Jump to content

Tlm 50 Big Bore Kit

john b

Recommended Posts



Thanks for that !

Yeah I've seen Peter Gaunt riding his at some trials - and it certainly is capable ! (as he is as a rider !)

We have tried the TLM before strip down - Its being prepped for my sons Christmas present (he's 12) and it works well - just need to rev and splat to get the front end up - but seems a great little bike - a great step uf from his Whitehawk 80

cheers - and think I'll invest in the 60cc kit


  • Like 1
Link to comment
Share on other sites

  • 2 weeks later...

Hello, the tlm 50 engine and the mt5 mb5 motors are not the same.To be fair to andy m there are a lot of internal parts that are interchangeable. Tlm motors are the next gen motor along similar to mbx 50,(brit market) mtx 50 s.h ( german market). Someone does a 70 kit. vsmotoparts.com. Not sure about exhaust port angle? ive done a fair bit to mine, 100cc.Stock gearing and pulls third up hills,( with a bit of run up:)great little bike. Always puts a smile on my face. Hope this is some help.

Link to comment
Share on other sites


Hi, i am also trying to upsize my tlm50, But can confirm that the mt50 big bore kit from pattern parts DOES not fit , I bought one and tried . What is my next move , any suggestions please ??

Link to comment
Share on other sites


Hi John, that would be really helpfull to me so will wait for your response, thank you. I am looking also to the kx65 piston solution which has been mentioned on these forums in the past , but dont know to what extent the piston needs to be modified , can anybody perhaps help .?.

Link to comment
Share on other sites

  • 3 weeks later...

Latest update

No joy from company in Holland (vsmotoparts) - spoke to them and they just said to have a look on the website for something I thought would fit ??

I have a friend who lives in Japan ( search on youtube and loads of videos of TLM50's trialling in japan !) who is investigating out there.....



Link to comment
Share on other sites

  • 2 months later...
  • 3 years later...
  • 4 years later...
  • 11 months later...

for future reference:

honda mt/mb and first model mtx cylinders, heads and crankshafts do not fit. The clutch and gearbox does but the gear ratio's are off so they are not useful.

the 50cc engines/engine parts that do fit:

  • MBX50 air cooled AC03,
  • MTX50 2nd model air cooled AD09
  • MBX50 water cooled AC04
  • MTX50R water cooled AD06
  • NSR50 water cooled AC08
  • CRM50 liquid cooled

you can also fit 80cc engines:

  • MBX80 liquid cooled HC04
  • MTX80r liquid cooled HD08
  • MTX80R2 liquid cooled HD09
  • NSR75 liquid cooled DC03
  • NS-1 75 liquid cooled
  • CRM 75 liquid cooled
  • CRM 80 liquid cooled.

for the 50cc engines above there are several 63/65cc (marketed as 70cc) big bore kits available, both taiwanese/chinese and better quality like Malossi.

for the 80cc engines above there are several kits available from 80 up to 100cc (often marketed as 110cc) from for example Athena and Gilardoni. Gilardoni also makes a 44 stroke crankshaft to be used with their big bore kit.


The standard TLM 50 engine can be converted to watercooled by installing the clutchcover with built in waterpump, from any one of the watercooled models mentioned above. Then it is just a matter of swapping the aircooled cilinder and head for those of a watercooled version.Do pay attention to the fact there are 2 diameters of kickstarter axles used, so make sure to get the right one.

VHM makes a CNC head for the watercooled 50cc and 80 cc models, so you can use custom inserts and have them made to your own specifications.

When installing any other cilinder than the stock one on the TLM50 be aware that there is a huge variation of port durations between all different cilinders. They range from 1.4kw @ 5000 rpm up to 5.8kw@ 10.000 rpm depending on model and country it was made for so most won't be suitable for any trial work because the torque is either lower than TLM 50 spec, or at a way to high rpm.

The easiest way to get way more torque and power than the stock TLM50 is to get a used 80cc watercooled engine, use a german GE3G cylinder (this has the lowest port timing), 18mm manifold and a genuine HM183 18mm carburettor (not a chinese copy). take out the gearbox, and install your TLM50 gearbox instead.


Edited by snailspeed
Link to comment
Share on other sites


Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...