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Honda updates for 2011

The last 5 years of Classictrial being involved with updating and improving Honda trials machines, have underlined the fact that while the stock bikes are ideally suited for use in easier club level events, they are somewhat lacking when being used in more serious competition.


At the moment it seems that cosmetic alterations to the TLR are far more popular than anything likely to improve function/performance, but this is perhaps understandable as while parts to alter the appearance of the TLR are easily available, there is very little that is likely to help with making the bikes work appreciably better!


We have found that modifications to the rather restrictive intake and exhaust systems, and replacing the stock CDI unit, means very noticeably improved engine performance. Changes to the steering geometry and footrest position, in combination with modern type rear suspension units provide greatly improved handling.


However in common with converting an old British road bike into a “P65” trials machine, getting a TLR to work reasonably well in more serious competition is something that can cost a substantial amount of money. This is something that obviously does need to be considered by anyone looking for a competitive machine, as something like a 200 Fantic in standard form,  is far more capable than a stock TLR.

Classictrial modified TLR200

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ClassicTrial picture, Classictrial modified TLR200, click to enlarge, click pop-up to close.

*Finally please remember that all of the above information is provided on the strict proviso that any modifications or changes not carried out specifically by Classictrial, are not guaranteed or warranted in any way, and are entirely the responsibility of the individual carrying them out, and that Classictrial are not responsible in any circumstances for  damage or injury, that may occur as a result of poor workmanship*

The evo TLR pictured here and owned by Barry Higgs in Somerset, is a machine which in development terms is probably about as far as you can take the TLR........while still keeping the cost of the build to a realistic level. Unfortunately to take things much further than this requires a great deal more money spending, and the final result may well not be all that is hoped for!


This update outlines all the alterations and modifications that have been carried out on Barry's bike, and while some of what's covered here can already be found elsewhere on the site, some of the content is entirely new. Everything on this page also relates directly to the stock TLR, and the original Honda parts we have used such as ATC200X top ends and ignition are easily available from Ebay.


For 2011  we will be concentrating on development of a modern day TS chassis to accept Fantic running gear. While we will still be offering tanks, carb kits, and frame upgrades for the TLR, Classictrial will not be involved with carrying out any future development work related to the Honda, so this will be our final update page concerning this area.  

Barry Higgs

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ClassicTrial picture, Barry Higgs, click to enlarge, click pop-up to close.

Chassis:

The stock Honda TLR frame is relatively light, and certainly strong enough for use in serious competition (especially so if modern suspension parts have been fitted!). However the steering angle and footrest position are not ideal for competition use, as stock steering tends to be rather vague, and the footrests must be relocated to work with modified steering geometry.


Geometry of the 200 and 250 TLR frames differs in that the steering angle of the bigger capacity bikes is slightly steeper, and alterations required are not the same for both bikes. The amount of trail used on these bikes appears to be very important, so you will need to make sure anyone carrying out modifications is aware of this, and able to provide accurate advice on the effects of any work they are going to do.


On the 250 changes to the steering angle and moving the  footrest position forward, should ideally be carried out in combination with extending the stock swinging arm slightly, as this is something that puts a little more weight on the front wheel and improves handling in difficult conditions. Longer swinging arms are not required on the 200, as the motors are far more predictable than the 250, and looping out due to a very light front end is a lot less likely!


Recently produced chassis kits for the TLR made with high specification chrom-moly tubing are very marginally lighter than the stock mild steel frames, and are very nicely made. Steering and handling on TS trials machines fitted with chrom-moly frames with the correct steering and suspension geometry, is likely to be slightly more positive than a properly modified OE frame.

Prototype tank-seat unit

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ClassicTrial picture, Prototype tank-seat unit, click to enlarge, click pop-up to close.

Smaller and much more compact modern type fuel tanks, designed to fit the top tube very closely, tend to make the TLR feel a lot more modern and  less bulky. Most TLR's today are likely to be fitted with   road/trail style tanks, which are rather bulky and cumbersome in comparison to our entirely new design.


We have produced a prototype of our new design using a kevlar/carbon pre-preg cover. This very much improves the rather dated appearance of the TLR, but more importantly means the bike feels a lot less old fashioned, and works better. We will be making a few production versions of these, but these will have only very limited availability.


Motor:

The 200cc TLR motor is standard form is very reliable, and certainly acceptable for use in easier events. However performance is compromised by very restrictive induction and exhaust system parts (which is also the case on the 250cc bikes). We have found that large volume straight through exhaust systems, with slightly longer front pipes work very well in combination with 24mm flat slide carbs.


Compression ratio on the stock motors can be increased, and this provides more torque and adds a little extra top end power. However increases in compression require more ignition advance, and the stock crank triggered system cannot provide this. We find the ATC200X head mounted ignition trigger works very well indeed, and provides a proper linear advance curve. The ATC200X type ignition can also be accurately fine tuned, and improves running very noticeably over the stock TLR set up.

ATC200X top end

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ClassicTrial picture, ATC200X top end, click to enlarge, click pop-up to close.

Wiseco XR200 pistons can be used in the TLR200 motors, and these provide increased compression, as well as a range of over sizes, meaning that re-boring is possible. We would not recommend large over-bores on any of the Honda trials motors, as this means the cylinder liners are going to be very thin, and problems with seizure/distortion may well result in some cases.


The intake port shape of the TLR motors is not greatly suited to trials applications, and careful reshaping of the port to increase gas speed at lower engine speeds is something that works very well, especially on the 250cc motors. Putting a 30 degree back cut on the inlet valve is also worth doing, and improves flow a little. We have also fitted smaller intake valve seats to the TLR heads, and this works well in combination with the other changes outlined here.


Problems with clutches on the TLR are very common, and as the clutch isn't much different from the one used on the CB125, from which the TLR 200 and 250 were derived, this is perhaps to be expected! Modified steel plates which allow additional oil to find its way between the plates, appear to reduce heat building up in the clutch, which means problems such as clutch judder are far less likely. Overly long and flexible clutch lighteners can also cause problems, as these reduce plate separation, which can also lead to overheating.


The widely spaced gear ratios used on the 200 are not a problem on bikes with modified motors, which can comfortably use 1st, 2nd, and 3rd gears in the sections. Gear box sprocket size should be 9T on the 200 and 10T on 250, with either a 42T or 44T rear sprocket according to personal preference and local conditions. Gear levers with folding tips are not ideal for the TLR, and the solid forged alloy type as used on the RTL are preferable. TY250 Mono OE alloy gear levers can be modified to fit, and are almost as good as the RTL type.

ATC200 ignition trigger

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ClassicTrial picture, ATC200 ignition trigger, click to enlarge, click pop-up to close.

Conclusion:

All in all the TLR 200 or 250 in standard form is a machine which is ideal for riders taking part in club level events, who want a reasonably capable and extremely reliable 4T bike. However the bikes can be improved notably with recourse to the alterations outlined here, and this means they are much better suited to more serious competition. It is though worth bearing in mind that the in depth modifications described here, can be quite costly, and its worth remembering this if you are on a strict budget.  


Of course in finality choice of machine is certainly very much a matter of personal preference, but hopefully consideration of the content of this page will assist anyone interested in the TLR Honda's, and provide a source of accurate advice on upgrades and improvements that actually work in competition, rather than just changing the appearance!

Competition back box

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ClassicTrial picture, Chinese 5 pin CDI unit showing connection detail, click to enlarge, click pop-up to close.