Fuel

[markbano]

I notice that the manual for the Kitty Cat instructs the user to avoid gas with ethynol or other similar additives.

Almost impossible to find fuel without that stuff around here. Anyone have any suggestions? Is it really a big deal one way or another?

Also - how important is it to use a specific type or grade of oil. I've been using 2 stroke oil but it is not one of the expensive brands. Of course, I've lost the main rod bearing on two engines now.

I'd appreciate some thoughts on gas and oil. Thanks!

[THX_138]

What year is your manual?

Ethynol or other similar additives are said to burn out a
"non-hardened" valve seat quicker. If you have a manual
from the 70's that explains it. If you have a newer sled,
chances are it has hardened valve seats for today's gasolines.

If it's an older engine and it concerns you, you can always try
to find "Lead Additive" for fuel and mix it with your gas mix.
I think that might help a little....not 100% sure.
I'm sure someone here can tell you better if the lead additive
will help at all.

[markbano]

The parts and service manual is dated 1988. The machines I have are a 1987 and a 1991.

I know somewhat had said that the ethynol causes the petcock seals on the fuel tanks to loose their elasticity and leak.

As for valves - well this is a little two stroke engine and it has no valves - just ports.

[72]

fuel blended with ethynol and other additives (like found at gas stations) will break down non-synthetic 2t oils quicker than "straight gas" , however the time it takes is still longer than you should keep pre-mix around for imho . some other options that might be available to you is find a speed shop that keeps a couple drums of race gas handy or a race track that sells gas on site (this time of year might be an issue) . another option (if you have a small airport in your area) is aviation fuel . one issue aviation fuel has is a lower specific gravity so rejetting could be required . a plus is that its 7+ points higher in octane than pump gas so it buys you some insurance from detonation/preignition if you spring an air leak or happen to get too hot . this is cheap insurance considering its only around a buck a gallon higher than what youll find at the pump .

ive dealt with vp fuels for a similar displacement 2t application in the past and they have a wide variety of fuels for pretty much any application, good customer service and offer they offer 5 gallon cans shipped . if you do a search for them you will find their web site . ive found the price increase of race gas dosent even come close to the increases at the pump making it more of a value than it was 3-5 years ago .

with the cost of gas being what it is ... the increased cost of a good synthetic 2t oil compared to the cheap stuff isnt even worth looking at . you might burn what ........10 gallons at best in a season for this application . i prefer motul but klotz has a better smell . sticking rings and cylinder scuffing can cost more than what 5 seasons of running the cheap stuff will save you . blending a little castor in with the synthetic will provide for better bottom end protection but not as much as propper engine setup . .................john

[markbano]

Thanks. Great advice and much appreciated.

I have access to 100LL aviation gas here at the airport where I live and I'm wondering if that would be a better gas to run in these machines. It is high lead but also high octane.

[kidsperformance]

when you increase the engine speed on a kitty motor you also increase the heat.....fuels out of a pump have way to much (garbge) additives to make them run right.....this is a carburated motor......everything (or majority) is injected to where there is 50-70lbs of fuel pressure.....fuels at the pump don't have enough distallation in them now because we are getting winter blends from the refineries.....This a fan cooled motor and heat will always increase as in turn the exhaust wave will move faster and faster and basically the heat will return back into the cylinder and then down the transfers eventually evaporating the fresh charge of fuel that is trying to make it's way into the cylinder......basically they are fighting each other and a bogg is usually the result....I have done extensive testing on my dyno with different fuels....hp is all about "burn rate" at peak cyl pressure at a certain crank angle.....The best fuel I have found is a fuel made by VP....it's called MS93....it has the distallation rate of the old pump gas that was produced back in the 90's.....when I used to race with my boys I would use 89 silver in the stock kitty and my sons yamaha can motor (other son raced go-karts after kitty cat racing)and they would just ROCK with power....100LL does not have a high enough 90% distallation rate......you would be better off with 82 U/L...but I don't know where you can find that....right now I found some fuel at a lil airport that has I think 87 octane fuel that they use in the Piper 150 & 175 airplanes.....they say those planes need low-octane fuel....I blend that 50-50 w/MS93 and my grandsons kitty cat just sings.....just like they used to....when our gov allowed BP to buy out Amoco that was part of the fuel changing process to make earth such a green place to live....(oh please)...If you would leave the gov hooked up and run any pump gas they would survive forever....it's when you try to get more speed out of them is when the problems start if you don't change other things......then you have guy's like me who are trying to get Grand Prix power out of a moped motor................... .......hope I shed some light on this or I probably confused the heck out of you

