The bike was a sales disaster in the UK, under powered vibrator which looked ok. It used the Belgarda frame and Paioli forks and many of the SZR's in the uk have been cannibalised for the frames and running gear for people who have put 500cc two stroke engines into them to make 500cc replica race machines, those machines not only look awesome they go like crazy round the tracks and some have put them on the road too. Will get some fork measurements at the weekend.
From reading I did, it's a modified TZR250 frame - that would make a fantastic basis for a race bike...
41mm USD forks I believe... Interesting concept... big single lungers were loved early on by the UK racing fanatics but mostly based around older engines... The Yamy was probably a bit stangled.
Some more info, the forks are made by Paoli Italy, The wheels are by Brembo Italy, Brakes are Brembo, rear shock marzocchi. The bike was built by Yamaha Italy Uses the Belgarda frame and swingarm as used on the TZR125 4DL. Lots of good quality running gear on the SZR so well worth getting hold of one just for the parts, if you can find one that is as they were only made for two or three years, The rest of the SZR parts can be sold off to spares hungry followers of the SZR. The frame and swingarm plus the body work off of the one I bought for spares went to guy who is building a track bike using a RD500 motor. I got half my money back on those parts alone.
After your other message I did do some research - seems they are extremely rare here which is a real shame as I'd love a pair of those wheels...
Handle bar arrangement has changed from the ace bar or clubman bars idea depending how old you are after a mock up. It just did not suite the bike. So i have a pair of SRAD 750 clip-ons on the way after being sent the wrong ones first time round. They have a one inch rise so maybe the perfect bars maybe. Meantime I now have matching wheels, I was going to take the rim tape off the front wheel but then found out it is lacquered over so had to fit the other SZR rear wheel. Fitted my original power RS tyres. Painted the chain guard gold to match the gold highlights on the forks and bottom yoke.
The conversion is now complete, The front mudguard fender will be painted black when the weather warms up here in England.
Went out for a test ride yesterday and it all works very well.The front brakes are fantastic and my only criticism is there is not enough lever travel for my liking which I will sort out. A few adjustments needed to re-route throttle cable as the revs rise a bit when the bars are turned full lock to the right, as well as the mudguard going black when the weather warms up the brake calipers will also be painted black.
Check the size of the master cylinder. If too large it will give a hard feel which you can remedy by going down in size by 1mm.
Thanks for the reply. Currently using a master cylinder from a Suzuki Bandit 650 which has 5/8 marking on it, do you know what should I be looking for ?
If the levers are aftermarket, or aftermarket OEM copies, sometimes they can be poorly made and not give adequate free play. You can correct this by filing down / sanding / grinding the nub that pushes the master cylinder piston in, until you achieve adequate free play. Otherwise, a quality set of aftermarket levers for the donor brake/clutch perches.
I got hold of black mudguard which looks a lot better now also done the calipers black. The front end looks so much better now. When it had the red it looked heavy and clunky at the front to me. Will post up a phot of the bike when I have finished fettling it.
Well the bike is now completed and back out terrorising the tarmac. While I was fettling the front end and getting it how I wanted it to be I had the cylinders honed and matched a pair of Wossner forged piston to them, the head was opened out and the squish area sorted to match the bores too and I put it back together. It is a good strong engine. Going back in the posts I was not to happy about the feel on the brake lever well I sorted that out by changing the pads, they had sbs pads in them so I changed them to Goldfren S33 compound pads and now the brakes are perfect with great feel and just the right amount of travel on the lever and they are far more powerful too. I use Goldfren S33 pads in my bikes since discovering how good they are and the bonus is they are loads cheaper than so called better brands. Here is a couple of before and after conversion photos of the finished bike.
There I was thinking I have finished the bike and in my biking utopia. Then this strange overpowering desire for more power happened, criteria is it has to remain reliable so no wild porting and somehow make the engine lighter. Thought about my options and done some research and came up with a TZR250 2XT top end and found a place in the UK that actually have 10 sets of 2XT top ends from very good ready to go with genuine pistons new rings, small end and pin and of course power valves to needing re-plating. The 2XT was only made for 6 to 8 moths and JDM only so very lucky to find the parts I need in the UK. Apart from being a plated bore rather than a cast sleeve they also have auxiliary exhaust ports. They are very expensive parts £1000 here in the UK for a ready to go set. The 2XT bike has a bigger intakes in the crank case but I am using 1kt my original engine which has smaller intake but with my already modified intake system it will work just fine. Will put up progress photos at the end of the month early October when I have the part and work has begun.
Been a bit slack with the updates. I have now fitted the 2xt top end after cleaning and painting the cylinders and cleaning the power valves. I have also fitted dual stage Boyesen reeds. The bike runs very well and has a heap load more power. I have ordered a new set of Martin Johnson track chambers and when they arrive and I fit them I can adjust the jetting for when it goes on the dyno for fine tuning and to make sure all is well with the tune. I will put up the dyno sheet when it is done. In standard trim these bikes make 45bhp at the crank according to the factory, the bike probably made more than that after the first round of tuning I done to it but never put it on the dyno to find out.
On the Dyno 44.5bhp at the back wheel and a good aggressive power delivery. The wonky fairing in the video has been fixed, one of the support brackets had slipped.
This is it the last I am doing to it honest , I have bought a pair of new Mikuni TMX30mm carbs, To my surprise the bottom and mid range have increased more than I thought they would and at the topend hits real hard but has the odd splutter at the top, so it is running safe for its trip to the Dyno to be set up and the all important power figures. With the 28mm carbs it was 44.5 bwhp so will be interesting to see what difference there will be. The Dyno is booked for the 1st of June is the earliest they could do it busy setting up race bikes and their own race bikes plus other street bike customers, worth the wait though.
1st of June came and off to the Dyno we went and it went not as expected.Rode the bike 23 miles to the dyno with no issue using only 1/4 throttle with the odd burst up to 8k, strapped it on the dyno and while it was warming up on idle it suddenly cut out no spark present and that turned out to be a fracture coil feed wire, try again and this time it started to run on one then the other would chime in now and again, bloody b'stard I thought, It was washing out on the right cylinder due to over fueling a lot. All that sorted out the best it would do was 43.9 bhp at the back wheel . Further investigation found that the airbox to carb rubbers which are the originals intended for the original 26mm carbs and worked perfectly fine on the 28mm carbs I had on there before were infact fluffing it all up by obscuring the back of the carb due to them being stretch and so deformed which caused the issue, also the slides were not fully opening an oversight on my part and requires the throttle tube stop be filed back a bit to give full lift. I now have some Samco type hose couplers 60mm to 51 mm to make some new airbox rubbers and sort the throttle lift and all should be back on track. It has been an eventful journey to this stage and I have learnt a lot more about tuning smokers and how b'stard expensive it is.It's worth it though. More updates to follow of the airbox rubber and throttle modifications to get the engine performing. Heres two pictures of it as it is now.