Speedshop

We now have available 12 volt conversion kits for DTs 250/360/400 1974-79: The problem with these machines is that Yamaha altered the generators often and also issued several factory re-calls adding different parts to some meaning that you cannot be sure what is actually fitted. They even had dealers rewinding the charge coils at one point! Yamaha tried many different combinations which means that to ensure good results you have to replace the lighting coil for a dedicated 12 volt unit. Our kit replaces all the lighting coils Yamaha used - no matter which configuration you have (so long as someone hasn't fitted an DT1/2/3 or RT generator) with a standard 12 volt one ensuring the charging system works properly in all cases. Some more background information is available here: http://www.rexs-speedshop.com/WebRoot/Store2/Shops/es143131/MediaGallery/Rexs_DT12VC_conversion_Information_Page.pdf Link to News page: http://www.rexs-speedshop.com/epages/es143131.sf/en_GB/?ObjectPath=/Shops/es143131/Categories/%22News%20%26%20Special%20Offers%22

Same fly wheel. The EMCU, (electronic magneto control unit) looks at the output coming from the source coil and works out the timing according to the AC frequency. This unit is basically a CDi unit however as there is no separate 'fire' signal it must calculate the timing based on engine speed. This is a function that standard CDi units don't have. We can schedule and change the timing for many different applications and give it 2 or 4 stroke timing curves again this is not possible with standard CDi units. We call this system an "Electronic Magneto" as its self generating using a magnet passing a winding to make its power in the same way as a traditional points magneto, only there are no points instead, an electronic timing controller. Although I say you can't change a the curve of a stock CDi unit thats not strictly true. When we were developing our DT175 replacement Cdi unit we did play about a lot with it and could change it. However we took the decision to stick with the standard timing curve that Yamaha used. I hasten to add, its no good coming to us and asking for a CDi that goes better. If you say to us here is a timing curve I want with the RPM and timing advance data then we can produce it (if we have data we know works then we can use that). We are electronic engineers not engine tuners! With our XT500 kits we worked with several racers to get the Dual Power system so it out performs even the digital internal rotor kits. We did the maths and electronics the racers told us where the timing needed to be.

We were asked to do an electronic ignition and 12 volt conversion to a points model DT175. Its very simple, we took one of our Electronic Magneto Control Units from our RMK-3 kit, re tweaked the timing curve for the smaller revvy 175 engine. Then we threw away the points and condenser. A quick rewind of the points source coil so instead of supplying 75 volts at 1.5 amps for points it now supplies 300 volts for CDi and hey-presto! We rewound the lighting coil to give much better low rev output. EMCU: We don't intend offering this as kit unless there is very sustained demand for it. We did it just as an exercise and to prove it works. www.rexs-speedshop.com

You have the bike in front of you - we have keyboards - go discover!

We now have new CDi units for the later DT125/175MX models (G&H) available. These have just a brown wire from the generator and not brown and red to power the box. We are well aware that you can buy these on eBay for much less. However many customers have come to us asking if we made one as they eBay ones don't seem to work well, with mis firing or holding back being common complaints. The reason for this is very clear when you compare the Yamaha DT timing curve compared with the eBay units. If you go to our website and open up the CDi unit product, one of the pictures shows you the Yamaha timing compared to the cheapy unbranded box. The eBay box is actually a generic moped unit which by chance works on the DT. As you can see it retards back 5 degrees from base and holds back engine performance - which is what you want on a moped, the Yamaha curve gives 7 degrees advance on top of the base timing figure. http://www.rexs-speedshop.com/epages/es143131.sf/en_GB/?ObjectID=54644348&ViewAction=ViewProduct I'm sure they will be a few people say they have the cheap one and the bike runs fine. You are welcome to bring it to us and we will put it through its paces on our test bed and see where the timing is. I'd bet a pound every time the timing would be nothing like the proper Yamaha box. We even have a trial unit here that you could fit to your bike and compare the difference in performance. So far people have not be able to believe how much better the bike is with our unit. (Of course if you like the difference you have to buy it - its not a freeby!) We have a DT generator that we can run to over 10,000 off the bike in our workshops and check the timing on: WE DONOT MONITOR FORUMS FOR QUESTIONS. IF YOU HAVE SOMETHING TO ASK YOU MUST E-MAIL US DIRECT TO BE SURE OF AN ANSWER. Google Rex's Speed Shop or go to www.rexs-speedshop.com for contact information

I was asked to draw out a wiring loom for a XJ600 (1980's model). There are a couple of versions within one document, one with single pick-ups and one with dual. Its a free down load available from our web site. Scroll down to the Speed shop custom looms heading then click on the link. http://www.rexs-speedshop.com/epages/es143131.sf/en_GB/?ObjectPath=/Shops/es143131/Categories/Tech_Support

I'm working on our website and adding some new help sheets, more are on their way over the next few weeks. We get asked a lot about battery eliminators so I've added an introduction to them and explained how they work along with some FAQs: Link to the info sheet: https://drive.google.com/file/d/0B0BD_MkiU7JpVmZFT0xtdnhzOFU/view Link to tech support: http://www.rexs-speedshop.com/epages/es143131.sf/en_GB/?ObjectPath=/Shops/es143131/Categories/Tech_Support

I have a listing for the type with the screw adjuster - I'll see if they are still available.