Bill

[kidsperformance]

One other thing I forgot to mention is that these engines are low compression....they have alot of squish clearance and a very low squish velocity...that's why they need low octance fuel.....anything else would never allow the motor to build any peak cyl pressure....MS93 has a 365 degree 90% distallation temp......that helps the piston crown temps that they experiance......kinda like throwing water on a hot frying pan as to throwing 90w gear lube in there....reading spark plugs is another way.....if the outer edge of the plug is black and you can't rub it off you have to much heat in the combustion chamber....basically the fuel is burning off and all is left is the oil in the chamber....you want it brown or light tan like the prosulen(sp)....sorry for the rambling

Bill

[markbano]

Really interesting stuff. Thanks.

As far as I know, the lower octane, higher led avgas is no longer sold - everything is 100LL now. If the fuel you used had a red tint that would have been the 87LL avgas that the smaller airplanes were designed to burn (Cessna 172s, etc.).

I bought a used 340 and I'm looking for another one. I'm going to govern the speed on bigger sleds for my boys next year rather than trying to overwork the Kitty engines. I'll leave that to the experts.

My two Kittys are running great with rebuilt engines and the governors re-installed. The boys are a little upset about the slower speed but still having fun on them. However, I'll likley be putting them up for sale for some younger kids to enjoy.

[kidsperformance]

this fuel was yellow in color.....same color the 87 stuff was back in the 90's...there is a story about this fuel that the guy at the airport knows the guy(owner) at the BP station and gets the 87 and 93 octane fuel without all the garbage additive's in it for him at the airport....it's actually not avaition fuel.....the specific gravity of this fuel is the same as it was back in the 90's.....presant day pump car that we all put in our car I can see the residue it leaves on my graduated cyl. proving to me it has the "Aohl" stuff in it.....which has not as much btu rating...it's also amazing what it cost because there is no road fuel tax on this stuff that we seem to put on here in IL....

Bill

[72]

This a fan cooled motor and heat will always increase as in turn the exhaust wave will move faster and faster and basically the heat will return back into the cylinder and then down the transfers eventually evaporating the fresh charge of fuel that is trying to make it's way into the cylinder......

is this strictly a pipe or more a pipe and cylinder scavening issue ? ...........j and i sent you a pm

[kidsperformance]

The waves would bounce back and forth even faster as it is because of the box muffler design...which in turn would become a scavenging issue as the heat increased as it trying to evaporate the light ends to mid-range area of the fuel(Temps).....the baffle plate inside and small stinger really choke things

[72]

if its a scavenging (pulling pulse/wave) issue then why is what is being being pushed back (pulse/wave) too early reaching all the way to the tranfers happening.... cause even for out of time charge(into the cylinder) from the pipe/box should never go that far( weather its a fuel charge or exhaust) .... . forgive me but this box system is new to me...... are things getting pushed out of time so far ? could it be just an echo from the original bouncing off the piston? my answer to this would be a pipe .......whats yours? ..............j

[kidsperformance]

We must remember where we are at....this motor was designed to run at 6000 rpm and with everythhing involved internally and externally will run with no problems for yrs.....I just purchased a 1980 KC for my grandson to race and the motor has never been touched.....course it in my hands and you know what I'm going to do... The port timing in these motors are so far out of whack for when the people tie open the govenors it only going to build heat and the motor will eventually shut down....once they cool off they are fine.....but keep them at 6000 rpm they will provide hrs and hrs of enjoyment and no parent headaches or upset kids.....when we start twisting these lil motors for racing they are only going 3-5 laps and have seen alot of damage in that short period of time with other people...* my early days of building pipes I have a few out there from yrs ago on some yard kitty's....don't know where there are now....but it made 20% more power, you jetted up one size(75), still gravity feed the carb, it would turn 10,500 rpm, wake up the whole neighborhood, and if you updated the rod would run a long time and never shut down because there was so much volume to the pipe in never got over 1000 degrees....you could look down the header and see where the fresh charge and the return charge met in the header thus some what never basically scavenging back into the cyl....stock cyl I think only have 16 degrees of blowdown.....If everyone start twisting the yard kitty motors you people need to use a good grade of fuel and the best out there so far is MS93 by VP.....If you put a 70 MJ and still use it as a yard kitty it will still eventually still shut down, but if you jet up to a 75 MJ it will by you some longer time and still may shut down depending on the load you put on it....whew.....my head starting to grow lumps

