GN4 10W40 in all my 4 strokes regardless of brand and non ethanol 93 from the pump

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6/23/2022 7:55 AM

Rotella t4 and pump gas

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6/23/2022 8:08 AM

Fouled Plug wrote:

Leaded fuel will add additional protection to the valves.

A good explanation from the internets.

'The lead oxide acts as a ...more

I’m far from a chemist but I thought modern fuels had an additive that did something similar?

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6/23/2022 8:28 AM

731chopper wrote:

Synthetic maxima. Four strokes run the oil all through the motor and transmission. It’s not referred to as transmission oil ...more

Fouled Plug wrote:

Leaded fuel will add additional protection to the valves.

A good explanation from the internets.

'The lead oxide acts as a ...more

731chopper wrote:

I’m far from a chemist but I thought modern fuels had an additive that did something similar?

I'm no chemist either haha. Likely best to contact fuel manufacturers to find out. I know a few people who are running Klotz fuel (can't remember the specific type) but it specifies 'uplon fuel lube' which is specified for fuel pumps etc.

I guess it makes sense all modern fuels should have a fuel pump additive (if they advertise it or not)

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6/23/2022 8:39 AM

I'm not sure I believe this, but several oil scientists and motorcycle engineers have told me to run a conventional oil for the break-in period, and then switch to synthetic. All of them say to change your oil more often, rather than buying more expensive oil. Of course, expensive oil AND changing it more often is the best combination.

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Braaapin' aint easy.

6/23/2022 9:22 AM

Falcon wrote:

I'm not sure I believe this, but several oil scientists and motorcycle engineers have told me to run a conventional oil for ...more

The thinking is things don’t break in correctly with synthetic because it is so slick.

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6/23/2022 9:49 AM

I run motul and 93 pump, I usually just get enough gas for the day, I’ll pump a couple gallons of 93 in my truck to make sure I’m getting straight 93, not a hose full of 87 then 93. Some ethanol guard also.

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6/23/2022 10:31 AM

Falcon wrote:

I'm not sure I believe this, but several oil scientists and motorcycle engineers have told me to run a conventional oil for ...more

wrc777 wrote:

The thinking is things don’t break in correctly with synthetic because it is so slick.

Also, incorrect.

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6/23/2022 1:14 PM

Renegade MX4 or HR102 is good stuff and is usually cheaper than VP a litte.

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