pump gas conversion

[lcp8410]

who can convert a pro 125/250 motor to run pump gas?must be someone here done it before.

[David Weaver]

Probably Not

The Yamato 250 is built for racing on mathanol. I doubt someone has de-tuned one to run on gas. Need to change carbs, perhaps reeds, heads and adjust timing. All in order to make it run slower??

Old engines now and those that are left are likely with collectors.

[lcp8410]

gas conversion

david, thanks for the advice.but im sure there must be someone here who can do the conversion.anyone?

[David_L6]

http://www.rb-designs.com/ can probably do the work on the cylinder head to lower the compression ratio for gasoline. You still have to figure out the correct jetting and timing though.

[lcp8410]

convert to gas

david thanks for the lead.but i need someone who can set up can set up the whole engine for me.anyone out there can do this?

[DeanFHobart]

Curious As To Why

Hello lcp8410,

I am curious as to why you want to do this.

Good luck with your project.

Best Regards,

Dean Hobart...........

[T Chance]

When I was 13 (long time ago as I just clicked over at 72) I had an Alcohol burning Champion Hot Rod. When I didn't have any racing fuel, I would run it on gasoline. The only change I would make would be to turn the needle valve in to make it run leaner. And back in the 70's Mercury bought a Konig, put smaller jets in it and ran it on the dyno on gasoline without any other changes.

You could probably get by with just putting smaller jets in but somewhere along the line my guess is you would destroy the engine. Just buy some methanol and castor oil and run it. VP Racing fuel has dealers all over the world.

[lcp8410]

convert to gas

t chance, what would u think it will destroy the motor in long run even with the proper fuel/air mixture?.is that because the higher compression,ignition timing or because less internal cooler on pump gas compare to alcohol fuel? like to hear more from u guy...

[T Chance]

Back when the Quincy Flathead was the dominate engine in Pro Racing there was a group in Iowa that ran the engine on gasoline and petroleum oil. They had a lot of internal mechanical problems with the engines that the alcohol burners (mine included) didn't. I don't know why, but that was what my comment was based on.

[Yellowjacket]

You could likely run it on 100LL avgas with just a change of jets. Or you could add some octane booster to bump up the octane of a premium pump gas, or, use unleaded racing gas. Don't know what the compression ratio is on that motor, but you need to either get the CR down or the fuel quality up to where it won't detonate.

After that, it's just jetting, and you should be able to upsize the jets to account for that pretty easily.

[G Stillwill]

I dont know what that motor cc's but you can use brass shims under the head like we do with the Hotrods to get the cc' up around 12 , rejet the carbs for gas and play with the timing it should run just fine with 100 octane or better racing gas.

[fourblade50]

for either the 125 or the 250 carb the needle and seat will need to be changed to a 2.5. the mikuni seat for gas is drilled to a 2.8 mm. main jet size should be in
the 360 range for gas. prop selection will be the big one and ignition timing. start the timing at .050 before tdc and advance from there in .005 incraments.
prop depth at 5/8 of an inch deep to start.

[David_L6]

Would it be possible to use a carb off of a dirt bike? I'm wondering if the jetting for a 125cc or 250cc two stroke dirt bike would be close to what's needed on this project??? The main problem that I can think of is that dirt bike carbs are set up for gravity feed.

[lcp8410]

pum gas conversion

four blade 50,sound like u are there before,that what i what to hear...can u tell me more detail on this convertion...the performance and reliability....

[raceright]

four blade 50,sound like u are there before,that what i what to hear...can u tell me more detail on this convertion...the performance and reliability....

skirt clearance