Kate & I would like to wish you all a happy Christmas!

The cost of rewinding to that spec is going to be close to that figure - with no way of knowing how the thing will work. When you go adding more windings the first thing that happens is that it'll make more power at low RPM, but less at high (great if you want to ride very slowly at night). Also when its in the high RPM range it'll get VERY hot. Generators are rated to run at around 60- 90 degrees C, add too many windings and you'll easily get it to run at well over 150C - without the engine heat. Unless the bike you have has a de-rated generator, I'd doubt you'd be able to increase its output by 20%. Thats a hell of an ask on a small stator!

plasticote "project" paint is both petrol and brake fluid proof. Get it at B&Q

There are several different carb assemblies. Don't mix them. You can get repair kits for these carbs and a good ultra sonic clean normally restores them to full working order.

Well I'd go with the box mover then. Rather then the specialists who have actually worked on these bikes. The 7 is for the 600 engine.

well first thing is have you got deep pockets, bigger rims are going to cost £££££££££££££. The over size RIMS (and spokes) on my SR500 cost £400, and then I had to build them myself! And then the tyres didn't fit so new tyres were needed. The chain clearance is good at 13mm with the new tyre, but you will need to watch this and clearance with the swingarm. You can get plastic sidewall peices that clip in to the rims and you can't tell them from white walls. You'll find them offered for sale with Harley/chopper shite.

Had the pleasure to meet the new Yamaha SR400 today. We had a photo shoot for a UK bike mag who wanted to compare The New Yamaha SR400 2014 model with a 1980 SR500 at the Speed Shop. The new 400 is so tractable in traffic, the fuel injection runs sweet. But its an extreme complication to the single cylinder format in my humble opinion.. My observation was that although everyone loved the new SR400 and they complained about the 1980's SR500 brakes and how it felt like an old bike........the old 500 was the one that was ridden many more times then the new 2014 bike and came back with bigger smiles. Draw your own conclusions! This is Kate, the lady that makes most of the Speed Shop CDi units: And then me the fugly chap who does the design work: A testiment to Yamaha and a good made to last design, 1980 and 2014 models of the same machine. And before you ask, Kate can kick start the 400s and ride the edges off the tyres. She is a little light to kick over the high comp SR500 engines I build but I'm teaching her a technique how to do it because I want my XS650 back

DPR8EA9 is right for the 400. http://www.rexs-speedshop.com/epages/es143131.sf/en_GB/?ObjectPath=/Shops/es143131/Products/DPR8EIX-9

They are very light. You need to be compident at starting big a single as there is no electric starter

We have two kits, basic and full with all the bulbs etc that you'll need: http://www.rexs-speedshop.com/epages/es143131.sf/en_GB/?ObjectPath=/Shops/es143131/Products/12VC-4

If someone has a 250 they ae prepared to loan us, we will look at building new cdi units for these bikes. I'm just finishing off work on IT490 lighting kits and tweaking the CDis then we'll have space in our workshop for this project.

These switches are notoriously unreliable...... if WD40 and adjustment make it better but not 100%...change the switch

unlikely

Halfords own range used to be really good. I have some of their imperial thin wall sockets. I was trying to change a brake pack on a Boeing 737 Classic, there's a ring of bolts that hold these to the undercarriage. This particular one was seized solid. We put a six foot jack handle from the hangar jack on the end of solid handle and me a 20 stone colleage hung off the end of this, while a third guy kept his boot on the socket to keep it in place. It worked and the socket didn't break out. No one would offer their snap-on or Stahlwille sockets for such abuse!

Got a Haynes book of myths? They usually have pictures and diagrams to help with this.

Could do, but nine times out of ten this sort of problem is fuel related in my experience. We do get the odd coil that breaks down at high RPM but its rare these days.

OK either the exhaust ports are full of coke, the cables are worn out and need replacing or the battery doesn't have the power. I'd take the valve out and clean it then work back to the cables then battery. The Yamaha power valve is a good design (unlike the suzuki version of similar vintage) and is easily stripped and cleaned. It should rotate with light and even force. I've had to use slide hammers on Suzuki RGV engines to get the silly split valve out of the barrel.