Are TL125’s worth the effort ?

Nice bike, but crap for trials ? This article looks at the issues about getting your TL125 ready for trials…or not

Are Honda TL125’s worth the effort ?

A couple of recent ebay listings in the UK show that there are potentially some stunning returns for completing a full Honda TL125 restoration, with road kit and and the original components. However, is it really worth the effort of making a TL125 that is to be used in trials. A standard TL125 is basically useless in trials and by the time you’ve finished getting the bike in sorted state, you’ve got little of the original bike left. With the money you’ve spent you could have bought a “proper” twinshock trials bike (like an SWM…)

The main issue I have is I really enjoy riding my TL125 at a trial, but I don’t ever expect to win and it needs to a classic trial on the easiest route. If you are good rider (and I’m not) then you can get good results at this type of trial, but you are not going to be competitive. If you like four stroke Honda’s, and you want to be competitive in twinshock trials, then flash the cash and go get a TLR250. You could get a TL200, TL250, TLR200, a Seeley or an RS200 (or something else exotic) and you would get an easier ride alround.

The problem is that the TL125’s are potentially a cheap place to start with four stroke trials. A good bike for a trials project will cost £200-400 on ebay, depeding on what useful bits it has on it. My issue is, that by the time you finish getting the bike ready, you may have very little of the original bike left and you’ve spent the same amount of money you would have spent on that TLR200 or Seeley. Unlike the these bikes, if you sell the TL125, rather than appreciating in value you are unlikely to get your money back.

So, for a quick run over the bike for my opinion (and there are plenty of others on the interweb) on what to check for, what to bin and what you may be able to live with.

Starting with the engine

tl125-engine-annotated-small.jpg

1. Top end. The earlier “K” models (1973-5) were not so common in the UK as they seem to be have been in the US. They had a single piece cylinder head whilst the later (1976-on) “S” model it is in 2 parts and like all small Honda 4-strokes have the problem of the camshaft running directly in the head. This wears (especially on badly lubricated engines) and requires engineering to fix, something that may only be possible on the two part heads. One of the main parts you now cannot find listed are “S” model cams, though some “K” ones seem to be available via David Silver and others. That said, you should still go for an “S” model engine if you can.

2. The reason for that is in part because it comes with the 124cc barrel. The boring out and stroking of TL125’s is a subject much discussed and is something you need a 124 barrel for. The stock 124cc or 122cc bike suffers a lot from the awesome 4bhp performance but more significantly from the ‘idle-cough’ response when you open the throttle in a section. Increasing the capacity removes the latter and improves the former issue.

The standard liner can be bored to 150cc, though this does result in something with the thickness of a pastry cutter. Disaster stories abound of crack liners, but been ok for me. Sammy Miller will provide the piston and bore out as a kit, but there are also people who will drop in a new thicker liner and a modified CB750 piston. You may get to 165cc this way, more if you want to stroke the bike also.

3. The gearing on the bike is set up for trials, with a low 1,2 and 3rd gear and a higher 4th and 5th gear. Other gear clusters (from CG’s, XL’s and SL’s) are not so good and are infact laid out differently. The TL also has a heavier crank, which is also very good. It means whilst there are lots of engine spares for this type of Honda, its good to keep with the TL components where possible.

TL125 Frame

Onto the other bike parts.

A. Exhaust. The stock exhaust on the TL depends on the model, but needs to be changed to improve perfomance and basically to get it out of the way. There is a (not cheap) Sammy Miller pipe which looks the part and does also improve performance. There are some alternatives and I’ve also seen plenty of self-built exhaust systems which sound good, but may not help where needed, ie providing power.

B. Airbox. The airbox takes up a lot of space and I’ve removed it to use a K&N clip on filter. This was in part due to a change of carburettor (see below).

C. Controls. I’ve swapped to Renthal bars and Domino levers and throttles on the bike and also ensured that the cables are new. The stock clutch is not really up for one-finger operation though there are some articles on lengthening the clutch arm etc. My thinking is that for trials where you can ride the TL, you shouldn’t really need to use the clutch anyway, but can see the reasoning on improving it from stock.

D. Front Forks. Probably the real weak spot on the stock bike as they really are not up to the job. They bottom out easily and the rake is all wrong. To improve the turning characteristics, you can drop the forks in the yokes so that there is 10-15mm of fork leg showing out of the top. This does prevent some of the dropping into turns, but this is also affected by the rear shock height and performance (see below). I’ve put an extra 50mm spring in each fork leg as a spacer in an attempt to beef up the damping and to stop it crashing down off drop-offs. Its still not perfect and getting a set of forks from a TY250R or later Honda or SWM maybe the best bet as you may also get a better brake drum also.

E. Carburettor. The original Mikuni carb on my TL was worn. I managed to avoid the cheap/nasty new Chinese copies and got hold of half a Honda CB360 set from Ebley Honda, though the choke is on the wrong side. This bolts directly onto barrel and the jetting seems to be spot on for the TL and has made an improvement with pick-up. There other carbs, like the later CG pumper carbs, but they really bend the rules in some respects (for AHMRA for example)

F. Frame. The stock frame on the TL125 is a pressed steel that isn’t up to trials, heavy, wrong geometry and not exactly very strong. There are some Sammy Miller Hiboy frames that appear on ebay and elsewhere. They are expensive (last seen for £350), but potentially can add significant value to the bike.

G. Rear Shocks. The rear shock lengths on the Honda are longer than normal, at over 14.2″. My TL125 has a couple of plates welded on top of the rear of the swingarm, allowing for the fitment of new aftermarket shocks. These seem to be available in lengths from 13.4-14″ as standard. I’ve put some NJB Clubman shocks on the bike as a good value, but working shocks, but you’ve plenty of choice including Betor’s, Falcon’s or Rockshocks, though the later will cost over £150.00 for a set. The NJB Clubman shocks are a very reasonable £55 and are up to the performance of the TL.

Other thoughts:
– loose weight, TL125’s are best suited to riders in the sub-65kg category. Bigger riders will always strugge to wrestle a good ride from a TL. Skinny blokes (and ladies) and under-18’s will be fine.
– brakes; they don’t seem to be any worse than other drumbrakes on twinshocks but they do lack stopping power in more challenging situations
– tank: is metal and dents. Mine has a couple of ding’s from knees and rocks, but nothing that doesn’t add to its glamour. Not sure about fibreglass or plastic alternatives, or whether there is a single seat-and-tank-unit. The original seat is a little bulky

On the whole, its a great bike to ride but only if the trial isn’t too hard. If want a Honda (and have the cash) get one of the later, more trials centric models. If not, maybe get an SWM, Bultaco, Montesa for similar money.

Some links
TL125 Home Page

Mark Worsfold’s TL125 projects

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