ERM Speedway bike.

[firko]

This is the Swedish ERM Jawa conversion Jonesy picked up in a package with the SRM elsewhere in this forum. The ERM was the very first 4V Jawa conversion, coming out prior to the Street conversion in 1974. The collection just keeps getting better.
                                                                                         
                                                                                       
                                                                                       

[steve234]

How's the tube valve coming out of the tyre, sweet idea!

[jimg1au]

when the trye spins the tube valve ripps out my long tracker is the same old school tyre spins tube spins no flat tyre

[Purple Dave]

Of course, only works on LEFT hand corners ( speedway )......disaster on RIGHT hand corners ( short circuit/dirt track )....

[Dutch]

Firko, I hope you don't mind but the story behind the ERM is slightly different than most people think.
The ERM started live as the JJM  (Jan Johanssen Motor)   It was Jan Johannsen that designed this DOHC 4V conversion in 1973.
Christer Lofqvist used the ERM (in fact a JJM) in the 1974 world final.
But even this JJM engine was not the very first jawa engine with a 4 valve conversion.
In 1972 there where 2 project at the same time, there was the VOS Special in the Netherlands, this was a Jawa with a new OHV 4V head, and in Germany there
was the engine from Willy Roth.
This was DOHC 4V head for a Jawa, camdrive was by a toothed belt, and 3 sparkplugs in the gead.

[firko]

Thanks Dutch, I've passed on your welcome info to Alan. The Swedes were really on top of their game back then, they've always been good innovators in motocross and speedway. We Aussies love the idea that the Street conversion was the first but deep down we always knew there were others. I think Neil Street publicised and marketed his conversion much more successfully than the other engineers.

[Tim754]

Got some of those side tubes and tyres (probably rotting/ rotted) in my wheel shed.
 Does it run Mark?

[Rosco86]

Made an error one night and put one of the steel valve caps with the wings to take the valve out on my jawa with the side exit via the tyre. Spun the back wheel over to fire it up, with the mikuni choke on she started to pop nicely. Grabbed the throttle and pushed the choke off only to find something drippy down the arm. She had ripped a lovely chunk out of the forearm. Hard to explain nowadays if someone asks about the scar. Easier to explain the scar where I have had the lower disc fused in the back. Son just says dad has one of those special arse cracks that goes to his shoulders.

[firko]

Apparently the ERM and the SRM are both in ready to go condition Tim. Al reckons he'd like to take 'em to HBBB next year.

[Tim754]

Yep I be there,  hope the Firko can be too!

[firko]

Yep I be there,  hope the Firko can be too! Smiley

Me too, I hope to have some interesting dirt track tackle to take out for a skid or two.