Thumper Club Forum

Technical => Bike Problems/Questions => Topic started by: turpitz764 on April 22, 2008, 02:26:49 PM

Title: jawa 500
Post by: turpitz764 on April 22, 2008, 02:26:49 PM

does anyone remember Jawa making a 500cc single in the 80s...think it had a rotax engine in it...wondeirng if anyone here owns one or knows anything about them...ive been looking on e bay for them but havent seen one yet. Im starting to wonder if it was all some crazy dream i had! Also am fed up with poeple advertising SRX400s for sale as some sort of begginers bike just because of its 33 bhp.  I own several bikes and I love the SRX and would never part with it. 

Title: Re: jawa 500
Post by: Steve H on April 22, 2008, 02:34:28 PM

This one ?
(http://www.thumperclub.com/photos/2005/annualrally2005_33.jpg)

The owner is Ian Bridges, this is a picture from the Annual Rally in 2005

Title: Re: jawa 500
Post by: guest146 on April 22, 2008, 05:42:14 PM

Also the speedway engine

Ken

Title: Re: jawa 500
Post by: SteveC#222 on April 22, 2008, 06:10:23 PM

I know the basic rotax engine came in various degrees of tune. Now don't quote me on this, but I seem to remember a rotax engined chop in Back street Heroes who had a got a useful increase in power from fitting the 'motocross' cam .   However I suspect it may not be quite that simple....... :-\

Title: Re: jawa 500
Post by: bullet350 on April 22, 2008, 08:11:26 PM

a friend of mine has an armstrong rotax 500, he's put a flat-track cam in it (probably the same as mx).

it goes like the clappers, but means that the engine will eat itself if the timing belt breaks. with a normal cam i think it has enough clearance.

bullet350

Title: Re: jawa 500
Post by: turpitz764 on April 22, 2008, 11:19:04 PM

thanks ...especially for the pic steve.  That is the one the 500R. 

Title: Re: jawa 500
Post by: 002 on April 23, 2008, 10:52:04 PM

There were 2 versions.....a MK1 and a MK2 sort of thing.Different bodywork,that sort of thing.
Put together by the importers,Skoda UK,just for our market I believe.Not too succesful,needed a few things sorted out.

Mind dont forget the several models that MZ produced using the Aircooled 500 Rotax.They were quite nicely done.
I had the 500 Saxon Tour very good little bike.
The engine did really show its off-road ancestry,but still a very neat package.

Jethro

Title: Re: jawa 500
Post by: guest27 on May 04, 2008, 03:08:40 PM

Hi THere
I had a Jawa 500R for a time - the engine is waiting to go in a yamaha frame and the frame etc went to Eastern Germany.

The MK1 had a TLS front brake that did not - was a scary thing.  MK2 had a disk as I remember.  The oil tank was the 2-stroke oil tank modded to take a return, thus the oil capacity was really low.  Have seen one modded to look like a Manx (ish).  I made a glassfibre centre tank for mine which upped the oil capacity but never seemed to seal properl;y - I still have it somewhere.

The 500 lump in the 500R was the lowest spec engine Rotax made - has a 2mm shorter stroke than the norm to lower compression and a really soft cam.  Tuning the babies is real easy - for a few horses, then harder the more you want.

The head is a Heron head so it should (should is a good word) be impossible to get the valves to hit the piston - or so I am told.

Some parts are expensive but others are common.

I have the Jawa engine book thing here - shows the parts but not how to mend it - parts list would be the word.

Basic 350 Jawa with a soft thumper lump.

R