Swiss Hutless Rondo Build

[NewbCarter]

And new , stronger springs for the exhaust to fix the leak..

But im afraid i killed the engine..

 

[NewbCarter]

Well .. until i open up the engine again , no saying for sure what is going on .

Couple of options really : 1) Key in the rotor broke 2) it also broke the starter ring , and so the engine goes in the bin.

 

[NewbCarter]

New dremel stuff ...

All the stuff you see was less then 10 USD shipped. HSS 3mm bits , sanding drums and disks ..

Steel wire brushes , and plastic ones too which are very useful for cleaning carbs and small engine parts.

May not be top but price:value cant be beaten.. this same stuff in the local hardware shop would easily 100 USD or more

 

[itsid]

Well .. until i open up the engine again , no saying for sure what is going on .

Couple of options really : 1) Key in the rotor broke 2) it also broke the starter ring , and so the engine goes in the bin.

WHAT??

you're not throwing a KT100 away, are you?

take it apart, clean everything up as good as you can,
sell reusable parts on ebay if you don't think you can revive it.

those engines getting rare, and parts are getting expensive;
70 bucks for a case, 40 for a head... 100 for the crankshaft...

really.. throwing it away is throwing away money

'sid

 

[NewbCarter]

WHAT??

you're not throwing a KT100 away, are you?

take it apart, clean everything up as good as you can,
sell reusable parts on ebay if you don't think you can revive it.

those engines getting rare, and parts are getting expensive;
70 bucks for a case, 40 for a head... 100 for the crankshaft...

really.. throwing it away is throwing away money

'sid

It turns over fine , i havent yet gotten to opening it ..

Just that its currently a bit of excess work , considering i have tests soon .. college time.

And nothing but troubles on the yamaha .. as you said , id probably sell the electric starter , keep the engine as is , because even being factory fitted , its very poorly engineered.

Worded it wrong , defo not throwing away .. try to fix it , if not , take the starter off , and set it aside .. maybe a minibike project ?

---------- Post added at 11:19 AM ---------- Previous post was at 11:18 AM ----------

Its like me and Mr. KarteMolim have issues together lol

 

[itsid]

poorly engineered? a KT100?

it's one of the most popular kart engines of it's time if not THE most popular one;
it's got competetive power whilst being not overly excessive to maintain
and for all I know it's fairly reliable and indeed of high quality.
certainly not inferior to say parilla engines of that time..

2stroke eniognes are simple but NOT trivial and I wouldn't dare to call a KT100 poorly engineered.
In fact I'd disagree with you about that

'sid

 

[NewbCarter]

poorly engineered? a KT100?

it's one of the most popular kart engines of it's time if not THE most popular one;
it's got competetive power whilst being not overly excessive to maintain
and for all I know it's fairly reliable and indeed of high quality.
certainly not inferior to say parilla engines of that time..

2stroke eniognes are simple but NOT trivial and I wouldn't dare to call a KT100 poorly engineered.
In fact I'd disagree with you about that

'sid

Not as a whole , but only the electric starter system .
Technically speaking , it is the same system as used in cars and for a closer comparison the 4stroke gx / clones.

Differences being , the 4strokes have both a longer and wider taper , with a bigger key .
And on the yamaha , the actual starter ring is even further away from the crank due to it being a seperate piece bolted onto the rotor , increasing weight of the whole assembly. And stock for stock , 4strokes of the range dont need to crank at 160psi ..

Of course , im probably exaggerating the problem due to it being a constant pain in ze rear , due to someone not maintaining it properly or for that matter reassembling it.

Heck , even people that got the pullstart from factory on their KTs , mostly removed those in favor of the external electric starter , due to it being a reliability issue at higher RPM .

Rant mode off..

But , as an engine .. yes , id be wrong to call it poorly engineered . In fact , i liked it when i opened the box it came in ..

 

[NewbCarter]

Bearing carriers , wheel nuts and other small bits on the way .

For now , only brake pads and 50mm wheel hubs to do , before the long awaited drive can happen .

In the meantime , not related to the Kart itself , but have been snooping around for buying opportunities .

1) Parilla TT37 Engine with Ibea L5 carb - asking price 260 Euro - actual value closer to 600.

2) Parilla TT27 ( or 31 not sure ) on a Birel frame complete for a hair over 280 euro - actual price is again closer to 600 . ( Motoplat ignition itself is worth 150+ Euro )

3) CRG SP97 JICA Engine - i want it . 150 Euro , complete engine . aaaa

And of course , the best find yet , for which im sorry that i bought what i did .

 

[NewbCarter]

And also coming is a HL304E carb with a repair kit , grand total of 35€ . Pretty much a steal .

Also going to a machine shop for a steering wheel adapter , and a proper carb adapter . I discovered a small leak the other day , which is causing erratic pump behaviour.

And the 304 is physically a smaller carb then either the 309 / 334 so it should help with the overly rich running.

 

[NewbCarter]

I hate to talk alot , so il let you guys decide what this is

 

[NewbCarter]

Hmm .. put on the steering wheel.. or under the nasaau panel , so they can be seen thru the wheel

 

[NewbCarter]

Found the source of the issue.

The spring inside the clutch start mechanism has probably weakened by time , thus it cannot push the starting gear away from the starter ring in time.

Engine starts , wants to turn over but since the starter gear is still engaged it slams into it and creating awful noise and giving me mini heart-attacks.

Decided to tear it apart , put a harder spring in and clean it up.

Interesting stuff coming up later..