[markbano]

Thus... my E-Mail on governors. I want people on the forum to understand the implications of removing the governor with no other modifications. When I joined the site there was plenty of tech talk about removing them but no corresponding warnings. It cost me two engines.

By the time I learned about the slotted connecting rod, I had already rebuilt one motor and had the other torn down with parts to put it together again. Knowing that my boys are on the old side for these machines anyway, I elected to just rebuild the second one stock and leave it - with the governors re-installed on both. However, I wanted to warn people on the website about simply removing the governors. It is a fact that it adds only a little speed and costs a lot of headache - particularly for those who cannot rebuild their own engines and/or do not know how to set them up properly to handle the higher RPM - which is probably most people. Websites like this one are great but can also lead people to make big mistakes because they are not armed with all of the necessary knowledge to understand the implications of what they are doing.

The other way go get more speed would be to change the gearing but that seems like a questionable idea, too. These machines already lack initial take-off power in their stock configuration. Changing the gearing would make that worse.

As for the 120 class of machines - I don't see the point. To me, it seems like too much money to spend on an 8MPH machine powered by a lawnmower engine. The sad reality is that there is no machine that fits kids in the 9-14 year old range. I've bought a 340 and am looking for another one and my plan is to govern them down for my boys. To me, that is money better spent once they grow out of the Kittys. I'd be interested in other peoples' thoughts on this.

Markbano

[harryparatestis]

Mark,
I have been through the whole Kitty Cat thing and I must say, I still love them. But once my kids got on a 120, they never wanted to ride the Kitty's anymore. They are a bit pricey, but you can find a nice used one for about a $1000.00 and you can get them to go about 25 mph with a few upgrades.

The advantage of a 120 is the fact that it will go through more then 4 inches of snow, and I dont have to be pushed out when they get stuck every couple of minutes. Dan's lift kits are nice and they will help them go through the snow, but they still ride like Buckboards because they have no suspension. When all is said and done. If you keep your stuff nice, You can still get your $1000 back out of a 120 when you sell it , Just like you can get $500 for your kitty when you go to sell it.

Some things I dont like about the 120's...They dont smell like 2 stroke and I like the smell of 2 stroke smoke. They also sound like lawnmowers.. as a matter of fact sometimes they are so quiet you even wonder if they are running. The 120's also cause me to drink more. I have the tendancy to drink more while I am watching my kids ride around having fun. as opposed to running all over the yard to give them a push when they get stuck in 5 inches of snow :D

KO

[markbano]

Well, you've got me rethinking a bit here- at least for my 7 year old. I've already made a deal on a 340 for my 9 year old, who is big for his age and would probably be big even on a 120.

Perhaps I should get a 120 for my 7 year old. I'll watch the listings. I may want some help figuring out the upgrades because 8 MPH ain't gonna fly with these boys anymore. Your comment about the machines being quiet raises a good point - I'm trying not to drive my neighbors nuts here. That would be a good thing.

As for drinking, I sit in a lawn chair in the snow and pretend to supervise the Kitty drivers while I drink. Since there are two of them, I expect them to make a reasonable effort to help get each other unstuck before I move my lazy behind off the chair...

[1121racinkitty]

BILL ROCKS!!!

[markbano]

Ok. Whatever you say, my friend.

[THX_138]

BILL ROCKS!!!!!

I'm guessing by your last few posts....

you REALLYYYYY like Bill

BILL ROCKS!!!

He's his own fan club!