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About mtrehy

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    United Kingdom
  1. mtrehy

    Won't start

    One simple thing you may not have checked is removing fuel tank breather.
  2. mtrehy


  3. mtrehy


    It is not the same kit that Honda Europe sells and unlikely that it will be available off the shelf in the near future or perhaps ever. KTM have a purpose built 450 rally bike which is available to customers (for around $50K) but even that is significantly different to the bike that the factory riders are using (but enough for mere mortals). Suspension on the Honda is far from stock and the swingarm will almost certainly be lengthened and likely to have frame and steering geometry changes also. They wouldn't be used in Baja with this set-up as it's a totally different race - i.e you don't need the navigation kit, water tank or 250km+ without refueling. Possibly the frame, swing arm, suspension and motor might migrate eventually if it is successful at Dakar. Debut is in Morocco in a couple of weeks so will be good to see how it goes there. Shame it took so many years for Honda to do this really. More info and pics here: http://world.honda.com/news/2012/c121002Dakar-Rally-CRF450-Rally/index.html
  4. Hi, Anyone know who manufacturers a radiator guard for a 99 CR250R? I've tried the usual suspects and can't find anything. Failing that, has anyone had any luck modifying something or fabbing up their own. Thanks.
  5. mtrehy

    Horn, Light, Kill Switch

    Hi, Can anyone point me in the direction of a handlebar switch that can control: Headlight (high / low) Horn Kill Switch I have found a few that will do this but they all include turn signals which I don't need and I hate to have a redundant switch for no reason. Thanks.
  6. mtrehy

    Super-B Battery Relocation

    If you look at my post I haven't used the word foolish or choke point... I complimented him on his innovation and effort... You're clearly incapable of basic comprehension. He removed the stock battery and saved 1.5kg. That's all well and good and a worthwhile weight saving. What he did next I think is highly dubious and it's important that alternative views are expressed on here. He could have left the 0.5kg super b in the original battery location. Instead he has moved 0.5kg lower down. Now I would doubt very much whether he would notice that BUT even if he could he has then added 0.5m of battery cable and another expansion bottle. So likely at best he has a net difference of 100g between having the super b in the standard lbattery ocation over where he has put it. I have a flowbench and have spent considerable time very recently playing around with the 450 head on it. If you think that you will get noticeable improvements with the airbox modifications he has done over what can be achieved with the standard battery in location and opening up the box I want to see your test results and dyno graphs because it's not what i would expect and I would be grateful for your help. MANU - The Honda Europe FIM WCCRC / Dakar rally bikes use a Super B which is fixed to the right hand side of the engine - they run a rear subframe fuel tank so no space in the standard location. MIght be worth you looking at that - Henk Hellegers who builds them is located quite close to you and you might be able to get a bracket off him. You could then run the stock expansion tank and the modified airbox as you have it.
  7. mtrehy

    Super-B Battery Relocation

    It's your bike, your time and your money and I'm glad your happy. However you didn't remove 2.1kg and replace it with 0.5kg lower down. You moved 0.5kg lower down because you could have left the 0.5kg SuperB in the original battery location. Hence, 0.5kg up or 0.5kg down... You then added 0.5m of battery cable high up and then added a baby bottle higher up again... You can multiply the air intake area by 1 million it still won't make any difference to intake flow and performance unless that is the point of restriction. good luck with the wrenching, i'm off for another dump!
  8. mtrehy

    Super-B Battery Relocation

    Sorry. i admire your efforts but I'm a cynic (and a realist). This seems like a load of effort for nothing or arguably negative end result. You've saved some weight on the battery (probably the same amount as taking a big dump), but there's no way that you are feeling the handling difference of that 0.5kg battery mounted slightly lower than if you had installed it in the standard battery location (it's all in your head). You've removed the expansion tank (and the amount of coolant that the tank holds) and replaced it with 0.5kg of battery. What is the net difference...? Unless you relocated the starter relay etc you've added probably 0.5kg of battery cable to run from the battery to the starter relay. (the red cable in your pics?) Which would negate any perceived (psychological) improved handling improvement. As for the airbox if you went from stock to what you have now then yes there would be a performance improvement but very unlikely that what you have now is giving any noticeable improvement over a properly opened up airbox. So you have put in hours of work, located your battery in a dodgy location, removed the expansion tank and spent a fortune on an expensive battery when all you needed was an hour on the toilet or to lose a couple of pounds in the gym. I'm all for innovation and experimentation though so thumbs up on that. I'm pretty sure you can find better ways to get handling and performance gains though with less time required, less financial outlay and less chance of a problems when you hit a rock or overheat.
  9. Problem is that you need to run the bike under load and watch the meter at the same time - realistically the only way to do this on a bike is on a dyno. You could install a wide-band lambda sensor in your header pipe and with a lambda reader with some method of data logging and then some testing on the road might get you somewhere. Look at http://www.innovatem...om/products.php but it will cost loads and will be tricky. Setting up a single carb on a thumper is fairly straight forward though and there's probably someone on here with the same set-up who can get you close.... Failing that - an hour on the dyno and you'd be sorted.
  10. mtrehy

