Methanol tips and tricks

[Raab51]

I’ve read many methanol posts about people wanting the power and not understanding what’s involved… hopefully this can clear up some of what’s involved in a proper methanol conversion and please give me lots of details on what I have missed. I understand this is a banshee forum and I run Hondas. Sorry if this isn’t  allowed. You guys are the authority on methanol and two stroke stuff! 

 

 

hopefully my post / asking for knowledge is pretty close a theoretical running project. 

 

 

I have early model Honda RS125 Road racing bikes. They weigh 165 lbs. power is around 38 to the tire on VP110.  The engines in these early model bikes are nearly identical to 89-04 CR125 engine cases. The porting on the RS is drastically different then the CR and does NOT use a power valve. Currently in a seven lap race I will use about 1/4 tank or less of vp110 fuel. The tank is 14 liters / 3.7 gallons. I’m hoping a full tank will get me through a seven lap race! 

 

 

I would like to convert to methanol for road racing my 125s. Flushing them on regular gas afterwards doesn’t seem like much of a Hassle on an already dedicated race bike. 

 

 

General theory: 

 

**Fuel needs**

 

Keihin PJ35 carb 

 

I need a main jet with twice as much surface area. I am typically running Keihin 162-168 main jets. 1.62 mm = 2.06 surface area. Twice the surface area is 4.12 = 2.29mm / 230 main jet as a starting point to get enough fuel. 

 

I will need VS107 #3.7 the 3.7mm Ø needle and seat kit with Viton o rings / tips. 

 

I will need a Viton bowl gasket as well and the jet o ring in the bowl. 

 

I need to remove the filter from inside the tank/ petcock and use the largest fuel lines I can clamp onto this carb. These tanks already have a direct to atmosphere breather on top of them. 

 

If any one thinks this is not worth modifying this carb I’d be happy to buy a methanol set up lectron. I’d love some real world experience feed back on aftermarket methanol spec carbs vs conversions. 

 

**Ignition needs** 

 

There are many programmable ignition systems out there. I was looking at a plug and play HPI as my top choice. Next would be a zeeltronic that would need to be wired in. Open to other brands. Cost isn’t so much an issue as quality. 

 

**spark plug**

 

I need to run 2-3 ranges hotter of a plug from what I understand? 

 

 

**cylinder head** 

 

I am running a VHM head with changeable inserts. I will be getting an uncut insert to have some one who knows what they are doing cut me a methanol specific head. Right now my squish is .7 mm. I added a flywheel weight and can easily rev to 14k. I would like to space my cylinder up a touch higher “.1/.2mm” and really bring in a lot more compression for this set up. 

 

**pre mix oil**

 

KLOTZ?

 

I have been running motul or repsol road racing oil at 20:1 with NO issues. I would like to keep it rich in oil if possible. 

 

**live data acquisition**

 

For the last ten years I’ve been using aircraft spruce EGT gauges. I have been to a Dyno with a wide band O2 sensor many times and I take notes. With just fuel tuning I am always spot on with this set up. 

 

**maintenance**

 

I do pistons every 300 miles and cranks every 1200 miles as called for in the manual.   Purging back to gasoline will not be a big hassle on this bike. 

 

Any and all input and guidance is greatly appreciated. I’m trying to make 6-9 more Hp and keep it reliable.

[registered user]

alot of that stuff u have to figure out on ya own. usually the carb jet hole is drilled out because its not big enuff 4 methanol but u could buy the biggest jets and c if it will work. and larger float bowl

same with needle. get a rich 1 and see if its enuff. and usually ya need a pv 4 additional fuel at full throttle

compression ,ign timing and other shit ya just gotta figure out or find sumbody wit dat same engine and they can help ya

youll chug more fuel so is ya tank big enuff ? then youll be carrying some extra weight

race gas might b a betta choice 4 u

Edited December 30, 2023 by registered user

[Tedder]

Registered user is 100% right. So many variables and a lot of testing that you'll need to do on your specific application. 

Number one, It will take a LOT more fuel to keep from burning it down. Guzzler, Opened vents, big bowls etc.  

Don't get greedy when your testing, Baby steps as you go - I use Digitrons and do plug reads to monitor my passes. ***Even so you'll likely eat a piston or two during your learning curve.

As for plugs - Most Banshees running gas use BR8 NGK's - On alcohol BR9's which is a colder plug are pretty much the standard.    

I use bored 39 PWKS and 41 Pro's (both the same bore size) in my 1/4 mile asphalt motors. The mains and dump tubes are drilled to .120 plus they have power jets. 

Pilots are as small as I can get away with (50 or 52 I believe) If you go to small you'll get lean hangs at best and at worst it'll rev to the moon at startup.

As posted earlier, Alcohol generally requires a different dome configuration and additional timing. 

Now let's throw a wrench in it all - My son (Banshee) and grandson (Apex) run 2 -300 ft dirt drags and the fuel requirements are very different. Smaller mains/dumps and very little or no power jets needed depending on distance and track bite.

Oil - I used to run 32:1 Blendzall but switched to 927. You'll have to do your own research to verify your oil choice is methanol compatible. I think mixing at 20:1 is fine. On a side note. I live in the Northeast. I liked Klotz Super Techniplate in gas motors for years but it's hygroscopic and did ugly things to the inside of our alcohol motors even with very good purging practices. 

Hope this helps

 

[SKEETER]

20 degrees of timing , and a decent lean hang is when they make da mozt powa

[registered user]

+6 vitos key and +4 on da plate should b just bout rite

[locogato11283]

Start rich.