 

[itsid]

great;
culprit identified ..
"harder spring" hopefully means "new original spring"

'sid

 

[NewbCarter]

Now the bits that most of you (i hope) will find interesting.

Below are pictures of the EGT probe il be using , and its location is marked by the two blue dots .

Why an EGT sensor when there is no fuel injection or such electronics ?

#1 Is that an EGT gauge is a very helpful tool that i recommend everyone with a 2stroke to have .

#2 Monitoring the sparkplug is a very boring rince and repeat process , but is essential for tuning a 2stroke engine. An EGT gauge can give you a rough estimate of id the engine lean or rich and in what RPM range without the need to stop and check the plug . Doesnt mean you can only rely on the EGT , but its a good base to start tuning from.

3# Safety .. you see temps increase rapidly without control ( or the opposite if you are too lean ) , you can stop and find the issue... 95% you wouldnt pay attention without it .

 

[itsid]

hmm..
nah, I'm not convinced!

Sure, if the fuel/air ratio is far from ideal you'll certainly can tell by the exhaust temp right away
(assuming you have the experience to "KNOW" what temps you should have and reached in what timespan and so on)
but with the experience required for that, I'm fairly certain you can "hear" and "feel" the ratio being off too.

And if it's just slightly off.. I doubt you can tell if the temp rose to your ideal temp in 60secs or 70secs much less if the temp is slightly off...
I mean 100° increments? even with ten division scale that'd only be legible in the shop, surely not on the track.

Also: air/fuel ratio should be set per race anyways...
(barometric pressure, temperature, humidity; sometimes even the track...)

And now: exhaust length is tuned for specific tracks as well (as well as gearing)
which means your gauge will read slightly different temperatures with the exact same fuel ratio on the exact same day...

No, exhaust temp... an indicator at best, nothing usefull for the average karter IMHO
(either you can tell how far you're off by the gauge, in which case you can likely tell without as well... or you can't in which case it's pointless eye candy)

'sid

PS that and the fuel/air ratio gauge however provide a nice sensor-set for an arduino based logger.
(no need for the gauges really.. just the sensors )
if you add two tiny steppers you can adjust the ratio on the fly

 

[NewbCarter]

hmm..
nah, I'm not convinced!

Sure, if the fuel/air ratio is far from ideal you'll certainly can tell by the exhaust temp right away
(assuming you have the experience to "KNOW" what temps you should have and reached in what timespan and so on)
but with the experience required for that, I'm fairly certain you can "hear" and "feel" the ratio being off too.

And if it's just slightly off.. I doubt you can tell if the temp rose to your ideal temp in 60secs or 70secs much less if the temp is slightly off...
I mean 100° increments? even with ten division scale that'd only be legible in the shop, surely not on the track.

Also: air/fuel ratio should be set per race anyways...
(barometric pressure, temperature, humidity; sometimes even the track...)

And now: exhaust length is tuned for specific tracks as well (as well as gearing)
which means your gauge will read slightly different temperatures with the exact same fuel ratio on the exact same day...

No, exhaust temp... an indicator at best, nothing usefull for the average karter IMHO
(either you can tell how far you're off by the gauge, in which case you can likely tell without as well... or you can't in which case it's pointless eye candy)

'sid

PS that and the fuel/air ratio gauge however provide a nice sensor-set for an arduino based logger.
(no need for the gauges really.. just the sensors )
if you add two tiny steppers you can adjust the ratio on the fly

All true sid , but have to remember ... i think im generalising , but most members on this forum are riding karts for recreational purposes , thus the DIY tag .

If i was racing , of course a 2$ probe and 10$ gauge wouldnt be in my inventory . And , dont want to blow my own horn but , id say i have enough experience with 2strokes to know what to do and when to do it .

But as i said , if i was racing , i wouldnt be using a KT100 , and wouldnt be using 10$ gauges .

But , i must disagree on the point of it being only eye-candy . RPM gauge is handy because during the adrenaline rush , or just fun driving , its very easy to over-rev the yamaha . 14,500RPM is the do not exceed point , and EGTs are expected to hover from 700.C to 900.C .

Lower than 700.C is too rich , 900.C is the "top" limit . Again , that is generalising , but its enough space to work with , and extract the most from the engine without wrecking it .

And the camera shows the gauge as being hard to read , but it has good enough increments to be useful .

+ i think this looks cool already ... not to mention when its properly mounted .

 

[itsid]

You underestimate the Kt100
it's raceworthy within his period it might not have been the fastest,
but it was surely competetive enough to be really popular amongst racers..
You'll rarely ever find one recreational karter that's willing to pay 1000 bucks or more for an engine that needs full service every few hours of driving (8-12hrs schedule or so?)

I still disagree with you about how usefull the gauge really is.
200° is just as accurate as "all the way in and 2.5turns out"

But if you feel more confident WITH one, then that's perfectly alight of course.
it's the "everybody should have one" I'm concerned about since it makes one think:
"Oh.. if the temp is between x and y my engine is dialed in correctly"
which is far from being true

And "looks cool" is exactly the definition for eye-candy
A tach.. sure.. very useful!
especially if you want to limit yourself to less than 14.5k
(I've seen KT100 revving at 16k but maybe that's been different models [year, iteration...])

exhaust temp... meh.. I'd not even bother to drill a hole tbh...
head temp perhaps... *shrugs*.. nevermind

'sid

 

[NewbCarter]

Leaving the EGT topic for another time ...

Dremel chucks just arrived. 1,5€. .5mm to 3.2mm .

 

[NewbCarter]

Moar parts

 

[NewbCarter]

Aaand the carriers + disk carrier dont fit