TDR 150cc A work in progress

[125cc mad]

So after replying to the post "TDR150 Pitbikes, what are your thoughts ?" and singing the praise of such a cheap new bike which I had only owned for 2 months and ridden 4 times all I can do is sit back in my chair and laugh at my post and review :/

Fast forward to today... Now it's an every 2nd day rider and I'm more used to the bike, so far the OE rear shock has blown out and been replaced.
After reading numerous threads on tuning Mikuni carbs and 140 / 150cc engines I since found out that the factory unit is a crappy 22mm one running a 95 main and a 15 pilot jets which explains the low down hesitation and then the mid to top end crackling and back firing on and off the throttle so I rang the guys at DHZ explained my woes and as of tomorrow I will be sporting a nice new 30mm Mikuni all jetted and prepped for the bike so in the mean time I have been port matching the inlet manifold to the the gaskets, Adjusted the tappets .003 inlet and .004 for exhaust, and cleaned up the ugly restrictive welds in the exhaust pipe header.
Bring on tomorrow hopefully it will be a totally different bike to ride.

All in all this is a huge thanks to everyone who posts here with technical info and general feed back.

 

[motorman]

30mm is pretty bloody huge carb for a 150.

Hope it works out for you.

A 26mm OKO would have been perfect.

 

[my67xr]

I would have just fitted a #20 pilot jet to the Mikuni 22/26 to solve the hesitation and leave it at that.

Or as motorman said, the OKO 26 and Uni Filter is a sweet carby on the 150 Lifan's, i had that set up on my Atomik Fuse 150, the front wheel was regularly in the air.

 

[125cc mad]

Hhhhmmm... I really quizzed the guy at DHZ and he assured me the 30mm is the right one, I hope he isn't just selling " bigger means better".
I told him I was more into trail riding not super cross lol.
I might get a #20 pilot just to be sure if the 30mm doesn't work out.

 

[my67xr]

The 30mm will have a #20 pilot jet in it already, so you could alway's just use that one in the 22/26 carby
You will also need to get some foam filter oil to oil the air filter too

Something like this
Castrol Foam Air Filter Oil - 3g - Supercheap Auto Australia

 

[125cc mad]

Cheers my67xr.. I ran an oiled filter on the 22/26 carby and the guys tell me it comes with a filter, manifold and accelerator cable so all going well I should be set there.
I guess at the very least when the need for speed gets to me I will have a decent sized carby to mount on a TB head.. but the forks need to be sorted out first
On the forks note I was looking to try the 20cent coin trick to help stiffen them up but there is a rod that runs down the center of the spring, any ideas or is it just a waste of time ?

 

[my67xr]

I haven't head of the 20c coin trick, but i did add some 1/2 thick spacer's to my fork's and some heavier oil on my Orion pit bike.
It really improved the feel, slightly stiffer and not as bouncy.
The oil that i drained out of them was like black cooking oil.

If you undo the cap off the top of the fork you'll find it has a rod screwed into it with a lock nut up against the cap.
Loosen the lock nut and unscrew the rod from the cap, take the nut off the rod and slide a spacer down over the rod (there should be a nylon spring locator sitting in the spring too) compress the spring and refit the lock nut
Then screw the rod back into the top cap till the thread bottom's out and do up the lock nut
Now it's ready to fit back into the top of the fork

 

[125cc mad]

Yeah I saw an old You Tube video where a guy had an early model pit pro except he used cut down pvc piping.

So today the new Mikuni 30mm went on the bike and I have to say so far straight out of the box the bike feels totally different a lot easier to start cold, very responsive off the throttle pulls right through the mid range and smooth at full song.
I have one question though, is it a good thing the bike started from dead cold with no choke off ? As that's what happened and it seemed to idle fine.

 

[my67xr]

You should only need the choke when it's below about 10° C
Do a plug chop now when you get a chance to see if the main jet is the correct size.
Run the bike at wot for 15 - 20 second's, switch it off (still hold the throttle wide open), pull in the clutch and bring the bike to a stop.
Carefully remove the spark plug and look at the colour of the insulation near the tip.
You want it to be a tan/coffee colour, if the insulator is black or dark then the main jetting is too rich.
If the insulator is white then the main jetting is too small.

Your Mikuni 22 with a #20 pilot jet would have also started a lot easier, and feel pretty much the same as the 30mm, but would be more responsive down low.