    New to the Scene

    I'm a short arse. Done properly. i.e internal spacers, revalve and correct springs and the bike will be transformed. I race mine fairly hard, very much "stood up", regularly take big jumps and bounce it off of rocks and the suspension is perfect, plush and responsive. If it's harsh and uncomfortable and you can't jump it then you went to the wrong suspension place. Lowered and carrying 30 litres of fuel: Try a lower seat first, the durelle gel seat takes off about an inch and a half. For what I use the bike for it's perfect as the bike is very heavy and occasionally need to hold it up with my legs if I go too slow at the top of a dune climb. Only need to drop the bike a few times when it weighs 140kg+ and the temps are 110 and things get hard very quick. I don't lower my mx bikes.
  11. mtrehy

    Valve retainers diff?

    components will have been designed to be as light as possible while still having the required strength. The bevel is to reduce weight and eliminate areas of stress build up and will be the result of FEA stress analysis by the honda engine design team. Not all relevant to your question but: inlet retainers fit inside a bucket, exhausts do not (not related to the bevel). stem diameters are different - 5.5 inlet, 5 exhaust. make sure cotters and retainers don't get mixed up as they are different. when disassembling, put each set of valve train components (valve, spring, spring seat, retainer, cotters etc) in a seperate bag with a piece of paper "left exhaust", "right inlet" etc.
  12. mtrehy

    Hel Stainless steel Braided brake lines

    I used HEL on a couple of bikes. Good quality, good service. At one time they would provide you free hoses if they didn't list your bike. All you had to do was send your hoses so they could make a pattern. They returned both sets. That's how I got my first set... Unfortunately the last set I bought they sent me the wrong rear hose and ignored all my requests (phone and email) to send the correct one. I won't buy from them again. Shame it came to that.
  13. mtrehy

    2006 450X Cylinder Head

    I would imagine that shops are more competent and prices more competitive in the US than where I am (middle east), but make sure you compare the cost of the work with the cost of simply buying a new head. New heads are surprisingly cheap (less than $300). Also check the guides and the condition of the rest of the head. I would give you something $ for the damaged head also.
  14. it's already explained above mate. required spring rate is based on the force produced by the accelerating valve and components. force=mass x acceleration. mass is the "weight' of related components, acceleration is produced by RPM and cam profile. There are several possible scenarios as to why the same spring is used in 2 different applications and how the forces produced remain the same and i've listed a few of them in the order of likeliness. 1. the applications rev range is different thus reducing acceleration 2. cam profiles are different thus reducing acceleration 3. installed height of the springs are different in each application 4. mass of the related components are different in each application 5. honda built the crf with springs that are unnecessarily stiff because they had a warehouse full of them and wanted to save money 6. honda built the trx with springs that are unnecessarily soft because they had a warehouse full of them and wanted to save money To say that the same valve spring is optimal for the exact same application for 2 vastly different valve masses shows a lack of understanding of basic engine design and operation. That's not to say that the application won't function as you need it to but there is no way it can be optimal for both. i'm surprised that your 'renowned' race shop is looking for functional and not optimal. Not sure why i bothered to explain that though as you will take it with a grain of salt anyway.
  15. Valve float occurs when the force created by the accelerated mass of the bucket, shim, valve, cotters, retainer, spring etc is greater than the force of the valve spring. Acceleration is a result of engine rpm and cam profile. We know the standard setup is good to over 10K so to have problems at 5K would need accelerated mass more than double standard. Density of stainless steel 7480 - 8000kg/m3 Density of Titanium 4500kg/m3 Obviously there will be a safety margin and you wouldn't expect the valves to float immediately on reaching the rev limiter. You can calculate safe RPM based on valve train component geometry and mass. If you have all the cam data, measurements, geometry and spring rates there are lot's of software packages that will simulate it accurately enough. I don't know much about atv's but my guess would be that the retard chariots aren't revved as high as the bikes so they get away with using the same valve spring with the heavier valve (just an assumption though - not gospel). Safest to buy springs that are rated and proven to work with the stainless inlet valves and there are no shortage of options.