RM85 indoor riding

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11/1/2018 12:24 PM

Up here in the great white north we do some indoor riding at the local go cart track. Just finished setting up my boys RM85. Because running clean is an issue most guys run Ipone oil at 50:1. I usually run non ethanol 91 octane fuel but was thinking I’d mix some with ( maybe at 50:50) with vp110 that I have. My theory is that the bike will run slightly leaner( and cleaner) given that engine loads aren’t as higher as outdoors we should be ok. Thoughts? Photo

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11/1/2018 1:08 PM

On a 50/50 mix you will still be rich as the VP110 will burn slower that regular pump gas and thus may require
re-jetting. There may also be some performance lose with the fuel burning slower. This is a border line case and may work ok with minor jetting changes.

Paw Paw

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11/1/2018 1:22 PM

You want to know which fuel will be least hazardous to breath as exhaust gas, but still win the mini-motard race? LOL! Get an Alta.
Uh, skip the leaded fuel.
You can always rent a multi-gas meter and test the spectator area. The common sensors are CO, CO2, NOx, SOx, CH4.

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KTM250SX YZ125 YZ85 PW80 ZX6 FZX700

11/1/2018 2:00 PM

YZed250 wrote:

You want to know which fuel will be least hazardous to breath as exhaust gas, but still win the mini-motard race? LOL! Get an Alta.
Uh, skip the leaded fuel.
You can always rent a multi-gas meter and test the spectator area. The common sensors are CO, CO2, NOx, SOx, CH4.

Not looking to be the air quality police....the place is well vented and the spectators are behind glass.
The Alta is a great idea except the rider is 12 and weighs as much as the Alta batteries lol

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11/1/2018 2:02 PM

Paw Paw 271 wrote:

On a 50/50 mix you will still be rich as the VP110 will burn slower that regular pump gas and thus may require
re-jetting. There may also be some performance lose with the fuel burning slower. This is a border line case and may work ok with minor jetting changes.

Paw Paw

I figured since the bike runs a bit rich anyways I wouldn't have to re-jet. Your right, might just have to try it,.

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11/2/2018 7:14 AM
Edited Date/Time: 11/2/2018 7:18 PM

If you go from straight gas to half vp110, you will have to rejet i guarantee you, so unless you have time to do that i wouldn't use the vp.

Also, if you are currently using a much richer oil ratio like 40.1 or more, then the jetting will be a little leaner at 50.1 but not by more than 1 jet size at the most.

Also, since it runs rich now and you want cleaner exhaust, you should lean it out. There is no point in trying to reinvent the wheel by mixing fuels etc.

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11/2/2018 6:34 PM

More oil leans out. Lesser riches.

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11/2/2018 7:19 PM
Edited Date/Time: 11/2/2018 7:20 PM

bf884 wrote:

More oil leans out. Lesser riches.

Yes, thanks, it was early when I posted, lol. I just corrected it.

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11/3/2018 6:04 AM

If you’re persistent with a fuel change you will have to look at the specific gravity of each fuel to determine which one may cause it to run slightly leaner. Off hand I can’t remember if a lower specif fuel gravity causes a leaner air fuel ratio or visversa.
Bf884 is right in that more oil in fuel causes a leaner air fuel ratio.

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