Finally found a good deal on a Kart - needs work, but that’s okay with me. He included 2 starting devices. A few unknowns I need help with:
This is an alcohol engine - after research it seems I would be better off starting with a regular gas engine to get the feel of things (maybe a predator?). Regardless, I think it would be fun to feel the alcohol’s power before converting. Where can I find more info on purchasing methanol, finding mixture ratios, etc? I don’t know much about this engine.
*Are the predator ghost engines directly compatible with my setup?
*What else should I know about this go kart and where can I find documentation?
Thanks all!
Where are you located?
Gilbert, AZ
What age bracket are you in?
Masters
On a scale of 1-10, how would you rate your mechanical ability, or willingness to wrench on things?
8
Experience
Lots of indoor electric experience and a few shifter cart rental sessions.
The motor on your kart is a Yamaha KT100 which is a 2 stroke motor which requires mixing fuel with 2-stroke oil. The predator is a 4 stroke engine. So while you could put a 4 stroke on this chassis they are different in several ways.
I have little experience with alcohol but it is usually used because it burns cool. If you want to stay with alcohol you will likely have to find a speed shop or race track that specializes in full-size race cars or possibly a fuel distributor that sells race fuel.
You’re not going to find much specific documentation that pertains to your chassis and motor but a lot of the information contained on this site and others will help you along the way. The KT100 has been around since the 60’s and I would guess your chassis is from the early 2000’s.
As Rob rightly noted, this is a 2-stroke KT100, not a 4-stroke like a Predator. Before spending too much money it’s important to identify your goals. As James asked and you answered, if you’re looking to eventually be racing down the road, you likely won’t be able to run KT100 anywhere anymore, as that class has been largely replaced throughout the country by more modern offerings like the KA100.
The popular entry-level class right now is based in the Briggs LO206 engine package which would be the go-to 4-stroke package. It’s important to note that a 206 or other 4-stroke may or may not fit onto a traditional chassis designed for 2-stroke (like this Birel). It may fit or it may fit with some modification to the frame.
While this kart might be good for turning laps and getting your feet wet (the Yamaha was a karting mainstay for decades), if you’re looking to race you probably want to see what classes are offered in your local series and have an eye on that so you don’t have to buy and sell a bunch of stuff before you get a package together that is compliant with your local racing series.
Another note is that the Yamaha is externally started as you noted in your original post, so it isn’t quite as convenient for solo track days unless you rig up your starter on a little set of wheels or something so you can start yourself.
As always with newbies, figure out where you’ll be racing or driving, identify what your local shops are and what brands they support so you can get setup help and spare parts easily (they’ll usually have used karts as well), and then you should have a pretty good idea of what kind of package you’re looking for.
Someone local to AZ can chime in on what the local scene is looking like right now.
Robert & TJ, thank you both so much for the wealth of information, looks like I’m the right place!
Based on what you mentioned, maybe I can get this engine running on gas (instead of alcohol) just to make things a bit easier and “try out”. Would this just take a jet change and timing? Also, what is the proper 2 stroke mix ratio & what oil do you guys typically run?
Looking at the dimensions of the LO206, it definitely would be a change to the mounting surface (at minimum).
As you recommended Robert, i’ll definitely be heading down to the local raceways!
I think if you’re up for some mechanical fun, give it a go on methanol first.
Although methanol is a little more work, I think converting to gas might not be worth it. You’ll need a different carb (Gas will likely be out of its range of adjustment), possibly different head and then change timing like you said.
For methanol many run a ratio of about 16:1 gas oil with a castor based racing two stroke oil.
It might have been me mentioned already, but the engine and carb have to be “pickled” before being put back into storage. Basically run the engine on few oz of of mixed gas to flush the methanol out because it’s corrosive to aluminum.
For the for stroke engines, ie Briggs 206 theres a few tricks to getting them to fit, but there’s literally 100’s of examples around the US where it’s been done.
The biggest question mark is wether the axle has a drive keyway to support the onboard drive of the common four stroke engines.
Oh, an external starter will be essential for the KT regardless of wether it’s gas or methanol.
I am not familiar with what is required to run the KT on alcohol vs gas. As James mentioned its likely more than just a needle adjustment. That may require more searching to find that answer. I do know you need a lot more alcohol relative to gas. These motors were used in other applications too, so you may find your answer in non-kart circles. With race gas I would run 16:1 ratio, no idea what alcohol would require.
As TJ mentioned the KT is becoming extinct so you might be able to find parts cheap, however, new parts are becoming harder to find.
I would imagine you are itching to get it going and I’m not sure what would be your easiest or least expensive way to do that. to give you some points;
A box stock predator 212 is about 6-7hp
A briggs 206 is about 9hp and I believe a stock ghost is about the same.
the KT on race gas was around 12-20 depending on the exhaust pipe.
Oh don’t be so soft Matt! Lots of us grew up learning and racing on the KT and we’re (mostly) fine today.
They aren’t as bulletproof or foolproof as more modern engines and require some more attention and maintenance, but in almost 15 years of racing Yamahas in all their various classes, I probably only seized 4-5 engines.
Generally I’d agree, but it depends on the person and their interests/situation too. If someone is up for playing with engines etc and they go in with both eyes open it can be a good experience.
Absolutely agree with that. Playing with the needles was a requirement to run KT. I mentioned playing with the needle adjustments to a newer KA guy and they are like “I have it set where I was told to set it” and a look of terror when I suggest adjusting on the track.
I have a love/hate relationship with the Yamaha. I can’t recall a day where it was just a good day at the track with one, tho! Seems to always be something with them.
Everyone in AZ runs an L206 or KZ. The road race guys run World Formulas and a few still run CR125’s. I’m local and have a really clean CRG going up for sale if you haven’t purchased that kart yet.
Thanks everyone - great details and history on the engine.
I forgot to mention I already bought this thing, too cheap not to.
I got it running yesterday on Methanol running 16:1 Castrol 927 (sure missed that smell). Thing feels/sounds like a 500cc’s little brother. It doesn’t like you giving it gas, it just boggs out, even when warmed up. It’ll let me rev it if I unscrew the (T-Handle) needle a bit, but then doesn’t want to calm down. It idles good at one full turn out.
Also - it needs a clutch, where can I find a rebuild for this thing?
It’s a 2-stroke racing engine, it shouldn’t want to idle so if it is you probably have the carb settings incorrectly set for actual driving.
No idea what your carb setup should look like on methanol, but on race gas we always ran around 2 turns out on the low speed needle (T-handle) and 1/8 to 1/4 turn out on the high speed needle (L-handle). As a piped Yamaha, it might require a leaner setting on the low speed needle to start and then adjustment to open it up once you’re at speed so it doesn’t flood on the low-end.
Clutch looks like a typical Horstman two-disk which I’m sure most kart shops have some spares in their backrooms for.
Likely the carb will need a rebuild if has been sitting for any length of time and that could be causing your issue. Its really the diaphragm more than anything. The kit should be readily available. Here it is from Comet:
Thanks TJ and Robert for the carb info, what you describe makes perfect sense based on what I was attempting yesterday. I’ll order one of those rebuild kids. Cool site!
As far as the clutch, I couldnt find one that matched any of the horstman’s, but I did find an emblem on the clutch saying Tomar. After researching I think its a Tomar TD-23 but not positive…
You may be right. The shoes on the clutch look to match the Tomar whereas the Horstman had more squared off shoes. I ran Tomar stuff for a bit too. They had a cool multi-disk dry clutch I used for Yamaha pipe when everyone else was running wet clutches. They make good stuff.
