Race gas or pump gas?

evaneyeball · Jan 20, 2020

i am having LED do my motor 86 250r to a 269 cc and the current head is a 23.5 cc dome. it will have a hinson clutch every thing a hot rods crank and pro x piston do i need to run race gas or not he says i most likely will. also ct ported it and he has to do some small porting changes. i will also pretty much only run it in the dunes.
does anyone know what piston i should use instead of pro x because i am not sure if i want to use another or go with the tried and true wiseco

american opel · Jan 20, 2020

piston has nothing to do with compression.i love the cast prox pistons.i he should be able to set it up for either..but i would go race fuel.alot more power.

acecarlos · Jan 20, 2020

All of these questions are 'Best' answered by the builder doing all the work on your engine or cylinder, as well as providing all the proper parts....he/she should fully advice, provide parts and any/all needed information, specially since it is their "build".

Carlos

The Norm · Jan 20, 2020

I would definitely call Arlen and have him set your compression for the gas you want to run. If you run race fuel (110 octane) in an engine set up for pump gas (92 octane) you are wasting money. You gain nothing hp wise from running race fuel in a pump gas engine! My 12 year old boys R's have 13.5:1 compression and running 92 octane pump gas. They routinely embarrass yfz's and raptor's with bolt ons. Arlen knows all this as he is a very experienced engine builder. My builder (Pete @ Hybrid Engineering) suggests setting up for race fuel because you have a better quality of fuel. I chose pump gas for my boys R's because they ride more than me lol

evaneyeball · Jan 21, 2020

i am just looking for another opinoin i know he is experiencd and thats why i am having him do the work. but also i am dropping off my cases on Wednesday. i am also wondering how this thing ran super strong before i took it apart to fix my cases. it has a 87-89 crank 85 cylinder a 86 piston and a 86 23.5 cc head with no base plate. in 86 cases if that makes a difference.

american opel · Jan 21, 2020

no way you were running a longrod crank with a short rod piston without a spacerplate.the piston would have came out of the top of the cylinder and hit the head.

The Norm · Jan 21, 2020

What dunes do you ride? We mostly hit Winchester.

evaneyeball · Jan 21, 2020

mostly Winchester, riley ranch and sand lake. but Winchester and riley are about 4 hours away so day trips are sandlake. but this spring my family and some friends are going to st.anthonys dunes and possibly Moab too

evaneyeball · Jan 21, 2020

i know the piston would have hit the head but it didnt and it ran super strongly too. the only explination is the head was bored to 23.5 cc could that have made a diffrence. but i am going to LED tomorrow so if nobody here knows he might know. i will post pics of every thing soon

Race gas or pump gas?

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