Modifying Carbs for E85

[gpr]

I have searched but didn't see much info on it. I have talked to a few different builders as well to pick their brains on setup up PWK carbs for e85 but didn't get much help.

 

Here is the story. Last year i wanted to convert my 41pwk carbs over to e85. I installed larger mains and pilots and got those dialed in, however i could never get the needles correct. On the dyno the WOT a/f ratios were good in the higher rpms, however down around 6000rpm when the bike was just starting to get on the pipes the engine would go stupid lean. So lean that it would detonate hard enough to close the gap on the spark plugs and kill the engine... I could never get it fixed so converted the carbs back to gas.

 

For those who are familiar with jetting and dyno tuning, when i would start the run it would be very rich, then lean way out and come back rich all within about 1500rpm around the 6000rpm mark. Is this because my needle tubes are too small?

 

I'm thinking i need to drill out the needle tubes, but don't know what to drill them too? I tried several different sets of needles to get more fuel but it did not help.

 

I have seen some have converted to e85, what did you do to your carbs to get it tuned correctly? Do you run power jets?

[BUILDER]

Sounds like you need to stay away from E85 lol

[camatv]

first off i'd get a pj for that carb

 

e85 and alky are very similar in what they want fuel delivery wise..  if you dont have it you need to make sure that you have enough fuel delivery capacity, drilled stock cap with no guts or billet cap possibly drilled as well. pingle and modified floats or larger float bowls.  then i would bet you would need to drill out the dump tubes in those pwk's probably around a .100 to start.  i'm not sure what needle is used in those carbs with alky but something similar is probably fine.  to me really e85 is a waste of time in an atv,  you ahve to treat it just like alky, purge, storage issues, and mileage is not all that much better.  plus alky is cheaper.  and well know how to tune and setup a banshee on any popular carb..  mikuni's pwk's or lectrons.  lectrons and mikunis can be swapped back and forth from gas to alky realtively easily.  lectrons usually only need a needle change to go back to gas if they are alky specific..  i would highly suggest using a set of those carbs if you really want to run e85.  packard i believe has a needle for e85 figured out.  it really sounds to me like the dump is too small and when you first hit the throttle there is not nearly enough initial fuel delivery.  

 

on a side note i have a 1950 ford 2 door coupe, i plan on rebuilding the 265 small block chevy thats in it and running e85 with some compression.  should be fun!

[gpr]

Thank you camatv for the help. I run e85 in everything and love the stuff. I have it in both my car and pickup. I also have converted many
4 stroke atv's but banshee tuning is somewhat new to me as i don't have much dyno 2 stroke time under my belt.

 

Like I said it is a strange situation as I can cruise atpart throttle on e85 on the dyno and it wasn't too lean. when starting the dyno pulls I punch it and the bike is reading rich, very rich. Then it leans way out and then goes rich again. I have plenty of fuel as once I am in the higher rpms I can make a pull no problem and keep enough fuel in the bowls, just down low right when it was getting on the pipe around 6500rpm it is very lean. I will try and find dyno graph to show you what I mean.

 

I will start by drilling out the dump tubes and go from there. One of the big reasons I don't want to switch carbs is I own basically ever size jet for these pwks, as they use the same mains as FCR carbs. Also I have probably 20 different needles and 20 different pilots. I'm thinking I will
try and get these 41pwk's to work and if I can't then I will buy a set of 39pwks and stick to gas. (have heard the 39's are less finicky)

 

I talked to Rob at RDZ, as he does a carb conversion. He said he drills the dump tubes out and you run the same needle that you do on
gas(didn't say how much he drilled). Then he adds a power jet to it.

 

Btw, there are huge benefits over gas or methanol in my opinion. E85 isn't corrosive like methanol and I never have purged a bike in my life on it and have seen no ill effects. Also it isn't as finicky as methanol, starts better in cold, runs cooler than gas and makes more power than gas, but not as much as methanol. The only drawl back to e85 is consistency, which is what most people say that have never ran it. If you tune on e85 and blend switches to e70 it will just richen your bike up by about half a point(I bet most peoples bikes are further off on jetting than that). It is very easy and cheap to measure ethanol %.

 

[gpr]

I have been told they are too small... But i don't really know of any larger carbs, or care to loose the bottom end going with larger ones.

 

It is a 16mm DM.

