Help with Margay race kart?

[Dang]

I got this Margay race kart from a guy who used to race it and the whole kart is disassemble. I am trying to identify the year and any possible information on the kart and engine so I can rebuilt the whole kart back together. The guy said he got the Margay kart in 98 and the engine on it is a 15hp 10,000RPM Yamaha KT-100SE. I was told it was clocked at 97mph with the whole gear setup. I am not sure if the engine is still any good. There's a sentrifical clutch on it for start/idle so you would pushed start to run it. The Margay kart, on the front right side of the spindle hanger there is a serial number 89894 stamp on it. That's about all the information I have so far, if anyone have any other information that would be helpful let me know thanks.

 

[anderkart]

Cool kart

I'm guessing its a mid-1990's model, but you'll find a form to send your frame #'s to margay for a positive model/year ID here at this link:--> http://www.margay.com/what-kart-do-i-have.html

While your engine might be able to hit 97mph on some tracks, most KT100 powered karts are usually geared to top out between 60-70mph at the track. That guy might have been exaggerating a bit... How many teeth are on your clutch and axle sprocket?

You wont be able to pushstart it with a clutch installed. Most guys with KT100's use a kartstarter like the pic below. Although you could pushstart it if you installed a solid drive-gear instead of a clutch.

2 other starting options are installing an on-board electric starter, or a recoil-pull rope assembly. These 2 options were not as commonly used on KT100's, so parts might be exspencive and dificult to locate.

The Allen bit at the end of kartstarters fits into the bolt holding your clutch on for starting. These usually cost around $250 new, but I might be able to help you find a good used kart starter for somewhere around $100 range. Sometimes guys use electric drills or build their own DIY kart starters too, but that can be tricky/dangerous, so let us know before you attempt either of those options. Do not attempt starting with any impact gun! You'll probably strip threads/break that bolt, or possibly snap the whole end of your crank right off...

 

[Dang]

Thanks for the information. I contact margay to identify the serial, it came up as a 1991 Margay Lynx A/C. For the engine there seem to be no compression or maybe cause the spark plug is remove? I took the engine head gasket off and rotate but the engine cylinder piston dont seem to be moving up and down so is the engine bad? The owner reassure me that the engine still work and running when i asked.....

 

[anderkart]

If your just spinning the clutch by hand, your piston wouldnt move at all. Your centrifugal clutch doesn't engage/lock up until somewhere around 10,000rpm. Try using a ratchet w/socket or Allen wrench to turn the bolt in the center of your clutch, I'll bet the piston moves up and down then...

 

[anderkart]

And yes you'll need the spark plug installed to feel any compression.

If you still have the head off, move the piston all the way down and post some pics of the cylinder wall inside. Does it look good in there? Are there any deep scratches/scrape-marks or other areas inside that look bad?

 

[Dang]

I took the head gasket off and the inside chamber look to be clean no scratches of anything major but the top piston has some dark black dry smudge. I am not sure if the smudges is rust or dry gasoline with oil.

 

[OzFab]

That's carbon build-up; perfectly normal

 

[Dang]

whats the best way to clean the carbon buildup on the piston?

 

[Dang]

There seem to be alot of rust on the bolts, kart and the drive axle. I think i got some work to do, gonna sand it out and repaint the whole roller before i work on the engine.

 

[Bluethunder3320]

looks like your engine has been bored .030" over. (30 mark on the piston) id just clean up all that gunk and hopefully its okay.

so does it turn over?

 

[anderkart]

You could clean the piston with a brass wire brush and/or maybe some carb/brake cleaner.
I'd get the piston all the way up up to the top first, then elevate the bottom of the engine slightly upward, so the debris/cleaner doesn't fall/drip into the piston rings, ports or crankcase.

Then after cleaning, push the piston all the way down, spray some carb/brake cleaner on a clean rag and wipe down the cylinder walls. Then let it completly dry, and put just a little motor oil on another clean rag and wipe the cylinder walls down to lube it.

I've heard you can usually re-use the copper KT100 head gaskets. Check out George Clausen's post in this thread for info: http://www.ekartingnews.com/viewtopic.php?p=121750&sid=fbee129f2b66540537cb9325fe195832

Do you already know how to use a torqe wrench? Let us know if you want some tips

 

[Dang]

looks like your engine has been bored .030" over. (30 mark on the piston) id just clean up all that gunk and hopefully its okay.

so does it turn over?

Is that a good thing since its been bored for the extra hp? I havent try to turn it over yet. I am gonna see if i can get a good deal on a kart starter or try one of the method Anderkart mention earlier.

 

[anderkart]

I could check around for a good deal on a used kart starter, hopefully within driving distance of you.
Are you in the new york city area, up-state or what?
(you can PM me here:--> http://www.diygokarts.com/vb/private.php?do=newpm&u=2988 if you wanna keep your town a secret)

 

[Dang]

You could clean the piston with a brass wire brush and/or maybe some carb/brake cleaner.
I'd get the piston all the way up up to the top first, then elevate the bottom of the engine slightly upward, so the debris/cleaner doesn't fall/drip into the piston rings, ports or crankcase.

Then after cleaning, push the piston all the way down, spray some carb/brake cleaner on a clean rag and wipe down the cylinder walls. Then let it completly dry, and put just a little motor oil on another clean rag and wipe the cylinder walls down to lube it.

I've heard you can usually re-use the copper KT100 head gaskets. Check out George Clausen's post in this thread for info: http://www.ekartingnews.com/viewtopic.php?p=121750&sid=fbee129f2b66540537cb9325fe195832

Do you already know how to use a torqe wrench? Let us know if you want some tips

**** i dont have a torque wrench to put the head gasket back and i dont wanna kill the engine using a regular wrench to tighten it haha...thanks for the advice.

 

[anderkart]

You can usually rent a good Inch-pound torqe wrench from auto parts stores.
(but ask when they last checked its calibration, to make sure its reading accurately)

Your 30-over piston/bore would just very slightly increase power, and there's plenty of larger piston sizes avalible in case you ever need-em.

 

[anderkart]

Heres a video you should check out, you'd use the same basic method, but just 4-bolts torqued to 144 inch pounds. Make sure you first clean the threads and use just a little oil (or I like to use a product called Never-Seize) to lube the threads so your sure they're not slightly binding up giving you an inaccurate torqe reading...

http://www.youtube.com/watch?v=Bi6-3a_4AgM

 

[Dang]

Thats a good video on torquing very helpful thanks.