mathew

Thought I would add this to the mix. An RK "U" ring chain fits fine on my montesa (and I would suspect any other trials) and a DID "T"ring chain should too. Having come from offroad bikes with o-ring chains that last forever while being dealt way more power on a heavier bike, it just killed me to put a non-oring chain on and have to mess with cleaning and oiling it and still wearing out in no time. The U and T ring chains are newer "narrow" versions of o-rings and are just barely wider than a standard chain, and both claim to have a decrease in friction vs standard o-ring. Sounded perfect to me so I tried it. I went with the RK since they used a standard clip on master link instead of DID using a rivet style. Have had it on my montesa for 2 years without ANY adjustment or lube of any kind. It is effectively maintenance free in trials use from what I can see.

Also make sure the fan is working. If the motor gets too hot, it goes into some kind of limp mode where it will idle fine but not allow much load. Mine acted like a fouled plug and/or running out of gas when this happened, apply power and it would miss/cough/sputter. It would run fine when first started and right up to when it got too hot. New fan and all was fixed.

I have an '05 that I bought used - and I fouled a plug within minutes. As mentioned above - make sure to let these bikes warm up WITHOUT applying any quick blips of throttle. While not as bad as my plug eating WR400F was, the programming is apparently ragged edge rich and when cold the plug is easily fouled. I think sometimes EFI is confused with perfect optimized combustion - not so. EFI is programmed for various conditions and Honda has obviously programmed this to feel responsive and never caugh or hesitate - but to get there means plenty rich. The WR was exactly the same way with an accelerator pump carb - if the throttle was whacked open a couple of times while the bike was still cold it was all over. The somewhat natural reaction if a bike starts missing when cold is to start blipping the throttle - but when its setup (either via EFI or an accel pump) to provide an extra rich mixture when blipped this ends up making things worse. Instead, let it idle or apply gradual steady load to get warmed up. I also switched to the optional hotter "5" heat range plug and have ran it for the past year without issue. Even on hot days I've not heard a bit of knocking so I think the 6 that comes stock is a bit conservative on the cold side and adds to the issue. Mathew

Here is an interesting note/comment regarding the injection system. I had the fan motor lock up on mine about a month ago. Was out trail riding just cruising along and all of a sudden you could not apply much power without the bike cutting out and feeling like it was running out of gas. Light loads were fine and it would idle. Hadn't noticed the fan at that time. Next morning fired it up and ran great .... until it fully warmed up at which point the cutting out came back. Then I noticed the fan not working. New fan, fixed problem - runs like normal. Moral of the story - at some level of coolant temp the ECU must prevent heavy loads from being applied to prevent a major overheat? This is apparently at a conservative temp because no coolant boiled out and I never heard any pinging or knocking (running just premium pump gas). The nice thing was it still ran good enough limp back to camp, just not fast. Brings me to a question - has anyone ever had coolant boil out of a 4rt? Still really enjoying this bike. Mathew

If you are fouling plugs - switch to the CR5EH-9 (or equivilent). Also (probably more important) make sure to let the bike warm up without without blipping the throttle constantly. Cold plug + large doses of fuel = fouled plug. I run a 5 and it still seems on the ragged edge of fouling when cold. Plugs need to be at a proper temp to self clean the large shots of fuel that are needed to give the instant response that the 4rt has.

I just had to make one for my '98 TXT. I had a puller for Honda's which was as you mentioned LH thread, while the gasgas was RH. M27 x 1.0 RH. Apparently (according to Jon from the GasGas website tech section) all of the kukosan ignitions have 27 x 1.0 RH thread, whereas most all japanese bike flywheels have a 27 x 1.0 LH. Anyway - I like projects for my lathe so I just made one with RH thread. My lathe doesn't have metric threading, but since 1.0 mm pitch is 25.4 thds per inch, I just used a 26 thd/inch setting and it worked fine. Hope that helps Mathew