[gpr]

Here is a dyno from last year when i was messing with it. Don't get too caught up on the hp or torque numbers as it was calibrated wrong and reading extremely low. Regaurdless this is showing the a/f that starts out lean from whicking the throttle open, goes rich, then goes lean again. It is the strangest thing I have ever seen, and has me dumbfounded on how to fix it.

 

Tried probably 6 different needles much smaller in diamerter then the cel's that were running on gas and it didn't help that much.

[gpr]

here is the graph, its pretty small cause of the size limit but you still get the idea.

[camatv]

what oil are you mixing in the e85?  is it staying mixed and not seperating?  

 

im wondering if the hit sucks the bowl dry then they resupply and bring the mix back>?  if on a dyno you can run a line up from the drains and watch the fuel level.  

 

if its a dm it DEFF needs pj's..  they are notorious for needing a LOT of fuel. i'm suprised you didnt destroy the motor slamming the plugs like that.. oh also  are you running a tighter plug gap?  .18 works well.. 

 

i never really looked at if it was corrosive or not..  i ran it a few times on a 700raptor with injection i was playing with.  it deff ran way cooler.  i played with it on one of the alky bikes too but it just didnt make the HP i was wanting and since i have so many alky bikes i said screw it.. now i run either pump  or alcohol

 

NOW on a side note..   what fuel pump should i use in the automotive area??  and on carbs and ignition any idears there? i havent done a lot of looking  but i want a motor with more comp for goofing on in the street.  i'm going to run a thumpr cam and just want the comp to make it bark a lil.  plus it smelling like corn should be fun.  there is a COOP 15 mins from my house with e85 pumps.  it comes from 25 miles away at the refinery they built a few years ago...  and  what color you think the flame throwers will belch  ha ha

[registered user]

they sell e85 around here. might try some in the lawmower

[registered user]

they sell e85 around here. might try some in the lawmower

hopefully it will blow the fuker up and i wont have to cut grass no more hahahahhhaa

[gpr]

I had a small bottle of redline alcohol 2 stroke oil i used when i was playing with it. i normally run the redline racing 2 stroke oil, does that stuff work with alcohol?

 

I thought about putting power jets on it, and a vacuum fuel pump just to make sure it would have enough fuel. however on the graph in the higher rpms the a/f ratio was down around 11.5:1 (btw, that is reading on a gas scale, using a gas scale i typically make peak power around 12.7:1), so it had plenty of fuel. I think i would be okay if i could just get that lean spot tuned out.

 

yep, e 85 runs cooler than gas and makes a little more power than gas. It isn't as much as methanol, but I'll give up a few pony's for the other benefits.

 

The odd thing is i had the head off of it, and it didn't look there was detonation. When it closed the plug gaps it must have done it very quickly. I couldn't see any pitting on the head or piston like you typically will with detonation. Plus i couldn't hear it either, and no speckling on the plug.... I believe the plug gap was around 20 thousands.

 

For your car setup are you going to be running efi or a carb? In the efi motors i have been running walbro 340 pumps. they are 255l/hr pumps and have worked well for me so far. I'm still running with stock plastic tanks and lines with no issues what so ever. the e85 will actually clean up the tank and lines and many times plug your fuel filter getting all the old crap out of it, so what for that. It is odd too as the exhaust will look clean instead of black and carboned up.

[gpr]

One more thing that puzzles me is when i was testing this on the dyno. This run was at WOT the entire time, so i don't know if it is the needle or dump tubes causing this lean issue? The needles are for part throttle tuning usually. Does the dump tube/needle affect wide open throttle. After trying the richest needles i could get for the carbs I started to think it might be the pipes.

 

I was running some  shearer BB inframe pipes which i believe were originally for a cheetah motor. I have some new pipes setup for a DM coming from shearer right now. Once i get those i think i am going to try the e85 again.

[camatv]

the a/f ratio for e85 is differnet than for gas..  i dont know for sure  or at what but..  i'd say deff get the dumps drilled, and get pj's in it.  maybe even need 2 pj's in to supply enough

 

i dont know on the massive failure of the plugs.   only time i have seen that was from a huge lean out..  the deto rattles so hard so quick it shuts the gap.   when they are close  they deto and shake the plugs out and damage the motor.  

 

when i use alky i just watch the plugs.  i have never dyno'd an alky bike with sniffers in it.  in the past i used EGT's and then tuned with plug color and heat after that.   the redline alcohol oil would have been fine.  alcohol will do the same thing as far as keeping things clean  most times if an alky motor is purged they will look brand new when you take them apart.   

 

i'm planning on running a carb.