a)its difficult to replace the stock one with a better one as the carburetor mounting is different from all the other types available in the country, most of the carbs available here in India ore of spigot or flange mount types but the ones in the kb /sx etc are clamp on types, if you are able to get one ,go for it, also you have to take into consideration the amount of space available as the carburetor is fully enclosed by the carb cover.

B)it is impossible to put reed valves on the kb simply because there is no space available to mount one ,besides rotary valves are considered slightly better compared to reed valves in terms of performance ,but much more complex in design and maintenance

PS: in Europe the kh 125s used to come with a vm22 carburetor if you can get one of those it think your job will be done

Hi KB100. Really appreciate your reply!

a) Will continue the search for the carb. Any specifics as to what the KB type carb is called? Is it CM / Spaco ? Looking at your earlier which has the KB manual on Picasa, it looks like any other 2 stroke carb.

b) Rotary valves - (I realized after posting my query, this was a dumb question on my part as KB has rotary valves). But the crux of the question remains..any better options than the stock valve?

c) Sprocketing - Stock setup of KB is 42T/13T (3.2307). Looking for a stronger acceleration using 45T/13 (3.38). This is still under the 10% range recommended for sprocketing, but will I end-up with with my engine racing (revving-up).

Re: Kawasaki kb100 RTZ rebuild

Hi Friends

Thank you for this thread - awesome advice, workshop manual, and stories.

I am Yash, live in Bangalore.

Have a 1995 KB100 RTZ bought in Vizag and saw me through college in Pune, several jobs in Pune & Bangalore and has been parked since past 7 years now.
Have amazing memories attached with my RTZ - Pune college days, trips to Mahabaleshwar, Sihangad fort, various dams around.
Was my daily driver upto 2005, when I bought a beat-up Alto and stopped commuting on the RTZ totally.

Do kickstart it once in a while, but since the past 2 years its been standing put gathering dust in the basement parking.
Everyone - friends, family - have needlessly advised me sell off this "piece of junk". But the thought never occured to me

Anyhow, 3 weeks ago, one of those rare weekends when I suddenly feel like giving my car some TLC (wash, wax, interiors), on impulse washed the RTZ too.
And got this sudden enthu to do him up right upto NEW condition.

Now, I am not sure how far I will get, but am sure going to try.
And since the few mechanics I spoke to don't even recognize RTZ name, I guess will do work myself.
So, here is where things stand.

1. Engine: Runs, high idling 4000 rpm. Block is oily, so leaking. Engine sound isn't neat, there's a lot of clatter.
2. Electricals: are shot though headlamp and one indicator works.
3. Instrument cluster: Speedo & RPM meter work. Lights and fuel gauge don't.
4. Suspension: Front forks are an oily mess, so they are likely shot. Rear shocks, I don't know. Likely gone, 18 years old.
5. Tyres: front looks ok. Rear needs replacement. Rear tyre wobbles too.

What I've done in last 2 weekends:
1. Changed the plug. Couldn't find NGK B7 ES. The shop owner gave me Bosch F002 G40 265 with 8mm gap. Is this ok?
2. The RTZ roared to life on the 5th kick, after more than 2 years. Idling at 4000 rpm. Too high !!
3. While opening the fuel tank, the jammed lock broke. Force opened it.
4. While turning the jammed fuel tap lock, broke the fuel tap assy.
5. Removed tank, cleaned it as best as I could to remove some rust (vinegar + Baking soda mix) & the broken lock pieces.

Purchased: Minda wiring kit. (existing wiring is in a mess), Tank lock, Fuel tap & the Bosch plug.

I know the engine requires work and possibly transmission/gearbox too. But dont know how to proceed.
Mechanics say - saar bike de do, ready karke dega - even though they hardly recognize it.

I need guidance on how should I proceed.
I'd like to get the engine to run and sound like new, then transmission -> brakes -> electricals -> suspension -> tyres -> looks.

Will get spares before starting work - but which ones are required, from where, how do I know if something needs replacement etc etc.
What next?

Regards

Re: Kawasaki kb100 RTZ rebuild

before you start the tear-down , get all the parts required, the bare minimum required is , engine gasket kit, o-ring kit, and oil seal kit, if the compression is too low you will need a re-bore that will amount to the next oversize piston , if your connecting rod is worn out and has developed play then you will have to at-least go for a new con-rod ,then you will have to replace the bearings , just remove the old ones note down the no and get them from the local skf or nrb dealer works out cheaper and better, then there is the cosmetic bits, chroming ,plating buffing etc ,new tires , since you are in blr parts are gonna be expensive if you buy it from the shops , if you buy them from the good Samaritans here of from facebook whow will be triying to "help fellow 2 stroke enthusiasts" it will be expensive x 2 or its higher multiples.

