Jawa moped tuning

Hey guys!

I would like to share something interesting with you.

Long time ago back in the early 70s in Czechslovakia there was this prototype of 50ccm motorcycle called Jawa Mistral.

This bike was supposed to get into the production in 1975, but that never happened. It was a quiet interesting bike, it had an engine modern 4 speed transmission and with electronic ignition system and 60W for lights. The engine was able to do 4,5hp at 6000RPM it had a bing 17 carb on it with number 85 main jet and number 35 pilot jet, yet its MPG was 235 miles / gallon.

Long story short the interesting part is that this engine had the same piston , the same rod and the same stroke/bore as the Jawa 207 and 210 mopeds.

Later on when they started to produce the Jawa 210 they have used the connecting rod and the piston from this engine as well as the cylinder insert,

But they degraded the power of it and changed the timing and the sizes of the ports.

Lately i was lucky enough and i have found the factory documentations and the timing angles of the cylinder, I used those angles to set up a port map i would like to share with you. With this map you could get some extra power at good mpg, Nothing drastical for racing, but it could make your moped more enjoyable.

Sadly currently i have no stock Jawa 210, so i cant try it myself, i am building my 80cc Jawa 210, you can follow my project here: http://www.bikepics.com/jawa/21080cc/14/pics.asp

if you have any questions please feel free to ask.

good luck

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Re: Jawa moped tuning

Downhill Harvey (OFMC) /

LOL, I like how you used the whole lawn mower fan shroud, to get the pull start. Nice ducting too,

pic of fan? (edited)

Re: Jawa moped tuning

haha, the shroud was the thing i needed to have in first place because of the cylinder i use, i took some pics, sorry for the quality

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Re: Jawa moped tuning

Downhill Harvey (OFMC) /

Re: Jawa moped tuning

Jonathan Eaton /

the rumors are true, 2015 year of the jawa

Re: Jawa moped tuning

I hope it is :)

Re: Jawa moped tuning

this is beautiful...

Re: Jawa moped tuning

Is that the Jikov 17mm off of a Jawa Mustang? I've been considering that as an upgrade from my Dellorto 15.15.

Re: Jawa moped tuning

Yes that carb if of a mustang, its not a bad carb but you cant get jets for it, you have to make them yourself, or some of the people have made adjustable ones , see the pic

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Re: Jawa moped tuning

Re: Jawa moped tuning

Wow! That's pretty slick! I'll have to find one to tinker with.

BTW, is that a Motobecane cylinder? I always thought those would be a close fit for a Jawa case.

Re: Jawa moped tuning

Thanks, the cylinder is actually from a czechslovak jawa made garden machine http://fichtljenco.rajce.idnes.cz/ZVL_Diamon_PA_80_generalka/

Re: Jawa moped tuning

Downhill Harvey (OFMC) /

Does your airbox quiet it down a lot?

Bitch'in computer desk,

Re: Jawa moped tuning

Yes it does, that was exactly the reason why i biult it, it keeps the performance and the ped is quieter this way, later on i have found a nicer factory made airbox from a garden machine with foam insert, thats what i will use on my 210/80 project

that desk is sadly not mine, i was planned to build something from this

but it ended up in my workshop, now i can fix jawas on it :D

Re: Jawa moped tuning

I love that the AP 80 engine uses the same ignition as Jawa!

It looks like you have mated the 210 gearbox to the Diamon cases?

Re: Jawa moped tuning

Yes i have cut the piece that holds the starter with the shroud off the PA 80 engine and got it welded up on the 210, i have also made a 207 one before, the right side part of the PA 80 engine fits togetber with the left side of the 207 engine that was an interesting engine too,

[email]http://p1.bikepics.com/2012/11/18/bikepics-2480756-full.jpg[/email]

Re: Jawa moped tuning

Oh, wow! Are those AP 80s hard to come by? I'm currently running a modified 210 cylinder on a 207 engine. I'm in the mid 40s (mph) right now.

Re: Jawa moped tuning

my 207/80 could go 44mph,

the reason why it couldnt go faster was that the cylinder is from a garden machine, so its characteristics are the following: high torque at low rpm and not too much RPM,,, i ported the cylinder but its limited by the construction of it, because its an one piece cast iron cylinder so i could not modify the scavenging ports.

so i got 10 000RPM out of it, but its torque its still int the middle range,

so practically i was using it with 12/35 gearing, and it ran 44mph at 10 000RPM, but when i changed the gearing to 12/31 the moped no longer could rev up to 10 000RPM because it had no enough torque in the high RPM range, so basically it was faster with easier gearing.

Thats why i am building a two speed 210 now, so i can split the RPM and use its torque to go faster,

Re: Jawa moped tuning

I am sorry I missed your question, the PA80 cylinder is not too common, but you can find here in Slovakia, And its really nice if you can get about 40-45mph from a 210 cylinder on a single speed engine!

maybe my video can tell you more about the torque the 80cc cylinder has, on the video its only doing 40mph, later on i was able to rev it more to get 44out of it, and at this time my RPM meter was a little over 10000RPM, but it was really quick

Re: Jawa moped tuning

I think the biggest improvement on mine was the addition of an expansion exhaust. It really did a lot to produce power at higher rpm. It did cost me some low-end, though. The pipe, I'm using is a Techno Bullet for Tomos. I had to enlarge my exhaust port, move the exhaust studs, and bend the pipe slightly.

Re: Jawa moped tuning

oh yeah, i am not too good on the exhaust field.. and i also want my moped to look like its not modified, i want its appearance to stay as close to stock as possible, because in my country our police does not tolerate modified vehicles...

Re: Jawa moped tuning

Ah, my mistake, it's the Techno Boss Anyway, I bought it because it's cheap, but it's also the most stock looking of the performance pipes.

Expansion chambers have a pretty dramatic effect on performance over a particular RPM range depending on the pipe. My Boss kicks in fairly high, so it's reasonably good for top-end.

Re: Jawa moped tuning

Jonathan Eaton Wrote:

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> the rumors are true, 2015 year of the jawa

Jawa teaser number 2

Different strokes for different folks.

Re: Jawa moped tuning

Wow! Nice! What crank is that?

Re: Jawa moped tuning

Eugen Németh Wrote:

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> Wow! Nice! What crank is that?

Puch

Re: Jawa moped tuning

what kind of? does it fit there or is it modified? could you tell me more about it?

Re: Jawa moped tuning

Puch one speed.

Modded. Not that complicated though, just cutting down the crank and shimming.

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i have one of those cranks, i will check that, its a nice idea if you can make the clutch to fit, what ignition will you use? and are you going to use a tuning cylinder kit for e50?

Re: Jawa moped tuning

i have seen something similar, but that bike was made by jawa, it was a late prototype made by jawa, (see the attachment)

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Re: Jawa moped tuning

I has lots of plans for this. I am doing one for pinball and one for MopedGP. One 40mm stroke, one 43mm. Clutch is gunna be special, Ignition is simple.

After I finish the motor I will write up some more info on it. Also, Year of the jawa is real.

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