My 91 CR125 Street Supermoto Bike Build, on going..

TrevSkee · Two Stroke Sniffer Joined: 29 Sep 2009 Karma :

Well well, new here fella's & woman.. Wink

Thought i shall show off what i got because its trapped in my back garden & i keep poking it with new parts once in a while Neutral

Well bought this a non runner for £400 Thumbs Down

mid feb this year, needing new piston n ring & a power valve cover, i wish that was all that it needed doing but always turns out to be a mega on going money grabbing £ucking project! Surprised

haha so i knew i was going to build something super with it as i do with everything i buy.. its personalization!

I rebuilt the topend myself (was easy as playing with lego) i sourced a topend with recent recon & bought new small end bearing, piston & ring & full gasket set, fitted all that & it started & runned fairly well for first time. Then the project began...

little clip of it then i got it going.. exhaust didnt fit header properly & rear pipe needed repacking why it sounds pop'ish, i sold the rear pipe & bought a 93 one
https://www.youtube.com/watch?v=9PL763QJBX0

As the pixs go from old (muddy) to how it is now (with both supermoto wheels on) i've spent abit over £1100 including buying it.. not bad huh?? Neutral

ballbag · Two Stroke Sniffer Joined: 12 Apr 2008 Karma :

Looks good, really good. Old school.

I doubt very much that the CR500 front pipe will do you any good tho. The shape and size of 2 stroke exhausts (front pipe) makes a massive difference to their performance, and their CC, porting etc makes a difference to what kind of size/shape pipe you want.

Basically I would imagine if you put a CR500 front pipe on your 125cc engine it would run like a bag of shite. Get an FMF 125 power pipe for your bike and it'll rip.

Now get a video up of you pulling a wheelie! Very Happy

Progression · Two Stroke Sniffer Joined: 27 Sep 2009 Karma :

Looks really good. You did a decent job of the transformation. Still reckon it would look better now if it was muddy Laughing

Prog

Gazdaman · I did a trackday!!! Joined: 12 Aug 2004 Karma :

Lovely bike, powdercoat that frame white and you're onto a winner.

Gaz

ms51ves3 · Super Spammer Joined: 07 Jun 2007 Karma :

Nice project, but as has been said, leave the CR500 expansion chamber for a CR500.

TrevSkee · Two Stroke Sniffer Joined: 29 Sep 2009 Karma :

Arrr think i'l be leaving the cr500 exhaust then, i only wanted it for how it looks fitted on the bike, what about a 250 one?? Laughing

Now the engine is bugger & bike nearly stripped i might aswell do the frame as i was guna leave that last. I now need to rebuild the bottom end aswell as the top skim head new piston & ring etc, its turnt into a full rebuild now, i would like to take on the rebuild myself as i done the topend just to get it running, but i dont know if i need new crankshaft? or to fit the bigend bearing myself?

If i did fit the new bigend bearing & rod, could i take it to a bike shop to get balanced etc then bring it back & fit it myself?

Gazdaman · I did a trackday!!! Joined: 12 Aug 2004 Karma :

Just whip the crank out, take it to a bike shop and ask them to swap the big end and con-rod over because it'll need a press.

Then take the crank back home and put it all back together. Simples.

And with regards to different exhausts, a 2 stroke works by using pressure waves to keep the mixture in the cylinder. So the exhaust (for best power) is very closely matched to the engine.

Use an exhaust meant for a different capacity and/or different bike/design/borexstroke and it'll run like shit.

You'll lose power and fuel economy.

So just stick with the correct exhaust, or an aftermarket one designed for your bike.

Gaz

Fnatic · World Chat Champion Joined: 11 May 2008 Karma :

As far as I am aware the expansion chamber on a 2 stroke exhaust use some very complex mathematics. I tried understanding it all once and failed.

TrevSkee · Two Stroke Sniffer Joined: 29 Sep 2009 Karma :

Gazdaman · I did a trackday!!! Joined: 12 Aug 2004 Karma :

Read a book called 2 stroke tuning, by Graham File.

I managed almost 3 pages before wanting to kill myself and everyone around me.

Gaz

smegballs · World Chat Champion Joined: 28 Oct 2007 Karma :

Ever read the four stroke tuning one.....

Its even worse. Rolling Eyes

Basically he says "dont think about it unless you have a full gas flow rig to work with"....

Now who wants to hear that...

TrevSkee · Two Stroke Sniffer Joined: 29 Sep 2009 Karma :

Well well sorry no updates if anyone is interested! Laughing

Money flow at this time of year & xmas comming up makes it shy, but still collecting parts i need to rebuild the engine & tools to take it apart properly only last tool i need is a bearing extractor then i can buy the rest of the parts i need, piston, rod & full gasket set etc

Last bit i bought for it was 2-3 weeks ago & was a gear lever, a nice red tip rfx hardware one for £15.00 Rolling Eyes

A mate of mine has a bike nut mate who i was guna borrow 4 stroke book havnt heard anything back yet & the 2 stroke one i saw one on ebay but forgot to bid on it Brick Wall

i only want to experience the head fcuk headache of it..
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My 1991 CR125 Street Supermoto Spec'd Project Build

STOP clicking that link ^ and wait for me to do a UPDATED post.. Wink

stevo as b4 · World Chat Champion Joined: 17 Jul 2003 Karma :

What is it about the 250cc and 500cc expansion chambers that looks better exactly? Apart from being a longer fatter snake than the 125's, i can't see what looks different/better about them?

TBH all the std black double skinned pipes, with nasty looking brackets and heat sheilds added with great big gobs of japanese at it's best welding, looks pants IMO!

A nice rolled cone style aftermarket pipe either clear coated or nickleplated is far more sexy!

TrevSkee · Two Stroke Sniffer Joined: 29 Sep 2009 Karma :

"personally" to me they look better, how they are to 125 or 250 ones, like for exp.. i bought £220 levers just because i liked them more than these other £40 set they do the same thing but mine look better to me Wink

That idea is well truly binned anyway just when i can find one & can afford it at the time it will be within my part collection
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My 1991 CR125 Street Supermoto Spec'd Project Build

STOP clicking that link ^ and wait for me to do a UPDATED post.. Wink

chris-red · Have you considered a TDM? Joined: 21 Sep 2005 Karma :

ballbag · Two Stroke Sniffer Joined: 12 Apr 2008 Karma :

TrevSkee · Two Stroke Sniffer Joined: 29 Sep 2009 Karma :

chris-red · Have you considered a TDM? Joined: 21 Sep 2005 Karma :

You really need to paint the frame, take everything off of it and get it powder coated it will be worth it. Thumbs Up

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MugenSeiki · Could Be A Chat Bot Joined: 13 Oct 2008 Karma :

Gazdaman · I did a trackday!!! Joined: 12 Aug 2004 Karma :