Please , whatever you do do not open up the bike without having the bare min of parts in hand, and for god sake dont dump the bike at some mechs place and after
6 months start moaning about getting ripped off, have patience get the parts first , find a mech you can trust, (if such a thing exists) and then start the build.

you can down load the workshop manual posted by psr sir and the parts cataloge from a few pages back this will help you with gettint the parts and the rebuild

Re: Kawasaki kb100 RTZ rebuild

Re: Kawasaki kb100 RTZ rebuild

for the rear shocks go for the sns units from discover cheap and best also a direct fit

front shocks im assuming the fork inner tubes , go for caliber ones with springs its a direct fit

as for the oil pump , forget the oil pump

bearings have to be bought individually

Re: Kawasaki kb100 RTZ rebuild

Hi Mates,

here i am going to post some updates on my kb 100 restoration.

Re: Kawasaki kb100 RTZ rebuild

The KB 100 comes with Mikuni VM 19 SC Side Draft Carburetor and not 18..
The Rotary Disc Valve is the next best thing to Fi in fuel inlet timing in to engine.....It maintains the fuel injection timing precisely as per design, IRRESPECTIVE of RPM , throttle, or Load.... In my KB 100 with 1,30,000 Kms the Rotary Valve is still Good...There is no need to change it unless it is damaged by the Mech.
@ KB 100 the VM 22 is for the KH 125, and fitting it on KB 100 will lead to loss in Low to mid power, and mess up Carb tuning...it will be very difficult to set it right since ,Venturi Velocity will drop and it is not a CV carb., to moderate our setting up mistakes.

Re: Kawasaki kb100 RTZ rebuild

Hi Yash,
I too live in Bangalore and have a KB100 RTZ that has been gathering dust over the past couple of years. I am not so knowledgable in working on bikes and don't want to risk anything. However, in the past mechanics in Bangalore have been rip-offs (at least the ones I have come across) who want to experiment on the bike. They don't know what's wrong but just want us to leave the bike with them.

Also sourcing parts in Bangalore is a difficult affair. I have never been able to source a single part here. I have some spares for my bike which have been sourced from my previous trips to places like Coimbatore and Trichy (at retail prices and not at a premium). 2 stroke bikes still live well in Tamil Nadu.

Well even I am interested in bringing my bike back to life. It would be a good idea to put an effort together than alone.

Re: Kawasaki kb100 RTZ rebuild

Pardon my ignorance, PSR sir, If the rotary disc valve system is so effective then why was it not as widely used as the reed valve system? Is it because of the complexity and expensive manufacturing?

Re: Kawasaki kb100 RTZ rebuild

No need to say pardon or being ignorant...all of us start that way and learn...I am still learning...
Yes you are right about the complexity and the cost.....Large scale Manufacturing is all about cost cutting...
Not just in India but in foreign countries too the Rotary Valve dismantling and fitting with correct timing is a headache for the Mechs., and many had done the work in a wrong way...so it is less popular ...

Re: Kawasaki kb100 RTZ rebuild

Thank you. That clarifies some things. No wonder I have never seen a properly running kb here. I am pretty sure the mechs screwed up timing and tuning thus kbs here always felt uninspiring.

Sent from my GT-I9001 using xBhp Connect mobile app

Re: Kawasaki kb100 RTZ rebuild

Hi All

Have convinced a Bajaj parts dealer & a Bajaj Serv Center to try to place orders for KB100 parts.
I am not optimistic, but still going to try.

They need the part# though.
Can anyone confirm whether I got these part# correct: (basing these off a KTZ100 pdf file parts catalouge)

1. Cylinder Head - 30-1010-22
2. Cylinder Engine - 30-1013-27
3. Piston - 30-1013-75
4. Piston Ring Set - 30-1013-67
5. Rotary Disc Valve - 30-10-1148
6. Crankshaft - 30-10-1031
7. Oil pump - 30-12-1007

If this option doesn't work out, what other options can I explore?

Regards

Re: Kawasaki kb100 RTZ rebuild

Hi all,

here i am going to post the final stages o fmy kb100 restoration.

Re: Kawasaki kb100 RTZ rebuild

Cool. Sooper cool.